SPECTRAL PROPERTIES OF TETRATHIABENZOQUINONES AND THEIR SELF-ASSEMBLYIN THE SOLID-STATE

Bis(1,4-dithiacyclohexano) [2,3-b:2',3'-e]-1,4-benzoquinone 3a and ana logous cyclic dithiaquinone derivatives were synthesized. The differen ce (Delta lambda) in lambda max of these dyes between the solution pha se and vapor deposited thin film indicates the degree of strength of t he intermolecular pi-pi interactions in the solid state. The Delta lam bda values were largely affected by the interlayer distances and the s teric requirements of the molecules. The three dimensional molecular s tacking of dye 3a was evaluated by X-ray crystal analysis and the subs tituent effects on the properties of analogous dyes were evaluated by the MOPAC and AMPAC calculation methods. The vapor deposited thin film of dye 3a gave large 3rd order nonlinear optical susceptibility. The intermolecular pi-pi interactions of the dye molecules play an importa nt role for these special functionalities. (C) 1997 Elsevier Science L td.