The binding of carboxylate- and acetylacetonate-linked chromophores to homodisperse polyoxotitanate nanoclusters with 17 Ti atoms or more are surveyed and found to be limited to chelate-bidentate and the bridging modes, the former being dominant for the acetylacetonate-linked chromophores, the latter for the carboxylate linkers. Chromophores with acetylacetonate linking groups invariably bind in the chelate mode, whereas carboxylic acid terminated chromophores more frequently are observed to have the bridging mode, with the exception of three cases in which a strong electron-donating substituent is present on two different sensitizers. The calculations for isonicotinateand nitrophenylacetylacetonate functionalized Ti17 clusters show the observed binding modes to correspond to the lower energy functionalized clusters, but do not predict the difference between the cinnamic acid and dimethylaminocinnamic acid binding to Ti17, which are bridging and chelate respectively. Both binding modes were never observed to occur for a single chromophore, even when synthetic conditions were varied. Density of state calculations show broadening and splitting of the chromophore LUMO on complexation due to interaction with the cluster's conduction band, as well as frequent penetration of sensitizer orbitals into the bandgap of the functionalized nanoparticle.

The excited state structure of [Cu(1)[(1,10-phenanthroline-N,N’) bis(triphenylphosphine)] cations in their crystalline [BF4] salt has been determined at both 180 and 90K by single-pulse time-resolved synchrotron experiments with the modified polychromatic Laue method. The two independent molecules in the crystal show distortions on MLCT excitation which differ in magnitude and direction, a difference attributed to a pronounced difference in the molecular environment of the two complexes. As the excited states differ, the decay of the emission is bi-exponential with two strongly different lifetimes, the longer lifetime, assigned to the more restricted molecule, becoming more prevalent as the temperature increases. Standard deviations in the current Laue study are very much lower than those achieved in a previous monochromatic study of a Cu(I) 2,9 dimethyl-phenanthroline substituted complex (J. Am. Chem. Soc. 2009, 131, 6566), but the magnitude of the shifts on excitation is similar, indicating that lattice restrictions dominate over the steric effect of the methyl substitution. Above all the study illustrates emphatically that molecules in solids have physical properties different from those of isolated molecules and that their properties depend on the specific molecular environment. This conclusion is relevant for the understanding of the properties of molecular solid state devices which are increasingly used in current technology.

The triplet excited state of a new crystalline form of a tetranuclear coordination d10–d10-type complex, Ag2Cu2L4 (L = 2-diphenylphosphino-3-methylindole ligand), containing AgI and CuI metal centers has been explored using the Laue pump–probe technique with ≈80 ps time resolution. The relatively short lifetime of 1 μs is accompanied by significant photoinduced structural changes, as large as the Ag1···Cu2 distance shortening by 0.59(3) Å. The results show a pronounced strengthening of the argentophilic interactions and formation of new Ag···Cu bonds on excitation. Theoretical calculations indicate that the structural changes are due to a ligand-to-metal charge transfer (LMCT) strengthening the Ag···Ag interaction, mainly occurring from the methylindole ligands to the silver metal centers. QM/MM optimizations of the ground and excited states of the complex support the experimental results. Comparison with isolated molecule optimizations demonstrates the restricting effect of the crystalline matrix on photoinduced distortions. The work represents the first time-resolved Laue diffraction study of a heteronuclear coordination complex and provides new information on the nature of photoresponse of coinage metal complexes, which have been the subject of extensive studies.

The structures of three newly synthesized phosphonate-substituted polyoxotitanates are reported. The Ti/O core of [Ti4O(OEt)12(PhenylPO3)] (1) is the building block for two larger phosphonate-substituted nanoclusters, [Ti25O26(OEt)36(PhenylPO3)6] (2) and [Ti26O26(OEt)39(PhenylPO3)6]Br (3). All compounds exhibit a not previously recognized triply bridging binding mode of the phosphonate anchor with short connecting Ti-O bonds, the average of which is 2.010(7) Å. Comparison with previously reported work suggests that the binding mode of the phosphonate anchor is strongly dependent on the structure of the underlying substrate.

The synthesis and crystallographic characterization of alkali-metal-doped ethoxotitanate clusters with 28 and 29 Ti atoms as well as a new dopant-free Ti28 cluster are presented. The light-metal-doped polyoxotitanate clusters in which the alkali-metal atom is the critical structure-determining component are the largest synthesized so far. Calculations show that doping with light alkali atoms narrows the band gap compared with the nondoped crystals but does not introduce additional energy levels within the band gap.