文献类型：期刊文献

英文题名：Axial Ligand Effects on Vibrational Dynamics of Iron in Heme Carbonyl Studied by Nuclear Resonance Vibrational Spectroscopy

作者：Ohta, Takehiro[1,2,3];Liu, Jin-Gang[1,2,4];Saito, Makina[5];Kobayashi, Yasuhiro[5,8];Yoda, Yoshitaka[7,8];Seto, Makoto[5,6,8];Naruta, Yoshinori[1,2,3]

机构：[1]Kyushu Univ, Inst Mat Chem & Engn, Fukuoka 8128581, Japan;[2]Kyushu Univ, Int Inst Carbon Neutral Energy Res WPI I2CNER, Fukuoka 8128581, Japan;[3]ACT C, JST, Kawaguchi, Saitama 3320012, Japan;[4]E China Univ Sci & Technol, Dept Chem, Shanghai 200237, Peoples R China;[5]Kyoto Univ, Inst Res Reactor, Osaka 5900494, Japan;[6]Japan Atom Energy Agcy, Mikazuki, Hyogo 6795148, Japan;[7]Japan Synchrotron Radiat Res Inst, Kobe, Hyogo 6795198, Japan;[8]Japan Sci & Technol Agcy, CREST, Kawaguchi, Saitama 3320012, Japan

年份：2012

卷号：116

期号：47

起止页码：13831

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY B

收录：;EI(收录号：20124915758373);WOS:【SCI-EXPANDED(收录号:WOS:000311650300002)】；

基金：This work was financially supported by Grants-in-Aid for Young Scientists (B) (no. 21750064, T.O.) from JSPS, MEXT project of Integrated Research on Chmiecal Synthesis to T.O. and Y.N., Innovative Areas (no. 20200050, J.G.L. and T.O.) from MEXT, and by the Elemental Science and Technology Project from MEXT to Y.N. The computations were partly carried out with help from the Research Institute for Information Technology, Kyushu University. The synchrotron radiation experiments were performed at the BL09XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2009A1450 and 2010B1521). T.O. thanks Lei Liu (Stanford University) for his help of the setup of the Gennrvs program.

语种：英文

外文关键词：Density functional theory - Dynamics - Iron compounds - Aromatic compounds - Ligands - Vibrational spectra - Vibrational spectroscopy

摘要：Nnclear resonance vibrational spectroscopy (NRVS) and density functional theory calculation (DFT) have been applied to illuminate the effect of axial ligation on the vibrational dynamics of iron in heme carbonyl. The,:analyses., of the NRVS data of five (5c) and six coordinate (6c) heme-CO complexes indicate that the prominent feature of Fe-57 partial vibrational density of state ((57)-FePVDOS) at the 250-300 cm(-1) region is significantly affected by the association of the axial ligand. The DFT calculations predict that the Prominent (FePVDOS)-Fe-57 is composed Of iron in motions: which are coupled with porphyrin pyrrole in plane (v(49), v(50), and v(53)), an out-of-plane (gamma(8)) (two of four pyrrole rings include the in-plane modes, while the rest of pyrrole rings vibrate along the out coordinate), and out-of-phase carbonyl. C and 0 atom displacement perpendicular to the Fe-C-O axis. Thus, in the case of the 5c CO-heme the prominent (FePVDOS)-Fe-57 shows sharp and intense feature because of the degeneracy of the e symmetry Mode Within the framework of C-4v symmetry molecule, whereas the,. association of the axial imidazole ligand in the 6c complex with the lowered symmetry results in split of the degenerate vibrational energy as indicated by broader and lower intensity features Of the corresponding NRVS peak compared to the 5c :structure. The vibrational energy of the iron in plane motion in the 6c complex is higher than that in Sc, implying that the iron in the 6c complex includes stronger in plane interaction with the porphyrin compared to Sc. The iron in plane mode above 500 cm(-1), which is predominantly coupled with the out carbonyl C and atom motion perpendicular to Fe-C-O, called as Fe-C-O bending mode (delta(Fe-C-O)); also suggests that the 6c structure involves a larger force constant for the e symmetry mode than 5c. The DFT calculations :along with the NRVS data suggest that the stiffened iron-in-plane Motion in the 6c complex can be ascribed to diminished pseudo-Jahn-Teller instability along the e symmetry displacement due to an increased a(i)-e Orbital energy gap caused by sigma* interaction between the iron d(z)(2) orbital and the nitrogen p orbital from the axial imidazole ligand. Thus, the present study implicates a. fundamental molecular mechanism of axial ligation of heme. in association. with a. diatomic gas molecule, which is a key primary step toward versatile biological functions.