title: Thermal and solvent effects on the NMR and UV parameters of some bioreductive drugs.
abstract: 15N NMR chemical shifts and n-->pi* electronic transition energy for metronidazole (1) has been calculated and compared with experimental data. A detailed computational study of 1 is presented, with special attention to the performance of various theoretical methods for reproducing spectroscopic parameters in solution. The most sophisticated approach involves density functional based on the Car-Parrinello molecular dynamics simulations of 1 in aqueous solution (BP86 level) and averaging chemical shifts and deltaE(n-->pi*) over snapshots from the trajectory. In the NMR and UV calculations for these snapshots (performed at the B3LYP level), a small number of discrete water molecules are retained, and the remaining bulk solution effects are included via a polarizable continuum model (PCM). A good agreement with experiment is also obtained using static geometry optimization and NMR computation of pristine 1 employing a PCM approach. Further theoretical predictions are also reported for 17O NMR and deltaE(n-->pi*) of three hydroxycinnamic acid derivatives, which suggest that it is essential to incorporate the dynamics and solvent effects for NMR and UV calculations in the condensed phase.
authors.affiliation: Departamento de Físico-Química and Laboratório de Impacto de Fótons e Elétrons, Instituto de Química, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Centro de Technologia, Bloco A, Lab. 406, Rio de Janeiro 21949-900, Rio de Janeiro, Brazil.
authors.forename: Teodorico C
authors.initials: TC
authors.lastname: Ramalho
authors.forename: Carlton A
authors.initials: CA
authors.lastname: Taft
mesh_terms: D000981:Antiprotozoal Agents / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003198:Computer Simulation; D003373:Coumaric Acids / Q000737:chemistry*; D004583:Electrons; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008795:Metronidazole / Q000737:chemistry*; D008956:Models, Chemical; D008962:Models, Theoretical; D008968:Molecular Conformation; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
chemical_list: D000981:Antiprotozoal Agents; D003373:Coumaric Acids; D012997:Solvents; D008795:Metronidazole