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Kühne IA, Ozarowski A, Sultan A, Esien K, Carter AB, Wix P, Casey A, Heerah-Booluck M, Keene TD, Müller-Bunz H, Felton S, Hill S, Morgan GG. Homochiral Mn 3+ Spin-Crossover Complexes: A Structural and Spectroscopic Study. Inorg Chem 2022; 61:3458-3471. [PMID: 35175771 PMCID: PMC8889584 DOI: 10.1021/acs.inorgchem.1c03379] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Structural, magnetic,
and spectroscopic data on a Mn3+ spin-crossover complex
with Schiff base ligand 4-OMe-Sal2323, isolated in crystal
lattices with five different counteranions,
are reported. Complexes of [Mn(4-OMe-Sal2323)]X where X
= ClO4– (1), BF4– (2), NO3– (3), Br– (4), and I– (5) crystallize isotypically in the chiral
orthorhombic space group P21212 with a range of spin state preferences for the [Mn(4-OMe-Sal2323)]+ complex cation over the temperature range
5–300 K. Complexes 1 and 2 are high-spin,
complex 4 undergoes a gradual and complete thermal spin
crossover, while complexes 3 and 5 show
stepped crossovers with different ratios of spin triplet and quintet
forms in the intermediate temperature range. High-field electron paramagnetic
resonance was used to measure the zero-field splitting parameters
associated with the spin triplet and quintet states at temperatures
below 10 K for complexes 4 and 2 with respective
values: DS=1 = +23.38(1) cm–1, ES=1 = +2.79(1) cm–1,
and DS=2 =
+6.9(3) cm–1, with a distribution of E parameters for the S = 2 state. Solid-state circular
dichroism (CD) spectra on high-spin complex 1 at room
temperature reveal a 2:1 ratio of enantiomers in the chiral conglomerate,
and solution CD measurements on the same sample in methanol show that
it is stable toward racemization. Solid-state UV–vis absorption
spectra on high-spin complex 1 and mixed S = 1/S = 2 sample 5 reveal different
intensities at higher energies, in line with the different electronic
composition. The statistical prevalence of homochiral crystallization
of [Mn(4-OMe-Sal2323)]+ in five lattices with
different achiral counterions suggests that the chirality may be directed
by the 4-OMe-Sal2323 ligand. Zero-field
splitting parameters of the spin triplet and
quintet forms of a spin-crossover Mn3+ complex stabilized
in lattices with different counterions are measured by high-field
electron paramagnetic resonance at different frequencies. The homochiral
crystallization of the enantiopure Δ or Λ forms of the
chelate complex, despite the use of achiral anions, is attributed
to the steric influence of the ligand substituent.
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Affiliation(s)
- Irina A Kühne
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland.,FZU - Institute of Physics - Czech Academy of Sciences, Na Slovance 1999/2, Prague 8 182 21, Czech Republic
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Aizuddin Sultan
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | - Kane Esien
- School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - Anthony B Carter
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | - Paul Wix
- School of Chemistry & CRANN Institute & AMBER Centre, Trinity College Dublin, University of Dublin, College Green, Dublin 2, Ireland
| | - Aoife Casey
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | | | - Tony D Keene
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | - Helge Müller-Bunz
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
| | - Solveig Felton
- School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - Stephen Hill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States.,Department of Physics, Florida State University, Tallahassee, Florida 32306, United States
| | - Grace G Morgan
- School of Chemistry, University College Dublin (UCD), Belfield, Dublin 4, Ireland
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2
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Tadyszak K, Wychowaniec JK, Załęski K, Coy E, Majchrzycki Ł, Carmieli R. Tuning Properties of Partially Reduced Graphene Oxide Fibers upon Calcium Doping. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E957. [PMID: 32443522 PMCID: PMC7325576 DOI: 10.3390/nano10050957] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 02/07/2023]
Abstract
The arrangement of two-dimensional graphene oxide sheets has been shown to influence physico-chemical properties of the final bulk structures. In particular, various graphene oxide microfibers remain of high interest in electronic applications due to their wire-like thin shapes and the ease of hydrothermal fabrication. In this research, we induced the internal ordering of graphene oxide flakes during typical hydrothermal fabrication via doping with Calcium ions (~6 wt.%) from the capillaries. The Ca2+ ions allowed for better graphene oxide flake connections formation during the hydrogelation and further modified the magnetic and electric properties of structures compared to previously studied aerogels. Moreover, we observed the unique pseudo-porous fiber structure and flakes connections perpendicular to the long fiber axis. Pulsed electron paramagnetic resonance (EPR) and conductivity measurements confirmed the denser flake ordering compared to previously studied aerogels. These studies ultimately suggest that doping graphene oxide with Ca2+ (or other) ions during hydrothermal methods could be used to better control the internal architecture and thus tune the properties of the formed structures.
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Affiliation(s)
- Krzysztof Tadyszak
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Jacek K. Wychowaniec
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland;
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland; (K.Z.); (E.C.)
| | - Karol Załęski
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland; (K.Z.); (E.C.)
| | - Emerson Coy
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614 Poznań, Poland; (K.Z.); (E.C.)
| | - Łukasz Majchrzycki
- Center of Advanced Technology, Adam Mickiewicz University, ul. Uniwersytetu Poznańskiego 10, 61-614 Poznań, Poland;
| | - Raanan Carmieli
- Department of Chemical Research Support, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel;
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3
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Tadyszak K, Musiał A, Ostrowski A, Wychowaniec JK. Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E798. [PMID: 32326319 PMCID: PMC7221827 DOI: 10.3390/nano10040798] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/12/2020] [Accepted: 04/17/2020] [Indexed: 01/17/2023]
Abstract
Carbon nanostructures are utilized in a plethora of applications ranging from biomedicine to electronics. Particularly interesting are carbon nanostructured quantum dots that can be simultaneously used for bimodal therapies with both targeting and imaging capabilities. Here, magnetic and optical properties of graphene oxide quantum dots (GOQDs) prepared by the top-down technique from graphene oxide and obtained using the Hummers' method were studied. Graphene oxide was ultra-sonicated, boiled in HNO3, ultra-centrifuged, and finally filtrated, reaching a mean flake size of ~30 nm with quantum dot properties. Flake size distributions were obtained from scanning electron microscopy (SEM) images after consecutive preparation steps. Energy-dispersive X-ray (EDX) confirmed that GOQDs were still oxidized after the fabrication procedure. Magnetic and photoluminescence measurements performed on the obtained GOQDs revealed their paramagnetic behavior and broad range optical photoluminescence around 500 nm, with magnetic moments of 2.41 µB. Finally, electron paramagnetic resonance (EPR) was used to separate the unforeseen contributions and typically not taken into account metal contaminations, and radicals from carbon defects. This study contributes to a better understanding of magnetic properties of carbon nanostructures, which could in the future be used for the design of multimodal imaging agents.
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Affiliation(s)
- Krzysztof Tadyszak
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Andrzej Musiał
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
| | - Adam Ostrowski
- Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
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4
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Krzystek J, Schnegg A, Aliabadi A, Holldack K, Stoian SA, Ozarowski A, Hicks SD, Abu-Omar MM, Thomas KE, Ghosh A, Caulfield KP, Tonzetich ZJ, Telser J. Advanced Paramagnetic Resonance Studies on Manganese and Iron Corroles with a Formal d 4 Electron Count. Inorg Chem 2020; 59:1075-1090. [PMID: 31909979 DOI: 10.1021/acs.inorgchem.9b02635] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metallocorroles wherein the metal ion is MnIII and formally FeIV are studied here using field- and frequency-domain electron paramagnetic resonance techniques. The MnIII corrole, Mn(tpfc) (tpfc = 5,10,15-tris(pentafluorophenyl)corrole trianion), exhibits the following S = 2 zero-field splitting (zfs) parameters: D = -2.67(1) cm-1, |E| = 0.023(5) cm-1. This result and those for other MnIII tetrapyrroles indicate that when D ≈ - 2.5 ± 0.5 cm-1 for 4- or 5-coordinate and D ≈ - 3.5 ± 0.5 cm-1 for 6-coordinate complexes, the ground state description is [MnIII(Cor3-)]0 or [MnIII(P2-)]+ (Cor = corrole, P = porphyrin). The situation for formally FeIV corroles is more complicated, and it has been shown that for Fe(Cor)X, when X = Ph (phenyl), the ground state is a spin triplet best described by [FeIV(Cor3-)]+, but when X = halide, the ground state corresponds to [FeIII(Cor•2-)]+, wherein an intermediate spin (S = 3/2) FeIII is antiferromagnetically coupled to a corrole radical dianion (S = 1/2) to also give an S = 1 ground state. These two valence isomers can be distinguished by their zfs parameters, as determined here for Fe(tpc)X, X = Ph, Cl (tpc = 5,10,15-triphenylcorrole trianion). The complex with axial phenyl gives D = 21.1(2) cm-1, while that with axial chloride gives D = 14.6(1) cm-1. The D value for Fe(tpc)Ph is in rough agreement with the range of values reported for other FeIV complexes. In contrast, the D value for Fe(tpc)Cl is inconsistent with an FeIV description and represents a different type of iron center. Computational studies corroborate the zfs for the two types of iron corrole complexes. Thus, the zfs of metallocorroles can be diagnostic as to the electronic structure of a formally high oxidation state metallocorrole, and by extension to metalloporphyrins, although such studies have yet to be performed.
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Affiliation(s)
- J Krzystek
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Alexander Schnegg
- EPR Research Group , Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim Ruhr , Germany.,Berlin Joint EPR Laboratory , Helmholtz-Zentrum Berlin , Kekulestraße 5 , D-12489 Berlin , Germany
| | - Azar Aliabadi
- Berlin Joint EPR Laboratory , Helmholtz-Zentrum Berlin , Kekulestraße 5 , D-12489 Berlin , Germany
| | - Karsten Holldack
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung am Elektronenspeicherring BESSY II , Albert-Einstein-Straße 15 , D-12489 Berlin , Germany
| | - Sebastian A Stoian
- Department of Chemistry , University of Idaho , Moscow , Idaho 83844 , United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Scott D Hicks
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Mahdi M Abu-Omar
- Departments of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106-9510 , United States
| | - Kolle E Thomas
- Department of Chemistry , UiT-The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Abhik Ghosh
- Department of Chemistry , UiT-The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Kenneth P Caulfield
- Department of Chemistry , University of Texas at San Antonio (UTSA) , One UTSA Circle , San Antonio , Texas 78249 , United States
| | - Zachary J Tonzetich
- Department of Chemistry , University of Texas at San Antonio (UTSA) , One UTSA Circle , San Antonio , Texas 78249 , United States
| | - Joshua Telser
- Department of Biological, Physical, and Health Sciences , Roosevelt University , Chicago , Illinois 60605 , United States
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5
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Palopoli C, Ferreyra J, Conte-Daban A, Richezzi M, Foi A, Doctorovich F, Anxolabéhère-Mallart E, Hureau C, Signorella SR. Insights into Second-Sphere Effects on Redox Potentials, Spectroscopic Properties, and Superoxide Dismutase Activity of Manganese Complexes with Schiff-Base Ligands. ACS OMEGA 2019; 4:48-57. [PMID: 31459311 PMCID: PMC6649300 DOI: 10.1021/acsomega.8b03018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 12/20/2018] [Indexed: 05/04/2023]
Abstract
Six Mn-Schiff base complexes, [Mn(X-salpn)]0/+ (salpn = 1,3-bis(sal-ic-ylidenamino)propane, X = H [1], 5-Cl [2], 2,5-F2 [3], 3,5-Cl2 [4], 5-NO2 [5], 3,5-(NO2)2 [6]), were synthesized and characterized in solution, and second-sphere effects on their electrochemical and spectroscopic properties were analyzed. The six complexes catalyze the dismutation of superoxide with catalytic rate constants in the range 0.65 to 1.54 × 106 M-1 s-1 obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutases assay, in aqueous medium of pH 7.8. In solution, these compounds possess two labile solvent molecules in the axial positions favoring coordination of the highly nucleophilic O2 •- to the metal center. Even complex 5, [Mn(5-(NO2)salpn) (OAc) (H2O)], with an axial acetate in the solid state, behaves as a 1:1 electrolyte in methanolic solution. Electron paramagnetic resonance and UV-vis monitoring of the reaction of [Mn(X-salpn)]0/+ with KO2 demonstrates that in diluted solutions these complexes behave as catalysts supporting several additions of excess O2 •-, but at high complex concentrations (≥0.75 mM) catalyst self-inhibition occurs by the formation of a catalytically inactive dimer. The correlation of spectroscopic, electrochemical, and kinetics data suggest that second-sphere effects control the oxidation states of Mn involved in the O2 •- dismutation cycle catalyzed by complexes 1-6 and modulate the strength of the Mn-substrate adduct for electron-transfer through an inner-sphere mechanism.
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Affiliation(s)
- Claudia Palopoli
- IQUIR
(Instituto de Química Rosario), Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET), Facultad de Ciencias
Bioquímicas y Farmacéuticas, Universidad Nacional de
Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Joaquín Ferreyra
- IQUIR
(Instituto de Química Rosario), Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET), Facultad de Ciencias
Bioquímicas y Farmacéuticas, Universidad Nacional de
Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | | | - Micaela Richezzi
- IQUIR
(Instituto de Química Rosario), Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET), Facultad de Ciencias
Bioquímicas y Farmacéuticas, Universidad Nacional de
Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Ana Foi
- Departamento
de Química Inorgánica, Analítica y Química
Física/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Fabio Doctorovich
- Departamento
de Química Inorgánica, Analítica y Química
Física/INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Elodie Anxolabéhère-Mallart
- Laboratoire
d’Electrochimie Moléculaire UMR CNRS-P7 7591, Université
Paris Diderot-Paris, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Christelle Hureau
- LCC-CNRS,
Université de Toulouse, 205 route de Narbonne, 31077 Toulouse, France
| | - Sandra R. Signorella
- IQUIR
(Instituto de Química Rosario), Consejo Nacional de Investigaciones
Científicas y Técnicas (CONICET), Facultad de Ciencias
Bioquímicas y Farmacéuticas, Universidad Nacional de
Rosario, Suipacha 531, S2002LRK Rosario, Argentina
- E-mail: (S.R.S.)
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