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Gavvala K.,Indian Institute of Science | Sasikala W.D.,Indian Institute of Science | Sengupta A.,Indian Institute of Science | Dalvi S.A.,Ramnarain Ruia College Matunga | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2013

This article reports the alteration of the excited state photophysics of a molecular rotor, namely 9-(dicyano-vinyl)julolidine (DCVJ), which has been extensively used to report protein aggregation and protein conformational changes, by the various cavity sizes of cyclodextrin (CD) macrocyclic hosts, with the help of steady state, time-resolved fluorescence techniques. It is observed that, in the presence of α-CD, the characteristic features of both the monomer and excimer emissions of DCVJ are almost unperturbed. However, in the presence of β-CD, the excited photophysics of the molecule is significantly perturbed, and it is noted that β-CD inhibits the excimer formation drift of DCVJ by incorporation of a DCVJ monomer inside its cavity. The most striking findings are observed in the case of γ-CD. Initially, the excimer peak intensity drops and the monomer intensity increases, due to the 1 : 1 DCVJ/γ-CD inclusion complex formation. Above a certain concentration, another DCVJ molecule is accommodated inside the γ-CD cavity and forms an excimer, which is reflected in the intensification of the excimer peak. At higher γ-CD concentration the fluorescence intensity of the excimer shoots up, due to the formation of 2 : 2 host-guest complex, in which an additional γ-CD molecule provides extra stabilization to the excimer. Insight on the molecular picture of this host-guest interaction has been provided by docking studies followed by quantum chemical calculations. © the Owner Societies 2013.

Kaparwan A.G.,Ramnarain Ruia College Matunga | Singh N.J.,Ramnarain Ruia College Matunga | Sathe P.A.,Ramnarain Ruia College Matunga
Eurasian Journal of Analytical Chemistry | Year: 2011

Direct and indirect oxidation of 1,5-diphenylcarbazide have been studied at hanging mercury drop electrode with differential pulse voltammetric technique. Direct oxidation of 1,5- diphenylcarbazide with KMnO 4 resulted in formation of 1,5-diphenylcarbazone in the system at the reduction potential of -0.3 Volts. Oxidation study with K 2Cr 2O 7 resulted in formation of 1,5-diphenylcarbazone at the reduction potential of -0.3 Volts along with formation of 1,5-diphenylcarbadiazone at the reduction potential of -0.6Volts in the system. Thus indicates that KMnO 4 can be utilized for controlled step oxidation of 1,5- diphenylcarbazide, whereas, K 2Cr 2O 7 can be utilized for maximum oxidation of 1,5- diphenylcarbazide. Indirect oxidation of 1,5-diphenylcarbazide was studied by dissolving 1,5- diphenylcarbazide in water mixed solvent systems for aerial oxidation due to formation of 1,5- diphenylcarbazone occurred and detected at the reduction potential of -0.3Volts. © 2011 Moment Publication.

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