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Spectroscopic and photophysical properties of dicopper(I) metallocyclophanes



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 C2 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 C2 isomer over the centrosymmetric Ci one. Geometry optimizations of the first excited state using TD-DFT indicate loss of C2 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. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010