Flexo-Ionic Effect of Ionic Liquid Crystal Elastomers

The first study of the flexo-ionic effect, i.e., mechanical deformation-induced electric signal, of the recently discovered ionic liquid crystal elastomers (iLCEs) is reported. The measured flexo-ionic coefficients were found to strongly depend on the director alignment of the iLCE films and can be over 200 µC/m. This value is orders of magnitude higher than the flexo-electric coefficient found in insulating liquid crystals and is comparable to the well-developed ionic polymers (iEAPs). The shortest response times, i.e., the largest bandwidth of the flexo-ionic responses, is achieved in planar alignment, when the director is uniformly parallel to the substrates. These results render high potential for iLCE-based devices for applications in sensors and wearable micropower generators.     

Oxidative Cleavage of Ketoximes with Iodosobenzene Diacetate

Hypervalent iodine oxidation of ketoximes (1) using iodosobenzene diacetate leads to cleavage of 1 with the formation of corresponding ketones (2) under neutral conditions in good yields. The scope and limitations of the reaction are discussed as well as the mechanism.     

Carbon-13 enrichment by IR laser chemistry of CHF3-Cl2

IR laser chemistry of CHF₃ is investigated in both neat form and in the presence of Cl₂ for carbon-13 enrichment. Infrared multiple-photon dissociation of CHF₃ is an order of magnitude more efficient in the scavenged system compared to the neat case. The photolysis of CHF₃/Cl₂ mixture results in two products, viz., CF₂Cl₂ and C₂F₄Cl₂ but with different enrichment factors. The parametric studies show that C₂F₄Cl₂ arises due to MPD of CF₂Cl₂ in secondary photolysis.     

Dissociation dynamics of thiolactic acid at 193 nm: detection of the nascent OH product by laser-induced fluorescence

Electronically excited thiolactic acid (2-mercaptopropionic acid), H(3)C-CH(SH)-COOH, undergoes the C-OH bond cleavage on excitation to the S(2) state at 193 nm, generating the primary product OH (v,J), which is detected by laser-induced fluorescence technique in a collisionless condition of flow system. The partitioning of the available energy between vibrational, rotational, and translational degrees of freedom of nascent photofragments is obtained from relative intensities of ro-vibronic lines in laser-induced fluorescence spectrum of OH, and their Doppler profiles. The rotational population of OH (v(")=0) is characterized by rotational temperature of 408+/-25 K. OH is produced in a vibrationally cold state, i.e., mostly in v(")=0. The average translational energy of OH (v(")=0,J(")) is found to be 21.5+/-2.0 kcal/mol, which implies 25.6 kcal/mol of energy in relative translation of photoproducts corresponding to the f(t) value of approximately 0.6. The observed high translational energy is due to the presence of a barrier in the exit channel, implying that the C-OH bond scission takes place on an electronically excited potential energy surface. The observed partitioning of the available energy between various degrees of the photofragments is theoretically modeled, and the hybrid model, with 26.0 kcal/mol of barrier in the exit channel, is found to explain the measured data quite well. The experimental results are also supported with ab initio molecular orbital calculations for both the ground and the excited electronic states. Time-dependent density functional theory is used to understand the nature of various electronic transitions connecting the lower excited states. Potential energy curves as a function of the C-OH bond length of thiolactic acid suggest distinct exit barriers in the S(1), T(1), and T(2) states. But, we could locate the transition state structure for OH formation in the S(1) state alone. Thus, although thiolactic acid is excited to the S(2) state at 193 nm, it undergoes internal conversion to S(1) where it dissociates to yield OH. In addition to the OH channel from excited electronic states, we studied theoretically all probable dissociation channels occurring on the ground electronic state of thiolactic acid.     

Evaluation of changes in mean-square nuclear charge radii of stable isotopes of erbium

Isotope shifts involving all the stable even-A isotopes of erbium have been studied in four transitions using optical technique and highly enriched isotopes. The value of change in mean-square charge radii r² deduced from our studies in 5806.05 Å (f¹² s²-f¹² sp) transition is in excellent agreement with muonic X-ray value. With negligible specific mass shift (SMS) in 5806.05 Å line, the SMS and field shifts in other lines are compared via King-Plot. In transitions involving change of 4f-electron (e.g., f¹²s²-f¹¹ds²), large negative SMS value is obtained which is very close to the theoretically predicted value.     

Design,Synthesis, and Functionalization of Imidazoheterocycles

Over the years, various strategies have been reported for the synthesis of imidazo[1,2‐a]pyridines due to their importance in different fields. In this account, we represent the methods developed by our group for the synthesis and functionalization of imidazo[1,2‐a]pyridines. Different synthetic strategies have been developed using easily accessible reactants for this purpose. We envisage that these newly developed protocols will be very useful for the synthesis of functionalized molecules bearing imidazo[1,2‐a]pyridine scaffolds. These strategies will also be attractive for the construction of other pharmaceutically important heterocycles.

     

Quaternion-Octonion SU(3) Flavor Symmetry

Starting with the quaternionic formulation of isospin SU(2) group, we have derived the relations for different components of isospin with quark states. Extending this formalism to the case of SU(3) group, we have considered the theory of octonion variables. Accordingly, the octonion splitting of SU(3) group have been reconsidered and various commutation relations for SU(3) group and its shift operators are also derived and verified for different isospin multiplets i.e. I, U and V-spins.     

Discrete Symmetries and Generalized Fields of Dyons

We have studied the different symmetric properties of the generalized Maxwell’s–Dirac equation along with their quantum properties. Applying the parity (℘), time reversal ( T\mathcal{T} ), charge conjugation (C\mathcal{C}) and their combined effect like parity time reversal (PT\mathcal{PT}), charge conjugation and parity (CP\mathcal{CP}) and CPT\mathcal{CP}T transformations to various equations of generalized fields of dyons, it is shown that the corresponding dynamical quantities and equations of dyons are invariant under these discrete symmetries.     

Volumetric,acoustic, optical and spectroscopic studies of binary mixtures of the ionic liquid, 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide and diethyl carbonate

The properties, density, speed of sound and refractive index of ‘IL’ [Bmim][NTf2], diethyl carbonate and their binary mixtures are measured over the whole composition range as a function of temperature between 303.15 and 323.15 K at atm. pressure. These values are used to calculate the excess molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, excess isentropic compressibility, free length, speeds of sound and isobaric thermal expansion coefficient for the mixture. Various rules were used to predict the refractive indices and the data have been compared with the experimental results. These excess properties are fitted to the Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. A qualitative analysis of these parameters indicates strong intermolecular interactions and the interaction increases with the increase in temperature. This was further supported by IR spectroscopy. In addition, analysis of data of the mixture was done through the Prigogine–Flory–Patterson theory.     

Isotope shifts and electronic configurations of the odd parity energy levels of singly ionised samarium

Isotope shift ΔT (148–154) has been evaluated for twelve low-lying even and 89 odd parity levels of singly ionised samarium (Sm II) from the isotope shift (IS) studies in 182 spectral lines of Sm II in the 3890–4525 Å region. These studies were carried out on a recording Fabry-Perot spectrometer using eriched isotopes¹⁴⁸Sm (96%) and¹⁵⁴Sm (98%) excited in liquid nitrogen-cooled hollow-cathodes. Earlier data on isotope shifts are available for only eight lines in this region. It has been found that for a few spectral lines there are errors both in magnitudes and signs of isotope shifts, reported earlier. Most of the 89 odd parity levels of Sm II, for which ΔT values have been evaluated presently, have in literature either no electronic configuration assignments or only tentative assignments. We have suggested the leading configuration for most of these odd levels of Sm II on the basis of ΔT values evaluated in the present studies.