A tricarboxylated PtCl(terpyridine) derivative exhibiting pH-dependent photocatalytic activity for H-2 evolution from water

作者：Yamauchi Kosei^*; Sakai Ken

来源：Dalton Transactions, 2015, 44(18): 8685-8696.

DOI：10.1039/c5dt00425j

The first negatively charged PtCl(tpy) (tpy = 2,2':6',2''-terpyridine) derivative, formulated as Na-2[PtCl( tctpy)].5H(2)O (tctpy = 2,2':6',2''-terpyridine-4,4',4''-tricarboxylate), was prepared, characterized, and investigated in detail for its activity as a single-component photocatalyst that drives water reduction to H-2 in the presence of a sacrificial electron donor (EDTA). This compound was confirmed to exist in its fully deprotonated form [PtCl(tctpy)](2-) in aqueous media at pH > 4.4. Despite its dianionic character, [PtCl (tctpy)](2-) was found to form a specific adduct with anionic EDTA (i.e., YH22- and YH3-, where YH4 is a fully protonated form of EDTA), enabling reductive quenching of the triplet metal-to-ligand charge transfer excited state within the adduct, leading to subsequent electron transfer steps correlated with Pt(II)-catalyzed H-2 evolution from water. Electrochemical studies also reveal that the compound exhibits a unique pH-dependent first reduction (i.e., tctpy-centered reduction), leading to our realization of the first example of a Pt(II)-based molecular system that photocatalyzes the H-2 evolution reaction accompanied by a ligand-based proton-coupled electron transfer (PCET) process.

• 出版日期2015