Spin-orbit and solvent effects in the luminescent [Re₆Q ₈(NCS)₆]^4-, Q = S, Se, Te clusters: Molecular sensors and molecular devices

Relativistic time-dependent density functional (TDDFT) calculations including spin orbit interactions via the zero order regular approximation (ZORA) and solvent effects using the COSMO model were carried out on the [Re₆Q₈(NCS)₆]^4-, (Q = S, Se, Te) clusters. These calculations indicate that the lowest energy allowed electronic transitions are characterized by being of LMCT type. The calculated absorption maximum tends to shift to longer wavelengths as the face-capping chalcogenide ligand becomes heavier. Thus our calculations predict that the [Re ₆Te₈(NCS)₆]^4- cluster might be also luminescent. Due to the unusual properties exhibited by these and other isoelectronic and isostructural hexarhenium (III) chalcogenide clusters, hexamolybdenum halide clusters and hexatungsten halide clusters, we propose here the design of nanodevices, such as, molecular sensors and molecular nanocells for molecular electronics.