Spectroscopic and photophysical properties of dicopper(I) metallocyclophanes

摘要

Electronic properties have been calculated for derivatives of long lived Cu(I) metallocyclophanes, which are self-assembling coordination complexes that have metal-ligand charge-transfer excited states. The molecules studied here are not the typical linear push-pull type with electron withdrawing and donating substituents at either end. The central C_2 axis is preserved by putting the same type of substituent on one end of the cylindrical molecule. In theory, a pseudo-octupolar species can be obtained by a proper balance of substituents at either end of the cylinder. DFT/PBE0 geometry optimizations of the quinoxaline/pyridine derivatives show a preference for the enantiomeric C_2 isomer over the centrosymmetric C_i one. Geometry optimizations of the first excited state using TD-DFT indicate loss of C _2 symmetry and return to the ground state. First order hyperpolarizabilities were calculated using analytic gradients. Gas phase hyperpolarizabilities were enhanced by an order of magnitude when recalculated using a Polarized Continuum Model for the polar solvent acetonitrile. Electron withdrawing groups gave positive total β and donating groups gave negative β, both approximately 400 × 10~(-30) esu.