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Seredyuk M, Znovjyak K, Valverde-Muñoz FJ, Muñoz MC, Fritsky IO, Real JA. Rotational order-disorder and spin crossover behaviour in a neutral iron(II) complex based on asymmetrically substituted large planar ionogenic ligand. Dalton Trans 2024; 53:8041-8049. [PMID: 38652019 DOI: 10.1039/d4dt00368c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Octahedrally coordinated spin crossover (SCO) FeII complexes represent an important class of switchable molecular materials. This study presents the synthesis and characterisation of a novel complex, [FeII(ppt-2Fph)2]0·2MeOH, where ppt-2Fph is a new asymmetric ionogenic tridentate planar ligand 2-(5-(2-fluorophenyl)-4H-1,2,4-triazol-3-yl)-6-(1H-pyrazol-1-yl)pyridine. The complex exhibits a hysteretic thermally induced SCO transition at 285 K on cooling and at 293 K on heating, as well as light induced excited spin state trapping (LIESST) at lower temperatures with a relaxation T(LIESST) temperature of 73 K. Single crystal analysis in both spin states shows that the compound undergoes an unusual partial (25%) reversible order-disorder of the asymmetrically substituted phenyl group coupled to the thermal SCO. The highly cooperative SCO transition, analysed by structural energy framework analysis at the B3LYP/6-31G(d,p) theory level, revealed the co-existence of stabilising and destabilising energy variations in the lattice. The observed antagonism of intermolecular interactions and synchronous rotational disorder, which contributes to the overall entropy change, is suggested to be at the origin of the cooperative SCO transition.
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Affiliation(s)
- Maksym Seredyuk
- Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, 01601 Kyiv, Ukraine.
- Instituto de Ciencia Molecular, Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain.
- Enamine Ltd., Winston Churchill Str. 78, 02094 Kyiv, Ukraine
| | - Kateryna Znovjyak
- Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, 01601 Kyiv, Ukraine.
| | - Francisco Javier Valverde-Muñoz
- Instituto de Ciencia Molecular, Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain.
| | - M Carmen Muñoz
- Departamento de Física Aplicada, Universitat Politècnica de València, Camino de Vera s/n, E-46022, Valencia, Spain
| | - Igor O Fritsky
- Department of Chemistry, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, 01601 Kyiv, Ukraine.
| | - José Antonio Real
- Instituto de Ciencia Molecular, Departamento de Química Inorgánica, Universidad de Valencia, 46980 Paterna, Valencia, Spain.
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Patyk-Kaźmierczak E, Izquierdo-Ruiz F, Lobato A, Kaźmierczak M, Moszczyńska I, Olejniczak A, Recio JM. The curious case of proton migration under pressure in the malonic acid and 4,4'-bipyridine cocrystal. IUCRJ 2024; 11:168-181. [PMID: 38275161 PMCID: PMC10916288 DOI: 10.1107/s2052252524000344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/09/2024] [Indexed: 01/27/2024]
Abstract
In the search for new active pharmaceutical ingredients, the precise control of the chemistry of cocrystals becomes essential. One crucial step within this chemistry is proton migration between cocrystal coformers to form a salt, usually anticipated by the empirical ΔpKa rule. Due to the effective role it plays in modifying intermolecular distances and interactions, pressure adds a new dimension to the ΔpKa rule. Still, this variable has been scarcely applied to induce proton-transfer reactions within these systems. In our study, high-pressure X-ray diffraction and Raman spectroscopy experiments, supported by DFT calculations, reveal modifications to the protonation states of the 4,4'-bipyridine (BIPY) and malonic acid (MA) cocrystal (BIPYMA) that allow the conversion of the cocrystal phase into ionic salt polymorphs. On compression, neutral BIPYMA and monoprotonated (BIPYH+MA-) species coexist up to 3.1 GPa, where a phase transition to a structure of P21/c symmetry occurs, induced by a double proton-transfer reaction forming BIPYH22+MA2-. The low-pressure C2/c phase is recovered at 2.4 GPa on decompression, leading to a 0.7 GPa hysteresis pressure range. This is one of a few studies on proton transfer in multicomponent crystals that shows how susceptible the interconversion between differently charged species is to even slight pressure changes, and how the proton transfer can be a triggering factor leading to changes in the crystal symmetry. These new data, coupled with information from previous reports on proton-transfer reactions between coformers, extend the applicability of the ΔpKa rule incorporating the pressure required to induce salt formation.
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Affiliation(s)
- Ewa Patyk-Kaźmierczak
- Facuty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań 61-614, Poland
| | - Fernando Izquierdo-Ruiz
- MALTA-Consolider Team and Departamento de Química Física, University Complutense of Madrid, Avda. de Séneca, 2 Ciudad Universitaria, Madrid 28040, Spain
| | - Alvaro Lobato
- MALTA-Consolider Team and Departamento de Química Física, University Complutense of Madrid, Avda. de Séneca, 2 Ciudad Universitaria, Madrid 28040, Spain
| | - Michał Kaźmierczak
- Facuty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań 61-614, Poland
| | - Ida Moszczyńska
- Facuty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań 61-614, Poland
| | - Anna Olejniczak
- Facuty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań 61-614, Poland
| | - J. Manuel Recio
- MALTA-Consolider Team and Departamento de Química Física y Analítica, University of Oviedo, Julián Clavería n° 8, Oviedo 33006, Spain
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Paliwoda D, Vendier L, Nicolazzi W, Molnár G, Bousseksou A. Pressure Tuning of Coupled Structural and Spin State Transitions in the Molecular Complex [Fe(H 2B(pz) 2) 2(phen)]. Inorg Chem 2022; 61:15991-16002. [PMID: 36162137 DOI: 10.1021/acs.inorgchem.2c02286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The large volume change, which accompanies the molecular spin crossover (SCO) phenomenon in some transition metal complexes, prompts frequently the coupling of the SCO with other instabilities. Understanding the driving mechanism(s) of such coupled phase transitions is not only important for fundamental reasons but also provides scope for the development of multifunctional materials. The general theoretical expectation is that the coupling has elastic origin, and the sequence of transitions can be tuned by an externally applied pressure, but dedicated experiments remain scarce. Here, we used high-pressure and low-temperature single-crystal X-ray diffraction to investigate the high-spin (HS) to low-spin (LS) transitions in the molecular complexes [FeII(H2B(pz)2)2(bipy)] and [FeII(H2B(pz)2)2(phen)]. In the bipyridine complex, the SCO is continuous and isostructural over the whole T, P-range (100-300 K, 0-2 GPa). In the phenanthroline derivative, however, the SCO is concomitant with a symmetry-breaking transition (C2/c to P1̅). Structural analysis reveals that the coupling between the two phenomena can be tuned by external pressure from a virtually simultaneous HSC2/c-LSP1̅ transition to the sequence of HSC2/c-LSC2/c-LSP1̅ transitions. The correlation of spontaneous strain and order parameter behaviors highlights that the "separated" transitions remain still connected via strain coupling, whereas the "simultaneous" transitions are partially split.
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Affiliation(s)
- Damian Paliwoda
- LCC, CNRS & Université de Toulouse (UPS, INP), 31077 Toulouse, France
| | - Laure Vendier
- LCC, CNRS & Université de Toulouse (UPS, INP), 31077 Toulouse, France
| | - William Nicolazzi
- LCC, CNRS & Université de Toulouse (UPS, INP), 31077 Toulouse, France
| | - Gábor Molnár
- LCC, CNRS & Université de Toulouse (UPS, INP), 31077 Toulouse, France
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Fernández-Blanco Á, Mariano LA, Piñeiro-López L, Real JA, Costa JS, Poloni R, Rodríguez-Velamazán JA. Hidden ordered structure in the archetypical Fe(pyrazine)[Pt(CN) 4] spin-crossover porous coordination compound. CrystEngComm 2022. [DOI: 10.1039/d2ce00895e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The actual low-spin state of Fe(pyrazine)Pt(CN)4 implies an ordered arrangement of the pyrazine rings, which significantly affects the spin transition.
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Affiliation(s)
- Ángel Fernández-Blanco
- Institut Laue Langevin, 71 Avenue des Martyrs, CS 20156-38042, Grenoble, France
- Univ. Grenoble Alpes, SIMaP, Grenoble-INP, CNRS, F-38042, Grenoble, France
| | - Lorenzo A. Mariano
- Univ. Grenoble Alpes, SIMaP, Grenoble-INP, CNRS, F-38042, Grenoble, France
| | - Lucía Piñeiro-López
- IMDEA Nanociencia, Faraday 9, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain
| | - José Antonio Real
- Departamento de Química Inorgánica, Insituto de Ciencia Molecular (ICMol), Universidad de Valencia, 46980, Paterna, Spain
| | - Jose Sanchez Costa
- IMDEA Nanociencia, Faraday 9, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain
| | - Roberta Poloni
- Univ. Grenoble Alpes, SIMaP, Grenoble-INP, CNRS, F-38042, Grenoble, France
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Romanenko GV, Letyagin GA, Ovcharenko VI. Effect of pressure on the structure of multispin complexes. RUSSIAN CHEMICAL REVIEWS 2022. [DOI: 10.1070/rcr5028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Attwood M, Akutsu H, Martin L, Blundell TJ, Le Maguere P, Turner SS. Exceptionally high temperature spin crossover in amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine iron(ii) complex revealed by variable temperature Raman spectroscopy and single crystal X-ray diffraction. Dalton Trans 2021; 50:11843-11851. [PMID: 34369514 DOI: 10.1039/d1dt01743h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of a novel amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine-4-carboxamide ligand (bppCONH2) is described. The complex salts [Fe(bppCONH2)2](BF4)2 and [Fe(bppCONH2)2](ClO4)2 were synthesised and characterised by SQUID magnetometry, differential scanning calorimetry, variable temperature Raman spectroscopy and single crystal X-ray diffraction. DSC measurements of [Fe(bppCONH2)2](BF4)2 indicate a spin-crossover (SCO) transition with T↑ at 481 K and T↓ at 461 K, showing a 20 K hysteresis. DSC for the perchlorate salt shows an SCO transition with T↑ at 459 K and T↓ at 445 K with a 14 K hysteresis. For the BF4- salt analysis of low and high-spin state crystal structures at 101, 290 and 500 K, suggest stabilisation of the low spin state due to the formation of 1D hydrogen-bonded cationic chains. Variable temperature Raman studies of the BF4 salt support the presence of a high temperature SCO. It is speculated that the presence of hysteresis may be attributed to differences in the inter-molecular hydrogen bonding in the low spin and high spin states.
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Affiliation(s)
- Max Attwood
- Department of Chemistry, University of Surrey, Guildford, GU2 7XH, UK.
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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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Phukkaphan N, Cruickshank DL, Murray KS, Phonsri W, Harding P, Harding DJ. Hysteretic spin crossover driven by anion conformational change. Chem Commun (Camb) 2017; 53:9801-9804. [DOI: 10.1039/c7cc05998a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An air stable FeIII complex showing a wide hysteresis near room temperature is described. The origin of the cooperativity is an unprecedented anion conformational change.
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Affiliation(s)
- Natnaree Phukkaphan
- Functional Materials and Nanotechnology Center of Excellence
- Walailak University
- Thasala
- Thailand
| | | | | | | | - Phimphaka Harding
- Functional Materials and Nanotechnology Center of Excellence
- Walailak University
- Thasala
- Thailand
| | - David J. Harding
- Functional Materials and Nanotechnology Center of Excellence
- Walailak University
- Thasala
- Thailand
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