THE EMISSION OF PYRIDINE AND POLYPYRIDINECHROMIUM(III) COMPLEXES IN RIGID AND FLUID MEDIA

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" THE EMISSION OF PYRIDINE AND POLYPYRIDINECHROMIUM(III) COMPLEXES IN RIGID AND FLUID MEDIA "
A. M. Ghaith

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112651
Doc. No	:	TLpq303556709
Main Entry	:	A. M. Ghaith
Title & Author	:	THE EMISSION OF PYRIDINE AND POLYPYRIDINECHROMIUM(III) COMPLEXES IN RIGID AND FLUID MEDIA\ A. M. Ghaith
College	:	The University of Arizona
Date	:	1987
student score	:	1987
Degree	:	Ph.D.
Page No	:	169
Abstract	:	The excited state emissions and lifetimes of (Cr(bipy)3) , cis - (Cr(bipy)2Cl2) , trans - (Cr(py)4FBr) , cis - (Cr(phen)2F2) , and trans - (Cr(py)4F2) were studied in hydroxylic and nonhydroxylic solvents at 77 K and as a function of temperature. The emission characteristics are determined by the relative disposition of 2E and one component of . The energy of these two levels is influenced by intramolecular and environmental factors, and solvent-induced level inversion occurs in cis - (Cr(phen)2F2) . The influence of temperature and solvent viscosity were studied in several glasses with variable melting ranges. The emission of all of the complexes, except (Cr(bipy)3) , were found to be influenced by solvent viscosity. This influence is large when 2E and the component of are close in energy, and level inversion upon melting of the solvent occurs in cis - (Cr(phen)2F2) . The decay of the emission of Cr(III) complexes normally shows small temperature dependence at lower temperatures and large temperature dependence at higher temperatures. The threshold for the appearance of strong temperature dependence depends on intramolecular and environmental factors. The decays of all the complexes except (Cr(bipy)3) show strong discontinuities in the rigid-fluid transition regions of the solvent glasses which are accompanied by risetimes in the decay profiles when the emission intensity is monitored at long wavelengths. This is attributed to solvent relaxation during the excited state lifetime.
Subject	:	Chemistry
	:	Pure sciences