Spectroscopic Studies of Phthalocyanines and Their Clusters with Small Molecules.

摘要

van der Waals clusters of free base phthalocyanine (H2Pc) and magnesium phthalocyanine (MgPc) with small hydrocarbons (CnH2n+2 (n = 1, 2, 3)), hydrogen bonding solvents (H2O, MeOH, EtOH), and CO2 are studied in the gas phase using supersonic molecular jet spectroscopy. Flourescence excitation spectra of the cluster systems are characterized in the O regions of the cluster S1, S0 transitions. Forbidden low frequency cluster chromophore out-of-plane vibronic transitions are induced by clustering in the majority of the cluster systems studied. This low frequency motion is characterized using an out-of-plane normal coordinate analysis on the H2Pc moeity. Calculations of the binding energy and ground state geometry for the clusters are carried out employing Lennard-Jones (6-12-1) and hydrogen bonding (10-12-1) potentials. Comparison between the calculations and experiments allow for the identification of specific configurations responsible for the cluster vibronic transitions observed. The cluster vibronic spectra and theoretical calculations suggest that stable H2Pc and MgPc solvation sites are located over the phthalocyano core and not over peripheral ring centers.