THEORETICAL INVESTIGATION OF THE 2ND-ORDER NONLINEAR-OPTICAL PROPERTIES OF CALIX[4]ARENE MOLECULES

We investigate theoretically the second-order nonlinear optical properties of a new class of compounds presenting more than one [Donor-pi conjugated segment-Acceptor] unit in a single molecule: the calix[4]arenes. We calculate the second-order polarizabilities beta for four conformers of calix[4]arenes; namely, the cone, partial cone, 1,2-alternate and 1,3-alternate conformations. The theoretical results are compared with Electric-Field-Induced Second Harmonic Generation (EFISGH) and Hyper Rayleigh Scattering (HRS) experimental data. We describe the evolution of the beta response with the change of conformation and point out the presence of strong pi-pi cofacial interactions which shift the charge transfer bands to shorter wavelengths.