Hemant K Kashyap

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The observation of a first sharp diffraction peak (FSDP) at low frequency in the X-ray and neutron scattering spectra of different imidazolium-based room-temperature ionic liquids (RTILs) (the so-called prepeak) has often been experimentally interpreted as indicative of mesoscopic organization leading to nanoscale segregation and the formation of domains of(More)
Solvation dynamics in four imidazolium cation based room temperature ionic liquids (RTIL) have been calculated by using the recently measured dielectric relaxation data [ J. Phys. Chem. B 2008, 112, 4854 ] as an input in a molecular hydrodynamic theory developed earlier for studying solvation energy relaxation in polar solvents. Coumarin 153 (C153),(More)
The structural landscape of room-temperature ionic liquids (RTILs) with longer cationic alkyl tail(s) exhibits polarity ordering (PO) along with charge ordering (CO). In polarity ordering, which is also referred to as intermediate-range ordering, polar groups are separated by segregated domains of apolar groups and vice versa. Charge ordering resembles(More)
Molecular dynamics simulations are utilized here to explore the nanoscale morphology and the nature of hydrogen bonding in the equimolar mixtures of butylammonium nitrate protic ionic liquid with ethanol, propanol, and butanol. The X-ray scattering experimental study of Greaves et al. [Phys. Chem. Chem. Phys. 13, 13 501 (2011)] has evidenced that(More)
The architecture of a biological membrane hinges upon the fundamental fact that its properties are determined by more than the sum of its individual components. Studies on model membranes have shown the need to characterize in molecular detail how properties such as thickness, fluidity, and macroscopic bending rigidity are regulated by the interactions(More)
In the present molecular dynamics study, we investigate the effects of increasing pressure on the structural morphology of trihexyl(tetradecyl)phosphonium bromide (P666,14+/Br-) and trihexyl(tetradecyl)phosphonium dicyanamide (P666,14+/DCA-) ionic liquids (ILs). Special attention was paid to how charge and polarity orderings, which are present in the(More)
Structural patterns that have the same spatial periodicity but a phase offset give rise to peaks and anti-peaks (negative-going peaks) at the same q value in the SAXS structure function S(q). As an example, in ionic liquids we often find charge alternation, and at the distance where one finds a density enhancement of charges of the same type one also finds(More)
X-ray scattering experiments and molecular dynamics simulations have been performed to investigate the structure of four room temperature ionic liquids (ILs) comprising the bis(trifluoromethylsulfonyl)amide (NTf(2)(-)) anion paired with the triethyloctylammonium (N(2228)(+)) and triethyloctylphosphonium (P(2228)(+)) cations and their isoelectronic diether(More)
The carbohydrate binding protein, Cyanovirin-N, obtained from cyanobacteria, consists of high-affinity and low-affinity binding domains. To avoid the formation of a domain swapped structure in solution and also to better focus on the binding of carbohydrates at the high-affinity site, the Ghirlanda group (Biochemistry, 46, 2007, 9199-9207) engineered the(More)
In this work we compare the role that different anions play in the structure function S(q) for a set of liquids with the same cation. It is well established that because of their amphiphilic nature and their often larger size, cations play a fundamental role in the structural landscape of ionic liquids. On the other hand, it is often atoms in the anions(More)