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Summary: 432 J. CHEM. SOC., CHEM. COMMUN., 1993
Synthesisand First Hyperpolarizabilitiesof Acceptor-substituted P-apo-8'-Carotenal
DerivedCompounds
Sandra Gilmour,a Seth R.Marder,atb Bruce G. Tiernannarband Lap-Tak Chengc
a Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
b Molecular Materials Resource Center, TheBeckman Institute, California Institute of Technology, Pasadena,CA91125,
USA
c Central Research and Development Department, E. 1. Du Pont de Nemours & Co. Inc., Experimental Station, PO Box
80356, Wilmington, Delaware 19880-0356,USA
The synthesis and second-ordernonlinear optical properties of acceptor-substitutedbiologically derived
(3-apo-8'-carotenalcompoundsare reported; electricfield-inducedsecondharmonicgeneration(EFISH) measurements
give values of p(0)which are 2-6 times greater than for 4-N,N-dimethylamino-4'-nitrostilbene (DANS).
In an attempt to understand the structural basis of molecular
polarizabilities and hyperpolarizabilities in conjugated organic
chromophores we have been investigating the parameters of
bond length alternation (BLA) and aromaticity. 1-3 Computa-
tional studies using MOPAC,4.5 together with experimental
electric field-induced second harmonic generation (EFISH)6,7
and third harmonic generation (THG) results on asymmetric
cyanines and polarized polyenes have lead us to believe that
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