A New Electron-Transfer Donor for Photoinduced Electron Transfer in Polypyridyl Molecular Assemblies.

A synthetic procedure has been devised for the preparation of the reductive quencher ligand 4-methyl-4'-(N-methyl-p-tolylaminomethyl)-2,2'-bipyridine (dmb-tol), which contains toluidine covalently bound to 2,2'-bipyridine. When bound to Re(I) in [Re(I)(dmb-tol)(CO)(3)Cl], laser flash Re(I) --> dmb metal-to-ligand charge-transfer (MLCT) excitation at 355 nm in CH(3)CN at 298 +/- 2 K is followed by efficient, rapid (<5 ns) appearance of a transient with an absorption feature at 470 nm. The transient spectrum is consistent with formation of the redox-separated state, [Re(I)(dmb(-)-tol(+))(CO)(3)Cl], which returns to the ground state by back electron transfer with k(ET) = (1.