Excited-state mixed valence in transition metal complexes.

Mixed valence in the lowest-energy metal-to-ligand charge-transfer excited state of di-(4-acetylpyridine)tetraammineruthenium(II) complexes is defined and analyzed. The excited state has two interchangeably equivalent ligands with different oxidation states. The electronic absorption band energies, selection rules, and bandwidths are analyzed quantitatively in terms of the signs and orientations of the transition dipole moments, sign and magnitude of the coupling, and resonance Raman analysis of displaced normal modes.

Tuning iridium(III) phenylpyridine complexes in the "almost blue" region.

We report on the synthesis and photophysical properties of blue emitting iridium(iii) complexes. The use of a negatively charged ligand, such as a triazolyl pyridine, allows a facile preparation, maintaining the high energy emission (blue region) of heteroleptic complexes. We discuss the role played by electron withdrawing substituents of a different nature and also how the substitution position of the same group influences the spectroscopical behaviour.

Aryl substituted ruthenium bis-terpyridine complexes: intercalation and groove binding with DNA.

The non-covalent interaction of five novel ruthenium(II) bis-terpyridine complexes with calf thymus DNA and, where appropriate, with poly[d(G-C)](2) and poly[d(A-T)](2) is described. Each complex is functionalised with aryl tail groups in the 4' position of the terpyridine ligands ((i) 9-anthracenyl, (ii) 4,4'-biphenyl, (iii) beta-naphthyl, (iv) 9-phenanthrenyl, and (v) 1-pyrenyl). Circular dichroism and linear dichroism show that the binding of three of the complexes (phenanthrenyl, anthracenyl and pyrenyl) at low metal complex concentration is dominated by intercalation of the aryl tail groups between the DNA bases.

Competing supramolecular interactions give a new twist to terpyridyl chemistry: anion- and solvent-induced formation of spiral arrays in silver(I) complexes of a simple terpyridine.

Multiple competing molecular interactions (metal-ligand, pi-stacking and hydrogen-bonding) in the silver(I) complexes of 4'-thiomethyl-2,2':6',2"-terpyridine give rise to a range of different molecular architectures, in which the metal-ligand coordination requirements are satisfied in quite different ways. Polynuclear supramolecular spirals, aggregated mononuclear and aggregated dinuclear units are all structurally characterised. The metallo-supramolecular architecture obtained displays a remarkable dependence both on the choice of non-coordinated anion and the type of solvent used (coordinating or non-coordinating).

Immobilization of π-Assembled Metallo-Supramolecular Arrays in Thin Films: From Crystal-Engineered Structures to Processable Materials.

Layer-by-layer deposition of π-assembled arrays of discrete metallo units with aryl tails and polystyrenesulfonate gives structurally well-defined thin films. The formation of these films, which is controlled by π-π interactions, metal-ion coordination, and electrostatic interactions, bridges the gap between supramolecular crystal engineering and design of layered materials.