The design and synthesis of a series of zwitterionic ionic liquids (ZILs) to understand the structure-property relationship towards an increase of the thermal stability, a variation of the glass transition temperature, the shape-tuning of nanostructured aggregates and the tuning of the stimuli responsiveness are demonstrated. The substitution reaction of imidazole with various aliphatic and aromatic bromides followed by the reaction of the corresponding substituted imidazoles with bromoalkyl carboxylic acids of varying spacer length produces the ZILs. In aqueous solution, a ZIL molecule either exist in its ionic liquid (substituted imidazolium bromide) form or its zwitterionic (substituted imidazolium alkyl carboxylate) form with an isoelectric point (pI) depending on the pH value of the solution. Upon changing the pH to near or above the pI, the aqueous ZIL solution undergoes transition from a transparent to a turbid phase due to the formation of insoluble hierarchical nanostructured aggregates of various morphologies, such as spheres, tripods, tetrapods, fern-like, flower-like, dendrites etc. depending on the pH of the solution and the nature of the alkyl/vinyl/aryl substituents. Upon heating the solution a phase transition occurs from turbid to transparent, exhibiting a distinct reversible upper critical solution temperature (UCST)-type cloud point (T ). It is observed that the cloud point varies with the nature of the substituent, an increase of the concentration of the ZIL as well as with changes of the pH of the solution.
Gastropods, an important group of mollusc, inhabitants of sediment-rich bottom zone have evidentiary role in freshwater ecosystem. Their community structure has been influenced by the water and soil quality parameters. Under the scenario of intensive agricultural practice and fast urbanization waterbodies particularly the ponds of lower Damodar basin in Howrah district, West Bengal, India are badly affected by growing pollution load. In current study, three lentic waterbodies i.e Shiberjala pond, Nayachak Wetland and Dhasa Waterbody were chosen to assess the gastropod diversity. Selected physico-chemical parameters including Temperature, Dissolved Oxygen, pH, Free Carbon di oxide, Nitrate and Phosphate of all three waterbodies were determined also. Dhasa Waterbody containing 7 species, exhibited highest species richness. The density and species richness showed spatial variation among study sites. Bellamya bengalensis was the dominant species found at all study sites. Melanoides tuberculata in spite of their absence in Shiberjala pond, appeared to be the second most dominant species. Brotia sp and Bithynia sp was the least abundant species. Gastropod species richness showed significant negative correlation with DO level(r=-0.705, P<0.05).Nitrate level was significantly positively correlated(r=0.474, P<0.05) with gastropod species richness and density. Phosphate level (r=0.33) also positively correlated with gastropod richness.
When protonic motion is explained as a purely quantum mechanical phenomenon, two extreme situations can be visualized as either the adiabatic or the nonadiabatic limit of proton transfer (PT). Strong orbital coupling between the donor and the acceptor pair in the proton transfer step drives PT mechanism in the adiabatic limit whereas in nonadiabatic limit PT predominantly occurs through tunneling. Here we proposed a unique way to experimentally observe the adiabaticity of PT by introducing chirality in the reaction coordinate of excited state proton transfer (ESPT). We successfully established the existence of prominent role of diastereomerism in the ESPT by both steady state and femtosecond time‐resolved transient absorption spectroscopic measurements in the adiabatic limit. The presented novel approach can overcome the limitations of only available experimental technique, i. e. kinetic isotope effect, to elucidate proton transfer mechanism.
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