Nadavala Siva Kumar

Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs) in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC) of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO) moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

Pyridinium-clubbed dicationic ionic liquid electrolytes for efficient next-generation photo harvesting

We have developed a new series of pyridinium based dicationic ionic liquids (DCILs) having excellent thermal stability and good ionic conductivity. The effectiveness of these DCIL based electrolytes in photovoltaic devices and the effect of different anions (e.g. iodine, bromide, and thiocyanate) versus the device performance are studied by cyclic voltammetry (CV), current–voltage (I–V) characteristics and electrochemical impedance spectroscopy (EIS). The electrolyte 2PrSCN based device C exhibited the highest photo conversion efficiency (PCE) of 5.23% under 1 sun (100 mW cm−2) illumination of light. We have also analyzed the influence of various anions in metal-free dye-sensitized TiO2 and the DCIL interface using the EIS technique. Device C based on 2PrSCN shows excellent long-term stability, maintaining <95% of the initial efficiency after 500 h.

Fabrication of D–π–A sensitizers based on different donors substituted with a dihydropyrrolo[3,4-c]pyrrole-1,4-dione bridge for DSSCs: influence of the CDCA co-absorbent

The effect of co-absorbance on the performance of DSSC devices with a new design of dimer sensitizers possessing a 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP) bridge and various donor groups (carbazole, diphenyl amine, indole) is reported in the present work. The co-absorbent (CDCA = chenodeoxycholic acid) was inserted into the sensitizers and the photovoltaic performance was studied. The co-absorbent had a significant effect on Jsc, Voc and the efficiency. Without incorporation of the co-absorbent, a higher efficiency of around 4.40% is exhibited (Jsc = 9.91 mA cm−2 and Voc = 0.678 V) by the R3 device, while after adding the co-absorbent, we have achieved an efficiency of around 4.44% (Jsc = 10.3 mA cm−2 and Voc = 0.693 V). Structure optimization and energy level calculations were carried out by density functional theory (DFT) with different donor substituents and DPP bridge based sensitizers. The co-absorbent and sensitizer based DSSCs were also characterised by impedance spectroscopy and incident photon to current conversion efficiency measurements.

A Stability-Indicating LC-MS Method for Determination of Perindopril and its Process Related Impurities

Perindopril erbumine belongs to the member of angiotensin-converting enzyme inhibitors group used in the treatment of heart failure and hypertension. Asimple and highly sensitive LC-MS method has been developed for the simultaneous determination of three process-related impurities (L-norvaline, L-norvaline ethyl ester HCl, and (S)-indoline-2-carboxylic acid) in perindopril. Samples were separated using 5 mM ammonium formate (A) and acetonitrile/methanol (B) as the mobile phase on a Symmetry C18 column (75 mm × 4.6 mm, 3.5 μm) using gradient elution mode at a flow rate of 0.6 mL/min. The proposed method was validated as per ICH guidelines and can be used for quality testing of perindopril and determining its process-related impurities in pharmaceuticals.

Novel nanohydrogel based on itaconic acid grafted tragacanth gum for controlled release of ampicillin

Nanohydrogel of tragacanth gum using microwave radiations is used for the controlled release of ampicillin. Tragacanth gum was grafted with itaconic acid, employing graft copolymerization in the presence of N, N1-methylene-bis-acrylamide (MBA) as cross linker, and potassium persulphate as initiator. The prepared nanohydrogel was characterized using FTIR, XRD, SEM, and TEM. Besides, the hydrogel was evaluated for in vitro drug release in distilled water and different pH values, and antimicrobial efficacy against E. Coli by well diffusion assay. In vitro drug release studies, at different pH values (2.2, 5.4 and 9.4), and distilled water, pH 2.2 was considered as the optimized pH for maximum drug release. Finally, through antimicrobial efficacy studies against E. Coli, it was observed that ampicillin loaded nanohydrogel, was more efficient in comparison to that of plain ampicillin drug.