PORPHYRIN BASED SELF-ASSEMBLED MONOLAYER THIN-FILMS - SYNTHESIS AND CHARACTERIZATION

The synthesis and characterization of covalently bound self-assembled monolayer thin films of 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) and its derivatives on fused quartz and silicon [100] substrates having a native oxide layer are described. The monolayer film consists of porphyrin macrocycle disk-like structures that were analyzed by UV-visible spectroscopy, X-ray photoelectron spectroscopy (XPS), and polarized FTIR-ATR measurements. One of the attractive features of these complexes is their large second-order nonlinear optical response, as expected for a strongly delocalized pi-electron system without inversion symmetry. Second-harmonic generation (SHG) measurements have been used to determine the absolute value of the dominant element of the nonlinear susceptibility, chi(zzz) approximately 2 x 10(-8) esu, the uniformity of these films, and the dispersion of the refractive indices. The average molecular orientation angle of the surface-bound chromophores was measured by both FTIR-ATR and SHG and found to be in good agreement.