LEWIS ACIDIC BORANE ADDUCTS OF PYRIDINES AND STILBAZOLES FOR NONLINEAR OPTICS

A series of neutral pyridyl adducts involving the strong Lewis acids B F3 and B(C6F5)(3) has been prepared, and their second-order nonlinear optical coefficients (EFISH method) have been examined. The formation of the pyridyl-boron bond leads to enhancement of the dipole moments a nd second-order NLO coefficients (beta and beta(0)). Reactions of DMAP (4-Me2N-C5H4N) with BH3, BF3, and B(C6F5)(3) give the corresponding n eutral pyridine adducts DMAP.-BH3 (orthorhombic, Pbca, a = 9.6914(7) A ngstrom; b = 11.7173(9) Angstrom; c = 22.718(2) Angstrom, V = 1622.4(5 ) Angstrom(3); Z = 8;p = 1.114 g cm(-3)), DMAP.BF3 (orthorhombic, Pbca , a = 10.430(3) Angstrom; b = 8.111(2) Angstrom; c = 20.295(7) Angstro m; V = 1717.0(9) Angstrom(3); Z = 8; p = 1.470 g cm(-3)) , and DMAP.B( C6F5)(3) (orthorhombic, Pbca, a = 12.322(1) Angstrom; b = 20.556(2) An gstrom; c = 28.455(3) Angstrom; V = 7207.4(14) Angstrom(3); Z = 8; p = 1.508 g cm(-3)). Reactions of Me2N-4-C6H4-CH=CH-C5H4N, MeO-4-C6H4-CH= CH-C5H4N, and Me2N-4-C6H4-C=C-C5H4N with BF3 and B(C6F5)(3) result in materials that are highly luminescent and incorporate structural. feat ures that are known to give rise to large second-order NLO effects. X- ray diffraction analysis for the compound Me2N-4-C6H4-C=C-C5H4N.B(C6F5 )(3) (monclinic, P2(1)/c, a = 9.883(2) Angstrom; b = 10.717(1) Angstro m; c = 28.421(4) Angstrom; beta = 91.96(1)degrees; V = 2993.4(8) Angst rom(3); Z = 4; p = 1.629 g cm(-3)) is also described.