The synthesis and characterization of a variety of new metalloporphyrin compounds is proposed. The work will emphasize, but will not be limited to, iron porphyrinate derivatives. Most classes of compounds proposed for study are related to developing an understanding of hemoprotein derivatives, which carry out a wide range of biological functions including oxygen utilization and transport, NO-based signaling, electron transport, drug metabolism and a variety of other enzymatic processes. Another class of derivatives is related to species important to photosynthetic reactions. The methods of three-dimensional X-ray crystal structure determination will be applied to define molecular structures and various detailed aspects of metalloporphyrin stereochemistry. Other methodologies to be applied, as appropriate, include characterization of magnetic properties by bulk temperature-dependent susceptibility and electron paramagnetic resonance (EPR) measurements. M?ssbauer spectroscopy, vibrational and UV-vis-near-IR spectroscopy, electrochemical properties, and molecular mechanics calculations. The research objectives, stated in the broadest terms, are to achieve a synthesis of the structural and physical properties of metalloporphyrins, particularly as these relationships pertain to an understanding of hemoprotein-based biological processes. In part, this will be accomplished by establishing possible stereochemical features of a metalloporphyrin group in its biological environment and to model specific prosthetic group behavior of selected hemoproteins. Such studies are expected to provide understanding of how protein structures could modulate metalloporphyrin geometry and how a wide variety of biological processes can be carried out with the same fundamental iron protoporphyrin IX unit. Iron porphyrinates to be studied include synthetic analogues of bis(histidine)-ligated cytochromes b and c to examine how features such as axial ligand orientation affect their electronic structure and oxidation-reduction properties. Another significant research objective is the exploration of electronic interactions in metalloporphyrins; detailed studies will examine coupling in systems with potential intra- and/or intermolecular pathways. Included in such studies are species with oxidized or reduced porphyrin cores in which pi-radical spin coupling is significant.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Metallobiochemistry Study Section (BMT)
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Flicker, Paula F
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University of Notre Dame
Schools of Arts and Sciences
Notre Dame
United States
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Scheidt, W Robert; Li, Jianfeng; Sage, J Timothy (2017) What Can Be Learned from Nuclear Resonance Vibrational Spectroscopy: Vibrational Dynamics and Hemes. Chem Rev 117:12532-12563
Serth-Guzzo, Judith A; Turowska-Tyrk, Ilona; Safo, Martin K et al. (2016) Characterization of the mixed axial ligand complex (4-cyanopyridine)(imidazole)(tetramesitylporphinato)iron(iii) perchlorate. Stabilization by synergic bonding. J Porphyr Phthalocyanines 20:254-264
Peng, Qian; Pavlik, Jeffrey W; Silvernail, Nathan J et al. (2016) 3D Motions of Iron in Six-Coordinate {FeNO}(7) Hemes by Nuclear Resonance Vibration Spectroscopy. Chemistry 22:6323-6332
Scheidt, W Robert; Duval, Hugues F; Oliver, Allen G (2016) Ring-strain release in neutral and dicationic 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2. Acta Crystallogr E Crystallogr Commun 72:824-8
Jentzen, Walter; Shelnutt, John A; Scheidt, W Robert (2016) Metalloporphines: Dimers and Trimers. Inorg Chem 55:6294-9
McCracken, John; Cappillino, Patrick J; McNally, Joshua S et al. (2015) Characterization of Water Coordination to Ferrous Nitrosyl Complexes with fac-N2O, cis-N2O2, and N2O3 Donor Ligands. Inorg Chem 54:6486-97
Hu, Chuanjiang; Schulz, Charles E; Scheidt, W Robert (2015) All high-spin (S = 2) iron(ii) hemes are NOT alike. Dalton Trans 44:18301-10
Li, Jianfeng; Noll, Bruce C; Schulz, Charles E et al. (2015) Bis(cyano) Iron(III) Porphyrinates: What Is the Ground State? Inorg Chem 54:6472-85
Scheidt, W Robert; Cheng, Beisong; Oliver, Allen G et al. (2015) Solid-state Porphyrin Interactions with Oppositely Charged Peripheral Groups. J Porphyr Phthalocyanines 19:1256-1261
Li, Ming; Scheidt, W Robert (2014) Structural characterization of the ?-Nitrido Complex {[Fe(OEP)]2N} J Porphyr Phthalocyanines 18:380-384

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