Condensed Phase Dispersive Interactions of Benzo[a]pyrene with Various Solvents and with DNA:  A Twist on Solvatochromism

Benzo[ a ]pyrene (B( a )P) is a carcinogen known to interact with DNA. In this paper we explore the possibility of using spectroscopic indicators of the interaction of B( a )P directly with dsDNA. In so doing we have examined the solvatochromism of B( a )P and modeled solvent shifts based on a purely dispersive interaction. Using this model it was possible to estimate the excited-state static polarizabilities of B( a )P as 4.9 (±0.1) × 10 -29, 4.2 (±0.1) × 10 -29, and 5.8 (±0.1) × 10 -29 m 3 for the S 1, S 2, and S 3 states, respectively. Moreover, we have used these polarizabilities to interpret the spectra of B( a )P in the presence of a 14 base-pair dsDNA oligomer in buffer solution. We provide spectral evidence that B( a )P and DNA interact, perhaps via intercalation.