Publications [#232031] of David N. Beratan

Journal Articles
  1. Priyadarshy, S; Therien, MJ; Beratan, DN, Acetylenyl-linked, porphyrin-bridged, donor-acceptor molecules: A theoretical analysis of the molecular first hyperpolarizability in highly conjugated push-pull chromophore structures, Journal of the American Chemical Society, vol. 118 no. 6 (1996), pp. 1504-1510 [pdf], [doi] .

    Abstract:
    We described the theoretical basis for the exceptionally large molecular first hyperpolarizabilities inherent to (5,15-diethynyl)porphinato)metal-bridged donor-acceptor (D-A) molecules. β values relevant for hyper-Rayleigh experiments are calculated at 1.064 and 0.830 μm for a complex with such a structure, [5-((4'-dimethylamino)phenyl)ethynyl)-15-((4''-nitrophenyl)ethynyl)-10 ,20-diphenylporphinato]zinc(II), and are 472 x 10-30 and 8152 x 10-30 cm5/esu, respectively. The values are 1 order of magnitude larger than that calculated for any other porphyrin bridged donor-acceptor chromophore studied to date. The considerably enhanced hyperpolarizability arises from the significant excited-state electronic asymmetry manifest in such structures (derived from the strong bridge-mediated D-A coupling enabled by the largely porphyrin-based excited state) and the large bridge-centered oscillator strength in this new class of D-bridge-A molecules. Our analysis of NLO properties (based upon INDO/SCI calculations within the sum over states formalism) shows a sensitivity to the degree of cumulenic character in the ground state. Calculations on structurally related multiporphyrin systems suggest candidate chromophores with further enhanced optical nonlinearities.