Highly polarizable chromophores for nonlinear optics: syntheses, structures and properties of donor-acceptor substituted thiophenes and oligothiophenes

• Published in: Tetrahedron Vol. 54; no. 29; pp. 8469 - 8480
• Main Authors: Steybe, Felix, Effenberger, Franz, Gubler, Ulrich, Bosshard, Christian, Günter, Peter
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 16.07.1998; Elsevier
• Subjects: Chemistry; Chemistry, Organic; Chromophores; Donor-acceptor systems; Electronic spectra; Physical Sciences; Science & Technology; Thiophenes; Chromophores; Donor-acceptor systems; Thiophenes; Electronic spectra; thiophenes; electronic spectra; 3RD-HARMONIC GENERATION; HYPERPOLARIZABILITY; HYPER-RAYLEIGH SCATTERING; SALTS; chromophores; DYE; donor-acceptor systems; 2ND-ORDER POLARIZABILITY; MOLECULAR-CRYSTALS; SYSTEMS; DERIVATIVES
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/S0040-4020(98)00450-5

A series of new chiral donor-acceptor substituted mono- ( 1a,b), bi- ( 2a,b,f) and terthiophenes ( 3) as well as thienyl- and bithienylpyridinium salts 1d-f and 2i-k with various counterions has been synthesized. This class of thiophenes exhibit excellent molecular nonlinear optical properties such as second-order polarizabilities β or second-order hyperpolarizabilities γ. With respect to an application as nonlinear optical materials, some of these compounds have been investigated by Kurtz powder technique as well as by X-ray crystallographic analysis. The second-harmonic generation (SHG) powder efficiencies are measured at 1.064 μm and 1.3 μm with urea as reference. Furthermore, the influence of the chiral donors prolinol and methoxy-methylpyrrolidine in the thiophene derivatives as well as the variation of counterions in the pyridinium salts on the orientation of the chromophores in the crystalline lattice was investigated. Thiophenes with chiral donors and thienylpyridinium salts with counterions X were synthesized and investigated for use as NLO materials.