Spectroscopic and photophysical properties of dicopper(I) metallocyclophanes

Abstract

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 b and donating groups gave negative b, both approximately 400 Â 10 À30 esu. V

A self-assembled, metallo-organic supramolecular frequency doubler

“…Those studies additionally predict pronounced NLO effects from appropriately substituted metallocyclophanes. 11 We now report the realization of these expectations in a selfassembled metallosupramolecular NLO-chromophore. Along partially analogous lines, through-space, donor-p-acceptor substituted [2.2]paracyclophane derivatives may possess higher nonlinear optical coefficients relative to non-cyclic model compounds.…”

“…This is relevant, since we previously showed that quinoxaline-pyridine hybrids and related compounds self-assemble in the presence of cuprous ions into noncentrosymmetrically (C 2 -symmetric) p-stacked, double-decker complexes. 9,10 Our computational studies 10,11 have furthermore indicated that the total energies of the C 2 configured compounds are generally lower than those of configurationally isomeric C i metallocyclophanes. Those studies additionally predict pronounced NLO effects from appropriately substituted metallocyclophanes.…”