Photophysics, photochemistry and solar energy conversion with tris(bipyridyl)ruthenium(II) and its analogues

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)

Old materials with new tricks: multifunctional open-framework materials.

The magnetic properties of many magnetic materials can be controlled by external stimuli. The principal focus here is on the thermal, photochemical, electrochemical, and chemical control of phase transitions that involve changes in magnetization. The molecular compounds described herein range from metal complexes, through pure organic compounds to composite materials. Most of the Review is devoted to the properties of valence-tautomeric compounds, molecular magnets, and spin-crossover complexes, which could find future application in memory devices or optical switches.

Control of magnetic properties through external stimuli.

Distance Dependence of Electron Transfer Rates

Mixed Valence Complexes of d5‐d6 Metal Centers

The contribution of mixed-valence electron delocalisation to the ferromagnetic exchange between the iron(III) ions in Prussian Blue {FeIII4[eII(CN)6]3·14H2O} has been estimated theoretically. Agreement between the calculated and observed values of the Curie temperature is quite good.

Charge transfer in mixed-valence solids. Part VIII. Contribution of valence delocalisation to the ferromagnetism of Prussian Blue

Trapping of valence states in a ruthenium(II,III)-pyrazine complex

A method is described for calculating coupling integrals between donor and acceptor ions in class II mixed valence compounds. Metal–ligand–metal interactions are simulated by a perturbation model, which is then used to calculate valence delocalization coefficients from empirical and theoretical information On metal → ligand and ligand → metal charge transfer in the component single-valence complexes. The model is tested by applying it to FeII,III cyanides (Prussian Blue and its discrete molecular analogues) and silicates (e.g. biotite micas). Good agreement is found between observed and calculated intensities of the mixed valence charge transfer transitions.

Charge transfer in mixed valence solids. Part VII. Perturbation calculations of valence delocalization in iron(II,III) cyanides and silicates

The semiempirical zero-differential-overlap molecular orbital model which was shown in earlier papers in this series to give a good account of the charge transfer and π-π* spectra of Fe(II) complexes with conjugated ligands such as 2,2′-bipyridyl and 1,10-phenanthroline is extended to complexes having openshell ground states, such as those of Fe(III), and to complexes of Ru(II) and Ru(III). The results are used to assign the observed charge transfer and intra-ligand absorption bands to specific orbital transitions. Observed and calculated intensities are in good agreement: reasons are advanced for the much lower intensity of the charge transfer bands in Ru(III) compared to Ru(II) complexes.

Bryan Mayoh

Papers

Charge transfer in mixed-valence solids. Part VIII. Contribution of valence delocalisation to the ferromagnetism of Prussian Blue

Trapping of valence states in a ruthenium(II,III)-pyrazine complex

Charge transfer in mixed valence solids. Part VII. Perturbation calculations of valence delocalization in iron(II,III) cyanides and silicates

The excited states of bipyridyl and phenanthroline complexes of Fe(III), Ru(II) and Ru(III): A molecular orbital study

Charge transfer in mixed valence solids part 7, perturbation calculations of valence delocalization in iron(ii, iii) cyanides and silicates