NLO properties of chiral phthalocyanine films

摘要

We studied linear and nonlinear optical properties of four different phthalocyanines: vanadyl and copper phthalocyanines substituted with chiral branched side chains, (S)(OMeBu)_8VOPc, (S)(OMeBu)_8CuPc; a racemic analogue (R,S)(OMeBu)_8VOPc; vanadyl phthalocyanine substituted with linear side chains, (OBu)_8VOPc. We investigated the molecular packing and their third-order nonlinear optical responses in terms of chirality, planarity, and side chain structures. Molecular arrangement of (S)(OMeBu)_8VOPc in the thin films was determined to be a columnar phase with rectangular 2D crystals by X-ray diffraction studies. The thin films of (S)(OMeBu)_8VOPc displayed CD activity. While, a chloroform solution of this compound did not show any CD. Therefore, we conclude that the CD in the films must result from the chiral aggregation of the molecules. The %~(3) value of the films of (S)(OMeBu)_8VOPc was determined for 6.7 x10~(-11) esu by third harmonic generation at 1.907μm and this value was larger than those of (R,S)(OMeBu)_8VOPc, (R,S)(OMeBu)_8CuPc, and (OBu)_8VOPc.