Bis-(benzene-thiol-ato)(2,2'-biquinoline)zinc(II).

The title compound, [Zn(C(6)H(5)S)(2)(C(18)H(12)N(2))], was prepared as a model for future complexes that will be incorporated into light-harvesting arrays. The Zn(II) atom lies on a twofold rotation axis and the ligands are arranged tetra-hedrally around this atom. The benzene-thiol-ate ligand and the biquinoline ligand are nearly perpendicular to one another, making a dihedral angle of 84.

Solvent dependence of intramolecular electron transfer in a helical oligoproline assembly.

The helical oligoproline assembly CH3-CO-Pro-Pro-Pro-Pra(Ptzpn)-Pro-Pro-Pra(RuIIb2m2+ -Pro-Pro-Pra(Anq)-Pro-Pro-Pro-NH2, having a spatially ordered array of functional sites protruding from the proline backbone, has been prepared. The 13-residue assembly formed a linear array containing a phenothiazine electron donor, a tris(bipyridine)ruthenium(II) chromophore, and an anthraquinone electron acceptor with the proline II secondary structure as shown by circular dichroism measurements. Following RuII --> b2m metal-to-ligand charge-transfer (MLCT) excitation at 457 nm, electron-transfer quenching occurs, ultimately to give a redox-separated (RS) state containing a phenothiazine (PTZ) radical cation at the Pra(Ptzpn) site and an anthraquinone (ANQ) radical anion at the Pra(Anq) site.