Quantum chemical calculations were carried out to investigate the nature of the bonding between a neutral Be 3 ring and noble gas atom. Electronic structure calculation for these complexes was carried out at different computational levels in association with natural bond orbital, quantum theory of atoms in molecules, electron localization function, symmetry adapted perturbation theory, and molecular electrostatic potential surface analysis of Be 3 complexes. The Be atoms in the Be 3 moiety are chemically bonded to one another, with the Be Be bond dissociation energy being $125 kJ mol À1 . The Be 3 ring interacts with the noble gases through noncovalent interactions. The binding energies of the noble gas atoms with the Be 3 ring increases with increase in their atomic number. The non-covalent interaction index, density overlap region indicator and independent gradient model analyses reveal the presence of non-covalent inter-fragment interactions in the complexes. Energy decomposition analysis reveals that dispersion plays the major role towards stabilizing these systems.

We report solvent-dependent excited state properties of three difuranone derivatives with a quinoidal backbone by steady-state and lifetime fluorescence measurements and theoretical calculations. Remarkable bathochromic shifts in fluorescence with diminished intensity indicate the occurrence of strong intramolecular charge-transfer transitions in high polar solvents. Cyclic voltammetric redox potentials reveal an interesting variation of biradical characters of the compounds with increasing solvent polarity. Solvent polarity also significantly modulates the energy levels of the charge-transfer (CT) states, as observed from the combined analyses of redox potentials and photophysical data via the Rehm–Weller equation. When high polar solvents favor forward CT by a more exoergic driving force and stabilize the charge-separated states, the reverse CT process diminishes. Estimated free energies of activation for CT suggest that high polar solvents lessen the activation barrier. Calculated excited state energies of the compounds at the CAM-B3LYP/6-31+G* level fulfill the primary conditions required for singlet fission, a process that can substantially increase the efficiency of solar cells, and the crystal packing for compound 1 also reveals a favorable geometry for singlet fission.

Quantum chemical calculations were carried out to investigate the noble gas binding ability of Be3B+ cluster. Calculations reveal that heavier noble gas atoms (ArXe) form stable complexes with this cluster. Detailed bonding analyses reveal that the noble gas atoms act as donor fragment in the formation of Ng → Be donor–acceptor bonds. Three noble gas atoms can consecutively form bonds with the Be atom of the Be3B+ cluster.