Chiral stilbazolium chromophores: An approach toward multiproperty materials combining conductivity and second-order optical nonlinearities

A new chiral cyanine dye, 4'-[2-(methoxymethyl)pyrrolidinyl]-1-methylstilba zolium iodide (MPMS+I-) is reported. It crystallizes in the monoclinic P2(1 ) space group. a = 16.559(2) Angstrom, b = 6.263(1) Angstrom, c = 24.477(3) Angstrom, beta = 109.20(1)degrees, Z = 2. The hyperpolarizability of MPMSI- is compared versus that of 4'-dimethylamino-1-methylstilbazolium iodide (DAMS(+)I(-)), MPMS+I- is phase matchable and exhibits an efficiency up to 80 times that of urea in second-harmonic generation (SHG). Both compounds ( C+I-) react with tetracyanoquinodimethane (TCNQ), and the resulting C+(TCNQ (2))(-) exhibit conductivities in the range 10(-3)-10(-2) S cm(-1). The pos sibility of combining conductivity and optical nonlinearities is discussed.