Theoretical chemical study on NLO properties of polypyridinopyridine and its derivatives

Abstract

With quantum chemical PM3/FF method, effects of strucure and substituents -NO 2 and -NH 2 on nonlinear optical properties of polypyridinopyridine(PPY) were discussed. The results showed that the β and y values were -5.54 x 10 -29 esu and -1.544 x 10 -32 esu, respectively. In three stable structures of equal-bond length structure (a), cis-structure (b) and trans-structure (c), the β and y values of (a) and (c) is larger than (b). More specially, β and y values of (c) increased promptly as the number of repeat unit increased. When the number of unit was over four, (c) gave the biggest β and y. In structures of PPY substituted by NO 2 and NH 2 , the effects of pull-push electron and π-electron delocalization became stronger, β increased effectively to about 1.6 x 10 -27 esu. PPY is a promising candidate of nonlinear optical (NLO) materials.