DIETHYLIMINIO)-1-PROPENYL]PHENYL)DICYANOMETHANIDE, A NOVEL BLUE WINDOW ZWITTERIONIC MOLECULE FOR NONLINEAR OPTICS

The crystal structure of the title compound, C17H16N4, (1), has been e lucidated. The molecule is shown to be planar with a highly delocalize d pi system between the two zwitterionic charge centres. This rational izes the strong solution dipole moment exhibited by this molecule (45 D) and its high measured first hyperpolarizability (190 x 10(-30) e.s. u.). The electronic spectrum of the molecule consists of strong transi tions in the visible region between 500 and 700 nm, but with an absenc e of absorption to either side. The unusually low optical absorption b etween 450 and 470 nm suggests that the description 'blue window mater ial' may be applied in relation to frequency doubling applications.