Perfluorinated phthalocyanines for optical limiting: Evidence for the direct correlation between substituent electron withdrawing character and the nonlinear optical effect

The optical limiting performance exhibited by phthalocyanines substituted with electron withdrawing atoms such as F, results considerably enhanced with respect to the optical limiting effect produced by unsubstituted or differently substituted phthalocyanines. This enhancement is verified by comparing under analogous conditions the nonlinear optical transmission of hexadecafluorophthalocyaninato complexes containing Ti-IV, V-IV, Zr-III, and In-III as coordination central atoms, and tetra- or octaalkylsubstituted phthalocyaninato complexes with the same central atoms by means of the Z-scan technique. The remarkable variations of the nonlinear transmittance of perfluorinated phthalocyanines in solution indicates the strong influence that electron-withdrawing groups exhibit upon the variations of the transition dipole moments involved in the electronic transition, which effectively limits the intense radiation. (C) 2003 American Institute of Physics.