[FeFe]-hydrogenase proteins can catalyze the reversible conversion between H2 and protons/electrons under mild conditions and thus are prime candidates for biomimetic efforts in developing hydrogen evolving complex catalysts for artificial photosynthetic systems. To date, significant progress in biomimetic synthesis and computational simulations of hydrogenase active sites have been made. However, changes in chemical and physical properties of the catalytic active sites under irradiation are still not fully understood. Furthermore, due to couplings of photolysis, solvent adducts, and the fluxional variations of the terminal ligands, it is difficult to distinguish photochemical processes by experimental spectroscopies. In addition, due to near-degeneracy problems, it remains a challenge to explore structural, energetic, electronic and optical properties of the active site of [FeFe]-hydrogenases using density functional theory (DFT) methods. In this work, the calibrated DFT and time-depended DFT (TDDFT) methods have been carried out on investigations of photochemical processes of [(μ-PDT)Fe2(CO)6] and [(μ-PDT)Fe2(CO)4L2] (PDT = SCH2CH2CH2S; L = CN−, PMe3, Me = CH3), including the ligand fluxionality, CO photodissociation reactions, and solvent adduct. The reproduced time-resolved IR and UV spectroscopies by the DFT and TDDFT calculations suggest that in addition to CO dissociation the fluxional isomerization is involved in photolysis on longer time scale.

Exploring photochemical processes of [FeFe]-hydrogenase analogues using DFT and TDDFT methods

254th National Meeting (2017)

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