title: Comparison of the solid-matrix luminescence properties and photophysical parameters of two products from benzo(a)pyrene-DNA adducts.
abstract: 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-10R-(N2-deoxyguanosyl-3'-phosphate)-7,8,9,10- tetrahydrobenzo(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% alpha-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% alpha-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.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Chemistry, University of Wyoming, Laramie 82071.
authors.forename: Y
authors.initials: Y
authors.lastname: Chu
authors.forename: R J
authors.initials: RJ
authors.lastname: Hurtubise
mesh_terms: D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / Q000031:analogs & derivatives / Q000737:chemistry; D001564:Benzo(a)pyrene / Q000031:analogs & derivatives / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D018736:DNA Adducts; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000737:chemistry; D049449:Luminescence; D010777:Photochemistry; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D018736:DNA Adducts; C056612:benzo(a)pyrene-DNA adduct; D001564:Benzo(a)pyrene; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; C040060:7,8-dihydroxy-9,10-epoxide-7,8,9,10-tetrahydrobenzo(a)pyrene-10-deoxyguanosine; C074998:benzo(a)pyrene-7,8,9,10-tetrol; D004247:DNA; D003849:Deoxyguanosine