Signaling Recognition Events with Fluorescent Sensors and Switches.

Ru(II) polypyridine complexes: photophysics, photochemistry, eletrochemistry, and chemiluminescence

Lanthanide-based luminescent hybrid materials.

Design principles of fluorescent molecular sensors for cation recognition

Great attention is currently paid to the synthesis of polynuclear transition metal complexes and the study of their photochemical, photophysical, and electrochemical properties. This interest is stimulated, in particular, by attempts to design and construct multicomponent systems (often called supramolecular species) capable of performing useful lightand/or redox-induced functions.1-16 A great deal of investigations on mononuclear transition metal complexes had previously shown that several families of these compounds are very interesting from the electrochemical, photochemical, and photophysical viewpoints.17-22 The metalligand interaction, in fact, is often (i) weak enough to allow the manifestation of intrinsic properties of metal and ligands (e.g., ligand-centered and metalcentered absorption bands and redox waves) and, at the same time, (ii) strong enough to cause the appearance of new properties, characteristic of the whole compound (e.g., metal-to-ligand or ligand-tometal charge-transfer bands). On passing from mononuclear to polynuclear transition metal complexes, the situation becomes even more interesting because in the latter (supramolecular) compounds one can find, besides properties related to each metal-based component, properties related to the structure and composition of the whole array. A suitable choice of the mononuclear building blocks and bridging ligands and an appropriate design of the (supramolecular) structure can in fact allow the occurrence of very interesting and potentially useful processes such as energy transfer along predetermined pathways, photoinduced charge separation, multielectron exchange at a predetermined potential, etc. The knowledge on the luminescence and redox properties of polynuclear transition metal complexes is rapidly accumulating, but it is disperse in a great number of journals. We have made an attempt to collect the available results, and we present them together with some fundamental introductory concepts and a few comments. One of the main problems, of course, was to delimit the field of this review. Using personal criteria which are related to our own research interests, we decided to consider only polynuclear transition metal complexes that can be defined as supramolecular species (section 2.2) and that are reported to exhibit luminescence. For such compounds only, the electrochemical properties have also been reviewed. Furthermore, we decided to include only classical (Werner-type) polynuclear transition metal compounds where the number of metal-based units is exactly known and the connection between the metal centers is provided only by bridging ligands. Thus, a number of interesting systems such as polymer-appended metal † In memoriam of Mauro Ciano. 759 Chem. Rev. 1996, 96, 759−833

Luminescent and Redox-Active Polynuclear Transition Metal Complexes.

Bimolecular electron transfer reactions of the excited states of transition metal complexes

The basic concepts for direct and catalyzed photodissociation of water have been summarized. Water dissociation in closed-cycle processes based on endothermic photochemical reactions offers a potential solution to the solar energy conversion problem. Transition metal complexes, whose excited state chemistry is extremely rich (23, 24) although mostly unexplored, are, in principle, suitable "catalysts" for cycles of this type. The most interesting cycles are those involving metal hydrido complexes or binuclear complexes in which the two metal atoms are bound into a macrocyclic ligand. Systematic investigations of the photochemistry of transition metal complexes with the aim of designing suitable systems for solar energy conversion have long-range promise and merit further consideration.

http://science.sciencemag.org/content/sci/189/4206/852.full.pdf

Solar Energy Conversion by Water Photodissociation: Transition metal complexes can provide low-energy cyclic systems for catalytic photodissociation of water.

Quenching and sensitization processes of coordination compounds

Vertical and "nonvertical" energy transfer processes. A general classical treatment

The rate constants for the quenching of the excited states of metal ions and complexes in homogeneous fluid solution are reported in this compilation. Values of kq for dynamic, collisional processes between excited species and quenchers have been critically evaluated, and are presented with the following information, among others, from the original publications, when available: description of the solution medium, temperature at which kq was determined, experimental method, range of quencher concentration used, lifetime of the excited state in the absence of quencher, activation parameters, quenching mechanism. Data collection is complete through the end of 1986, and covers the coordination compounds of 26 metals, including the ions and complexes of the inner‐ and outer‐transition metals, and porphyrin complexes of nontransition metals. Data for 261 excited states quenched by more than 400 inorganic quenchers and 600 organic quenchers have been extracted from almost 500 publications. The introduction to th...

Fabrizio Bolletta

Papers

Bimolecular electron transfer reactions of the excited states of transition metal complexes

Solar Energy Conversion by Water Photodissociation: Transition metal complexes can provide low-energy cyclic systems for catalytic photodissociation of water.

Quenching and sensitization processes of coordination compounds

Vertical and "nonvertical" energy transfer processes. A general classical treatment

Rate Constants for the Quenching of Excited States of Metal Complexes in Fluid Solution