MOLECULAR AND CRYSTAL-STRUCTURES OF A CLASS OF PUSH-PULL QUINONOID COMPOUNDS WITH POTENTIAL NONLINEAR-OPTICAL APPLICATIONS

Molecular and crystal structures of three compounds with electron dono r-conjugation unit-electron acceptor framework are reported where the conjugation unit is formally a quinonoid ring. Semiempirical quantum c hemical calculations indicate large hyperpolarizabilities in these pus h-pull molecules. Since all the crystal structures are found to belong to centrosymmetric space groups, modifications are necessary for quad ratic nonlinear optical applications.