Abstract
Investigations on the excited state absorption signal of
5,10,15,20-tetra( 4- pyridyl)-21H, 23H-porphyrin, modified by either
changing the central ion or adding peripheral groups, were performed
using 5 ns laser pulses at 532 nm, in association with linear absorbance
and fluorescence decay time measurements. The reverse saturable
absorption ( RSA) increases remarkably when Zn2+ replaces H+ at the
central position of the porphyrin ring. However, it decreases when
RuCl2( CO)( PPh3)(2) and RuCl2( CO)( dppb) groups are attached at
outlying positions through the pyridine rings, for both the free base
and zinc porphyrins. A theoretical model based on Jablonski diagram was
used to verify the main reason for the decrease on the RSA signal caused
by ruthenium groups.
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