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Trapali A, Muppal M, Pandey S, Boillot ML, Repain V, Dappe YJ, Dayen JF, Rivière E, Guillot R, Arrio MA, Otero E, Bellec A, Mallah T. Investigation of the spin crossover behaviour of a sublimable Fe(II)-qsal complex: from the bulk to a submonolayer on graphene/SiO 2. Dalton Trans 2024; 53:12519-12526. [PMID: 39012501 DOI: 10.1039/d4dt01417k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
We synthesized a sublimable molecular spin crossover Fe(II) complex based on the Schiff base tridentate ligand qsal-NEt2 (5-diethylamino-2-((quinolin-8-ylimino)methyl)phenol). The compound undergoes a transition in temperature with thermally induced excited spin state-trapping (TIESST) for high-temperature sweep rates, which can be suppressed by reducing the sweep rate. The X-ray absorption spectroscopy (XAS) studies on the microcrystalline powder confirm the TIESST effect. The molecules are deposited under ultra-high vacuum on a graphene/SiO2 substrate as a submonolayer. Investigation of the submonolayer by XAS reveals the molecular integrity and shows a spin crossover for the whole temperature range from 350 to 4 K, with residual HS species at low temperature and no TIESST effect. DFT calculations suggest a distribution of energetically similar adsorption configurations on graphene, i.e., with smooth crossover behaviour and the absence of TIESST, consistent with very weak intermolecular interactions and the absence of large molecular islands within the submonolayer.
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Affiliation(s)
- Adelais Trapali
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay 12 Cedex, France.
| | - Mukil Muppal
- Université Paris Cit é, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013, Paris, France
| | - Satakshi Pandey
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg, 67034, France
| | - Marie-Laure Boillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay 12 Cedex, France.
| | - Vincent Repain
- Université Paris Cit é, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013, Paris, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, Cedex, France
| | - Jean-François Dayen
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504, 23 rue du Loess, Strasbourg, 67034, France
| | - Eric Rivière
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay 12 Cedex, France.
| | - Régis Guillot
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay 12 Cedex, France.
| | - Marie-Anne Arrio
- Institutde Mineŕalogie, dePhysiquedes Mateŕiauxetde Cosmochimie, CNRS, Université Pierreet Marie Curie, UMR 7590, Paris, France
| | - Edwige Otero
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
| | - Amandine Bellec
- Université Paris Cit é, CNRS, Laboratoire Matériaux et Phénomènes Quantiques, F-75013, Paris, France
| | - Talal Mallah
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay, CNRS, UMR 8182, 91405 Orsay 12 Cedex, France.
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Ferraz Lobato L, Ciattini S, Gallo A, Allão Cassaro RA, Sorace L, Poneti G. Thermodynamics of spin crossover in a bis(terpyridine) cobalt(II) complex featuring a thioether functionality. Dalton Trans 2024; 53:9933-9941. [PMID: 38808660 DOI: 10.1039/d4dt00574k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
In this contribution, a terpyridine-based ligand bearing a thioether functionality is used to prepare a new cobalt(II) spin crossover complex: [Co(TerpyPhSMe)2](PF6)2 (1), where TerpyPhSMe is 4'-(4-methylthiophenyl)-2,2':6',2''-terpyridine. Its structure, determined by single crystal X-ray diffraction, reveals a mer coordination of the tridentate terpyridine ligands, leading to a tetragonally compressed octahedron. Intermolecular interactions in the crystal lattice freeze the complex in the high spin state in the solid state at all temperatures, as indicated by magnetometry and Electron Paramagnetic Resonance (EPR) spectra. When dissolved in acetonitrile, however, temperature dependent electronic, 1H-NMR and EPR spectra highlight an entropy-driven spin crossover transition, whose thermodynamics parameters have been determined. This is the first report of a cobalt(II) SCO complex featuring a thioether group, allowing its implementation in chemically grown bistable monolayers and may open important perspectives for the use of such systems in molecular spintronics.
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Affiliation(s)
- Lúcio Ferraz Lobato
- Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-909, Brazil
| | - Samuele Ciattini
- Interdepartmental Center for Crystallography (CRIST), University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Angelo Gallo
- Department of Chemistry, University of Turin, Via Pietro Giuria 7, 10125 Torino, Italy
| | - Rafael A Allão Cassaro
- Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-909, Brazil
| | - Lorenzo Sorace
- Department of Chemistry "U. Schiff" and INSTM Research Unit, University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-909, Brazil
- Dipartimento di Scienze Ecologiche e Biologiche, Università degli Studi della Tuscia, Largo dell'Università, 01100, Viterbo, Italy.
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3
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Jornet-Mollá V, Rodríguez-Tarrazó MI, Dolz-Lozano MJ, Giménez-Saiz C, Romero FM. Hydrogen-bonded assemblies of iron(II) spin crossover complexes. Dalton Trans 2024; 53:7848-7856. [PMID: 38625687 DOI: 10.1039/d4dt00579a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
The paper reports on the synthesis, crystal structure, thermal and magnetic properties of spin crossover (SCO) salts containing the [Fe(bpp)2]2+ cation (bpp = 2,6-bis(pyrazol-3-yl)pyridine) and different rigid polycarboxylate anions, such as anthracene-9,10-dicarboxylate (ADC), benzene-1,3,5-tricarboxylate (BTC) and biphenyl-4,4'-dicarboxylate (BPDC). Compound [Fe(bpp)2](ADC)·9H2O (1) shows a porous hydrogen-bonded structure with water molecules sitting in the channels. It contains low-spin (LS) Fe2+ cations that undergo crossover to the high-spin (HS) state upon dehydration. Anhydrous 1 remains HS on cooling at low temperatures. A similar magnetic behaviour is obtained for the partially protonated BTC salt [Fe(bpp)2](HBTC)·5H2O (2), showing a spin change concomitant with dehydration to a HS phase that undergoes gradual and partial SCO on cooling, affecting 25% of the Fe2+ cations. Instead, the BPDC salt [Fe(bpp)2](BPDC)·5H2O (3) has a ground HS state in its fully hydrated form.
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Affiliation(s)
- Verónica Jornet-Mollá
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Marina I Rodríguez-Tarrazó
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Miquel J Dolz-Lozano
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Carlos Giménez-Saiz
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Francisco M Romero
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
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Kelly CT, Jordan R, Felton S, Müller‐Bunz H, Morgan GG. Spontaneous Chiral Resolution of a Mn III Spin-Crossover Complex with High Temperature 80 K Hysteresis. Chemistry 2023; 29:e202300275. [PMID: 37037023 PMCID: PMC10946779 DOI: 10.1002/chem.202300275] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 04/12/2023]
Abstract
Non-centrosymmetric spin-switchable systems are of interest for their prospective applications as magnetically active non-linear optical materials and in multiferroic devices. Chiral resolution of simple spin-crossover chelate complexes into the Δ and Λ forms offers a facile route to homochiral magnetic switches, which could be easily enantiomerically enriched. Here, we report the spontaneous resolution of a new hysteretic spin-crossover complex, [MnIII (sal2 323)]SCN ⋅ EtOH (1), into Δ and Λ forms, without the use of chiral reagents, where sal2 323 is a Schiff base resulting from condensation of 1,2-bis(3-aminopropylamino)ethane with 2-hydroxybenzaldehyde. The enantiopurity of the Δ and Λ isomers was confirmed by single crystal X-ray diffraction and circular dichroism. Quantum chemistry calculations were used to investigate the electronic structure. The opening of a wide 80 K thermal hysteresis window at high temperature highlights the potential for good magneto-optical function at ambient temperature for materials of this type.
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Affiliation(s)
- Conor T. Kelly
- School of ChemistryUniversity College DublinBelfield, Dublin 4Ireland
| | - Ross Jordan
- Centre for Quantum Materials and TechnologiesSchool of Mathematics and PhysicsQueen's University BelfastBelfastBT7 1NNUK
| | - Solveig Felton
- Centre for Quantum Materials and TechnologiesSchool of Mathematics and PhysicsQueen's University BelfastBelfastBT7 1NNUK
| | - Helge Müller‐Bunz
- School of ChemistryUniversity College DublinBelfield, Dublin 4Ireland
| | - Grace G. Morgan
- School of ChemistryUniversity College DublinBelfield, Dublin 4Ireland
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5
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Moledo Vicente Guedes A, Sodré de Abreu L, Maldonado IAV, Fernandes WS, Cardozo TM, A Allão Cassaro R, Scarpellini M, Poneti G. Valence tautomerism in a cobalt-dioxolene complex containing an imidazolic ancillary ligand. RSC Adv 2023; 13:20050-20057. [PMID: 37409047 PMCID: PMC10318486 DOI: 10.1039/d3ra03235c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023] Open
Abstract
This work reports the synthesis, structural, spectroscopic and magnetic investigation of two complexes, [Co(bmimapy)(3,5-DTBCat)]PF6·H2O (1) and [Co(bmimapy)(TCCat)]PF6·H2O (2), where bmimapy is an imidazolic tetradentate ancillary ligand and 3,5-DTBCat and TCCat are the 3,5-di-tert-butyl-catecholate and tetrachlorocatecholate anions, respectively. Their structures have been elucidated using single crystal X-ray diffraction, showing a pseudo-octahedral cobalt ion bound to a chelating dioxolene ligand and the ancillary bmimapy ligand in a folded conformation. Magnetometry displayed an entropy-driven, incomplete, Valence Tautomeric (VT) process for 1 in the 300-380 K temperature range, while 2 displayed a temperature independent, diamagnetic low-spin cobalt(iii)-catecholate charge distribution. This behaviour was interpreted on the basis of the cyclic voltammetric analysis, allowing the estimation of the free energy difference associated with the VT interconversion of +8 and +96 kJ mol-1 for 1 and 2, respectively. A DFT analysis of this free energy difference highlighted the ability of the methyl-imidazole pendant arm of bmimapy favouring the onset of the VT phenomenon. This work introduces the imidazolic bmimapy ligand to the scientific community working in the field of valence tautomerism, increasing the library of ancillary ligands to prepare temperature switchable molecular magnetic materials.
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Affiliation(s)
| | - Leandro Sodré de Abreu
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | | | - William Silva Fernandes
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Thiago Messias Cardozo
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Rafael A Allão Cassaro
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Marciela Scarpellini
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro Rio de Janeiro RJ 21941-909 Brazil
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6
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Nikovskiy I, Aleshin DY, Novikov VV, Polezhaev AV, Khakina EA, Melnikova EK, Nelyubina YV. Selective Pathway toward Heteroleptic Spin-Crossover Iron(II) Complexes with Pyridine-Based N-Donor Ligands. Inorg Chem 2022; 61:20866-20877. [PMID: 36511893 DOI: 10.1021/acs.inorgchem.2c03270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A new synthetic pathway is devised to selectively produce previously elusive heteroleptic iron(II) complexes of terpyridine and N,N'-disubstituted bis(pyrazol-3-yl)pyridines that stabilize the opposite spin states of the metal ion. Such a combination of the ligands in a series of the heteroleptic complexes induces the spin-crossover (SCO) not experienced by the homoleptic complexes of these ligands or shifts it to lower/higher temperatures respective to the SCO-active homoleptic complex. The midpoint temperatures of the resulting SCO span from ca. 200 K to the ambient temperature and beyond the highest temperature accessible by NMR spectroscopy and SQUID magnetometry. The proposed "one-pot" approach is applicable to other N-donor ligands to selectively produce heteroleptic complexes─including those inaccessible by alternative synthetic pathways─with highly tunable SCO behaviors for practical applications in sensing, switching, and multifunctional devices.
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Affiliation(s)
- Igor Nikovskiy
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
| | - Dmitry Yu Aleshin
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia
| | - Valentin V Novikov
- Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia.,Moscow Institute of Physics and Technology, Institutskiy per., 9, 141700Dolgoprudny, Russia
| | - Alexander V Polezhaev
- Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
| | - Ekaterina A Khakina
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,HSE University, Miasnitskaya Str., 20, 101000Moscow, Russia
| | - Elizaveta K Melnikova
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia
| | - Yulia V Nelyubina
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova Str., 28, 119991Moscow, Russia.,Bauman Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005Moscow, Russia
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7
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Morrow JR, Raymond JJ, Chowdhury MSI, Sahoo PR. Redox-Responsive MRI Probes Based on First-Row Transition-Metal Complexes. Inorg Chem 2022; 61:14487-14499. [PMID: 36067522 DOI: 10.1021/acs.inorgchem.2c02197] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The presence of multiple oxidation and spin states of first-row transition-metal complexes facilitates the development of switchable MRI probes. Redox-responsive probes capitalize on a change in the magnetic properties of the different oxidation states of the paramagnetic metal ion center upon exposure to biological oxidants and reductants. Transition-metal complexes that are useful for MRI can be categorized according to whether they accelerate water proton relaxation (T1 or T2 agents), induce paramagnetic shifts of 1H or 19F resonances (paraSHIFT agents), or are chemical exchange saturation transfer (CEST) agents. The various oxidation state couples and their properties as MRI probes are summarized with a focus on Co(II)/Co(III) or Fe(II)/Fe(III) complexes as small molecules or as liposomal agents. Solution studies of these MRI probes are reviewed with an emphasis on redox changes upon treatment with oxidants or with enzymes that are physiologically important in inflammation and disease. Finally, we outline the challenges of developing these probes further for in vivo MRI applications.
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Affiliation(s)
- Janet R Morrow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Jaclyn J Raymond
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Md Saiful I Chowdhury
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
| | - Priya Ranjan Sahoo
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, New York 14260, United States
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8
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Mel’nikova EK, Nikovskii IA, Polezhaev AV, Nelyubina YV. Solvatomorphs of Iron(II) Complex with N,N'-Disubstituted 2,6-Bis(pyrazol-3-yl)pyridine with a Temperature-Induced Spin Transition in Solution. RUSS J COORD CHEM+ 2022. [DOI: 10.1134/s1070328422080048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract
The reaction of the tridentate ligand 4-(2,6-bis(5-tert-butyl-1-(2,6-dichlorophenyl)-1H-pyrazol-3-yl)pyridin-4-yl)benzonitrile (L) with iron(II) salt gave the complex [Fe(L)2](BF4)2, which was isolated in a pure state and characterized by elemental analysis, NMR spectroscopy, and X-ray diffraction as two crystal polymorphs differing in the nature of the solvent molecule in the crystal (solvatomorphs I and II). According to the results of X-ray diffraction study (CCDC nos. 2104367 (I), 2104368 (II)), the iron(II) ion in these compounds occurs in different spin states and does not undergo a temperature-induced spin transition, which was previously observed for this complex in solution. The details of supramolecular organization of two solvatomorphs that prevent this transition were studied using the Hirshfeld surface analysis.
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Three Novel Thiazole-Arm Containing 1,3,4-Oxadiazole-Based [HS-HS] Fe(II) Dinuclear Complexes. CRYSTALS 2022. [DOI: 10.3390/cryst12030404] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Novel synthesis of 2,5-bis[(1,3-thiazol-2-ylmethyl)amino]methyl-1,3,4-oxadiazole (LThiazole) is reported, along with the preparation of three new dinuclear Fe(II) complexes with different counterions [FeII2(μ2-LThiazole)2](BF4)4·2CH3CN (1), [FeII2(μ2-LThiazole)2](ClO4)4 (2) and [FeII2(μ2-LThiazole)2](CF3SO3)4·2CH3CN (3). The obtained complexes were characterized by single-crystal X-ray crystallography, SQUID magnetometry and IR spectroscopy. The structure of the crystalline material was determined at 120 K for 1 and 3. The magnetic properties of all three complexes (1–3) were measured between 2–300 K and clearly show that all three complexes stay in the high-spin state over the measured temperature range.
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10
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Göbel C, Marquardt K, Baabe D, Drechsler M, Loch P, Breu J, Greiner A, Schmalz H, Weber B. Realizing shape and size control for the synthesis of coordination polymer nanoparticles templated by diblock copolymer micelles. NANOSCALE 2022; 14:3131-3147. [PMID: 35142327 DOI: 10.1039/d1nr07743k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The combination of polymers with nanoparticles offers the possibility to obtain customizable composite materials with additional properties such as sensing or bistability provided by a switchable spin crossover (SCO) core. For all applications, a precise control over size and shape of the nanomaterial is highly important as it will significantly influence its final properties. By confined synthesis of iron(II) SCO coordination polymers within the P4VP cores of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) micelles in THF we are able to control the size and also the shape of the resulting SCO nanocomposite particles by the composition of the PS-b-P4VP diblock copolymers (dBCPs) and the amount of complex employed. For the nanocomposite samples with the highest P4VP content, a morphological transition from spherical nanoparticles to worm-like structures was observed with increasing coordination polymer content, which can be explained with the impact of complex coordination on the self-assembly of the dBCP. Furthermore, the SCO nanocomposites showed transition temperatures of T1/2 = 217 K, up to 27 K wide hysteresis loops and a decrease of the residual high-spin fraction down to γHS = 14% in the worm-like structures, as determined by magnetic susceptibility measurements and Mössbauer spectroscopy. Thus, SCO properties close or even better (hysteresis) to those of the bulk material can be obtained and furthermore tuned through size and shape control realized by tailoring the block length ratio of the PS-b-P4VP dBCPs.
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Affiliation(s)
- Christoph Göbel
- Department of Chemistry, Inorganic Chemistry IV, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
| | - Katharina Marquardt
- Bavarian Research Institute of Experimental Geochemistry and Geophysics (BGI), Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Dirk Baabe
- Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
| | - Markus Drechsler
- Bavarian Polymer Institute (BPI), Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Patrick Loch
- Department of Chemistry, Inorganic Chemistry I, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Josef Breu
- Department of Chemistry, Inorganic Chemistry I, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Andreas Greiner
- Department of Chemistry, Macromolecular Chemistry II and Bavarian Polymer Institute (BPI), Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Holger Schmalz
- Department of Chemistry, Macromolecular Chemistry II and Bavarian Polymer Institute (BPI), Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Birgit Weber
- Department of Chemistry, Inorganic Chemistry IV, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany.
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11
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Lee AL, Pandey AK, Chiniforoush S, Mandal M, Li J, Cramer CJ, Haynes CL, Pomerantz WCK. Development of a Highly Responsive Organofluorine Temperature Sensor for 19F Magnetic Resonance Applications. Anal Chem 2022; 94:3782-3790. [PMID: 35191677 DOI: 10.1021/acs.analchem.1c04248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Temperature can affect many biological and chemical processes within a body. During in vivo measurements, varied temperature can impact the accurate quantification of additional abiotic factors such as oxygen. During magnetic resonance imaging (MRI) measurements, the temperature of the sample can increase with the absorption of radiofrequency energy, which needs to be well-regulated for thermal therapies and long exposure. To address this potentially confounding effect, temperature can be probed intentionally using reporter molecules to determine the temperature in vivo. This work describes a combined experimental and computational approach for the design of fluorinated molecular temperature sensors with the potential to improve the accuracy and sensitivity of 19F MRI-based temperature monitoring. These fluorinated sensors are being developed to overcome the temperature sensitivity and tissue limitations of the proton resonance frequency (10 × 10-3 ppm °C-1), a standard parameter used for temperature mapping in MRI. Here, we develop (perfluoro-[1,1'-biphenyl]-4,4'-diyl)bis((heptadecafluorodecyl)sulfane), which has a nearly 2-fold increase in temperature responsiveness, compared to the proton resonance frequency and the 19F MRI temperature sensor perfluorotributylamine, when tested under identical NMR conditions. While 19F MRI is in the early stages of translation into clinical practice, development of alternative sensors with improved diagnostic abilities will help advance the development and incorporation of fluorine magnetic resonance techniques for clinical use.
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Affiliation(s)
- Amani L Lee
- University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Anil K Pandey
- University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Sina Chiniforoush
- University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Mukunda Mandal
- University of Minnesota, Minneapolis, Minnesota 55414, United States
| | - Jiaqian Li
- University of Minnesota, Minneapolis, Minnesota 55414, United States
| | | | - Christy L Haynes
- University of Minnesota, Minneapolis, Minnesota 55414, United States
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12
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Aleshin D, Nikovskiy I, Novikov VV, Polezhaev AV, Melnikova EK, Nelyubina YV. Room-Temperature Spin Crossover in a Solution of Iron(II) Complexes with N, N'-Disubstituted Bis(pyrazol-3-yl)pyridines. ACS OMEGA 2021; 6:33111-33121. [PMID: 34901662 PMCID: PMC8655922 DOI: 10.1021/acsomega.1c05463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/09/2021] [Indexed: 05/15/2023]
Abstract
Here, we report a combined study of the effects of two chemical modifications to an N,N'-disubstituted bis(pyrazol-3-yl)pyridine (3-bpp) and of different solvents on the spin-crossover (SCO) behavior in otherwise high-spin iron(II) complexes by solution NMR spectroscopy. The observed stabilization of the low-spin state by electron-withdrawing substituents in the two positions of the ligand that induce opposite electronic effects in SCO-active iron(II) complexes of isomeric bis(pyrazol-1-yl)pyridines (1-bpp) was previously hidden by NH functionalities in 3-bpp precluding the molecular design of SCO compounds with this family of ligands. With the recent SCO-assisting substituent design, the uncovered trends converged toward the first iron(II) complex of N,N'-disubstituted 3-bpp to undergo an almost complete SCO centered at room temperature in a less polar solvent of a high hydrogen-bond acceptor ability.
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Affiliation(s)
- Dmitry
Yu Aleshin
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
| | - Igor Nikovskiy
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
- Bauman
Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005 Moscow, Russia
| | - Valentin V. Novikov
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
- Moscow
Institute of Physics and Technology, Institutskiy per., 9, 141700 Dolgoprudny, Russia
| | - Alexander V. Polezhaev
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
- Bauman
Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005 Moscow, Russia
| | - Elizaveta K. Melnikova
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
- Lomonosov
Moscow State University, Leninskiye Gory, 1-3, 119991 Moscow, Russia
| | - Yulia V. Nelyubina
- A.N.
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of
Sciences, Vavilova Str., 28, 119991 Moscow, Russia
- Bauman
Moscow State Technical University, 2nd Baumanskaya Str., 5, 105005 Moscow, Russia
- Moscow
Institute of Physics and Technology, Institutskiy per., 9, 141700 Dolgoprudny, Russia
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13
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Livesay BN, Shores MP. Influence of Coordinated Triflate Anions on the Solution Magnetic Properties of a Neutral Iron(II) Complex. Inorg Chem 2021; 60:15445-15455. [PMID: 34596394 DOI: 10.1021/acs.inorgchem.1c02112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In an effort to probe the impacts of speciation on spin-state switching, the synthesis and unique solution-phase magnetic properties of [((TIPSC≡C)3tren)Fe(OTf)2] (1) are described. Analysis of the single-crystal X-ray diffraction data shows that the tris(iminoalkyne) ligand coordinates to the iron(II) center through all four nitrogen atoms, while the other two coordination sites are filled by the oxygen atoms from triflate anions. Solid-state variable-temperature (VT) magnetic studies show that 1 remains high-spin (HS) at all temperatures. In the presence of moderately strong coordinating solvents, solvent replaces the two bound triflate counteranions, as observed by 19F NMR spectroscopy and supported by conductivity measurements. VT solution measurements show 1 to be in the HS state when this solvent is oxygen-donating but low-spin (LS) with a nitrogen-donating solvent. In the noncoordinating solvent dichloromethane, both triflates are bound to the iron(II) center at room temperature, but upon cooling, 1 undergoes a coordination change, resulting in the loss of one triflate, as shown by 19F NMR. With the moderately coordinating solvent acetone, triflate dissociation upon cooling results in a spin-switching species with a T1/2 value of 171 K, characterized via 19F NMR, Evans' method, and solution magnetometry measurements. Solution magnetic measurements collected in structurally similar cyclopentanone suggest that the spin-state switching event is exclusive to the acetone environment, suggesting the influence of both the local coordination environment and aggregation. Additionally, a comparison of the solvodoynamic diameters via dynamic light scattering suggests that aggregation of 1 is significantly different in (CH3)2CO and (CD3)2CO, leading to the observation of spin-switching behavior in the former and fully HS behavior in the latter. This study highlights the sensitivity of solution magnetic properties to solvent choice.
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Affiliation(s)
- Brooke N Livesay
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Matthew P Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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14
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Gkolfi P, Tsivaka D, Tsougos I, Vassiou K, Malina O, Polaskova M, Polyzou CD, Chasapis CT, Tangoulis V. A facile approach to prepare silica hybrid, spin-crossover water-soluble nanoparticles as potential candidates for thermally responsive MRI agents. Dalton Trans 2021; 50:13227-13231. [PMID: 34546269 DOI: 10.1039/d1dt02479e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A reverse micelle method was used for the synthesis of water-soluble silica hybrid, spin-crossover (SCO) nanoparticles (NPs). MRI experiments provided temperature dependent T2 values, indicating their potential use as smart MRI agents, while lyophilization of NP dispersions in water yielded powders with a preserved but modified thermal hysteretic magnetic profile.
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Affiliation(s)
- Patroula Gkolfi
- Department of Chemistry, Laboratory of Inorganic Chemistry, University of Patras, 26504, Patras, Greece.
| | - Dimitra Tsivaka
- Department of Medical Physics, University Hospital of Larissa, University of Thessaly, Biopolis, GR-41110 Larissa, Greece.
| | - Ioannis Tsougos
- Department of Medical Physics, University Hospital of Larissa, University of Thessaly, Biopolis, GR-41110 Larissa, Greece.
| | - Katerina Vassiou
- Department of Radiology, University Hospital of Larissa, University of Thessaly, Biopolis, GR-41110 Larissa, Greece
| | - Ondřej Malina
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Czech Republic.
| | - Michaela Polaskova
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Czech Republic. .,Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, 17. Listopadu 1192/12, 771 46 Olomouc, Czech Republic
| | - Christina D Polyzou
- Department of Chemistry, Laboratory of Inorganic Chemistry, University of Patras, 26504, Patras, Greece.
| | - Christos T Chasapis
- NMR Facility, Instrumental Analysis Laboratory, School of Natural Sciences, University of Patras, 26504, Patras, Greece
| | - Vassilis Tangoulis
- Department of Chemistry, Laboratory of Inorganic Chemistry, University of Patras, 26504, Patras, Greece.
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15
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Capel Berdiell I, Davies DJ, Woodworth J, Kulmaczewski R, Cespedes O, Halcrow MA. Structures and Spin States of Iron(II) Complexes of Isomeric 2,6-Di(1,2,3-triazolyl)pyridine Ligands. Inorg Chem 2021; 60:14988-15000. [PMID: 34547208 DOI: 10.1021/acs.inorgchem.1c02404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Iron(II) complex salts of 2,6-di(1,2,3-triazol-1-yl)pyridine (L1) are unexpectedly unstable in undried solvent. This is explained by the isolation of [Fe(L1)4(H2O)2][ClO4]2 and [Fe(NCS)2(L1)2(H2O)2]·L1, containing L1 bound as a monodentate ligand rather than in the expected tridentate fashion. These complexes associate into 44 grid structures through O-H···N hydrogen bonding; a solvate of a related 44 coordination framework, catena-[Cu(μ-L1)2(H2O)2][BF4]2, is also presented. The isomeric ligands 2,6-di(1,2,3-triazol-2-yl)pyridine (L2) and 2,6-di(1H-1,2,3-triazol-4-yl)pyridine (L3) bind to iron(II) in a more typical tridentate fashion. Solvates of [Fe(L3)2][ClO4]2 are low-spin and diamagnetic in the solid state and in solution, while [Fe(L2)2][ClO4]2 and [Co(L3)2][BF4]2 are fully high-spin. Treatment of L3 with methyl iodide affords 2,6-di(2-methyl-1,2,3-triazol-4-yl)pyridine (L4) and 2-(1-methyl-1,2,3-triazol-4-yl)-6-(2-methyl-1,2,3-triazol-4-yl)pyridine (L5). While salts of [Fe(L5)2]2+ are low-spin in the solid state, [Fe(L4)2][ClO4]2·H2O is high-spin, and [Fe(L4)2][ClO4]2·3MeNO2 exhibits a hysteretic spin transition to 50% completeness at T1/2 = 128 K (ΔT1/2 = 6 K). This transition proceeds via a symmetry-breaking phase transition to an unusual low-temperature phase containing three unique cation sites with high-spin, low-spin, and 1:1 mixed-spin populations. The unusual distribution of the spin states in the low-temperature phase reflects "spin-state frustration" of the mixed-spin cation site by an equal number of high-spin and low-spin nearest neighbors. Gas-phase density functional theory calculations reproduce the spin-state preferences of these and some related complexes. These highlight the interplay between the σ-basicity and π-acidity of the heterocyclic donors in this ligand type, which have opposing influences on the molecular ligand field. The Brønsted basicities of L1-L3 are very sensitive to the linkage isomerism of their triazolyl donors, which explains why their iron complex spin states show more variation than the better-known iron(II)/2,6-dipyrazolylpyridine system.
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Affiliation(s)
- Izar Capel Berdiell
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Daniel J Davies
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Jack Woodworth
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, E. C. Stoner Building, Leeds LS2 9JT, U.K
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K
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16
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Hardy M, Tessarolo J, Holstein JJ, Struch N, Wagner N, Weisbarth R, Engeser M, Beck J, Horiuchi S, Clever GH, Lützen A. A Family of Heterobimetallic Cubes Shows Spin-Crossover Behaviour Near Room Temperature. Angew Chem Int Ed Engl 2021; 60:22562-22569. [PMID: 34382295 PMCID: PMC8519129 DOI: 10.1002/anie.202108792] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/04/2021] [Indexed: 11/08/2022]
Abstract
Using 4-(4'-pyridyl)aniline as a simple organic building block in combination with three different aldehyde components together with metal(II) salts gave three different Fe8 Pt6 -cubes and their corresponding Zn8 Pt6 analogues by employing the subcomponent self-assembly approach. Whereas the use of zinc(II) salts gave rise to diamagnetic cages, iron(II) salts yielded metallosupramolecular cages that show spin-crossover behaviour in solution. The spin-transition temperature T1/2 depends on the incorporated aldehyde component, giving a construction kit for the deliberate synthesis of spin-crossover compounds with tailored transition properties. Incorporation of 4-thiazolecarbaldehyde or N-methyl-2-imidazole-carbaldehyde yielded cages that undergo spin-crossover around room temperature whereas the cage obtained using 1H-4-imidazolecarbaldehyde shows a spin-transition at low temperatures. Three new structures were characterized by synchrotron X-ray diffraction and all structures were characterized by mass spectrometry, NMR and UV/Vis spectroscopy.
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Affiliation(s)
- Matthias Hardy
- Rheinische Friedrich-Wilhelms-Universität BonnKekulé-Institut für Organische Chemie und BiochemieGerhard-Domagk-Str. 153121BonnGermany
- Current address: BASF SESpeyerer Str. 267117LimburgerhofGermany
| | - Jacopo Tessarolo
- Technische Universität DortmundOtto-Hahn-Str. 644227DortmundGermany
| | | | - Niklas Struch
- Rheinische Friedrich-Wilhelms-Universität BonnKekulé-Institut für Organische Chemie und BiochemieGerhard-Domagk-Str. 153121BonnGermany
- Current address: Arlanxeo (Deutschland) GmbHAlte Heerstraße 241540DormagenGermany
| | - Norbert Wagner
- Rheinische Friedrich-Wilhelms-Universität BonnInstitut für Anorganische ChemieGerhard-Domagk-Str. 153121BonnGermany
| | - Ralf Weisbarth
- Rheinische Friedrich-Wilhelms-Universität BonnInstitut für Anorganische ChemieGerhard-Domagk-Str. 153121BonnGermany
| | - Marianne Engeser
- Rheinische Friedrich-Wilhelms-Universität BonnKekulé-Institut für Organische Chemie und BiochemieGerhard-Domagk-Str. 153121BonnGermany
| | - Johannes Beck
- Rheinische Friedrich-Wilhelms-Universität BonnInstitut für Anorganische ChemieGerhard-Domagk-Str. 153121BonnGermany
| | - Shinnosuke Horiuchi
- Technische Universität DortmundOtto-Hahn-Str. 644227DortmundGermany
- Division of Chemistry and Materials ScienceGraduate School of EngineeringNagasaki University, Bunkyo-machiNagasaki852-8521Japan
| | - Guido H. Clever
- Technische Universität DortmundOtto-Hahn-Str. 644227DortmundGermany
| | - Arne Lützen
- Rheinische Friedrich-Wilhelms-Universität BonnKekulé-Institut für Organische Chemie und BiochemieGerhard-Domagk-Str. 153121BonnGermany
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17
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Hardy M, Tessarolo J, Holstein JJ, Struch N, Wagner N, Weisbarth R, Engeser M, Beck J, Horiuchi S, Clever GH, Lützen A. Eine Familie von Heterobimetallischen Würfeln zeigt Spin‐Crossover‐Verhalten nahe Raumtemperatur. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Matthias Hardy
- Rheinische Friedrich-Wilhelms-Universität Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
- Derzeitige Adresse: BASF SE Speyerer Str. 2 67117 Limburgerhof Deutschland
| | - Jacopo Tessarolo
- Technische Universität Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Julian J. Holstein
- Technische Universität Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Niklas Struch
- Rheinische Friedrich-Wilhelms-Universität Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
- Derzeitige Adresse: Arlanxeo (Deutschland) GmbH Alte Heerstraße 2 41540 Dormagen Deutschland
| | - Norbert Wagner
- Rheinische Friedrich-Wilhelms-Universität Bonn Institut für Anorganische Chemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
| | - Ralf Weisbarth
- Rheinische Friedrich-Wilhelms-Universität Bonn Institut für Anorganische Chemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
| | - Marianne Engeser
- Rheinische Friedrich-Wilhelms-Universität Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
| | - Johannes Beck
- Rheinische Friedrich-Wilhelms-Universität Bonn Institut für Anorganische Chemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
| | - Shinnosuke Horiuchi
- Technische Universität Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
- Division of Chemistry and Materials Science Graduate School of Engineering Nagasaki University, Bunkyo-machi Nagasaki 852-8521 Japan
| | - Guido H. Clever
- Technische Universität Dortmund Otto-Hahn-Str. 6 44227 Dortmund Deutschland
| | - Arne Lützen
- Rheinische Friedrich-Wilhelms-Universität Bonn Kekulé-Institut für Organische Chemie und Biochemie Gerhard-Domagk-Str. 1 53121 Bonn Deutschland
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18
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Baranyai Z, Carniato F, Nucera A, Horváth D, Tei L, Platas-Iglesias C, Botta M. Defining the conditions for the development of the emerging class of Fe III-based MRI contrast agents. Chem Sci 2021; 12:11138-11145. [PMID: 34522311 PMCID: PMC8386674 DOI: 10.1039/d1sc02200h] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/07/2021] [Indexed: 02/05/2023] Open
Abstract
Fe(iii) complexes are attracting growing interest in chemists developing diagnostic probes for Magnetic Resonance Imaging because they leverage on an endogenous metal and show superior stability. However, in this case a detailed understanding of the relationship between the chemical structure of the complexes, their magnetic, thermodynamic, kinetic and redox properties and the molecular parameters governing the efficacy (relaxivity) is still far from being available. We have carried out an integrated 1H and 17O NMR relaxometric study as a function of temperature and magnetic field, on the aqua ion and three complexes chosen as reference models, together with theoretical calculations, to obtain accurate values of the parameters that control their relaxivity. Moreover, thermodynamic stability and dissociation kinetics of the Fe(iii) chelates, measured in association with the ascorbate reduction behaviour, highlight their role and mutual influence in achieving the stability required for use in vivo. An integrated 1H and 17O NMR relaxometric study on model systems allowed to highlight that the Fe(III) complexes might represent the best alternative to Gd-based MRI contrast agents at the magnetic fields of current and future clinical scanners.![]()
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Affiliation(s)
- Zsolt Baranyai
- Bracco Research Centre, Bracco Imaging S.p.A. Via Ribes 5 10010 Colleretto Giacosa Italy
| | - Fabio Carniato
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
| | - Alessandro Nucera
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
| | - Dávid Horváth
- Bracco Research Centre, Bracco Imaging S.p.A. Via Ribes 5 10010 Colleretto Giacosa Italy.,Department of Physical Chemistry, University of Debrecen Egyetem tér 1. H-4010 Debrecen Hungary
| | - Lorenzo Tei
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas (CICA), Departamento de Química, Facultade de Ciencias, Universidade da Coruña 15071 A Coruña Galicia Spain
| | - Mauro Botta
- Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale "A. Avogadro" Viale T. Michel 11 15121 Alessandria Italy
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19
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Wellm V, Näther C, Herges R. Molecular Spin State Switching and Photochromism in the Red and Near Infrared with Ni(II) Chlorin and Ni(II) Bacteriochlorin. J Org Chem 2021; 86:9503-9514. [PMID: 34181424 DOI: 10.1021/acs.joc.1c00806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molecules or ions are either paramagnetic (unpaired electrons) or diamagnetic (all electrons are paired). Switching between the two states under ambient conditions was considered a typical solid state phenomenon and has been termed spin crossover. The first single-molecule spin state switches operated with light in solution were developed a decade ago and offer a number of technical applications that are not accessible to solid state systems. Magnetic switching in biological environments, however, requires water solubility, and for in vivo applications, switching wavelengths within the bio-optical window (650-950 nm) are needed. We now present molecular spin state switches that are water-soluble and switchable in the far-red and near-infrared region. At the same time, they are photochromic compounds with excellent photophysical properties. trans-cis isomerization is induced with 505 nm radiation, and cis-trans conversion with 620 or 720 nm radiation. The metastable cis isomers are stable at room temperature for at least several weeks. The detailed mechanism of this surprising and unprecedented long wavelength photoisomerization of azobenzenes is still under investigation.
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Affiliation(s)
- Vanessa Wellm
- Otto Diels-Institute of Organic Chemistry, University of Kiel, Otto-Hahn-Platz 4, Kiel D-24118, Germany
| | - Christian Näther
- Institute of Inorganic Chemistry, University of Kiel, Max-Eyth-Straße 2, Kiel D-24118, Germany
| | - Rainer Herges
- Otto Diels-Institute of Organic Chemistry, University of Kiel, Otto-Hahn-Platz 4, Kiel D-24118, Germany
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20
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Wellm V, Groebner J, Heitmann G, Sönnichsen FD, Herges R. Towards Photoswitchable Contrast Agents for Absolute 3D Temperature MR Imaging. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vanessa Wellm
- Otto Diels Institute of Organic Chemistry Christian Albrechts University Otto Hahn Platz 4 24118 Kiel Germany
| | - Jens Groebner
- Department of Electrical Engineering and Information Technology South Westphalian University of Applied Sciences Bahnhofsallee 5 58507 Luedenscheid Germany
| | - Gernot Heitmann
- IWS Innovations- und Wissenstrategien GmbH Aviares Research Network Deichstraße 25 20459 Hamburg Germany
| | - Frank D. Sönnichsen
- Otto Diels Institute of Organic Chemistry Christian Albrechts University Otto Hahn Platz 4 24118 Kiel Germany
| | - Rainer Herges
- Otto Diels Institute of Organic Chemistry Christian Albrechts University Otto Hahn Platz 4 24118 Kiel Germany
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21
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Wellm V, Groebner J, Heitmann G, Sönnichsen FD, Herges R. Towards Photoswitchable Contrast Agents for Absolute 3D Temperature MR Imaging. Angew Chem Int Ed Engl 2021; 60:8220-8226. [PMID: 33606332 PMCID: PMC8048480 DOI: 10.1002/anie.202015851] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Indexed: 12/27/2022]
Abstract
Temperature can be used as clinical marker for tissue metabolism and the detection of inflammations or tumors. The use of magnetic resonance imaging (MRI) for monitoring physiological parameters like the temperature noninvasively is steadily increasing. In this study, we present a proof-of-principle study of MRI contrast agents (CA) for absolute and concentration independent temperature imaging. These CAs are based on azoimidazole substituted NiII porphyrins, which can undergo Light-Driven Coordination-Induced Spin State Switching (LD-CISSS) in solution. Monitoring the fast first order kinetic of back isomerisation (cis to trans) with standard clinical MR imaging sequences allows the determination of half-lives, that can be directly translated into absolute temperatures. Different temperature responsive CAs were successfully tested as prototypes in methanol-based gels and created temperature maps of gradient phantoms with high spatial resolution (0.13×0.13×1.1 mm) and low temperature errors (<0.22 °C). The method is sufficiently fast to record the temperature flow from a heat source as a film.
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Affiliation(s)
- Vanessa Wellm
- Otto Diels Institute of Organic ChemistryChristian Albrechts UniversityOtto Hahn Platz 424118KielGermany
| | - Jens Groebner
- Department of Electrical Engineering and Information TechnologySouth Westphalian University of Applied SciencesBahnhofsallee 558507LuedenscheidGermany
| | - Gernot Heitmann
- IWS Innovations- und Wissenstrategien GmbHAviares Research NetworkDeichstraße 2520459HamburgGermany
| | - Frank D. Sönnichsen
- Otto Diels Institute of Organic ChemistryChristian Albrechts UniversityOtto Hahn Platz 424118KielGermany
| | - Rainer Herges
- Otto Diels Institute of Organic ChemistryChristian Albrechts UniversityOtto Hahn Platz 424118KielGermany
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22
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Jornet-Mollá V, Giménez-Saiz C, Vieira BJC, Waerenborgh JC, Romero FM. Temperature dependence of desolvation effects in hydrogen-bonded spin crossover complexes. Dalton Trans 2021; 50:2536-2544. [PMID: 33522546 DOI: 10.1039/d0dt03986a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The synthesis, crystal structure and (photo)magnetic properties of the anhydrous spin crossover salt of formula [Fe(bpp)2](C6H8O4) (1) (bpp = 2,6-bis(pyrazol-3-yl)pyridine; C6H8O4 = adipate dianion), obtained by desolvation at 400 K of the original tetrahydrate in a single-crystal-to-single-crystal (SC-SC) transformation, are reported. This work offers a comparison between this compound and the previously reported hydrated material ([Fe(bpp)2](C6H8O4)·4H2O, 1·4H2O), highlighting the significance of the thermal conditions used in the dehydration-rehydration processes. In both compounds, a hydrogen-bonded network between iron(ii) complexes and adipate anions is observed. The original tetrahydrate (1·4H2O) is low-spin and desolvation at 450 K triggers a low-spin (LS) to high-spin (HS) transition to an amorphous phase that remains stable over the whole temperature range of study. Surprisingly, the dehydrated compound at 400 K (1) keeps the crystallinity, undergoes a partial spin crossover (T1/2 = 180 K) and a quantitative LS to HS photomagnetic conversion at low temperatures, with a T(LIESST) value of 61 K.
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Affiliation(s)
- Verónica Jornet-Mollá
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain.
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23
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Subasinghe SAAS, Romero J, Ward CL, Bailey MD, Zehner DR, Mehta PJ, Carniato F, Botta M, Yustein JT, Pautler RG, Allen MJ. Magnetic resonance thermometry using a Gd III-based contrast agent. Chem Commun (Camb) 2021; 57:1770-1773. [PMID: 33475101 PMCID: PMC7897303 DOI: 10.1039/d0cc06400a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The complexes described here serve as contrast agents for magnetic resonance imaging thermometry. The complexes differentially enhance contrast between 275 and 325 K. The basis of the temperature response of the fluorinated contrast complex is the modulation of water exchange caused by trifluoromethyl groups that can be chemically controlled.
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Affiliation(s)
- S A Amali S Subasinghe
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
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Wang H, Wong A, Lewis LC, Nemeth GR, Jordan VC, Bacon JW, Caravan P, Shafaat HS, Gale EM. Rational Ligand Design Enables pH Control over Aqueous Iron Magnetostructural Dynamics and Relaxometric Properties. Inorg Chem 2020; 59:17712-17721. [PMID: 33216537 DOI: 10.1021/acs.inorgchem.0c02923] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Complexes of Fe3+ engage in rich aqueous solution speciation chemistry in which discrete molecules can react with solvent water to form multinuclear μ-oxo and μ-hydroxide bridged species. Here we demonstrate how pH- and concentration-dependent equilibration between monomeric and μ-oxo-bridged dimeric Fe3+ complexes can be controlled through judicious ligand design. We purposed this chemistry to develop a first-in-class Fe3+-based MR imaging probe, Fe-PyCy2AI, that undergoes relaxivity change via pH-mediated control of monomer vs dimer speciation. The monomeric complex exists in a S = 5/2 configuration capable of inducing efficient T1-relaxation, whereas the antiferromagnetically coupled dimeric complex is a much weaker relaxation agent. The mechanisms underpinning the pH dependence on relaxivity were interrogated by using a combination of pH potentiometry, 1H and 17O relaxometry, electronic absorption spectroscopy, bulk magnetic susceptibility, electron paramagnetic resonance spectroscopy, and X-ray crystallography measurements. Taken together, the data demonstrate that PyCy2AI forms a ternary complex with high-spin Fe3+ and a rapidly exchanging water coligand, [Fe(PyCy2AI)(H2O)]+ (ML), which can deprotonate to form the high-spin complex [Fe(PyCy2AI)(OH)] (ML(OH)). Under titration conditions of 7 mM Fe complex, water coligand deprotonation occurs with an apparent pKa 6.46. Complex ML(OH) dimerizes to form the antiferromagnetically coupled dimeric complex [(Fe(PyCy2AI))2O] ((ML)2O) with an association constant (Ka) of 5.3 ± 2.2 mM-1. The relaxivity of the monomeric complexes are between 7- and 18-fold greater than the antiferromagnetically coupled dimer at applied field strengths ranging between 1.4 and 11.7 T. ML(OH) and (ML)2O interconvert rapidly within the pH 6.0-7.4 range that is relevant to human pathophysiology, resulting in substantial observed relaxivity change. Controlling Fe3+ μ-oxo bridging interactions through rational ligand design and in response to local chemical environment offers a robust mechanism for biochemically responsive MR signal modulation.
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Affiliation(s)
| | | | - Luke C Lewis
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | | | | | - Jeffrey W Bacon
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | | | - Hannah S Shafaat
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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Du K, Zemerov SD, Hurtado Parra S, Kikkawa JM, Dmochowski IJ. Paramagnetic Organocobalt Capsule Revealing Xenon Host-Guest Chemistry. Inorg Chem 2020; 59:13831-13844. [PMID: 32207611 PMCID: PMC7672707 DOI: 10.1021/acs.inorgchem.9b03634] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We investigated Xe binding in a previously reported paramagnetic metal-organic tetrahedral capsule, [Co4L6]4-, where L2- = 4,4'-bis[(2-pyridinylmethylene)amino][1,1'-biphenyl]-2,2'-disulfonate. The Xe-inclusion complex, [XeCo4L6]4-, was confirmed by 1H NMR spectroscopy to be the dominant species in aqueous solution saturated with Xe gas. The measured Xe dissociation rate in [XeCo4L6]4-, koff = 4.45(5) × 102 s-1, was at least 40 times greater than that in the analogous [XeFe4L6]4- complex, highlighting the capability of metal-ligand interactions to tune the capsule size and guest permeability. The rapid exchange of 129Xe nuclei in [XeCo4L6]4- produced significant hyperpolarized 129Xe chemical exchange saturation transfer (hyper-CEST) NMR signal at 298 K, detected at a concentration of [XeCo4L6]4- as low as 100 pM, with presaturation at -89 ppm, which was referenced to solvated 129Xe in H2O. The saturation offset was highly temperature-dependent with a slope of -0.41(3) ppm/K, which is attributed to hyperfine interactions between the encapsulated 129Xe nucleus and electron spins on the four CoII centers. As such, [XeCo4L6]4- represents the first example of a paramagnetic hyper-CEST (paraHYPERCEST) sensor. Remarkably, the hyper-CEST 129Xe NMR resonance for [XeCo4L6]4- (δ = -89 ppm) was shifted 105 ppm upfield from the diamagnetic analogue [XeFe4L6]4- (δ = +16 ppm). The Xe inclusion complex was further characterized in the crystal structure of (C(NH2)3)4[Xe0.7Co4L6]·75 H2O (1). Hydrogen bonding between capsule-linker sulfonate groups and exogenous guanidinium cations, (C(NH2)3)+, stabilized capsule-capsule interactions in the solid state and also assisted in trapping a Xe atom (∼42 Å3) in the large (135 Å3) cavity of 1. Magnetic susceptibility measurements confirmed the presence of four noninteracting, magnetically anisotropic high-spin CoII centers in 1. Furthermore, [Co4L6]4- was found to be stable toward aggregation and oxidation, and the CEST performance of [XeCo4L6]4- was unaffected by biological macromolecules in H2O. These results recommend metal-organic capsules for fundamental investigations of Xe host-guest chemistry as well as applications with highly sensitive 129Xe-based sensors.
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Abozeid SM, Asik D, Sokolow GE, Lovell JF, Nazarenko AY, Morrow JR. Co II Complexes as Liposomal CEST Agents. Angew Chem Int Ed Engl 2020; 59:12093-12097. [PMID: 32330368 PMCID: PMC7502271 DOI: 10.1002/anie.202003479] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Indexed: 12/23/2022]
Abstract
Three paramagnetic CoII macrocyclic complexes containing 2-hydroxypropyl pendant groups, 1,1',1'',1'''-(1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrayl)tetrakis- (propan-2-ol) ([Co(L1)]2+ , 1,1'-(4,11-dibenzyl-1,4,8,11-tetraazacyclotetradecane-1,8-diyl)bis(propan-2-ol) ([Co(L2)]2+ ), and 1,1'-(4,11-dibenzyl-1,4,8,11-tetraazacyclotetradecane-1,8-diyl)bis(octadecan-2-ol) ([Co(L3)]2+ ) were synthesized to prepare transition metal liposomal chemical exchange saturation transfer (lipoCEST) agents. In solution, ([Co(L1)]2+ ) forms two isomers as shown by 1 H NMR spectroscopy. X-ray crystallographic studies show one isomer with 1,8-pendants in cis-configuration and a second isomer with 1,4-pendants in trans-configuration. The [Co(L2)]2+ complex has 1,8-pendants in a cis-configuration. Remarkably, the paramagnetic-induced shift of water 1 H NMR resonances in the presence of the [Co(L1)]2+ complex is as large as that observed for one of the most effective LnIII water proton shift agents. Incorporation of [Co(L1)]2+ into the liposome aqueous core, followed by dialysis against a solution of 300 mOsm L-1 produces a CEST peak at 3.5 ppm. Incorporation of the amphiphilic [Co(L3)]2+ complex into the liposome bilayer produces a more highly shifted CEST peak at -13 ppm. Taken together, these data demonstrate the feasibility of preparing CoII lipoCEST agents.
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Affiliation(s)
- Samira M. Abozeid
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, United States
| | - Didar Asik
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, United States
| | - Gregory E. Sokolow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, United States
| | - Jonathan F. Lovell
- Department of Biomedical Engineering, University at Buffalo, the State University of New York, Amherst, NY 14260, United States
| | - Alexander Y. Nazarenko
- Chemistry Department, SUNY College at Buffalo, 1300 Elmwood Avenue, Buffalo, NY 14222, United States
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, the State University of New York, Amherst, NY 14260, United States
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Bond CJ, Cineus R, Nazarenko AY, Spernyak JA, Morrow JR. Isomeric Co(ii) paraCEST agents as pH responsive MRI probes. Dalton Trans 2020; 49:279-284. [PMID: 31833500 DOI: 10.1039/c9dt04558a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A newly discovered isomer of Co(ii) (1,4,8,11-tetrakis(carbamoylmethyl)-1,4,8,11-tetraazacyclotetradecane = CCRM) produces four highly paramagnetically shifted chemical exchange saturation transfer (CEST) peaks. The 1,8-pendants of the complex are bound in a trans-arrangement to produce a Co(ii) complex of increased kinetic inertness. The isomers have a stabilized Co(ii) center (E1/2 of 540 to 550 mV versus SHE). Both the 1,8 and the 1,4-isomer are excellent pH probes in solution and in tissue homogenate by virtue of their highly paramagnetically shifted amide protons. These isomers produce both a ratiometric pH readout as well as amide proton exchange rate constants that correlate to pH.
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Affiliation(s)
- Christopher J Bond
- Department of Chemistry, Natural Sciences Complex, University at Buffalo, the State University of New York, Amherst, NY 14260, USA.
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Abozeid SM, Asik D, Sokolow GE, Lovell JF, Nazarenko AY, Morrow JR. Co
II
Complexes as Liposomal CEST Agents. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202003479] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Samira M. Abozeid
- Department of Chemistry University at Buffalo, The State University of New York Amherst NY 14260 USA
| | - Didar Asik
- Department of Chemistry University at Buffalo, The State University of New York Amherst NY 14260 USA
| | - Gregory E. Sokolow
- Department of Chemistry University at Buffalo, The State University of New York Amherst NY 14260 USA
| | - Jonathan F. Lovell
- Department of Biomedical Engineering University at Buffalo The State University of New York Amherst NY 14260 USA
| | | | - Janet R. Morrow
- Department of Chemistry University at Buffalo, The State University of New York Amherst NY 14260 USA
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Gupta A, Caravan P, Price WS, Platas-Iglesias C, Gale EM. Applications for Transition-Metal Chemistry in Contrast-Enhanced Magnetic Resonance Imaging. Inorg Chem 2020; 59:6648-6678. [PMID: 32367714 DOI: 10.1021/acs.inorgchem.0c00510] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Contrast-enhanced magnetic resonance imaging (MRI) is an indispensable tool for diagnostic medicine. However, safety concerns related to gadolinium in commercial MRI contrast agents have emerged in recent years. For patients suffering from severe renal impairment, there is an important unmet medical need to perform contrast-enhanced MRI without gadolinium. There are also concerns over the long-term effects of retained gadolinium within the general patient population. Demand for gadolinium-free MRI contrast agents is driving a new wave of inorganic chemistry innovation as researchers explore paramagnetic transition-metal complexes as potential alternatives. Furthermore, advances in personalized care making use of molecular-level information have motivated inorganic chemists to develop MRI contrast agents that can detect pathologic changes at the molecular level. Recent studies have highlighted how reaction-based modulation of transition-metal paramagnetism offers a highly effective mechanism to achieve MRI contrast enhancement that is specific to biochemical processes. This Viewpoint highlights how recent advances in transition-metal chemistry are leading the way for a new generation of MRI contrast agents.
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Affiliation(s)
- Abhishek Gupta
- Nanoscale Organisation and Dynamics Group, School of Science and Health, Western Sydney University, Penrith, New South Wales 2751, Australia.,Ingham Institute of Applied Medical Research, Liverpool, New South Wales 2170, Australia
| | | | - William S Price
- Nanoscale Organisation and Dynamics Group, School of Science and Health, Western Sydney University, Penrith, New South Wales 2751, Australia.,Ingham Institute of Applied Medical Research, Liverpool, New South Wales 2170, Australia
| | - Carlos Platas-Iglesias
- Centro de Investigacións Científicas Avanzadas and Departamento de Química, Facultade de Ciencias, Universidade da Coruña, A Coruña, Galicia 15071, Spain
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30
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Halcrow MA. Manipulating metal spin states for biomimetic, catalytic and molecular materials chemistry. Dalton Trans 2020; 49:15560-15567. [DOI: 10.1039/d0dt01919d] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The relationship between ligand design and spin state in base metal compounds is surveyed. Implications and applications of these principles for light-harvesting dyes, catalysis and materials chemistry are summarised.
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Halcrow MA, Capel Berdiell I, Pask CM, Kulmaczewski R. Relationship between the Molecular Structure and Switching Temperature in a Library of Spin-Crossover Molecular Materials. Inorg Chem 2019; 58:9811-9821. [PMID: 31335133 DOI: 10.1021/acs.inorgchem.9b00843] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Structure-function relationships relating the spin-crossover (SCO) midpoint temperature (T1/2) in the solid state are surveyed for 43 members of the iron(II) dipyrazolylpyridine family of SCO compounds. The difference between T1/2 in the solid state and in solution [ΔT(latt)] is proposed as a measure of the lattice contribution to the transition temperature. Negative linear correlations between the SCO temperature and the magnitude of the rearrangement of the coordination sphere during SCO are evident among isostructural or near-isostructural subsets of compounds; that is, a larger change in the molecular structure during SCO stabilizes the high-spin state of a material. Improved correlations are often obtained when ΔT(latt), rather than the raw T1/2 value, is considered as the measure of the SCO temperature. Different lattice types show different tendencies to stabilize the high-spin or low-spin state of the molecules they contain, which correlates with the structural changes that most influence ΔT(latt) in each case. These relationships are mostly unaffected by the SCO cooperativity in the compounds or by the involvement of any crystallographic phase changes. One or two materials within each subset are outliers in some or all of these correlations, however, which, in some cases, can be attributed to small differences in their ligand geometry or unusual phase behavior during SCO. A reinvestigation of the structural chemistry of [Fe(3-bpp)2][NCS]2·nH2O [3-bpp = bis(1H-pyrazol-3-yl)pyridine; n = 0 or 2], undertaken as part of this study, is also presented.
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Affiliation(s)
- Malcolm A Halcrow
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Izar Capel Berdiell
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Christopher M Pask
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
| | - Rafal Kulmaczewski
- School of Chemistry , University of Leeds , Woodhouse Lane , Leeds LS2 9JT , U.K
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Gardinier JR, Meise KJ, Jahan F, Wang D, Lindeman SV. Selective Isomer Formation and Crystallization-Directed Magnetic Behavior in Nitrogen-Confused C-Scorpionate Complexes of Fe(O 3SCF 3) 2. Inorg Chem 2019; 58:8953-8968. [PMID: 31247826 DOI: 10.1021/acs.inorgchem.8b03454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The complex [Fe(HL*)2](OTf)2, 1, where HL* = bis(3,5-dimethylpyrazol-1-yl)(3-1H-pyrazole)methane, was prepared in order to compare its magnetic properties with those of the analogous parent complex, [Fe(HL)2](OTf)2, that lacks methyl groups on pyrazolyl rings and that undergoes spin crossover (SCO) from the low spin (LS) to the high spin (HS) form above room temperature. It was anticipated that this new semibulky derivative should favor the HS state and undergo SCO at a lower temperature range. During this study, six crystalline forms of 1 were prepared by controlling the crystallization conditions. Thus, when reagents are combined in CH3CN, an equilibrium mixture of cis and trans isomers is established that favors the latter below 311 K. The trans isomer can be isolated exclusively as a mixture of solvates, LS trans-1·2CH3CN and HS trans-1·4CH3CN, by cooling CH3CN solutions to -20 °C with the former being favored at high concentrations and short crystallization times. Subsequently, vapor diffusion of Et2O into CH3CN solutions of pure trans-1·2CH3CN gives solvate-free HS trans-1. Subjecting trans-1·2CH3CN to vacuum at room temperature gives microcrystalline trans-1·CH3CN, identified by elemental analysis and its distinct powder X-ray diffraction pattern. If an isomeric mixture of 1 is subject to room-temperature vapor diffusion, then a crystalline mixture of HS isomers cis-1 and trans-1 is obtained. Finally, slowly cooling hot acetonitrile solutions of isomeric mixtures of 1 to room temperature gives large prisms of HS co-1, a species with both cis and trans isomers in the unit cell. The complexes trans-1, trans-1·CH3CN, cis-1, and co-1 undergo SCO below 250 K while trans-1·xCH3CN (x = 2, 4) solvates do not undergo SCO before desolvation.
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Affiliation(s)
- James R Gardinier
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
| | - Kristin J Meise
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
| | - Fathiya Jahan
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
| | - Denan Wang
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
| | - Sergey V Lindeman
- Department of Chemistry , Marquette University , Milwaukee , Wisconsin 53201-1881 , United States
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Bond CJ, Sokolow GE, Crawley MR, Burns PJ, Cox JM, Mayilmurugan R, Morrow JR. Exploring Inner-Sphere Water Interactions of Fe(II) and Co(II) Complexes of 12-Membered Macrocycles To Develop CEST MRI Probes. Inorg Chem 2019; 58:8710-8719. [PMID: 31247845 DOI: 10.1021/acs.inorgchem.9b01072] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Several paramagnetic Co(II) and Fe(II) macrocyclic complexes were prepared with the goal of introducing a bound water ligand to produce paramagnetically shifted water 1H resonances and for paramagnetic chemical exchange saturation transfer (paraCEST) applications. Three 12-membered macrocycles with amide pendent groups including 1,7-bis(carbamoylmethyl)-1,4,7,10-tetraazacyclodocane (DCMC), 4,7,10-tris(carbamoylmethyl)-,4,7,10-triaza-12-crown-ether (N3OA), and 4,10-bis(carbamoylmethyl)-4,10-diaza-12-crown-ether (NODA) were prepared and their Co(II) complexes were characterized in the solid state and in solution. The crystal structure of [Co(DCMC)]Br2 featured a six-coordinated Co(II) center with distorted octahedral geometry, while [Co(NODA)(OH2)]Cl2 and [Co(N3OA)](NO3)2 were seven-coordinated. The analogous Fe(II) complexes of NODA and NO3A were successfully prepared, but the complex of DCMC oxidized rapidly to the Fe(III) form. Similarly, [Fe(NODA)]2+ oxidized over several days, forming crystals of the Fe(III) complex isolated as the μ-O bridged dimer. Magnetic susceptibility values and paramagnetic NMR spectra of the Fe(II) complexes of NODA and N3OA, as well as Co(II) complexes of DCMC, NODA, and N3OA, were consistent with high spin complexes. CEST peaks ranging from 60 ppm to 70 ppm, attributed to NH groups of the amide pendents, were identified. Variable-temperature 17O NMR spectra of Co(II) and Fe(II) NODA complexes were consistent with rapid exchange of the water ligand with bulk water. Notably, the Co(II) and Fe(II) complexes presented here produced substantial paramagnetic shifts of bulk water 1H resonances, independent of having an inner-sphere water.
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Affiliation(s)
- Christopher J Bond
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Gregory E Sokolow
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Matthew R Crawley
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Patrick J Burns
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Jordan M Cox
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Ramasamy Mayilmurugan
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
| | - Janet R Morrow
- Department of Chemistry , University at Buffalo, State University of New York , Amherst , New York 14260 , United States
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Rodríguez-Jiménez S, Brooker S. Qualitative Guest Sensing via Iron(II) Triazole Complexes. Inorg Chem 2019; 58:8188-8197. [PMID: 31124665 DOI: 10.1021/acs.inorgchem.9b01006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The pyridazine-pyridine triazole-based Rat ligand, Lpydzpy [4-(4-methylphenyl)-3-(3-pyridazinyl)-5-(2-pyridinyl)-1,2,4-triazole], is potentially ditopic. Nevertheless, Lpydzpy is shown herein to exclusively form mononuclear iron(II) complexes, [FeII(Lpydzpy)2(NCE)2]·solvent, in the presence of coordinating NCE anions (E = S or Se). Specifically, a new family of 10 mononuclear complexes, in which Lpydzpy binds in a monotopic bidentate manner, has been made: two solvent-free complexes, [FeII(Lpydzpy)2(NCS)2] (1) and [FeII(Lpydzpy)2(NCSe)2] (2); six solvatomorphs, 1·4CH3CN, 2·4CH3CN, 1·2.25CH3CN, 2·3CH3CN, 2·tetrahydrofuran, and 2·CHCl3; and a pair of desolvated polymorphs, 1' and 2'. Seven of them are spin crossover-active, the exceptions being 1, 2, and 2'. This is confirmed by single-crystal X-ray diffraction (XRD) for 1, 2, 1·4CH3CN, and 2·4CH3CN and is consistent with variable-temperature optical microscopy observations on single crystals of 1·4CH3CN and 2·4CH3CN and on samples of 1' and 2'. Powder XRD, thermogravimetric analysis, and solid-state magnetometry reveal that desolvated 1' and 2' are capable of absorbing and desorbing a range of volatile guests: CH3CN in both cases and also tetrahydrofuran and CHCl3 in the case of 2'.
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Affiliation(s)
- Santiago Rodríguez-Jiménez
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
| | - Sally Brooker
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology , University of Otago , P.O. Box 56, Dunedin 9054 , New Zealand
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Scepaniak JJ, Kang EB, John M, Kaminsky W, Dechert S, Meyer F. Non‐Macrocyclic Schiff Base Complexes of Iron(II) as ParaCEST Agents for MRI. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201801565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Jeremiah J. Scepaniak
- Institut für Anorganische Chemie Georg‐August‐Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
- Department of Chemistry Drexel University 32 S. 32nd St. Disque Hall 506 19104 Philadelphia PA USA
| | - Eun Byoung Kang
- Department of Chemistry Drexel University 32 S. 32nd St. Disque Hall 506 19104 Philadelphia PA USA
| | - Michael John
- Institut für Anorganische Chemie Georg‐August‐Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Werner Kaminsky
- Department of Chemistry University of Washington Box 351700 98195‐1700 Seattle WA USA
| | - Sebastian Dechert
- Institut für Anorganische Chemie Georg‐August‐Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
| | - Franc Meyer
- Institut für Anorganische Chemie Georg‐August‐Universität Göttingen Tammannstrasse 4 37077 Göttingen Germany
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Du K, Thorarinsdottir AE, Harris TD. Selective Binding and Quantitation of Calcium with a Cobalt-Based Magnetic Resonance Probe. J Am Chem Soc 2019; 141:7163-7172. [PMID: 30946580 DOI: 10.1021/jacs.9b02661] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
We report a cobalt-based paramagnetic chemical exchange saturation transfer (PARACEST) magnetic resonance (MR) probe that is able to selectively bind and quantitate the concentration of Ca2+ ions under physiological conditions. The parent LCo complex features CEST-active carboxamide groups and an uncoordinated crown ether moiety in close proximity to a high-spin pseudo-octahedral CoII center. Addition of Na+, Mg2+, K+, and Ca2+ leads to binding of these metal ions within the crown ether. Single-crystal X-ray diffraction and solid-state magnetic measurements reveal the presence of a cation-specific coordination environment and magnetic anisotropy of CoII, with axial zero-field splitting parameters for the Na+- and Ca2+-bound complexes differing by over 90%. Owing to these differences, solution-based measurements under physiological conditions indicate reversible binding of Na+ and Ca2+ to give well-separated CEST peaks at 69 and 80 ppm for [LCoNa]+ and [LCoCa]2+, respectively. Dissociation constants for different cation-bound complexes of LCo, as determined by 1H NMR spectroscopy, demonstrate high selectivity toward Ca2+. This finding, in conjunction with the large excess of Na+ in physiological environments, minimizes interference from related cations, such as Mg2+ and K+. Finally, variable-[Ca2+] CEST spectra establish the ratio between the CEST peak intensities for the Ca2+- and Na+-bound probes (CEST80 ppm/CEST69 ppm) as a measure of [Ca2+], providing the first example of a ratiometric quantitation of Ca2+ concentration using PARACEST. Taken together, these results demonstrate the ability of transition metal PARACEST probes to afford a concentration-independent measure of [Ca2+] and provide a new approach for designing MR probes for cation sensing.
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Affiliation(s)
- Kang Du
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - Agnes E Thorarinsdottir
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
| | - T David Harris
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208-3113 , United States
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Corbin BA, Pollard AC, Allen MJ, Pagel MD. Summary of Imaging in 2020: Visualizing the Future of Healthcare with MR Imaging. Mol Imaging Biol 2019; 21:193-199. [PMID: 30680525 PMCID: PMC6450763 DOI: 10.1007/s11307-019-01315-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Imaging in 2020 meeting convenes biannually to discuss innovations in medical imaging. The 2018 meeting, titled "Visualizing the Future of Healthcare with MR Imaging," sought to encourage discussions of the future goals of MRI research, feature important discoveries, and foster scientific discourse between scientists from a variety of fields of expertise. Here, we highlight presented research and resulting discussions of the meeting.
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Affiliation(s)
- Brooke A Corbin
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, USA
| | - Alyssa C Pollard
- Department of Chemistry, Rice University, 6100 S Main Street, Houston, TX, USA
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, 1881 East Road, Houston, TX, USA
| | - Matthew J Allen
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, USA.
| | - Mark D Pagel
- Department of Chemistry, Rice University, 6100 S Main Street, Houston, TX, USA.
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, 1881 East Road, Houston, TX, USA.
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Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties. MAGNETOCHEMISTRY 2019. [DOI: 10.3390/magnetochemistry5010019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As observed in the few parent examples that are based on the symmetrical N-functionalized tacn ligands, the triazacyclononane ring is facially coordinated and the N-donor atoms of the three functional groups (two pyridine and one aniline groups) are disposed in the same side of the tacn ring, leading to a distorted FeN6 environment. The magnetic studies of 1 revealed the presence of an incomplete spin crossover (SCO) transition above 425 K, whose progress would be prevented by a very exothermic thermal decomposition at ca. 472 K, as shown by thermogravimetric and DSC measurements.
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Dey B, Roy S, Titiš J, Boča R, Bera SP, Mondal A, Konar S. Above Room Temperature Spin Transition in Thermally Stable Mononuclear Fe(III) Complexes. Inorg Chem 2019; 58:1134-1146. [DOI: 10.1021/acs.inorgchem.8b02405] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Bijoy Dey
- Department of Chemistry, IISER Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Subhadip Roy
- Department of Chemistry, IISER Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Ján Titiš
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 917 01 Trnava, Slovakia
| | - Roman Boča
- Department of Chemistry, Faculty of Natural Sciences, University of SS Cyril and Methodius, 917 01 Trnava, Slovakia
| | - Siba Prasad Bera
- Department of Chemistry, IISER Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Arpan Mondal
- Department of Chemistry, IISER Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Sanjit Konar
- Department of Chemistry, IISER Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
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Thorarinsdottir AE, Harris TD. Dramatic enhancement in pH sensitivity and signal intensity through ligand modification of a dicobalt PARACEST probe. Chem Commun (Camb) 2019; 55:794-797. [DOI: 10.1039/c8cc09520e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A ratiometric dicobalt PARACEST pH probe that exhibits dramatic enhancements in sensitivity and signal intensity over analogous probes is reported.
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Wolny JA, Schünemann V, Németh Z, Vankó G. Spectroscopic techniques to characterize the spin state: Vibrational, optical, Mössbauer, NMR, and X-ray spectroscopy. CR CHIM 2018. [DOI: 10.1016/j.crci.2018.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Application of spin-crossover water soluble nanoparticles for use as MRI contrast agents. Sci Rep 2018; 8:14911. [PMID: 30297794 PMCID: PMC6175957 DOI: 10.1038/s41598-018-33362-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/26/2018] [Indexed: 11/26/2022] Open
Abstract
Water soluble spin-crossover (SCO) iron(II) nanoparticles (NPs) were synthesized by the polyethylene glycol (PEG) coating of [Fe(Htrz)3-3×(NH2trz)3×](BF4)2 (x = 0, 0.1, 0.5 and 1). The NPs with x = 0.1 show gradual SCO behavior over 280–330 K in water. The relaxation times, T1 and T2, were determined and the thermally-responsive T2 values making these NPs a candidate for use as a MRI contrast agent.
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Nebbali K, Mekuimemba CD, Charles C, Yefsah S, Chastanet G, Mota AJ, Colacio E, Triki S. One-Dimensional Thiocyanato-Bridged Fe(II) Spin Crossover Cooperative Polymer With Unusual FeN 5S Coordination Sphere. Inorg Chem 2018; 57:12338-12346. [PMID: 30207469 DOI: 10.1021/acs.inorgchem.8b02061] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present here a novel example of spin crossover phenomenon on a Fe(II) one-dimensional chain with unusual N5S coordination sphere. The [{Fe(tpc-OMe)(NCS)(μ-NCS)} n] (1) compound was prepared using the tridentate tpc-OMe ligand (tpc-OMe = tris(2-pyridyl)methoxymethane), FeCl2·4H2O, and the KSCN salt. Crystallographic investigations revealed that the Fe(II) ions are connected by a single bridging NCS- ligand (μ-κN:κS-SCN coordination mode) to afford a zigzag neutral chain running along the [010] direction, in which the thiocyanato bridging groups adopt a cis head-to-tail configuration. The (N5S) metal environment arises from one thiocyanato-κS and two thiocyanato-κN ligands and from three pyridine of the fac-tpc-OMe tripodal ligand. This compound presents a unique extension of Fe(II) binuclear complexes into linear chains built on similar tripodal ligands and bridging thiocyanate anions. Compound 1 shows a spin crossover (SCO) behavior which has been evidenced by magnetic, calorimetric, and structural investigations, revealing a sharp cooperative spin transition with a transition temperature of ca. 199 K. Temperature scan rate studies revealed a very narrow hysteresis loop (∼1 K wide). Photoswitching of this compound was also performed, evidencing a very fast relaxation process at low temperature. Among other factors, the linearity of the N-bound terminal thiocyanato ligand appears as the main structural characteristic at the origin of the presence of the SCO transition in compound 1 and in the two others Fe(II) previous systems involving thiocyanato-bridges and tripodal tris(2-pyridyl)methane ligands.
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Affiliation(s)
- Kahina Nebbali
- UMR-CNRS 6521 , University de Brest (UBO) , 6 Av. V. Le Gorgeu , C.S. 93837, F-29238, Brest CEDEX 3 , France.,Faculté des Sciences , Université Mouloud Mammeri , Tizi-Ouzou 15000 , Algérie
| | - Cle Donacier Mekuimemba
- UMR-CNRS 6521 , University de Brest (UBO) , 6 Av. V. Le Gorgeu , C.S. 93837, F-29238, Brest CEDEX 3 , France
| | - Catherine Charles
- UMR-CNRS 6521 , University de Brest (UBO) , 6 Av. V. Le Gorgeu , C.S. 93837, F-29238, Brest CEDEX 3 , France
| | - Said Yefsah
- Faculté des Sciences , Université Mouloud Mammeri , Tizi-Ouzou 15000 , Algérie
| | - Guillaume Chastanet
- Institut de Chimie de la Matière Condensée de Bordeaux , Universite de Bordeaux́ , 87 Av. Doc. A. Schweitzer , F-33608 Pessac , France
| | - Antonio J Mota
- Departamento de Química Inorgánica, Facultad de Ciencias , Universidad de Granada , Av. Fuentenueva S/N , 18071 Granada , Spain
| | - Enrique Colacio
- Departamento de Química Inorgánica, Facultad de Ciencias , Universidad de Granada , Av. Fuentenueva S/N , 18071 Granada , Spain
| | - Smail Triki
- UMR-CNRS 6521 , University de Brest (UBO) , 6 Av. V. Le Gorgeu , C.S. 93837, F-29238, Brest CEDEX 3 , France
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Thorarinsdottir AE, Tatro SM, Harris TD. Electronic Effects of Ligand Substitution in a Family of CoII2 PARACEST pH Probes. Inorg Chem 2018; 57:11252-11263. [DOI: 10.1021/acs.inorgchem.8b01896] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
| | - Scott M. Tatro
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - T. David Harris
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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García-López V, Waerenborgh JC, Vieira BJC, Clemente-León M, Coronado E. Iron(ii) complexes of tris(2-pyridylmethyl)amine (TPMA) and neutral bidentate ligands showing thermal- and photo-induced spin crossover. Dalton Trans 2018; 47:9156-9163. [PMID: 29946627 DOI: 10.1039/c8dt01425f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three new mononuclear Fe(ii) complexes have been prepared and characterized by the combination of tetradentate tris(2-pyridylmethyl)amine (TPMA) with three neutral bidentate ligands, such as ethylenediamine (en), 1,2-diaminopropane (pn) and 2-picolylamine (2-pic), in compounds [FeII(TPMA)(en)](ClO4)2 (1), [FeII(TPMA)(2-pic)](ClO4)2 (2) and [FeII(TPMA)(pn)](ClO4)2 (3). Structural and magnetic characterization demonstrates that the three compounds present a complete SCO behavior. The absence of strong intermolecular interactions and solvent molecules leads to reversible and gradual spin transitions. The different ligands allow tuning T1/2 from 130 K (2) to 325 K (3). The compound with the lowest T1/2 (2) shows the LIESST effect with a TLIESST of 43 K. Interestingly, the use of these relatively small bidentate ligands leads to the crystallization in non-centrosymmetric space groups in contrast with previous studies using other bidentate ligands.
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Affiliation(s)
- Víctor García-López
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático José Beltrán 2, 46980 Paterna, Spain.
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Tsitovich PB, Gendron F, Nazarenko AY, Livesay BN, Lopez AP, Shores MP, Autschbach J, Morrow JR. Low-Spin Fe(III) Macrocyclic Complexes of Imidazole-Appended 1,4,7-Triazacyclononane as Paramagnetic Probes. Inorg Chem 2018; 57:8364-8374. [DOI: 10.1021/acs.inorgchem.8b01022] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Pavel B. Tsitovich
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Frédéric Gendron
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Alexander Y. Nazarenko
- Chemistry Department, State University of New York, College at Buffalo, 1300 Elmwood Avenue, Buffalo, New York 14222, United States
| | - Brooke N. Livesay
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Alejandra P. Lopez
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Matthew P. Shores
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
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47
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Tsukiashi A, Min KS, Terasawa H, Yoshinaga S, Takeda M, Ohtani R, Nakamura M, Lindoy LF, Hayami S. Proton Relaxation Time in Water-soluble Metal Complex Nanoparticles. CHEM LETT 2018. [DOI: 10.1246/cl.180038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Asami Tsukiashi
- Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Kil Sik Min
- Department of Chemistry Education and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea
| | - Hiroaki Terasawa
- Department of Structural Bioimaging, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Sosuke Yoshinaga
- Department of Structural Bioimaging, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Mitsuhiro Takeda
- Department of Structural Bioimaging, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Ryo Ohtani
- Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | - Masaaki Nakamura
- Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
| | | | - Shinya Hayami
- Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan
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Tsitovich PB, Tittiris TY, Cox JM, Benedict JB, Morrow JR. Fe(ii) and Co(ii) N-methylated CYCLEN complexes as paraSHIFT agents with large temperature dependent shifts. Dalton Trans 2018; 47:916-924. [PMID: 29260180 DOI: 10.1039/c7dt03812g] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Several complexes of Co(ii) or Fe(ii) with 1,4,7,10-tetraazacyclododecane (CYCLEN) appended with 1,7-(6-methyl)2-picolyl groups are studied as 1H NMR paraSHIFT agents (paramagnetic shift agents) for the registration of temperature. Two of the complexes, [Co(BMPC)]2+ and [Fe(BMPC)]2+, contain methyl groups only on the methyl picolyl pendents. Two other complexes, [Co(2MPC)]2+ and [Fe(2MPC)]2+, contain picolyl groups and also methyl groups on the macrocyclic amines. All macrocyclic complexes are in high spin form as shown by solution magnetic moments in the range of 5.0-5.9μBM and 5.3-5.8μBM for Co(ii) and Fe(ii) complexes, respectively. The 1H NMR spectra of both of the Fe(ii) complexes and one of the Co(ii) complexes are consistent with a predominant diastereomeric form in deuterium oxide solutions. The highly shifted methyl proton resonances for [Co(2MPC)]2+ appear at 164 and -113 ppm for macrocycle and pendent picolyl methyls and show temperature coefficients of -0.58 ppm °C-1 and 0.49 ppm °C-1, respectively. Fe(ii) complexes have less shifted methyl proton resonances and smaller temperature coefficients. The 1H resonances of [Fe(2MPC)]2+ appear at 105 ppm and -46 ppm with corresponding temperature coefficients (CT) of -0.29 ppm °C-1 and 0.22 ppm °C-1, respectively. The relatively narrow linewidths of [Fe(2MPC)]2+, however, produce superior CT/FWHM values of 0.44 and 0.31 °C-1 for the N-methyl and picolyl proton resonances where FWHM is the full width at half maximum of the 1H resonance. The crystal structure of [Co(BMPC)]Cl2 shows a six-coordinate Co(ii) bound to the macrocyclic amines and two pendent picolyl groups. The distorted trigonal prismatic geometry of the complex resembles that of an analogous complex containing four 6-methyl-2-picolyl groups, in which only two picolyl pendents are coordinated.
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Affiliation(s)
- Pavel B Tsitovich
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, NY 14260, USA.
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Abozeid SM, Snyder EM, Tittiris TY, Steuerwald CM, Nazarenko AY, Morrow JR. Inner-Sphere and Outer-Sphere Water Interactions in Co(II) paraCEST Agents. Inorg Chem 2018; 57:2085-2095. [DOI: 10.1021/acs.inorgchem.7b02977] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Samira M. Abozeid
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Eric M. Snyder
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Timothy Y. Tittiris
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Charles M. Steuerwald
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
| | - Alexander Y. Nazarenko
- Chemistry Department, SUNY College at Buffalo, 1300 Elmwood Avenue, Buffalo, New York 14222, United States
| | - Janet R. Morrow
- Department of Chemistry, University at Buffalo, State University of New York, Amherst, New York 14260, United States
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Attwood M, Turner SS. Back to back 2,6-bis(pyrazol-1-yl)pyridine and 2,2′:6′,2″-terpyridine ligands: Untapped potential for spin crossover research and beyond. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.09.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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