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Abdullin D, Brehm P, Fleck N, Spicher S, Grimme S, Schiemann O. Pulsed EPR Dipolar Spectroscopy on Spin Pairs with one Highly Anisotropic Spin Center: The Low-Spin Fe III Case. Chemistry 2019; 25:14388-14398. [PMID: 31386227 PMCID: PMC6900076 DOI: 10.1002/chem.201902908] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/05/2019] [Indexed: 02/01/2023]
Abstract
Pulsed electron paramagnetic resonance (EPR) dipolar spectroscopy (PDS) offers several methods for measuring dipolar coupling constants and thus the distance between electron spin centers. Up to now, PDS measurements have been mostly applied to spin centers whose g-anisotropies are moderate and therefore have a negligible effect on the dipolar coupling constants. In contrast, spin centers with large g-anisotropy yield dipolar coupling constants that depend on the g-values. In this case, the usual methods of extracting distances from the raw PDS data cannot be applied. Here, the effect of the g-anisotropy on PDS data is studied in detail on the example of the low-spin Fe3+ ion. First, this effect is described theoretically, using the work of Bedilo and Maryasov (Appl. Magn. Reson. 2006, 30, 683-702) as a basis. Then, two known Fe3+ /nitroxide compounds and one new Fe3+ /trityl compound were synthesized and PDS measurements were carried out on them using a method called relaxation induced dipolar modulation enhancement (RIDME). Based on the theoretical results, a RIDME data analysis procedure was developed, which facilitated the extraction of the inter-spin distance and the orientation of the inter-spin vector relative to the Fe3+ g-tensor frame from the RIDME data. The accuracy of the determined distances and orientations was confirmed by comparison with MD simulations. This method can thus be applied to the highly relevant class of metalloproteins with, for example, low-spin Fe3+ ions.
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Affiliation(s)
- Dinar Abdullin
- Institute of Physical and Theoretical ChemistryUniversity of Bonn53115BonnGermany
| | - Philipp Brehm
- Institute of Physical and Theoretical ChemistryUniversity of Bonn53115BonnGermany
- Current address: Institute of Inorganic ChemistryUniversity of Bonn53115BonnGermany
| | - Nico Fleck
- Institute of Physical and Theoretical ChemistryUniversity of Bonn53115BonnGermany
| | - Sebastian Spicher
- Mulliken Center for Theoretical ChemistryUniversity of Bonn53115BonnGermany
| | - Stefan Grimme
- Mulliken Center for Theoretical ChemistryUniversity of Bonn53115BonnGermany
| | - Olav Schiemann
- Institute of Physical and Theoretical ChemistryUniversity of Bonn53115BonnGermany
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Fathi-Rasekh M, Rohde GT, Hart MD, Nakakita T, Zatsikha YV, Valiev RR, Barybin MV, Nemykin VN. Positional Isomers of Isocyanoazulenes as Axial Ligands Coordinated to Ruthenium(II) Tetraphenylporphyrin: Fine-Tuning Redox and Optical Profiles. Inorg Chem 2019; 58:9316-9325. [PMID: 31240923 DOI: 10.1021/acs.inorgchem.9b01030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two isomeric ruthenium(II)/5,10,15,20-tetraphenylporphyrin complexes featuring axially coordinated redox-active, low-optical gap 2- or 6-isocyanoazulene ligands have been isolated and characterized by NMR, UV-vis, and magnetic circular dichroism (MCD) spectroscopic methods, high-resolution mass spectrometry, and single-crystal X-ray crystallography. The UV-vis and MCD spectra support the presence of the low-energy, azulene-centered transitions in the Q band region of the porphyrin chromophore. The first coordination sphere in new L2RuTPP complexes reflects compressed tetragonal geometry. The redox properties of the new compounds were assessed by electrochemical and spectroelectrochemical means and correlated with the electronic structures predicted by density functional theory and CASSCF calculations. Both experimental and theoretical data are consistent with the first two reduction processes involving the axial azulenic ligands, whereas the oxidation profile (in the direction of increasing potential) is exerted by the ruthenium ion, the porphyrin core, and the axial azulenic moieties.
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Affiliation(s)
- Mahtab Fathi-Rasekh
- Department of Chemistry and Biochemistry , University of Minnesota Duluth , 1039 University Drive , Duluth , Minnesota 55812 , United States
| | | | - Mason D Hart
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
| | - Toshinori Nakakita
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
| | - Yuriy V Zatsikha
- Department of Chemistry , University of Manitoba , 144 Dysart Road , Winnipeg , MB R3T 2N2 , Canada
| | - Rashid R Valiev
- Tomsk State University , 36, Lenin Avenue , 634050 Tomsk , Russia.,University of Helsinki , P.O. Box 55, FIN-00014 Helsinki , Finland
| | - Mikhail V Barybin
- Department of Chemistry , University of Kansas , 1567 Irving Hill Road , Lawrence , Kansas 66045 , United States
| | - Victor N Nemykin
- Department of Chemistry and Biochemistry , University of Minnesota Duluth , 1039 University Drive , Duluth , Minnesota 55812 , United States.,Department of Chemistry , University of Manitoba , 144 Dysart Road , Winnipeg , MB R3T 2N2 , Canada
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Van Doorslaer S. Understanding heme proteins with hyperfine spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:79-88. [PMID: 28579104 DOI: 10.1016/j.jmr.2017.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 06/07/2023]
Abstract
Heme proteins are versatile proteins that are involved in a large number of biological processes. Many spectroscopic methods are used to gain insight into the different mechanistic processes governing heme-protein functions. Since many (intermediate) states of heme proteins are paramagnetic, electron paramagnetic resonance (EPR) methods, such as hyperfine spectroscopy, offer unique tools for these investigations. This perspective gives an overview of the use of state-of-the-art hyperfine spectroscopy in heme research, focusing on the advantages, limits and challenges of the different techniques.
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Affiliation(s)
- Sabine Van Doorslaer
- BIMEF Laboratory, Department of Physics, University of Antwerp, B-2610 Antwerp, Belgium.
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Abstract
The synthesis of six new bis(cyano) iron(III) porphyrinate derivatives is reported. The anionic porphyrin complexes utilized tetraphenylporphyrin, tetramesitylporphyrin, and tetratolylporphyrin as the porphyrin ligand. The potassium salts of Kryptofix-222 and 18-C-6 were used as the cations. These complexes have been characterized by X-ray structure analysis, solid-state Mössbauer spectroscopy, and EPR spectroscopy, both in frozen CH2Cl2 solution and in the microcrystalline state. These data show that these anionic complexes can exist in either the (dxz,dyz)(4)(dxy)(1) or the (dxy)(2)(dxz,dyz)(3) electronic configuration and some can clearly readily interconvert. This is a reflection that these two states can be very close in energy. In addition to the effects of varying the porphyrin ligand, subtle effects of the cyanide ligand environment in the solid state and in solution are sufficient to shift the balance between the two electronic states.
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Ikezaki A, Ono J, Ohgo Y, Fukagawa M, Ikeue T, Nakamura M. Electronic structure of low-spin six-coordinate iron(III) meso-tetrapropylchlorin complexes. J PORPHYR PHTHALOCYA 2014. [DOI: 10.1142/s1088424614500576] [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
Low-spin iron(III) tetrapropylchlorins [ Fe ( T n PrC ) L 2]± (L = HIm, 1-MeIm, DMAP, CN-, 4-CNPy, tBuNC) adopt the dxy-type ground state regardless of the nature of axial ligands. Among the complexes examined, [ Fe ( T n PrC )( t BuNC )2]+ has shown quite unique spectroscopic properties as described below. (1) 1 H NMR signals were extremely broad as compared with those of other complexes. In particular, 5,20- CH 2(α) signal was too broad to detect. (2) No signals except C γ were observed in 13 C NMR spectra. (3) Tetragonal splitting parameter (|Δ|) estimated by the EPR g values at 4.2 K reached as much as 12.4 λ, which is the largest |Δ| value among all the low-spin iron(III) porphyrins and porphyrinoids reported previously. On the basis of these results, we have concluded that [ Fe ( T n PrC )( t BuNC )2]+ adopts the low-spin iron(III) with (dxz, dyz)4(dxy)1 electronic ground state at 4.2–30 K where the EPR spectra are taken, while it should be expressed as the low-spin Fe ( II ) chlorin π-radical cation [ Fe II ( T n PrC .)( t BuNC )2]+ at ambient temperature where the NMR spectra are taken.
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Affiliation(s)
- Akira Ikezaki
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Jyunpei Ono
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Yoshiki Ohgo
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Mari Fukagawa
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Takahisa Ikeue
- Department of Material Science, Interdisciplinary Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan
| | - Mikio Nakamura
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
- Research Center for Materials with Integrated Properties, Toho University, Funabashi 274-8510, Japan
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Austeria MP, Pancharatna PD, Balakrishnarajan MM. Electronic Origin of Out-of-Plane Distortions in Porphyrins. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402157] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Nakamura M, Ikezaki A, Takahashi M. Metal-Porphyrin Orbital Interactions in Paramagnetic Iron Complexes Having Planar and Deformed Porphyrin Ring. J CHIN CHEM SOC-TAIP 2012. [DOI: 10.1002/jccs.201200474] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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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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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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Rury AS, Goodrich LE, Galinato MGI, Lehnert N, Sension RJ. Ligand Recruitment and Spin Transitions in the Solid-State Photochemistry of Fe(III)TPPCl. J Phys Chem A 2012; 116:8321-33. [DOI: 10.1021/jp304667t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aaron S. Rury
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109,
United States
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Lauren E. Goodrich
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Mary Grace I. Galinato
- School of Science, Penn State Erie, The Behrend College, Erie, Pennsylvania
16563, United States
| | - Nicolai Lehnert
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
| | - Roseanne J. Sension
- Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109,
United States
- Department
of Chemistry, University of Michigan, Ann
Arbor, Michigan 48109,
United States
- Department
of Physics, University of Michigan, Ann
Arbor, Michigan 48109,
United States
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Kurahashi S, Ikeue T, Sugimori T, Takahashi M, Mikuriya M, Handa M, Ikezaki A, Nakamura M. Formation and characterization of five- and six-coordinate iron(III) corrolazine complexes. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424612500460] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Electronic structures of five- and six-coordinate iron(III) corrolazine complexes are determined by means of 1H NMR, 13C NMR, EPR, and Mössbauer spectroscopy as well as SQUID magnetometry. A series of five-coordinate complexes, [FeIII(TBP8Cz)(L)]* where the axial ligands(L) are cyanide(CN-), imidazole(HIm), 1-methylimidazole(1-MeIm), 4-(N,N-dimethylamino)pyridine(DMAP), pyridine(Py), 4-cyanopyridine(4-CNPy), and tert-butylisocyanide(tBuNC), are obtained by the addition of 1 to 2 equiv. of the ligands to the dichloromethane solutions of FeIII(TBP8Cz) at 298 K: TBP8Cz is a trianion of 2,3,7,8,12,13,17,18-octakis(4-tert-butylphenyl)corrolazine. These complexes commonly show the S = 3/2 at 298 K. By contrast, formation of the six-coordinate complexes depends on the nature of the axial ligands. While the addition of 3 equiv. of CN- has completely converted FeIII(TBP8Cz) to (Bu4N)2[FeIII(TBP8Cz)(CN)2] at 298 K, the conversion to the bis-adduct is only attained below ca. 200 K in the case of HIm, 1-MeIm, and DMAP even in the presence of 50 equiv. of the ligands. If the axial ligand is Py, 4-CNPy, or tBuNC, the formation of [FeIII(TBP8Cz)(L)2] is confirmed only at an extremely low temperature (15 K). Close inspection of the 1H NMR and EPR spectra has revealed that all the bis-adducts adopt the (dxy)2(dxz, dyz)3 ground state. While FeIII(TBP8Cz) forms paramagnetic bis- and mono-adduct in toluene solution at 298 K in the presence of excess amount of CN- and tBuNC, respectively, the corresponding porphyrazine complex, [FeIII(TBP8Pz)]Cl , forms diamagnetic bis-CN and bis-tBuNC under the same conditions: TBP8Pz is a dianion of 2,3,7,8,12,13,17,18-octakis(4-tert-butylphenyl)-porphyrazine. Thus, the iron(III) ion of porphyrazine complex is more easily reduced than that of the corresponding corrolazine complex.
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Affiliation(s)
- Satoshi Kurahashi
- Department of Chemistry and Research Center for Coordination Molecule-Based Devices, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
| | - Takahisa Ikeue
- Department of Material Science, Interdisciplinary Faculty of Science and Engineering, Shimane University 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Tamotsu Sugimori
- Division of Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Masashi Takahashi
- Department of Chemistry, Faculty of Science, Toho University, Funabashi 274-8510, Japan
- Research Center for Materials with Integrated Properties, Toho University, Funabashi 274-8510, Japan
| | - Masahiro Mikuriya
- Department of Chemistry and Research Center for Coordination Molecule-Based Devices, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan
| | - Makoto Handa
- Department of Material Science, Interdisciplinary Faculty of Science and Engineering, Shimane University 1060, Nishikawatsu, Matsue 690-8504, Japan
| | - Akira Ikezaki
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Mikio Nakamura
- Research Center for Materials with Integrated Properties, Toho University, Funabashi 274-8510, Japan
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Ikeue T, Kurahashi S, Handa M, Sugimori T, Nakamura M. Electronic structure of five- and six-coordinate iron(III) tetraazaporphyrin complexes: pyrrole-Cαchemical shift as a useful probe. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424608000418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Electronic structure of a series of five-coordinate Fe ( OArTAzP ) X ( OAr = octaaryltetraazaporphyrin , X = Cl-, Br-, I-; Ar = 4-tert-butylphenyl) have been examined on the basis of1H NMR,13C NMR, and EPR spectroscopy as well as SQUID magnetometry. These complexes adopt the intermediate-spin state as in the case of analogous complexes reported by Fitzgerald et al. (Inorg. Chem. 1992; 31: 2006-2013) and Stuzhin et al. (Inorg. Chim. Acta 1995; 236: 131-139). The13C NMR studies using13C -enriched complexes at the pyrrole α positions have revealed that the pyrrole- Cαsignals appear at extraordinary upfield positions, i.e. -130 to -250 ppm at 273 K, due to the dz2-a2 uand dπ-3 eginteractions. The Curie plots of the pyrrole- Cαsignals have further revealed that the iodide complex adopts a much purer intermediate-spin state than the bromide and chloride complexes. In contrast to the case of Fe ( OArTAzP ) X , six-coordinate [ Fe ( OArTAzP )( CN )2]-showed the pyrrole- Cαsignal at 47 ppm at 273 K, which indicates that the complex adopts the low-spin state with the ( dxy)2( dxz, dyz)3electron configuration. Thus, the13C NMR chemical shift of the pyrrole- Cαsignal turns out to be quite a good probe to elucidate the spin state and electron configuration of iron(III) tetraazaporphyrins, where the1H NMR spectroscopy is less useful because of the absence of the hydrogen atoms as well as the alkyl or aryl groups directly attached to the meso positions.
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Affiliation(s)
- Takahisa Ikeue
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Satoshi Kurahashi
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Makoto Handa
- Department of Chemistry, Faculty of Material Science, Shimane University, Matsue 690-8504, Japan
| | - Tamotu Sugimori
- Division of Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Mikio Nakamura
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Research Center for Materials with Integrated Properties, Toho University, Funabashi 274-8510, Japan
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Myśliborski R, Rachlewicz K, Latos-Grażyński L. Low-spin organoiron(III) N-confused pyriporphyrin. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424607000229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Oxidation of ( PyP H) Fe II Br , an iron(II) complex of 6,11,16,21-tetraaryl-3-aza-m-benziporphyrin ( N -confused pyriporphyrin, ( PyP H) H ) has been followed, in the presence of pyridine, by 1 H and 2 H NMR spectroscopy. One-electron oxidation with dioxygen, accompanied by deprotonation of a C (22) H fragment and formation of a Fe - C (22) bond, produced a low-spin, six-coordinate iron(III) complex [( PyP ) Fe III( py )2]+ as confirmed by combination of 1 H NMR, EPR and structural data. The characteristic patterns of 1 H NMR pyrrole and meso-aryl resonances resemble features assigned to the less common, low-spin ground electronic state (( d xz d yz )4( d xy )1) of iron(III) regular porphyrins. A conformational rearrangement process has been detected which involves two structures differentiated by macrocyclic ruffling. The structure of { H [( PyP ) Fe III( py )2]2}( Fe III Br 4)3· CH 2 Cl 2 has been determined by X-ray crystallography. The cationic complex involves a six-coordinate iron atom bound to the N -confused pyriporphyrin through its three nitrogens ( Fe - N (23) = 1.924(7), Fe - N (24) = 1.979(7), Fe - N (25) = 1.9343(7) Å) and the pirydyl trigonal C (22) atom ( Fe (1)- C (22) = 1.972(10) Å). The porphyrin is strongly ruffled, defining two deep grooves along C meso - C meso axes at right angles to each other. Two axial pyridine ligands are located in the prearranged equatorial ligand grooves. The iron lies in the N 3 C plane of the macrocycle defined by coordinating nitrogen and carbon atoms. In the solid, pairs of molecules are positioned along the line defined by Fe (1)- C (22) and Fe (2)- C (91) bonds. The structure demonstrates the head-to-head arrangement of two [( PyP ) Fe III( py )2]+ subunits revealing the adjacency of the two perimeter nitrogen atoms (the N (3)⋯ N (72) distance = 2.587(10) Å) linked by the N ⋯ H ⋯ N hydrogen bond.
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Affiliation(s)
- Radomir Myśliborski
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St. Wrocław 50 383, Poland
| | - Krystyna Rachlewicz
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St. Wrocław 50 383, Poland
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Ohgo Y, Neya S, Hashizume D, Ozeki T, Nakamura M. Unusual electronic structure of bis-isocyanide complexes of iron(iii) porphyrinoids. Dalton Trans 2012; 41:3126-9. [DOI: 10.1039/c2dt12249a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Niibori Y, Ikezaki A, Nakamura M. Methodology to determine the NMR chemical shifts of carbon atoms with radical character: A case of low-spin bis(tert-butylisocyanide) complex of (meso-tetrapropylporphyrinato)iron(III). INORG CHEM COMMUN 2011. [DOI: 10.1016/j.inoche.2011.05.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ikeue T, Handa M, Chamberlin A, Ghosh A, Ongayi O, Vicente MGH, Ikezaki A, Nakamura M. Benzoannelation Stabilizes the dxy1 State of Low-Spin Iron(III) Porphyrinates. Inorg Chem 2011; 50:3567-81. [DOI: 10.1021/ic1024873] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Takahisa Ikeue
- Department of Chemistry, Faculty of Material Science, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504, Japan
| | - Makoto Handa
- Department of Chemistry, Faculty of Material Science, Shimane University, 1060 Nishikawatsu-cho, Matsue-shi, Shimane 690-8504, Japan
| | - Adam Chamberlin
- Department of Chemistry and the Center for Theoretical and Computational Chemistry, University of Tromso, Breivika, N-9037 Tromso, Norway
| | - Abhik Ghosh
- Department of Chemistry and the Center for Theoretical and Computational Chemistry, University of Tromso, Breivika, N-9037 Tromso, Norway
| | - Owendi Ongayi
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - M. Graça H. Vicente
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Akira Ikezaki
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
| | - Mikio Nakamura
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Ikezaki A, Nakamura M. Formation and characterization of a six-coordinate iron(iii) complex with the most ruffled porphyrin ring. Dalton Trans 2011; 40:3455-8. [DOI: 10.1039/c1dt10042d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Tozuka A, Ohgo Y, Ikezaki A, Taniguchi M, Nakamura M. Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions. Inorg Chem 2010; 49:10400-8. [PMID: 20942414 DOI: 10.1021/ic101184y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bis(pyridine)[meso-tetrakis(heptafluoropropyl)porphyrinato]iron(III), [Fe(THFPrP)Py(2)](+), was reported to be the low-spin complex that adopts the purest (d(xz), d(yz))(4)(d(xy))(1) ground state where the energy gap between the iron d(xy) and d(π)(d(xz), d(yz)) orbitals is larger than the corresponding energy gaps of any other complexes reported previously (Moore, K. T.; Fletcher, J. T.; Therien, M. J. J. Am. Chem. Soc. 1999, 121, 5196-5209). Although the highly ruffled porphyrin core expected for this complex contributes to the stabilization of the (d(xz), d(yz))(4)(d(xy))(1) ground state, the strongly electron withdrawing C(3)F(7) groups at the meso positions should stabilize the (d(xy))(2)(d(xz), d(yz))(3) ground state. Thus, we have reexamined the electronic structure of [Fe(THFPrP)Py(2)](+) by means of (1)H NMR, (19)F NMR, and electron paramagnetic resonance (EPR) spectroscopy. The CD(2)Cl(2) solution of [Fe(THFPrP)Py(2)](+) shows the pyrrole-H signal at -10.25 ppm (298 K) in (1)H NMR, the CF(2)(α) signal at -74.6 ppm (298 K) in (19)F NMR, and the large g(max) type signal at g = 3.16 (4.2 K) in the EPR. Thus, contrary to the previous report, the complex is unambiguously shown to adopt the (d(xy))(2)(d(xz), d(yz))(3) ground state. Comparison of the spectroscopic data of a series of [Fe(THFPrP)L(2)](+) with those of the corresponding meso-tetrapropylporphyrin complexes [Fe(TPrP)L(2)](+) with various axial ligands (L) has shown that the meso-C(3)F(7) groups stabilize the (d(xy))(2)(d(xz), d(yz))(3) ground state. Therefore, it is clear that the less common (d(xz), d(yz))(4)(d(xy))(1) ground state can be stabilized by the three major factors: (i) axial ligand with low-lying π* orbitals, (ii) ruffled porphyrin ring, and (iii) electron donating substituent at the meso position.
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Affiliation(s)
- Akira Tozuka
- Division of Chemistry, Graduate School of Science, Toho University, Funabashi 274-8510, Japan
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Li M, Neal TJ, Ehlinger N, Schulz CE, Scheidt WR. Inter-Ring Interactions in [Fe(TalkylP)(Cl)] (alkyl = ethyl, n-propyl, n-hexyl) Complexes: Control by meso-Substituted Groups. J PORPHYR PHTHALOCYA 2010; 14:115-122. [PMID: 20526455 PMCID: PMC2879655 DOI: 10.1142/s1088424610001714] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Syntheses, molecular structures and magnetic susceptibilities of three meso-substituted high-spin iron(III) porphyrinate complexes ([Fe(TEtP)(Cl)], [Fe(TPrP)(Cl)], and [Fe(THexP)(Cl)]) are described. It was determined that the inter-ring interactions within each dimeric unit change upon alteration of the alkyl groups at the meso-positions. Magnetic exchange couplings between iron centers of the dimers are in accord with the trends in structural inter-ring geometries. Crystal data for [Fe(TEtP)(Cl)]: a = 10.1710(5) Å, b = 11.309(3) Å, c = 12.170(3) Å, α = 91.774(9) °, β = 113.170(14) °, γ = 112.149(9) °, V = 1165.2(4) Å(3), triclinic, P1̄, Z = 2, R(1) = 0.0844 and ωR(2) = 0.2073 for observed data. Crystal data for [Fe([Fe(TPrP)(Cl)])(Cl)]: a = 13.040(2) Å, b = 15.221(2) Å, c = 14.6681(9) Å, β = 109.997(11) °, V = 2735.9(7) Å(3), monoclinic, P2(1)/n, Z = 4, R(1) = 0.0477 and ωR(2) = 0.1176 for observed data. Crystal data for [Fe(THexP)(Cl)]: a = 10.246(7) Å, b = 12.834(4) Å, c = 17.420(15) Å, α = 69.74(3) °, β = 87.52(4) °, γ, = 84.89(3) °, V = 2140(2) Å(3), triclinic, P1̄, Z = 2, R(1) = 0.1024 and ωR(2) = 0.2659 for observed data.
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Affiliation(s)
- Ming Li
- The Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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21
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Ikezaki A, Ohgo Y, Nakamura M. NMR studies on the electronic structure of one-electron oxidized complexes of iron(III) porphyrinates. Coord Chem Rev 2009. [DOI: 10.1016/j.ccr.2009.01.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Ikezaki A, Takahashi M, Nakamura M. Models for Cytochromes c′: Observation of an Extremely Labile Spin State in Monoimidazole Complexes of Saddle-Shaped Iron(III) Porphyrinates. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200902224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Ikezaki A, Takahashi M, Nakamura M. Models for Cytochromes c′: Observation of an Extremely Labile Spin State in Monoimidazole Complexes of Saddle-Shaped Iron(III) Porphyrinates. Angew Chem Int Ed Engl 2009; 48:6300-3. [DOI: 10.1002/anie.200902224] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Cheng RJ, Lee CH, Chao CW. An unexpected bonding interaction between d(xy) and axial cyanide mediated by porphyrin deformation. Chem Commun (Camb) 2009:2526-8. [PMID: 19532878 DOI: 10.1039/b901116a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Through density functional calculation and NMR spectroscopy, an unexpected bonding interaction between d(xy) and axial cyanides is revealed to account for the lower shielding of axial cyanide of ruffled [Fe(TRP)(CN)(2)](-) complexes with the contribution of the unusual low-spin electronic structure (d(xz)d(yz))(4)(d(xy))(1).
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Affiliation(s)
- Ru-Jen Cheng
- Department of Chemistry, National Chung-Hsing University, Taichung, Taiwan, Republic of China.
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25
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Zoppellaro G, Harbitz E, Kaur R, Ensign AA, Bren KL, Andersson KK. Modulation of the ligand-field anisotropy in a series of ferric low-spin cytochrome c mutants derived from Pseudomonas aeruginosa cytochrome c-551 and Nitrosomonas europaea cytochrome c-552: a nuclear magnetic resonance and electron paramagnetic resonance study. J Am Chem Soc 2008; 130:15348-60. [PMID: 18947229 PMCID: PMC2664661 DOI: 10.1021/ja8033312] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochromes of the c type with histidine-methionine (His-Met) heme axial ligation play important roles in electron-transfer reactions and in enzymes. In this work, two series of cytochrome c mutants derived from Pseudomonas aeruginosa (Pa c-551) and from the ammonia-oxidizing bacterium Nitrosomonas europaea (Ne c-552) were engineered and overexpressed. In these proteins, point mutations were induced in a key residue (Asn64) near the Met axial ligand; these mutations have a considerable impact both on heme ligand-field strength and on the Met orientation and dynamics (fluxionality), as judged by low-temperature electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectra. Ne c-552 has a ferric low-spin (S = 1/2) EPR signal characterized by large g anisotropy with g(max) resonance at 3.34; a similar large g(max) value EPR signal is found in the mitochondrial complex III cytochrome c1. In Ne c-552, deletion of Asn64 (NeN64Delta) changes the heme ligand field from more axial to rhombic (small g anisotropy and g(max) at 3.13) and furthermore hinders the Met fluxionality present in the wild-type protein. In Pa c-551 (g(max) at 3.20), replacement of Asn64 with valine (PaN64V) induces a decrease in the axial strain (g(max) at 3.05) and changes the Met configuration. Another set of mutants prepared by insertion (ins) and/or deletion (Delta) of a valine residue adjacent to Asn64, resulting in modifications in the length of the axial Met-donating loop (NeV65Delta, NeG50N/V65Delta, PaN50G/V65ins), did not result in appreciable alterations of the originally weak (Ne c-552) or very weak (Pa c-551) axial field but had an impact on Met orientation, fluxionality, and relaxation dynamics. Comparison of the electronic fingerprints in the overexpressed proteins and their mutants reveals a linear relationship between axial strain and average paramagnetic heme methyl shifts, irrespective of Met orientation or dynamics. Thus, for these His-Met axially coordinated Fe(III), the large g(max) value EPR signal does not represent a special case as is observed for bis-His axially coordinated Fe(III) with the two His planes perpendicular to each other.
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Affiliation(s)
- Giorgio Zoppellaro
- Department of Molecular Biosciences, University of Oslo, Post Office Box 1041 Blindern, Oslo NO-0316, Norway
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Factors that stabilize the electron configuration in iron(III) porphyrinates: A case of bis(benzaldehyde) complex. INORG CHEM COMMUN 2008. [DOI: 10.1016/j.inoche.2008.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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27
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Nakamura M, Ohgo Y, Ikezaki A. Electronic ground states of low-spin iron(III) porphyrinoids. J Inorg Biochem 2008; 102:433-45. [DOI: 10.1016/j.jinorgbio.2007.10.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 09/29/2007] [Accepted: 10/12/2007] [Indexed: 11/27/2022]
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Moreira LM, Vieira dos Santos F, Lyon JP, Maftoum-Costa M, Pacheco-Soares C, Soares da Silva N. Photodynamic Therapy: Porphyrins and Phthalocyanines as Photosensitizers. Aust J Chem 2008. [DOI: 10.1071/ch08145] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The present work is focussed on the principles of photodynamic therapy (PDT), emphasizing the photochemical mechanisms of reactive oxygen species formation and the consequent biochemical processes generated by the action of reactive oxygen species on various biological macromolecules and organelles. This paper also presents some of the most used photosensitizers, including Photofrin, and the new prototypes of photosensitizers, analysing their physicochemical and spectroscopic properties. At this point, the review discusses the therapeutic window of absorption of specific wavelengths involving first- and second-generation photosensitizers, as well as the principal light sources used in PDT. Additionally, the aggregation process, which consists in a phenomenon common to several photosensitizers, is studied. J-aggregates and H-aggregates are discussed, along with their spectroscopic effects. Most photosensitizers have a significant hydrophobic character; thus, the study of the types of aggregation in aqueous solvent is very relevant. Important aspects of the coordination chemistry of metalloporphyrins and metallophthalocyanines used as photosensitizers are also discussed. The state-of-the-art in PDT is evaluated, discussing recent articles in this area. Furthermore, macrocyclic photosensitizers, such as porphyrins and phthalocyanines, are specifically described. The present review is an important contribution, because PDT is one of the most auspicious advances in the therapy against cancer and other non-malignant diseases.
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Juillard S, Bondon A, Simonneaux G. Proton NMR Study of Low‐Spin
meso
‐Unsubstituted β‐Substituted Alkyl Iron Porphyrins: Remarkable Influence of Peripheral Substitution on Spin Density. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sandrine Juillard
- Laboratoire de Chimie Organométallique et Biologique, UMR CNRS 6226 Campus de Beaulieu,Université de Rennes 1, 35042 Rennes, France
| | - Arnaud Bondon
- RMN‐ILP, UMR CNRS 6026, IFR 140 PRISM, Campus de Villejean, Université de Rennes 1, 35043 Rennes, France
| | - Gérard Simonneaux
- Laboratoire de Chimie Organométallique et Biologique, UMR CNRS 6226 Campus de Beaulieu,Université de Rennes 1, 35042 Rennes, France
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30
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Pacholska‐Dudziak E, Latos‐Grażyński L. NMR Studies of Paramagnetic Metallocarbaporphyrinoids. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ewa Pacholska‐Dudziak
- Department of Chemistry, University of Wrocław, 14 F. Joliot‐Curie St., Wrocław 50 383, Poland
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Li J, Noll BC, Schulz CE, Scheidt WR. New insights on the electronic and molecular structure of cyanide-ligated iron(III) porphyrinates. Inorg Chem 2007; 46:2286-98. [PMID: 17309249 PMCID: PMC2532704 DOI: 10.1021/ic061463u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The preparation and characterization of several new cyano-ligated six-coordinate low-spin iron(III) porphyrinates are reported. The synthesis and structure of the new bis(cyanide) derivative K(222)][Fe(TMP)(CN)2] (TMP = tetramesitylporphyrinate) is described. Three mixed-ligand species of the general form [Fe(Porph)(CN)(L)], where L = 1-methylimidazole or pyridine, have also been prepared and structurally characterized. All complexes have been studied with EPR spectroscopy in frozen solution and in microcrystalline form. In some cases, especially those of the bis(cyanide) derivative above and the previously reported [Fe(TPP)(CN)2](-), there are significant differences in the EPR spectra as a result of the state change. These spectral differences can be correlated with changes in the electron configuration that are the likely result of a differing environment of the coordinated cyanide ligands; the core conformation and electronic structure of the porphyrin ligand are unlikely to play a role. All four new complexes and [Fe(TPP)(CN)2](-) have been studied by Mössbauer spectroscopy with variable-temperature and applied magnetic-field measurements. The sign of the quadrupole splitting value has been established as negative. These measurements have allowed us to give estimates of the energy difference between the two close-lying dpi (dxz and dyz) orbitals. These splitting values range from approximately 267 cm-1 for [Fe(TPP)(CN)2](-) to approximately 614 cm(-1) for [Fe(TPP)(CN)(Py)].
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Affiliation(s)
- Jianfeng Li
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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Teschner T, Yatsunyk L, Schünemann V, Paulsen H, Winkler H, Hu C, Scheidt WR, Walker FA, Trautwein AX. Models of the membrane-bound cytochromes: mössbauer spectra of crystalline low-spin ferriheme complexes having axial ligand plane dihedral angles ranging from 0 degree to 90 degrees. J Am Chem Soc 2006; 128:1379-89. [PMID: 16433558 PMCID: PMC1525297 DOI: 10.1021/ja056343k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Crystalline samples of four low-spin Fe(III) octaalkyltetraphenylporphyrinate and two low-spin Fe(III) tetramesitylporphyrinate complexes, all of which are models of the bis-histidine-coordinated cytochromes of mitochondrial complexes II, III, and IV and chloroplast complex b(6)f, and whose molecular structures and EPR spectra have been reported previously, have been investigated in detail by Mössbauer spectroscopy. The six complexes and the dihedral angles between axial ligand planes of each are [(TMP)Fe(1-MeIm)(2)]ClO(4) (0 degree), paral-[(OMTPP)Fe(1-MeIm)(2)]Cl (19.5 degrees), paral-[(TMP)Fe(5-MeHIm)(2)]ClO(4) (26 degrees, 30 degrees for two molecules in the unit cell whose EPR spectra overlap), [(OETPP)Fe(4-Me(2)NPy)(2)]Cl (70 degrees), perp-[(OETPP)Fe(1-MeIm)(2)]Cl (73 degrees), and perp-[(OMTPP)Fe(1-MeIm)(2)]Cl (90 degrees). Of these, the first three have been shown to exhibit normal rhombic EPR spectra, each with three clearly resolved g-values, while the last three have been shown to exhibit "large g(max)" EPR spectra at 4.2 K. It is found that the hyperfine coupling constants of the complexes are consistent with those reported previously for low-spin ferriheme systems, with the largest-magnitude hyperfine coupling constant, A(zz), being considerably smaller for the "parallel" complexes (400-540 kG) than for the strictly perpendicular complex (902 kG), A(xx) being negative for all six complexes, and A(zz) and A(xx) being of similar magnitude for the "parallel" complexes (for example, for [(TMP)Fe(1-MeIm)(2)]Cl, A(zz) = 400 kG, A(xx) = -400 kG). In all cases, A(yy) is small but difficult to estimate with accuracy. With results for six structurally characterized model systems, we find for the first time qualitative correlations of g(zz), A(zz), and DeltaE(Q) with axial ligand plane dihedral angle Deltavarphi.
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34
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Drain CM, Smeureanu G, Patel S, Gong X, Garno J, Arijeloye J. Porphyrin nanoparticles as supramolecular systems. NEW J CHEM 2006. [DOI: 10.1039/b607289e] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Ohgo Y, Neya S, Uekusa H, Nakamura M. An isocyanide probe for heme electronic structure: bis(tert-butylisocyanide) complex of diazaporphyrin showing a unique (dxy)2(dxz, dyz)3 ground state. Chem Commun (Camb) 2006:4590-2. [PMID: 17082852 DOI: 10.1039/b609910f] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Isocyanide-bound model hemes always adopt the (dxz, dyz)4(dxy)1 ground state, however, we have found that the replacement of porphyrin by diazaporphyrin leads to the formation of an unprecedented low-spin bis(tert-butylisocyanide) complex with the (dxy)2(dxz, dyz)3 ground state.
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Affiliation(s)
- Yoshiki Ohgo
- Department of Chemistry, School of Medicine, Toho University, Ota-ku, Tokyo 143-8540, Japan.
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36
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Berlicka A, Latos-Grazyński L, Lis T. 1H NMR Investigation of High-Spin and Low-Spin Iron(III) meso-Ethynylporphyrins. Inorg Chem 2005; 44:4522-33. [PMID: 15962959 DOI: 10.1021/ic050158q] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 1H NMR spectra of iron(III) 5-ethynyl-10,15,20-tri(p-tolyl)porphyrin [(ETrTP)Fe(III)X(n)], iron(III) 5-(phenylethynyl)-10,15,20-tri(p-tolyl)porphyrin [(PETrTP)Fe(III)X(n)], iron(III) 5-(phenylbutadiynyl)-10,15,20-tri(p-tolyl)porphyrin [(PBTrTP)Fe(III)X(n)], iron(III) 5,10,15,20-tetra(phenylethynyl)porphyrin [(TPEP)Fe(III)X(n)], iron(III) 1,4-bis-[10,15,20-tri(p-tolyl)porphyrin-5-yl]-1,3-butadiyne {[(TrTP)Fe(III)X(n)]2 B}, and 5,10,15-triphenylporphyrin [(TrPP)Fe(III)X(n)] have been studied to elucidate the impact of meso-ethynyl substitution on the electronic structure and spin density distribution of high-spin (X = Cl-, n = 1) and low-spin (X = CN-, n = 2) derivatives. The meso substituents, i.e., ethynyl, phenylethynyl, and phenylbutadiynyl, provided insight into the efficiency of spin density delocalization along structural elements that are typically applied to transmit electronic effects along multipart polyporphyrinic systems. The positive spin density localized at the meso-carbon of high-spin iron(III) ethynylporphyrins is effectively delocalized along the ethyne or butadiyne fragment as illustrated by the comparison of isotropic shifts of C(meso)-H and -CC-H determined for (TrPP)Fe(III)Cl (-82.6 ppm, 293 K) and (ETrTP)Fe(III)Cl (-49.5 ppm, 298 K). The replacement of the ethynyl hydrogen by phenyl or phenylethynyl provided evidence for the pi spin density distribution around the introduced phenyl ring. An analysis of the isotropic shifts for the low-spin bis-cyanide iron(III) porphyrins series reveals the analogous mechanism of spin density transfer. Treatment of high-spin [(TrTP)Fe(III)Cl]2 B with a base resulted in formation of the cyclic [(TrTP)Fe(III)OFe(III)(TrTP)B]2 complex linked by two mu-oxo bridges. (TPEP)H2 has been characterized by X-ray crystallography as a porphyrin dication where two molecules of trifluoroacetic acid associate with two coordinated trifluoroacetate anions. The X-ray structure of bis-tetrahydrofuran 1,4-bis[10,15,20-tri(p-tolyl)porphyrinatozinc(II)-5-yl]-1,3-butadiyne complex {[(TrTP)Zn(II)(THF)]2 B} reveals two parallel, non-coplanar [(TrTP)Zn(THF)] subunits linked by the linear butadiyne moiety.
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Affiliation(s)
- Anna Berlicka
- Department of Chemistry, University of Wrocław, 50 383 Wrocław, Poland
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37
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Ohgo Y, Ikeue T, Takahashi M, Takeda M, Nakamura M. Anomalous Difference in Magnetic Behavior between Highly Saddled Iron(III) Porphyrin Complexes in the Solid State. Eur J Inorg Chem 2004. [DOI: 10.1002/ejic.200300566] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Saitoh T, Tachibana Y, Higuchi Y, Hori H, Akutsu H. Correlation between thegTensors and the Nonplanarity of Porphyrin Rings inDesulfovibrio vulgarisMiyazaki F Cytochromec3, Studied by Single Crystal EPR. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2004. [DOI: 10.1246/bcsj.77.357] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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39
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Electronic effects of para-substituents on the electron configuration of dicyano[meso-tetrakis(p-substituted phenyl)porphyrinato]iron(III) complexes. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00819-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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40
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Ohgo Y, Ikeue T, Saitoh T, Nakamura M. Structure Analysis of Highly S4-Ruffled Bis(2-methylimidazole)(meso-tetraethylporphyrinato)iron(III) Chloride. CHEM LETT 2002. [DOI: 10.1246/cl.2002.432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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41
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Kalish H, Camp JE, Stepień M, Latos-Grazyński L, Olmstead MM, Balch AL. meso Substituent effects on the geometric and electronic structures of high-spin and low-spin iron(III) complexes of mono-meso-substituted octaethylporphyrins. Inorg Chem 2002; 41:989-97. [PMID: 11849103 DOI: 10.1021/ic011034q] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Introduction of a single meso substituent into ClFe(III)(OEP) or K[(NC)(2)Fe(OEP)] results in significant changes in the geometric and/or spectroscopic properties of these complexes. The mono-meso-substituted iron(III) complexes ClFe(III)(meso-Ph-OEP), ClFe(III)(meso-n-Bu-OEP), ClFe(III)(meso-MeO-OEP), ClFe(III)(meso-Cl-OEP), ClFe(III)(meso-NC-OEP), ClFe(III)(meso-HC(O)-OEP), and ClFe(III)(meso-O(2)N-OEP) have been isolated and characterized by their UV/vis and paramagnetically shifted (1)H NMR spectra. The structures of both ClFe(III)(meso-Ph-OEP) and ClFe(III)(meso-NC-OEP) have been determined by X-ray crystallography. Both molecules have five-coordinate structures typical for high-spin (S = 5/2) iron(III) complexes. However, the porphyrins themselves no longer have the domed shape seen in ClFe(III)(OEP), and the N(4) coordination environment possesses a slight rectangular distortion. These high-spin, mono-meso-substituted iron(III) complexes display (1)H NMR spectra in chloroform-d solution which indicate that the conformational changes seen in the solid-state structures are altered by normal molecular motion to produce spectra consistent with C(s) molecular symmetry. In pyridine solution the high-spin six-coordinate complexes [(py)ClFe(III)(meso-R-OEP)] form. In methanol solution in the presence of excess potassium cyanide, the low-spin six-coordinate complexes K[(NC)(2)Fe(III)(meso-R-OEP)] form. The (1)H NMR spectra of these show that electron-donating substituents produce an upfield relocation of the meso-proton chemical shifts. This relocation is interpreted in terms of increased contribution from the less common (d(xz),d(yz))(4)(d(xy))(1) ground electronic state as the meso substituent becomes more electron donating.
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Affiliation(s)
- Heather Kalish
- Department of Chemistry, University of California, Davis, California 95616, USA
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