Bichromophoric molecules as absolute standards for the triplet sensitised production of singlet oxygen

• Main Author: Forward, Philip James
• Published: University of Manchester 1995
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.617023

A series of bichromophoric molecules containing aromatic ketone and hyrocarbon residues linked by a chain of two methylene groups were prepared by chemical synthesis. Time-resolved photochemical experiments using kinetic emission and absorption spectroscopy were carried out to evaluate the bichromophoric compounds for use as reference standards for the triplet sensitised production of singlet oxygen in organic and aqueous solvents. The efficiency of singlet oxygen formation was found to vary considerably with solvent A comprehensive photophysical study was performed on phenalenone to investigate its potential as a universal reference standard for singlet oxygen formation in both organic and aqueous media. Singlet oxygen yield data were obtained from experiments in benzene which conflicted with recently published work. The experiments also led to the calculation of an accurate value for the molar absorption coefficient of the triplet state of benzophenone in benzene. Time-resolved infrared luminescence detection was employed in an attempt to quantify the possible effect of the substituent group on the observed yield of singlet oxygen from several naphthalene derivatives relative to naphthalene, for which a value of unity, from data using various experimental techniques, has been published. A series of substituted naphthalenes were found to have singlet oxygen yields which were experimentally indishtinguishable from that of naphthalene and were therefore taken to be unity.