title: Challenging the auxiliary donor effect on molecular hyperpolarizability in thiophene-containing nonlinear chromophores: X-ray crystallographic and optical measurements on two new isomeric chromophores.
abstract: To reexamine the established "auxiliary donor" effect of thiophene in nonlinear optical (NLO) chromophores, we have prepared two isomeric donor-acceptor azo dyes, differing only in the position of the thiophene. Experimental analysis of these chromophores, including electric field-induced second harmonic generation (EFISH) and X-ray crystallography, contradicts previous experimental findings on similar chromophores but is consistent with the majority of computational precedents. We have found that the thiophene on the donor side produces a compound with a larger dipole moment; however, the isomer with the thiophene on the acceptor side is more nonlinear and has a higher figure of merit for NLO device applications.
authors.affiliation: Department of Electrical Engineering, University of California, 1156 High Street, Santa Cruz, California 95064, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Moylan
authors.forename: Brian J
authors.initials: BJ
authors.lastname: McNelis
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Nathan
authors.forename: Michael A
authors.initials: MA
authors.lastname: Marques
authors.forename: Eric L
authors.initials: EL
authors.lastname: Hermstad
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Brichler
mesh_terms: D001391:Azo Compounds / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004396:Coloring Agents / Q000737:chemistry; D018360:Crystallography, X-Ray; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D013876:Thiophenes