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COMPARISON OF THE SOLID‐MATRIX LUMINESCENCE PROPERTIES AND PHOTOPHYSICAL PARAMETERS OF TWO PRODUCTS FROM BENZO(a)PYRENE‐DNA ADDUCTS
Author(s) -
Chu Yu,
Hurtubise Robert J.
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb09663.x
Subject(s) - chemistry , luminescence , pyrene , fluorescence , phosphorescence , matrix (chemical analysis) , photochemistry , benzo(a)pyrene , analytical chemistry (journal) , materials science , organic chemistry , chromatography , physics , optoelectronics , quantum mechanics
The solid‐matrix luminescence properties and several calculated photophysical parameters of two important products from the benzo(a)pyrene‐DNA adducts were compared. The products were benzo(a)pyrene‐r‐7,t‐8,9,c‐10‐tetrahydrotetrol (I‐1) and 7R,8S,9S‐trihydroxy‐10‐( N 2 ‐deoxyguanosyl‐3′‐phosphate)‐7,8,9,10‐tetrahydroben‐zo(a)pyrene (BPDE‐dG). The solid‐matrix luminescence data were obtained for I‐1 and BPDE‐dG adsorbed on two different solid matrices, namely, 1%α‐cyclodextrin (CD)/NaCl and 25% trehalose/NaCl and at two different temperatures (93 K and 296 K). The 25% trehalose/NaCl gave higher fluorescence and phosphorescence quantum yields from both I‐1 and BPDE‐dG in contrast to the 1%α‐CD/NaCl matrix. The BPDE‐dG showed lower fluorescence quantum yields on the solid matrices compared to I‐1. The lower fluorescence quantum yields for BPDE‐dG were attributed to a photoinduced electron transfer mechanism. In contrast to the room‐temperature solution fluorescence of BPDE‐dG, BPDE‐dG gave rather high fluorescence quantum yields at room temperature when adsorbed on the two solid matrices. From solid‐matrix luminescence quantum yields and solid‐matrix luminescence lifetimes, many photophysical parameters were calculated and compared. Several differences among the rate constants were noted with the two solid matrices for BPDE‐dG and I‐1. For example, BPDE‐dG showed internal conversion at 296 K with 25% trehalose/NaCl, but no internal conversion was observed at 93 K with this solid matrix. Also, for BPDE‐dG the phosphorescence rate constants at 296 K and 93 K were very small with 25% trehalose/NaCl, but the intersystem crossing rate constants from the triplet state to the ground state were very large. The results from this work show how solid‐matrix luminescence can be employed to obtain unique luminescence information from the I‐1 and BPDE‐dG systems.