Encapsulating [FeFe]-hydrogenase model compounds in peptide hydrogels dramatically modifies stability and photochemistry

Frederix, Pim and Kania, Rafal and Wright, Joseph A. and Lamprou, Dimitrios and Ulijn, Rein and Pickett, Christopher J. and Hunt, Neil (2012) Encapsulating [FeFe]-hydrogenase model compounds in peptide hydrogels dramatically modifies stability and photochemistry. Dalton Transactions, 41 (42). pp. 13112-13119. ISSN 1472-7773

Abstract

A [FeFe]-hydrogenase model compound (µ-S(CH2)3S)Fe2(CO)4(PMe3)2 [1] has been encapsulated in a Low Molecular Weight (LMW) hydrogelator (Fmoc-Leu-Leu). Linear infrared absorption spectroscopy, gel melting and ultrafast time-resolved infrared spectroscopy experiments reveal significant contrasts in chemical environment and photochemistry between the encapsulated molecules and solution phase systems. Specifically, the gel provides a more rigid hydrogen bonding environment, which restricts isomerisation following photolysis while imparting significant increases in stability relative to a similarly aqueous solution. Since understanding and ultimately controlling the mechanistic role of ligands near Fe centers is likely to be crucial in exploiting artificial hydrogenases, these gels may offer a new option for future materials design involving catalysts.

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