1
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Clendening RA, Delancey SS, Poore AT, Xue S, Guo Y, Tian S, Ren T. Enabling Valence Delocalization in Iron(III) Macrocyclic Complexes through Ring Unsaturation. Inorg Chem 2023; 62:11121-11133. [PMID: 37390479 PMCID: PMC10688613 DOI: 10.1021/acs.inorgchem.3c01179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
The complexes [FeIII(HMC)(C2DMA)2]CF3SO3 ([2]OTf) and [FeIII(HMTI)(C2Y)2]CF3SO3 ([3a-c]OTf) have been prepared and thoroughly characterized (HMC = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane; HMTI = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene; Y = Fc (ferrocenyl, [3a]OTf), 4-(N,N-dimethyl)anilino (DMA, [3b]OTf), or 4-(N,N-bis(4-methoxyphenyl)anilino (TPA, [3c]OTf); OTf- = CF3SO3-)). Vibrational and electronic absorption spectroelectrochemical analyses following one-electron oxidation of the ethynyl substituent Y revealed evidence of strong coupling in the resultant mixed valent species for all HMTI-based complexes. However, the analogous mixed valent ion based on [2]OTf appeared to be more localized. Thus, the tetra-imino macrocycle HMTI has enabled significant valence delocalization along the -C2-FeIII-C2- bridge. Electron paramagnetic resonance and Mössbauer spectroscopic studies of [3b]OTf reveal that the π-acidity of HMTI lowers the energy of the FeIII dπ orbitals compared to the purely σ-donating HMC. This observation provides a basis for the interpretation of the macrocycle-dependent valence (de)localization.
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Affiliation(s)
- Reese A. Clendening
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Stephanie S. Delancey
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Andrew T. Poore
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Shan Xue
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Shiliang Tian
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Tong Ren
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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2
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Park Y, Zhong H, Pabst TP, Kim J, Chirik PJ. Pentamethylcyclopentadienyl Metalloradical Iron Complexes Containing Redox Noninnocent α-Diimine-Type Ligands: Synthesis, Molecular, and Electronic Structures. Organometallics 2023. [DOI: 10.1021/acs.organomet.3c00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/15/2023]
Affiliation(s)
- Yoonsu Park
- Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States
| | - Hongyu Zhong
- Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States
| | - Tyler P. Pabst
- Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States
| | - Junho Kim
- Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J. Chirik
- Department of Chemistry, Frick Laboratory, Princeton University, Princeton, New Jersey 08544, United States
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3
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Guo WX, shen Z, Su YF, Li K, Lin WQ, Chen GH, Guan J, Wang XM, Li Z, Yu Z, Zou Z. Iron-N-Heterocyclic Carbene Complexes as Efficient Electrocatalysts for Water Oxidation in Acidic Conditions. Dalton Trans 2022; 51:12494-12501. [DOI: 10.1039/d2dt01474b] [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 development of stable, earth-abundant, and high-activity molecular water oxidation catalysts in acidic and neutral conditions remains a great challenge. Here, the use of N-heterocyclic carbene (NHC)-based iron(III) complex 1...
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4
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Keshari K, Bera M, Velasco L, Munshi S, Gupta G, Moonshiram D, Paria S. Characterization and reactivity study of non-heme high-valent iron-hydroxo complexes. Chem Sci 2021; 12:4418-4424. [PMID: 34163706 PMCID: PMC8179568 DOI: 10.1039/d0sc07054h] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A terminal FeIIIOH complex, [FeIII(L)(OH)]2− (1), has been synthesized and structurally characterized (H4L = 1,2-bis(2-hydroxy-2-methylpropanamido)benzene). The oxidation reaction of 1 with one equiv. of tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBAH) or ceric ammonium nitrate (CAN) in acetonitrile at −45 °C results in the formation of a FeIIIOH ligand radical complex, [FeIII(L˙)(OH)]− (2), which is hereby characterized by UV-visible, 1H nuclear magnetic resonance, electron paramagnetic resonance, and X-ray absorption spectroscopy techniques. The reaction of 2 with a triphenylcarbon radical further gives triphenylmethanol and mimics the so-called oxygen rebound step of Cpd II of cytochrome P450. Furthermore, the reaction of 2 was explored with different 4-substituted-2,6-di-tert-butylphenols. Based on kinetic analysis, a hydrogen atom transfer (HAT) mechanism has been established. A pKa value of 19.3 and a BDFE value of 78.2 kcal/mol have been estimated for complex 2. One-electron oxidation of an FeIII–OH complex (1) results in the formation of a FeIII–OH ligand radical complex (2). Its reaction with (C6H5)3C˙ results in the formation of (C6H5)3COH, which is a functional mimic of compound II of cytochrome P450.![]()
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Affiliation(s)
- Kritika Keshari
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Moumita Bera
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Lucía Velasco
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sandip Munshi
- School of Chemical Sciences, Indian Association for the Cultivation of Science 2A & 2B Raja S. C. Mullick Road, Jadavpur Kolkata 700032 India
| | - Geetika Gupta
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
| | - Dooshaye Moonshiram
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia Calle Faraday, 9 28049 Madrid Spain
| | - Sayantan Paria
- Department of Chemistry, Indian Institute of Technology Delhi Hauz Khas New Delhi 110016 India
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5
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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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Oldengott J, Richthofen C, Walleck S, Stammler A, Bögge H, Glaser T. Trinuclear Triplesalophen Building Blocks with Terminal Cyanides and Implications for the Spin‐Polarization Mechanism for Low‐Spin Fe
III
and Cr
III
Ions. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201801042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jan Oldengott
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
| | - Carl‐Georg Richthofen
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
| | - Stephan Walleck
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
| | - Anja Stammler
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
| | - Hartmut Bögge
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I Fakultät für Chemie Universität Bielefeld Universitätsstr. 25 33615 Bielefeld Germany
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7
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Kjær KS, Kaul N, Prakash O, Chábera P, Rosemann NW, Honarfar A, Gordivska O, Fredin LA, Bergquist KE, Häggström L, Ericsson T, Lindh L, Yartsev A, Styring S, Huang P, Uhlig J, Bendix J, Strand D, Sundström V, Persson P, Lomoth R, Wärnmark K. Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime. Science 2018; 363:249-253. [DOI: 10.1126/science.aau7160] [Citation(s) in RCA: 167] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 11/14/2018] [Indexed: 01/04/2023]
Abstract
Iron’s abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer states of most iron complexes are limited by picosecond or subpicosecond deactivation through low-lying metal-centered states, resulting in inefficient electron-transfer reactivity and complete lack of photoluminescence. In this study, we show that octahedral coordination of iron(III) by two mono-anionic facialtris-carbene ligands can markedly suppress such deactivation. The resulting complex [Fe(phtmeimb)2]+, where phtmeimb is {phenyl[tris(3-methylimidazol-1-ylidene)]borate}−, exhibits strong, visible, room temperature photoluminescence with a 2.0-nanosecond lifetime and 2% quantum yield via spin-allowed transition from a doublet ligand-to-metal charge-transfer (2LMCT) state to the doublet ground state. Reductive and oxidative electron-transfer reactions were observed for the2LMCT state of [Fe(phtmeimb)2]+in bimolecular quenching studies with methylviologen and diphenylamine.
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8
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Light-controlled switching of the spin state of iron(III). Nat Commun 2018; 9:4750. [PMID: 30420598 PMCID: PMC6232099 DOI: 10.1038/s41467-018-07023-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/08/2018] [Indexed: 11/17/2022] Open
Abstract
Controlled switching of the spin state of transition metal ions, particularly of FeII and FeIII, is a prerequisite to achieve selectivity, efficiency, and catalysis in a number of metalloenzymes. Here we report on an iron(III) porphyrin with a photochromic axial ligand which, upon irradiation with two different wavelengths reversibly switches its spin state between low-spin (S = 1/2) and high-spin (S = 5/2) in solution (DMSO-acetone, 2:598). The switching efficiency is 76% at room temperature. The system is neither oxygen nor water sensitive, and no fatigue was observed after more than 1000 switching cycles. Concomitant with the spin-flip is a change in redox potential by ~60 mV. Besides serving as a simple model for the first step of the cytochrome P450 catalytic cycle, the spin switch can be used to switch the spin-lattice relaxation time T1 of the water protons by a factor of 15. Controlled switching of the spin state of transition metal ions is key in many enzymatic reactions, but difficult to replicate in synthetic systems. Here the authors report on an iron(III) porphyrin with a photochromic axial ligand that, in solution, reversibly switches between low-spin and high-spin upon irradiation with two different wavelengths.
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9
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Ide Y, Murai N, Ishimae H, Suzuki M, Mori S, Takahashi M, Nakamura M, Yoshino K, Ikeue T. Spin-crossover between high-spin (S = 5/2) and low-spin (S = 1/2) states in six-coordinate iron(iii) porphyrin complexes having two pyridine-N oxide derivatives. Dalton Trans 2016; 46:242-249. [PMID: 27924994 DOI: 10.1039/c6dt03859j] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In contrast to the general tendency that six coordinate iron(iii) porphyrin complexes with neutral oxygen ligands adopt a high-spin state in a wide range of temperature, some complexes with substituted pyridine N-oxides have exhibited spin-crossover from high-spin to low-spin states with decreasing temperature both in solution and in the solid state.
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Affiliation(s)
- Yuki Ide
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Nami Murai
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Hiroki Ishimae
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Masaaki Suzuki
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
| | - Shigeki Mori
- Advanced Research Support Center, Ehime University, 2-5, Bunkyo-cho, Matsuyama, 790-8577, Japan
| | - Masashi Takahashi
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
| | - Mikio Nakamura
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
| | - Katsumi Yoshino
- Shimane Institute for Industrial Technology, 1 Hokuryo, Matsue, Shimane 690-0816, Japan
| | - Takahisa Ikeue
- Department of Chemistry, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
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10
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Dey S, Ikbal SA, Rath SP. Self-assembly of cobalt(ii) and zinc(ii) tetranitrooctaethylporphyrin via bidentate axial ligands: synthesis, structure, surface morphology and effect of axial coordination. NEW J CHEM 2014. [DOI: 10.1039/c3nj01248d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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11
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Anbalagan K, Ganeshraja A. Electron-rich ligand modified, ferromagnetic luminescent cis-[CoIII(en)2(RNH2)Cl]Cl2 complexes and their electrochemical reduction behavior. INORG CHEM COMMUN 2013. [DOI: 10.1016/j.inoche.2013.09.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Patra R, Sahoo D, Dey S, Sil D, Rath SP. Switching Orientation of Two Axial Imidazole Ligands between Parallel and Perpendicular in Low-Spin Fe(III) and Fe(II) Nonplanar Porphyrinates. Inorg Chem 2012; 51:11294-305. [DOI: 10.1021/ic300229u] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ranjan Patra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Dipankar Sahoo
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Soumyajit Dey
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Debangsu Sil
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
| | - Sankar Prasad Rath
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India
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13
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Tanabe M, Matsuoka H, Ohba Y, Yamauchi S, Sugisaki K, Toyota K, Sato K, Takui T, Goldberg I, Saltsman I, Gross Z. Time-Resolved Electron Paramagnetic Resonance and Phosphorescence Studies of the Lowest Excited Triplet States of Rh(III) Corrole Complexes. J Phys Chem A 2012; 116:9662-73. [DOI: 10.1021/jp3071037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mana Tanabe
- Institute of Multidisciplinary Research for
Advanced Materials, Tohoku University,
Sendai 980-8577, Japan
| | - Hideto Matsuoka
- Institute of Multidisciplinary Research for
Advanced Materials, Tohoku University,
Sendai 980-8577, Japan
| | - Yasunori Ohba
- Institute of Multidisciplinary Research for
Advanced Materials, Tohoku University,
Sendai 980-8577, Japan
| | - Seigo Yamauchi
- Institute of Multidisciplinary Research for
Advanced Materials, Tohoku University,
Sendai 980-8577, Japan
| | - Kenji Sugisaki
- Department of Chemistry, Graduate School
of Science, Osaka City University, Osaka
558-8585, Japan
| | - Kazuo Toyota
- Department of Chemistry, Graduate School
of Science, Osaka City University, Osaka
558-8585, Japan
| | - Kazunobu Sato
- Department of Chemistry, Graduate School
of Science, Osaka City University, Osaka
558-8585, Japan
| | - Takeji Takui
- Department of Chemistry, Graduate School
of Science, Osaka City University, Osaka
558-8585, Japan
| | - Israel Goldberg
- School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel
| | - Irena Saltsman
- Schulich
Faculty of Chemistry, Technion, Israel Institute of Technology, Haifa 32000, Israel
| | - Zeev Gross
- Schulich
Faculty of Chemistry, Technion, Israel Institute of Technology, Haifa 32000, Israel
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14
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Van Doorslaer S, Tilleman L, Verrept B, Desmet F, Maurelli S, Trandafir F, Moens L, Dewilde S. Marked difference in the electronic structure of cyanide-ligated ferric protoglobins and myoglobin due to heme ruffling. Inorg Chem 2012; 51:8834-41. [PMID: 22877248 DOI: 10.1021/ic3007074] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Electron paramagnetic resonance experiments reveal a significant difference between the principal g values (and hence ligand-field parameters) of the ferric cyanide-ligated form of different variants of the protoglobin of Methanosarcina acetivorans (MaPgb) and of horse heart myoglobin (hhMb). The largest principal g value of the ferric cyanide-ligated MaPgb variants is found to be significantly lower than for any of the other globins reported so far. This is at least partially caused by the strong heme distortions as proven by the determination of the hyperfine interaction of the heme nitrogens and mesoprotons. Furthermore, the experiments confirm recent theoretical predictions [Forti, F.; Boechi, L., Bikiel, D., Martí, M.A.; Nardini, M.; Bolognesi, M.; Viappiani, C.; Estrin, D.; Luque, F. J. J. Phys. Chem. B 2011, 115, 13771-13780] that Phe(G8)145 plays a crucial role in the ligand modulation in MaPgb. Finally, the influence of the N-terminal 20 amino-acid chain on the heme pocket in these protoglobins is also proven.
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15
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Moreira LM, Poli AL, Lyon JP, Aimbire F, Toledo JC, Costa-Filho AJ, Imasato H. Ligand changes in ferric species of the giant extracellular hemoglobin of Glossoscolex paulistusas function of pH: correlations between redox, spectroscopic and oligomeric properties and general implications with different hemoproteins. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s108842461000201x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The present review is focused on the relationship between oligomeric and heme properties of HbGp, emphasizing the characteristics that can be generalized to other hemoproteins. This study represents the state-of-the-art with respect to the approaches for investigating giant extracellular hemoglobins as well as the correlation between oligomeric assembly alterations and their consequent changes in the first coordination sphere. A wide introduction focused on the properties of this hemoglobin is developed. Indeed, this hemoprotein is considered an interesting prototype of blood substitute and biosensor due to its peculiar properties, such as resistance to autoxidation and oligomeric stability. Previous studies by our group employing UV-vis, EPR and CD spectroscopies have been revised in a complete approach, in agreement with recent and relevant data from the literature. In fact, a consistent and inter-related spectroscopic study is described propitiating a wide assignment of "fingerprint" peaks found in the techniques evaluated in this paper. This review furnishes physicochemical information regarding the identification of ferric heme species of hemoproteins and metallic complexes through their spectroscopic bands. This effort at the attribution of UV-vis, EPR and CD peaks is not restricted to HbGp, and includes a comparative analysis of several hemoproteins involving relevant implications regarding several types of iron-porphyrin systems.
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Affiliation(s)
- Leonardo Marmo Moreira
- Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, 12244-000 São José dos Campos SP, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, 13560-970 São Carlos SP, Brazil
- Instituto de Pesquisa e Qualidade Acadêmica (IPQA), Universidade Camilo Castelo Branco, São José dos Campos SP, Brazil
| | - Alessandra Lima Poli
- Instituto de Química de São Carlos, Universidade de São Paulo, 13560-970 São Carlos SP, Brazil
| | - Juliana Pereira Lyon
- Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, 12244-000 São José dos Campos SP, Brazil
| | - Flávio Aimbire
- Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, 12244-000 São José dos Campos SP, Brazil
- Instituto de Pesquisa e Qualidade Acadêmica (IPQA), Universidade Camilo Castelo Branco, São José dos Campos SP, Brazil
| | | | | | - Hidetake Imasato
- Instituto de Química de São Carlos, Universidade de São Paulo, 13560-970 São Carlos SP, Brazil
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16
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Rajapandian V, Subramanian V. Calculations on the Structure and Spectral Properties of Cytochrome c551 Using DFT and ONIOM Methods. J Phys Chem A 2011; 115:2866-76. [DOI: 10.1021/jp110983v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- V. Rajapandian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai 600 020, India
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17
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Abstract
The 1H NMR spectra of a series of mono- and dinuclear pyridine complexes [FeL1(R1/R2)(py)2] and [Fe2L2(R1/R2)(py)4] have been investigated in a mixed toluene-d8/pyridine-d5 solution. The equatorial tetradentade Schiff base like ligands L1(R1/R2) and L2(R1/R2) with a N2O22- coordination sphere for each metal center have been obtained by condensation of a substituted malonodialdehyde (R1/R2 are Me/COOEt, Me/COMe, or OEt/COOEt) with o-phenylenediamine (L1(R1/R2)) or 1,2,4,5-tetraaminobenzene (L2(R1/R2)). The 1H NMR resonances were assigned by comparison of differently substituted complexes in combination with a line-width comparison. The 1H NMR shifts from 188 to 358 K show a strong influence of the spin state of the iron center. The behavior of the pure high-spin iron(II) complexes is close to ideal Curie behavior. Analysis of the resonance shifts of the spin-transition complexes can be used for determining the high-spin mole fraction of the complex in solution at different temperatures. Magnetic susceptibility measurements in solution using the Evans method were made for all six complexes. Significant differences between the spin-transition behavior of the complexes in solution of those in the solid state were found. However, the plots of microeff as a function of temperature obtained using the Evans method and those obtained by interpretation of the NMR shifts were virtually identical. The isotropic shifts of protons in the complexes proved to be suitable tools for following a spin transition in solution. Comparison of the microeff plots of the mono- and dinuclear complexes in solution reveals slight differences between the steepness of the curves that may be attributable to cooperative interactions between the metal centers in the case of the dinuclear complexes.
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Affiliation(s)
- Birgit Weber
- Department of Chemistry and Biochemistry, Ludwig Maximilian University Munich, Butenandtstrasse 5-13 (Haus D), München, Germany.
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18
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Bordbar AK, Hosseinzadeh R. Binding of cetylpyridinum chloride to glucose oxidase. Colloids Surf B Biointerfaces 2006; 53:288-95. [PMID: 17110091 DOI: 10.1016/j.colsurfb.2006.09.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 09/01/2006] [Accepted: 09/26/2006] [Indexed: 11/18/2022]
Abstract
The binding of cetylpyridinum chloride (CPC) with glucose oxidase (GOD) has been extensively studied at various experimental conditions such as ionic strength, urea concentration and pH at 25 degrees C, using ion-selective membrane electrodes, UV-vis absorption spectroscopy and enzyme activity assay method. The accurate binding isotherms have been obtained and analyzed in terms of Scatchard plot and binding capacity concept. The results represent two binding set system for most of studied conditions. The values of Hill equation parameters have been estimated and used for calculation of intrinsic Gibbs free energy of binding. The results have been interpreted in terms of structural viewpoint of GOD and nature of interactions in the solution. The interpretations are in good agreement with denaturation experiment. Activity measurements represent the significant activation of enzyme due to binding of first CPC molecules. However, the binding of subsequent CPC diminished the activity of enzyme which may be due to the binding of second CPC to enzyme active site. The complete deactivation of enzyme is reached due to binding of about five CPC ions.
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Affiliation(s)
- Abdol-Khalegh Bordbar
- Laboratory of Biophysical Chemistry, Department of Chemistry, Isfahan University, Isfahan, 81746-73441, Iran.
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Kano K, Kitagishi H, Mabuchi T, Kodera M, Hirota S. A Myoglobin Functional Model Composed of a Ferrous Porphyrin and a Cyclodextrin Dimer with an Imidazole Linker. Chem Asian J 2006; 1:358-66. [PMID: 17441072 DOI: 10.1002/asia.200600070] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A 1:1 inclusion complex (Fe(II)PImCD) of 5,10,15,20-tetrakis- (4-sulfonatophenyl)porphinatoiron(II) (Fe(II)P) and an O-methylated beta-cyclodextrin dimer with an imidazole linker (ImCD) was found to bind dioxygen in aqueous solution. The half-saturation pressure of dioxygen (P(1/2)O2) is 1.7 torr at 25 degrees C, which is 10 times lower than that for a previous myoglobin functional model (hemoCD) with a pyridine linker. Meanwhile, the half-life of oxygenated Fe(II)PImCD is 3 h, which is 10 times shorter than that of oxygenated hemoCD. The covering of the iron(II) center by a microscopic environment is essential for preventing autoxidation of oxygenated ferrous porphyrin, which is promoted by nucleophilic attack of H2O and/or nucleophiles such as inorganic anions. Due to structural requirements, covering of the Fe(II) center of Fe(II)PImCD is insufficient compared with the case of hemoCD. As a result, water molecules can penetrate more easily the cleft of the O2-Fe(II)PImCD complex and act as an autoxidation inducer. This structure also causes poorer selectivity against carbon monoxide (M = 1040). In contrast, the dioxygen affinity of Fe(II)PImCD is much higher than that of hemoCD because the imidazole moiety is a stronger electron donor than pyridine.
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Affiliation(s)
- Koji Kano
- Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
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Cai S, Shokhireva TK, Lichtenberger DL, Walker FA. NMR and EPR studies of chloroiron(III) tetraphenyl-chlorin and its complexes with imidazoles and pyridines of widely differing basicities. Inorg Chem 2006; 45:3519-31. [PMID: 16634582 PMCID: PMC2504473 DOI: 10.1021/ic0515352] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The NMR and EPR spectra of two bisimidazole and three bispyridine complexes of tetraphenylchlorinatoiron(III), [(TPC)Fe(L)2]+ (L = Im-d4, 2-MeHIm, 4-Me2NPy, Py, and 4-CNPy), have been investigated. The full resonance assignments of the [(TPC)Fe(L)2]+ complexes of this study have been made from correlation spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY) experiments and Amsterdam density functional (ADF) calculations. Unlike the [(OEC)Fe(L)2]+ complexes reported previously (Cai, S.; Lichtenberger, D. L.; Walker, F. A. Inorg. Chem. 2005, 44, 1890-1903), the NMR data for the [(TPC)Fe(L)2]+ complexes of this study indicate that the ground state is S = 1/2 for each bisligand complex, whereas a higher spin state was present at NMR temperatures for the Py and 4-CNPy complexes of (OEC)Fe(III). The pyrrole-8,17 and pyrroline-H of all [TPCFe(L)2]+ show large magnitude chemical shifts (hence indicating large spin density on the adjacent carbons that are part of the pi system), while pyrrole-12,13-CH2 and -7,18-CH2 protons show much smaller chemical shifts, as predicted by the spin densities obtained from ADF calculations. The magnitude of the chemical shifts decreases with decreasing donor ability of the substituted pyridine ligands, with the nonhindered imidazole ligand having slightly larger magnitude chemical shifts than the most basic pyridine, even though its basicity is significantly lower (4-Me2NPyH+ pKa = 9.7, H2Im+ pKa = 6.65 (adjusted for the statistical factor of 2 protons)). The temperature dependence of the chemical shifts of all but the 4-Me2NPy bisligand complexes studied over the temperature range of the NMR investigations shows that they have mixed (dxy)2(dxz,dyz)3/(dxzdyz)4(dxy)1 electron configurations that cannot be resolved by temperature-dependent fitting of the proton chemical shifts, with an S = 3/2 excited state in each case that in most cases lies at more than kT at room temperature above the ground state. The observed pattern of chemical shifts of the 4-CNPy complex and analysis of the temperature dependence indicate that it has a pure (dxzdyz)4(dxy)1 ground state and that it is ruffled, because ruffling mixes the a(2u)(pi)-like orbital of the chlorin into the singly occupied molecular orbital (SOMO). This mixing accounts for the negative chemical shift of the pyrroline-H (-6.5 ppm at -40 degrees C) and thus the negative spin density at the pyrroline-alpha-carbons, but the mixing is not to the same extent as observed for [(TPC)Fe(t-BuNC)2]+, whose pyrroline-H chemical shift is -36 ppm at 25 degrees C (Simonneaux, G.; Kobeissi, M. J. Chem. Soc., Dalton Trans. 2001, 1587-1592). Peak assignments for high-spin (TPC)FeCl have been made by saturation transfer techniques that depend on chemical exchange between this complex and its bis-4-Me2NPy adduct.
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Affiliation(s)
- Sheng Cai
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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