Molecular structure of 5-chloro-2-[p-t-butylphenyl]benzoxazole. Relation between structure and antimicrobial activity of 2,5-disubstituted benzoxazoles

As part of our investigation on antimicrobial agents, the structure of 5-ch loro-2- [p-t-butylphenyl]benzoxazole is reported: C17H16ClNO, mel. mass 285 .77, monoclinic, space group: C2/c; a = 32.164(6) Angstrom, b = 6.756(1) An gstrom, c = 13.710(3) Angstrom; beta = 92.73(3)degrees; V= 2975.8(10) Angst rom(3); and, = 1.276 g cm(-3); Z = 8; F(000) = 1200; mu(CuKalpha)= 2.219 mm (-1). Final R = 0.0658 for 2621 reflections with F > 4 sigma(F). Final atom ic coordinates for this 2,5-disubstituted benzoxazole were used as a starti ng point in molecular modelling of remaining 32 derivatives searched as ant imicrobial agents. Electronic parameters calculated with quantum chemistry methods and classical Hansch's constants were applied in searching for stru cture-activity correlation. It was established that geometrical para meters (area and volume) and LUMO energy values seem to be most important for the activity.