Ultrasonic mediated synthesis of new benzo[a]phenoxazinium chlorides and their photophysical studies

Ultrasonic irradiation was demonstrated to be an efficient technique for activating various organic transformations, allowing short reaction times, high yields and sometimes good selectivity. Three new benzo[a]phenoxazinium chlorides possessing isopentylamino, (2-cyclohexylethyl)amino and phenethylamino groups at 5-position of the heterocyclic systems were efficiently synthesized under ultrasound irradiation. Photophysical characterization in ethanol and water, as well as acid-base equilibrium studies of the probes were carried out.Fundação para a Ciência e Tecnologia (FCT, Portugal) - financial support to the NMR portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to the Research Centres CFUM [PEst-C/FIS/UI0607/2011 (F-COMP-01-0124-FEDER-022711)] and CQ/UM [PEst-C/QUI/UI0686/2011 (FCOMP-01-0124-FEDER-022716)]. A post-doctoral grant to B. R. Raju (SFRH/BPD/62881/2009) is also financed by FCT, POPH-QREN, FSE