Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

222 Biennial Report 2005-07is ascribed to fast electron exchange due to close proximity of the corresponding radical ions.Debarati Dey, Adity Bose(neé Chowdhury), Chitra Raha, Manas Chakraborty†, Samita Basu CSD6.1.7.7 Interaction of dibenzo[a,c]phenazine with hydroxylic solventsIntermolecular hydrogen bonding is a site-specific local interaction between hydrogen donor andacceptor molecules that plays a dominant role in various forms of molecular recognition processes.We have synthesized dibenzo[a,c]phenazine (DBPZ) and found that it acts as a hydrogen-bondingprobe that remains insensitive to polarity of the solvents. Steady state and time-resolved fluorescencestudies of DBPZ reveal that with hydroxylic solvents (e.g., water, methanol, ethanol,isopropanol, t-butanol) DBPZ forms hydrogen bond extensively only in the excited state and thatis supported by the enhancement of the fluorescence intensity as well as the fluorescence lifetime.This fact is further supported by theoretical studies using GAMESS software.Debarati Dey, Adity Bose (neé Chowdhury), Chitra Raha, Dhananjay Bhattacharya, Shyam SundarMaity†, Sanjib Ghosh†, Samita BasuCSD6.1.7.8 Interactions between 9,10-anthraquinone and aromatic amines in homogeneousand micellar media: a laser flash photolysis and magnetic field effectstudyThe interactions between 9,10-anthraquinone (AQ) and different aromatic amines, N,N dimethylanilineand 4,4 ′ bis (dimethylamino) diphenylmethane (DMDPM), have been studied using absorption,steady-state fluorescence, and laser flash photolysis techniques and magnetic field effect in organichomogeneous and heterogeneous micellar media, where electron transfer from amines to excitedAQ is observed. Another novel feature is the abnormal behaviour of DMDPM in micellar mediumpertaining to energy transfer between DMDPM and AQ, which is prominent due to caging of boththe molecules and restricted motion of DMDPM in hydrophobic region of micelle.Adity Bose (neé Chowdhury), Chitra Raha, Samita BasuCSD6.1.7.9 Structure dependent switchover of reaction modes: a laser flash photolysisand magnetic field effect studyWe have investigated the mode of interactions of 2-methyl-1,4-naphthoquinone (menadione, MQ)with some organic amine bases e.g., triethylamine (TEA), N, N-dimethylaniline (DMA) and 4,4 ′ bis(dimethylamino)diphenylmethane (DMDPM), using polar organic homogeneous medium (acetonitrile)and heterogeneous micellar medium (SDS). In acetonitrile MQ undergoes electron transfer(ET) with all three amines but in SDS micelles it abstracts hydrogen from DMA and DMDPM,although ET persists with TEA. The differential behavior between AQ and MQ with amines isobserved due to the difference in structure of the molecules, where AQ has an extra phenyl ringcompared to MQ, and the solvents.Adity Bose (neé Chowdhury), Debarati Dey, Chitra Raha, Samita BasuCSD