A series of bimetallic ruthenium complexes [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)] featuring diethynylaromatic bridging ligands (Ar = 1,4-phenylene, 1,4-naphthylene, 9,10-anthrylene) have been prepared and some representative molecular structures determined. A combination of UV-vis-NIR and IR spectroelectrochemical methods and density functional theory (DFT) have been used to demonstrate that one-electron oxidation of compounds [{Ru(dppe)Cp*}(2)(μ-C≡CArC≡C)](HC≡CArC≡CH = 1,4-diethynylbenzene; 1,4-diethynyl-2,5-dimethoxybenzene; 1,4-diethynylnaphthalene; 9,10-diethynylanthracene) yields solutions containing radical cations that exhibit characteristics of both oxidation of the diethynylaromatic portion of the bridge, and a mixed-valence state. The simultaneous population of bridge-oxidized and mixed-valence states is likely related to a number of factors, including orientation of the plane of the aromatic portion of the bridging ligand with respect to the metal d-orbitals of appropriate π-symmetry.

Spinning to improve (band) shape: A blend of theoretical and experimental work demonstrates that the rotational conformation of mixed-valence complexes influences the low-energy (NIR) transitions in such molecules. Interpretations of the NIR band shapes are presented.

The hydrothermal synthesis of the novel Na[LnSiO4] (Ln = Gd, Eu, Tb) disordered orthorhombic system is reported. At 100 K, and above, these materials are best described in the centrosymmetric orthorhombic Pnma space group. At lower temperatures (structure solved at 30 K) the unit cell changes to body-centered with Imma symmetry. The materials exhibit unique photophysical properties, arising from both, this phase transformation, and the disorder of the Ln(3+) ions, located at a site with D2d point symmetry. Na[(Gd0.8Eu0.1Tb0.1)SiO4] is an unprecedented case of a luminescent ratiometric thermometer based on a very stable silicate matrix. Moreover, it is the first example of an optical thermometer whose performance (viz., excellent sensitivity at cryogenic temperatures <100 K) is determined mainly by a structural transition, opening up new opportunities for designing such devices.

The influence of molecular conformation on the oxidation (ionisation) potential and electronic structure associated with several TPD-style hole transport materials has been assessed through a combination of single crystal X-ray diffraction, electrochemical and spectroelectrochemical methods and DFT calculations. The introduction of methyl groups can be used to tune the ionisation potential of these molecular species through a combination of electronic (inductive) and thermodynamic effects, while the conformation of the biphenyl portion of the molecular framework is found to play the greatest role in determining the Marcus-type reorganisation energy associated with the charge transport process on the molecular level.

A combination of IR spectroelectrochemistry and DFT calculations has been used to demonstrate that the vinyl ligands in the complexes [Ru(CHdCHC 6 H 4 Me-4)Cl(CO)-(PMe 3 ) 3 ] and [{RuCl(CO)(PMe 3 ) 3 } 2 (μ-CHdCHC 6 H 4 CHd CH)] are redox noninnocent, and one-electron oxidation results in radical cations that are best described in terms of metal-stabilized organic radicals.