title: Electronic transitions involved in the absorption spectrum and dual luminescence of tetranuclear cubane [Cu4I4(pyridine)4] cluster: a density functional theory/time-dependent density functional theory investigation.
abstract: We present a combined density functional theory (DFT)/time-dependent density functional theory (TDDFT) study of the geometry, electronic structure, and absorption and emission properties of the tetranuclear "cubane" Cu4I4py4 (py = pyridine) system. The geometry of the singlet ground state and of the two lowest triplet states of the title complex were optimized, followed by TDDFT excited-state calculations. This procedure allowed us to characterize the nature of the excited states involved in the absorption spectrum and those responsible for the dual emission bands observed for this complex. In agreement with earlier experimental proposals, we find that while in absorption the halide-to-pyridine charge-transfer excited state (XLCT*) has a lower energy than the cluster-centered excited state (CC*), a strong geometrical relaxation on the triplet cluster-centered state surface leads to a reverse order of the excited states in emission.
authors.affiliation: Istituto CNR di Scienze e Tecnologie Molecolari, c/o Dipartimento di Chimica, Università degli studi di Perugia, via Elce di Sotto, 8, I-60123 Perugia, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: De Angelis
authors.forename: Simona
authors.initials: S
authors.lastname: Fantacci
authors.forename: Antonio
authors.initials: A
authors.lastname: Sgamellotti
authors.forename: Elena
authors.initials: E
authors.lastname: Cariati
authors.forename: Renato
authors.initials: R
authors.lastname: Ugo
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ford