Flash-photolysis studies of trans-[Cr(cyclam)(CN)(2)]ClO4 (cyclam = 1,4,7,11-tetraaza-cyclotetradecane) complex: Dependence of its luminescence lifetime on solvents, concentration and temperature
L. Vincze et al., Flash-photolysis studies of trans-[Cr(cyclam)(CN)(2)]ClO4 (cyclam = 1,4,7,11-tetraaza-cyclotetradecane) complex: Dependence of its luminescence lifetime on solvents, concentration and temperature, I J CHEM A, 37(12), 1998, pp. 1041-1044
Citations number
9
Categorie Soggetti
Chemistry
Journal title
INDIAN JOURNAL OF CHEMISTRY SECTION A-INORGANIC BIO-INORGANIC PHYSICAL THEORETICAL & ANALYTICAL CHEMISTRY
The luminescence lifetime (tau(lum)) Of the title complex (I) has been dete
rmined in eight solvents. It has been found that in spite of former assumpt
ions the luminescence lifetime of I depends on the concentration of the com
plex. The self-quenching and Stem-Volmer constants, and the relative values
of luminescence quantum yields have been determined in eight solvents. The
re is no measurable self-quenching in 1,2-ethane-diol and N,N-dimethylforma
mide, dynamic self-quenching has been found (K-SV values are 50-180 M-1) in
N,N-dimethylacetamide, dimethylsulphoxide, water, propylene carbonate and
pyridine. In acetonitrile the presence of both dynamic and static self-quen
ching has been assumed based on high Stern-Volmer constant (K-SV = 2600 M-1
) and low luminescence quantum yield which decreases further when the compl
ex concentration increases. The apparent activation energies have also been
studied; they decrease when the self-quenching becomes faster.