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-methylstilbazolium iodide (MPMS + I - ) is reported. It crystallizes in the monoclinic P 2 1 space group. a = 16.559(2) Å, b = 6.263(1) Å, c = 24.477(3) Å, β = 109.20(1)°, Z = 2. The hyperpolarizability of MPMS + I - 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 possibility of combining conductivity and optical nonlinearities is discussed.