Abstract

As a result of our discovery of a novel reaction of TCNQ with triethylamine¹ which led to the synthesis of DEMI (structure I, fig. 1)², we have prepared a range of similar adducts of TCNQ with tertiary ethyl amines (structures I - VII). All of these adducts have similar structural components, a dicyanomethanide group separated from an electron deficient amino moiety by an aromatic/quinoidal ring and a "conjugated" π system. The spectral properties of these species are therefore very similar, comprising a broad charge transfer band with very little absorption to either side of it, in fact a "blue window" centred on 460 nm (fig. 2, below). As a result of their charge separated ground state, these molecules have large theoretical μβ(0) products, indicative of a high second order nonlinearity. The molecular figure of merit, μβ(0) has been calculated for I as -17,500 x 10^-48esu. Three TCNQ adducts prepared by conventional reactions of TCNQ with secondary amines⁶ are included (IIX - X) for comparison purposes. The μβ(0) product of X has been determined⁷ to be -840 x 10^-48 esu, assuming a calculated μ of 3.5 D. This material is however extremely insoluble and therefore difficult to work with.

© 1995 Optical Society of America