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Verma PK, Sawant SD. Unravelling reaction selectivities via bio-inspired porphyrinoid tetradentate frameworks. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214239] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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2
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Osadchuk I, Aav R, Borovkov V, Clot E. Chirogenesis in Zinc Porphyrins: Theoretical Evaluation of Electronic Transitions, Controlling Structural Factors and Axial Ligation. Chemphyschem 2021; 22:1817-1833. [PMID: 34213815 PMCID: PMC8457158 DOI: 10.1002/cphc.202100345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/24/2021] [Indexed: 12/15/2022]
Abstract
In the present work, sixteen different zinc porphyrins (possessing different meso substituents) with and without a chiral guest were modelled using DFT and TD-DFT approaches in order to understand the influence of various controlling factors on electronic circular dichroism (ECD) spectra. Two major aspects are influenced by these factors: excitation energy of the electronic transitions and their intensity. In the case of excitation energy, the influence increases in the following order: orientation of the peripheral substituents
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Affiliation(s)
- Irina Osadchuk
- Department of Chemistry and BiotechnologySchool of ScienceTallinn University of Technology AddressAkadeemia tee 1512618TallinnEstonia
- ICGMUniv MontpellierCNRS, ENSCMMontpellierFrance
| | - Riina Aav
- Department of Chemistry and BiotechnologySchool of ScienceTallinn University of Technology AddressAkadeemia tee 1512618TallinnEstonia
| | - Victor Borovkov
- Department of Chemistry and BiotechnologySchool of ScienceTallinn University of Technology AddressAkadeemia tee 1512618TallinnEstonia
| | - Eric Clot
- ICGMUniv MontpellierCNRS, ENSCMMontpellierFrance
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3
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Novikova NI, Lo ASV, Gordon KC, Brothers PJ, Simpson MC. Diboron Porphyrins: The Raman Signature of the In-Plane Tetragonal Elongation of the Macrocycle. J Phys Chem A 2018; 122:5121-5131. [PMID: 29745659 DOI: 10.1021/acs.jpca.8b01925] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We describe an unusual in-plane type of porphyrin core distortion, tetragonal elongation (TE), observed experimentally in diboron porphyrins. The vibrational spectra of several of these complexes exhibit shifts that we have assigned to this TE distortion by comparing experimental spectra with DFT computational findings. The influence of TE in porphyrin systems was isolated using DFT analysis of the well-known model compounds Ni(II)porphine and Zn(II)porphine, with the macrocycle ring constrained to eliminate the influence of out-of-plane (OOP) distortions. A significant down-shift in frequencies was observed for porphyrin normal vibrational modes, particularly the in-plane A1g/B1g modes that are dominated by contributions from stretching and bending of Cα-Cm coordinates. In contrast, TE had little effect on the v(Pyrhalfring) and δ(Pyrdef) modes, though the lowered symmetry of the system resulted in significant splitting of the B2u and B3u modes. The impact of the TE distortion upon the diboron porphyrin vibrational spectrum was probed experimentally using Raman spectroscopy of B2O2(BCl3)2(TTP), B2OF2(TTP), and B2OPhOH2(TTP) (TTP = 5,10,15,20-(tetra- p-tolyl)porphyrin). Comparing the experimentally obtained spectral signatures to the computational findings allowed us to assign the large shifts observed for the v2 and v3 modes to the TE distortion in diboron porphyrins.
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Affiliation(s)
- Nina I Novikova
- The University of Auckland , School of Chemical Sciences , Auckland 1010 , New Zealand.,The MacDiarmid Institute , Victoria University of Wellington , PO Box 600, Wellington 6012 , New Zealand.,The Dodd-Walls Centre , University of Otago , P.O. Box 56, Dunedin 9016 , New Zealand
| | - Alvie S V Lo
- The MacDiarmid Institute , Victoria University of Wellington , PO Box 600, Wellington 6012 , New Zealand.,The Dodd-Walls Centre , University of Otago , P.O. Box 56, Dunedin 9016 , New Zealand.,University of Otago , Department of Chemistry , P.O. Box 56, Dunedin 9016 , New Zealand
| | - Keith C Gordon
- The MacDiarmid Institute , Victoria University of Wellington , PO Box 600, Wellington 6012 , New Zealand.,The Dodd-Walls Centre , University of Otago , P.O. Box 56, Dunedin 9016 , New Zealand.,University of Otago , Department of Chemistry , P.O. Box 56, Dunedin 9016 , New Zealand
| | - Penelope J Brothers
- The University of Auckland , School of Chemical Sciences , Auckland 1010 , New Zealand.,The MacDiarmid Institute , Victoria University of Wellington , PO Box 600, Wellington 6012 , New Zealand
| | - M Cather Simpson
- The University of Auckland , School of Chemical Sciences , Auckland 1010 , New Zealand.,The MacDiarmid Institute , Victoria University of Wellington , PO Box 600, Wellington 6012 , New Zealand.,The Dodd-Walls Centre , University of Otago , P.O. Box 56, Dunedin 9016 , New Zealand.,The University of Auckland , Department of Physics , Auckland 1010 , New Zealand
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4
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Sterically induced distortions of nickel(II) porphyrins – Comprehensive investigation by DFT calculations and resonance Raman spectroscopy. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2017.12.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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5
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Gorski A, Starukhin A, Stavrov S, Gawinkowski S, Waluk J. Resonance Raman spectroscopy study of protonated porphyrin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 173:350-355. [PMID: 27685003 DOI: 10.1016/j.saa.2016.09.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/14/2016] [Accepted: 09/20/2016] [Indexed: 06/06/2023]
Abstract
Resonance Raman microscopy was used to study the resonance Raman scattering of the diacid (diprotonated form) of free-base porphyrin (21H,23H-porphine) in a crystal powder and KBr pellets. Intensive lines in the spectral range between 100÷1000cm-1 have been detected and assigned as spectral manifestation of out-of-plane modes. The Raman spectra were simulated by means of DFT methods and compared with the experimental data. It is evident from experimental and theoretical results that the activation of out-of-plane modes arises from saddle distortion of the porphyrin macrocycle upon formation of its diprotonated form.
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Affiliation(s)
- A Gorski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka, 44/52, 01-224 Warsaw, Poland.
| | - A Starukhin
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka, 44/52, 01-224 Warsaw, Poland; B. I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nezalezhnasti Ave., 70, 220072 Minsk, Belarus
| | - S Stavrov
- Sackler Institute of Molecular Medicine, Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - S Gawinkowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka, 44/52, 01-224 Warsaw, Poland
| | - J Waluk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka, 44/52, 01-224 Warsaw, Poland; Faculty of Mathematics and Natural Sciences, College of Science, Cardinal Stefan Wyszyński University, Dewajtis 5, 01-815 Warsaw, Poland
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6
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Hamer M, Rezzano IN. Classical Characterization Techniques to Reveal the Structural Model of Nanocomposites with Bimetallic Monolayers of Porphyrins. Inorg Chem 2016; 55:8595-602. [PMID: 27482597 DOI: 10.1021/acs.inorgchem.6b01136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nanocomposites with bimetallic monolayers of porphyrins were prepared. The well-ordered metalloporphyrin monolayers covalently linked to the gold surface produce an important increase of the B band (∼400 nm) shifted 20 nm relative to that of the related high-spin iron(III) complexes in solution. The position of the B band in the bimetallic architectures is highly dependent on the relative amount of the two porphyrins, showing the most significant shift for the SiO2/APTES/AuNp/Fe-TPyP&M-TPyP (1:1) (30 nm, M = Ni(II) or Cu(II)). Resonance Raman based on the oxidation state marker bands (1553, 1354, and 390 cm(-1)) indicates that Fe-TPyP attached on gold nanoparticles adopts a low-spin Fe(II) conformation, which changes to Fe(II) intermediate spin or a low-spin Fe(III) in the presence of Cu-TPyP or Ni-TPyP. Surface-enhanced Raman scattering studies confirmed the hypothesis. MALDI-TOF analysis of the composites on gold nanoparticles was very useful in the detection of oxygenated forms of the metal complexes.
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Affiliation(s)
- Mariana Hamer
- Universidad de Buenos Aires , Facultad de Farmacia y Bioquı́mica, CONICET-IQUIFIB, Junin 956, CP 1113 Buenos Aires, Argentina
| | - Irene N Rezzano
- Universidad de Buenos Aires , Facultad de Farmacia y Bioquı́mica, CONICET-IQUIFIB, Junin 956, CP 1113 Buenos Aires, Argentina
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7
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Investigations of heme distortion, low-frequency vibrational excitations, and electron transfer in cytochrome c. Proc Natl Acad Sci U S A 2014; 111:6570-5. [PMID: 24753591 DOI: 10.1073/pnas.1322274111] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytochrome (cyt) c is an important electron transfer protein. The ruffling deformation of its heme cofactor has been suggested to relate to its electron transfer rate. However, there is no direct experimental evidence demonstrating this correlation. In this work, we studied Pseudomonas aeruginosa cytochrome c551 and its F7A mutant. These two proteins, although similar in their X-ray crystal structure, display a significant difference in their heme out-of-plane deformations, mainly along the ruffling coordinate. Resonance Raman and vibrational coherence measurements also indicate significant differences in ruffling-sensitive modes, particularly the low-frequency γa mode found between ∼50-60 cm(-1). This supports previous assignments of γa as having a large ruffling content. Measurement of the photoreduction kinetics finds an order of magnitude decrease of the photoreduction cross-section in the F7A mutant, which has nearly twice the ruffling deformation as the WT. Additional measurements on cytochrome c demonstrate that heme ruffling is correlated exponentially with the electron transfer rates and suggest that ruffling could play an important role in redox control. A major relaxation of heme ruffling in cytochrome c, upon binding to the mitochondrial membrane, is discussed in this context.
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Valicsek Z, Lendvay G, Horváth O. Equilibrium, photophysical, photochemical and quantum chemical examination of anionic mercury(I) porphyrins. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424609001261] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hg22+ ion and 5,10,15,20-tetrakis(parasulphonato-phenyl)porphyrin anion can form 2:1 (2 clusters:1 porphyrin) and 2:2 complexes, while the formation of the 1:1 species is not observable: it is only an intermediate, similarly to the cases of other large metal ions of small charge-density. The differences between mercury(I) and mercury(II) porphyrins in the composition of monoporphyrins (2:1 vs. 1:1), in the stability and the Soret absorption based on the arrangement of 2:2 complexes (asymmetric vs. probably symmetric sandwich-structure), in the kinetic behavior (molecularities and the special dimerization of HgIIP4-), in the product of the photoinduced dissociations of 2:2 bisporphyrins (free-base ligand vs. 1:1 complex) can prove that no mercury(II) porphyrins can form due to the possible disproportion of dimercury(I) ions. However, the similarities in the absorption, photophysical and photochemical features (also to other out-of-plane metalloporphyrins) suggest that the out-of-plane position of metal center and the distorted structure of complexes may be responsible for these common properties, the so-called sitting-atop characteristics. Moreover, the calculated structural data of the theoretically studied 1:1 mercury(I) porphyrin are very similar to those of Hg II P as a consequence of the charge separation in the cluster based on the strength of metal-nitrogen bonds. In the case of the 2:2 species, neither the increased distance (because of the Hg-Hg bond), nor the absence of 45° rotation of the two ligands can significantly modify the π-π interaction because its both measured and calculated absorption spectra are similar to those of Hg II2 P 2.
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Affiliation(s)
- Zsolt Valicsek
- Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, P.O. Box 158, H-8201 Veszprém, Hungary
| | - György Lendvay
- Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, P.O. Box 158, H-8201 Veszprém, Hungary
- Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary
| | - Ottó Horváth
- Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, P.O. Box 158, H-8201 Veszprém, Hungary
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Jiang L, Engle JT, Sirk L, Hartley CS, Ziegler CJ, Wang H. Triphenylene-fused porphyrins. Org Lett 2011; 13:3020-3. [PMID: 21604789 DOI: 10.1021/ol200853g] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Triphenylene has been successfully fused to the porphyrin periphery through a convenient oxidative ring-closure reaction. Bistriphenylene-fused porphyrins and a dibenzo[fg,op]tetracene-fused porphyrin have also been obtained using a similar approach. These π-extended porphyrins exhibited broadened and bathochromic shifted UV-vis absorptions.
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Affiliation(s)
- Lin Jiang
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, USA
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Girichev GV, Giricheva NI, Golubchikov OA, Mimenkov YV, Semeikin AS, Shlykov SA. Octamethylporphyrin copper, C28H28N4Cu – A first experimental structure determination of porphyrins in gas phase. J Mol Struct 2010. [DOI: 10.1016/j.molstruc.2010.02.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Mitin AV, Kubicki JD. Quantum mechanical investigations of heme structure and vibrational spectra: effects of conformation, oxidation state, and electric field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:548-554. [PMID: 19063621 DOI: 10.1021/la802647c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Three conformers of a complex consisting of a Fe-porphyrin ring with axial imidazole groups FeP(Im)(2) that differed by orientation of axial imidazole groups were studied with quantum mechanical calculations in both reduced (neutral) and oxidized (cationic) states. In the reduced state, all three conformers correspond to local minima. On the other hand, in the oxidized state the conformer with the imidazole groups perpendicular to one another does not have a local minimum, which suggests that there could be changes in the structure of heme groups depending on oxidation state. The relative energy differences between conformers are small as well the differences of orbital energies. However, the populations of Fe 3d orbitals, and hence charge distributions, are predicted to change significantly between conformations. The orientation of heme groups can affect the kinetics of interheme electron transfer, so this electronic population redistribution will affect electron transfer kinetics. A comparison of calculated Raman spectra with measured surface-enhanced Raman spectra (Biju et al. Langmuir 2007, 23, 1333) shows excellent agreement for frequencies, but correlations of Raman intensities are less satisfactory. Possible explanations of the observed discrepancies could arise due to a problem in assignments of vibration bands in the experiment, a dependence of Raman spectra on heme complex on oxidation state, long-range protein structure, or membrane electric field are discussed. In particular, it was shown that the oxidation state does not dramatically alter the calculated Raman spectrum. However, the cell membrane electric field can significantly modify Raman spectra. An interpretation of the experimental oxidized cytochrome surface-enhanced Raman spectra is discussed.
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Affiliation(s)
- Alexander V Mitin
- The Center for Environmental Kinetics Analysis, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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12
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Valicsek Z, Lendvay G, Horváth O. Equilibrium, photophysical, photochemical, and quantum chemical examination of anionic mercury(II) mono- and bisporphyrins. J Phys Chem B 2008; 112:14509-24. [PMID: 18954102 DOI: 10.1021/jp804039s] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mercury(II) ion and 5,10,15,20-tetrakis(parasulfonato-phenyl)porphyrin anion can form 1:1, 2:2, and 3:2 (metal ion/porphyrin) out-of-plane (OOP) complexes, from which Hg2P2(8-) has not been identified until now. Identification of this species significantly promoted the confirmation of the composition and the precise elucidation of the equilibrium of Hg3P2(6-). Since the formation of each complex is too fast, their kinetic behavior was studied from the side of dissociation. The rate-determining step in dissociations, as well as in the formation of the 2:2 complex, that is, the dimerization of 1:1 complex, proved to be virtually first-order under these conditions, while the consecutive formations of HgP(4-) and Hg3P2(6-) are second-order reactions. The equilibria can be spectrophotometrically investigated because the Soret- as well as the Q-absorption bands of the free-base ligand are more and more red-shifted in the series of 1:1, 2:2, and 3:2 complexes, and the split of Q-bands disappears as the singlet-1 excited states become degenerate; in the case of bisporphyrins, the bands broaden, especially in the longer-wavelength region of the spectra. The quantum yield and the lifetime of S1-fluorescence from the macrocycle is decreased by the insertion of a mercury(II) ion due to distortion, and in bisporphyrins the luminescence totally ceases because their more complicated structure promotes other ways of energy dissipation. The lifetime of the triplet excited-state is also reduced by metalation. The transient absorption measured upon excitation of Hg3P2(6-) probably originates from Hg2P2(8-) formed by efficient photodissocation during the laser pulse. This photoinduced dissociation is characteristic to out-of-plane complexes, but in metallo-monoporphyrins it needs the energetically higher Soret-excitation; in bisporphyrins, it can take place during irradiation at the longer Q-wavelengths. Investigation of the intramolecular photoredox reactions has proved that for the increased efficiency of the indirect photoinduced LMCT, not the redox potential, but the position of the metal center is responsible. The two orders of magnitude higher photoredux quantum yield for the 3:2 complex, compared to that of the 2:2 species, can be explained by the repulsive effect of the inner mercury(II) ion pushing the other two farther out of the ligand cavity. In bisporphyrins the second excited states are photochemically more reactive than the first ones, while most of the photochemical processes of HgP(4-) originate from the first excited state. According to our quantum chemical calculations, the mercury(II) ion causes the expansion of the porphyrin-cavity; therefore its out-of-plane position is smaller than the value expected based on its ionic radius. In the hitherto unknown 2:2 dimer two 1:1 saucer-shaped monomers are kept together by secondary forces, mostly by pi-pi interaction, but their relative arrangement was not unequivocally determined by the two DFT functionals used. The arrangements with a symmetry axis or plane perpendicular to both rings are not favored; instead, the two monomers are shifted along the porphyrin planes, either in a Hg-P-Hg-P or a Hg-P-P-Hg order. Our time-dependent density functional theory (TD-DFT) calculations indicate that the electronic spectra are not very sensitive to the structure of the dimer, even though the environment of the porphyrin rings is quite different if one of the metal ions is between or outside of both macrocycles. The calculated spectral shifts agree only partially with the experimental data. The TD-DFT calculations suggest that the chromophores are not fully independent in the bisporphyrins and that the observed spectral shift cannot be uniquely assigned to the geometrical distortion of the porphyrin macrocyle.
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Affiliation(s)
- Zsolt Valicsek
- Department of General and Inorganic Chemistry, Institute of Chemistry, University of Pannonia, H-8201 Veszprem, P.O. Box 158, Hungary.
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Huang Q, Medforth CJ, Schweitzer-Stenner R. Nonplanar heme deformations and excited state displacements in nickel porphyrins detected by Raman spectroscopy at soret excitation. J Phys Chem A 2007; 109:10493-502. [PMID: 16834304 DOI: 10.1021/jp052986a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have correlated the Raman intensities of out-of-plane modes of nickel porphyrins with the nonplanar deformations of specific symmetries, i.e., static normal coordinate deformations (SNCDs) expressed in terms of irreducible representations of the unperturbed D(4h) point group. The model porphyrins Ni(II) octaethyltetraphenylporphyrin (NiOETPP), Ni(II) tetra(isopropyl)porphyrin (NiT((i)Pr)P), Ni(II) tetra(tert-butyl)porphyrin (NiT((t)Bu)P), and Ni(II) meso-tetraphenylporphyrin (NiTPP) were chosen because they exhibit significant out-of-plane deformations of different symmetries. At B-band excitation, the Raman scattering of out-of-plane modes becomes activated mostly via the Franck-Condon mechanism. Some characteristic bands from out-of-plane modes in the spectra were identified as reliable predictors of the type and magnitude of out-of-plane deformation. The gamma(10)-gamma(13) bands are indicators of ruffling (B(1u)) deformations for porphyrins, as confirmed by data for NiTPP, NiT((i)Pr)P, and NiT((t)Bu)P, where the Raman intensity increases with the magnitude of the ruffling deformation. The gamma(15)-gamma(17) bands are indicators of saddling (B(2u)) deformations, as shown by data for NiOETPP, which is highly saddled. By comparing the relative intensities of these prominent Raman bands we estimated the vibronic coupling parameters using a self-consistent analysis, and showed that they reproduce the respective B-band absorption profiles. We also identified the deformations along the lowest wavenumber normal coordinates as the predominant reason for the Raman activity of out-of-plane modes. Our results suggest that some of the normal coordinates (gamma(10) and gamma(13)) may be used as tools to quantitatively probe the nonplanar deformations of metalloporphyrins with alkyl substituents at the meso-positions. Out-of-plane deformations also increase the vibronic coupling strength of some low frequency in-plane Raman modes, namely, nu(7) and nu(8). Generally, the Raman data suggest that the excited B-state is substantially more nonplanar than the ground state. The overall larger vibronic coupling of ruffled porphyrins yields substantially larger dipole strengths for the vibronic sidebands associated with the B-state transition, so that the relative absorptivity of the B(v) band can be used as a convenient tool to probe the nonplanarity of the porphyrin macrocycle.
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Affiliation(s)
- Qing Huang
- Department of Chemistry, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
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14
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Liao MS, Watts JD, Huang MJ. Electronic Structure of Some Substituted Iron(II) Porphyrins. Are They Intermediate or High Spin? J Phys Chem A 2007; 111:5927-35. [PMID: 17559200 DOI: 10.1021/jp070734z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electronic structure of some substituted, four-coordinate iron(II) porphyrins has been investigated with DFT methods. These systems include iron tetraphenylporphine (FeTPP), iron octamethyltetrabenzporphine (FeOTBP), iron tetra(alpha,alpha,alpha,alpha-orthopivalamide)phenylporphine (FeTpivPP, also called "picket fence" porphyrin), halogenated iron porphyrins (FeTPPXn, X=F, Cl; n=20, 28), and iron octaethylporphine (FeOEP). A number of density functionals were used in the calculations. Different from the popular, intermediate-spin FeTPP, the ground states of FeOTBP, FeTPPCl28, and FeTPPF20betaCl8 are predicted to be high spin. The calculated result for FeOTBP is in agreement with the early experimental measurement, thereby changing the previous conclusion drawn from the calculations with only the BP functional (J. Chem. Phys. 2002, 116, 3635). But FeTpivPP might have an intermediate-spin ground state, a conclusion that is different from the "experimental" one. With a notably expanded Fe-N bond length, FeOEP might exist as an admixed-spin (S=1, 2) state. We also calculated the electron affinities (EAs) for the various iron porphyrins and compared them to experiment. On the basis of the calculated trends in the EAs and in the orbital energies, the experimental EAs for FeTpivPP, FeTPPF20, and FeTPPCl28 may be too small by 0.4-0.5 eV.
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Affiliation(s)
- Meng-Sheng Liao
- Department of Chemistry, Jackson State University, P.O. Box 17910, Jackson, Mississippi 39217, USA
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15
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Jarzecki AA, Spiro TG. Porphyrin distortion from resonance Raman intensities of out-of-plane modes: Computation and modeling of N-methylmesoporphyrin, a ferrochelatase transition state analog. J Phys Chem A 2007; 109:421-30. [PMID: 16833362 DOI: 10.1021/jp0470142] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Resonance Raman spectra of porphyrins are computed with DFT/CIS methodology to monitor out-of-plane distortions. A framework is established for assessing protein-induced distortion of porphyrin bound to a ferrochealatase antibody. Tests on undistorted porphyrins give good agreement with the experimental intensity pattern of in-plane modes for free-base porphine (FBP) and mesorporphyrin IX free base (MP). The computed spectrum of N-methylmesoporphyrin (NMP), in which the methyl-substituted pyrrole ring is tilted 32 degrees from the mean porpyrin plane, also gives reasonable agreement with experiment and reveals activation of out-of-plane (oop) vibrational modes. To model oop distortions systematically, an artificial molecule, FBP-X8, was constructed, in which the H atoms attached to the FBP pyrrole Cb atoms are replaced by heavy substituents, as in physiological porphyrins. Oop mode enhancements are computed for FBP-X8 by displacing it along the canonical distortion coordinates: doming, saddling, ruffling and waving. When FBP-X8 is constrained to the NMP porphyrin geometry, normal coordinate decomposition reveals significant contributions also from modes higher in frequency than the canonical modes, and they contribute importantly to the computed RR intensities. NMP-constrained FBP-X8 gives a reasonable facsimile of the NMP RR spectrum, but better results are obtained with a full computation of MP, constrained in the same way; thus the physiological substituents have significant influence on the RR spectra, over and above their effective masses. Attention focuses on a mode analogous to gamma 15 in 4-fold symmetric porphyrins, which is a kind of saddling mode. This mode is selectively enhanced in NMP-constrained MP; a corresponding RR band is induced upon binding MP to a ferrochelatase antibody.
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Affiliation(s)
- Andrzej A Jarzecki
- Department of Chemistry, Princeton University, Princeton New Jersey 08544, USA
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16
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Challa JR, Gunaratne TC, Simpson MC. State Preparation and Excited Electronic and Vibrational Behavior in Hemes. J Phys Chem B 2006; 110:19956-65. [PMID: 17020382 DOI: 10.1021/jp063543p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The temporally overlapping, ultrafast electronic and vibrational dynamics of a model five-coordinate, high-spin heme in a nominally isotropic solvent environment has been studied for the first time with three complementary ultrafast techniques: transient absorption, time-resolved resonance Raman Stokes, and time-resolved resonance Raman anti-Stokes spectroscopies. Vibrational dynamics associated with an evolving ground-state species dominate the observations. Excitation into the blue side of the Soret band led to very rapid S2 --> S1 decay (sub-100 fs), followed by somewhat slower (800 fs) S1 --> S0 nonradiative decay. The initial vibrationally excited, non-Boltzmann S0 state was modeled as shifted to lower energy by 300 cm(-1) and broadened by 20%. On a approximately 10 ps time scale, the S0 state evolved into its room-temperature, thermal distribution S0 profile largely through VER. Anti-Stokes signals disappear very rapidly, indicating that the vibrational energy redistributes internally in about 1-3 ps from the initial accepting modes associated with S1 --> S0 internal conversion to the rest of the macrocycle. Comparisons of anti-Stokes mode intensities and lifetimes from TRARRS studies in which the initial excited state was prepared by ligand photolysis [Mizutani, T.; Kitagawa, T. Science 1997, 278, 443, and Chem. Rec. 2001, 1, 258] suggest that, while transient absorption studies appear to be relatively insensitive to initial preparation of the electronic excited state, the subsequent vibrational dynamics are not. Direct, time-resolved evaluation of vibrational lifetimes provides insight into fast internal conversion in hemes and the pathways of subsequent vibrational energy flow in the ground state. The overall similarity of the model heme electronic dynamics to those of biological systems may be a sign that the protein's influence upon the dynamics of the heme active site is rather subtle.
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Affiliation(s)
- J Reddy Challa
- Center for Chemical Dynamics, Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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Zhang YH, Ruan WJ, Li ZY, Wu Y, Zheng JY. DFT study on the influence of meso-phenyl substitution on the geometric, electronic structure and vibrational spectra of free base porphyrin. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2005.04.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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