Tayur Narasingarao Guru Row

The study of phase transitions in minerals or synthetic compounds analogous to mineral structures is of fundamental interest in different scientific disciplines, with applications ranging from understanding the Earth's geological history to advancing materials science and technology. They provide valuable data and insight into developing new functional materials with desired properties. In this context, we have investigated the structural phase transitions of Na6Zn(SO4)4, a synthetic compound analogous to the Vanthoffite mineral Na6Mg(SO4)4, which occurs abundantly in nature as oceanic salt deposits. The room temperature crystal structure is refined from powder X-ray diffraction (PXRD) data, and it belongs to a monoclinic system, space group P21/c, with Z = 2. Differential scanning calorimetry analysis suggests the possibility of multiple structural phase transitions between 338 and 400 degrees C. These phase transitions are substantiated by in situ powder X-ray diffraction and Raman spectroscopy. PXRD data with temperature reveal structural phase transitions with a change in crystal symmetry accompanied by the appearance/disappearance of diffraction peaks. Further, the dynamics of the SO4 tetrahedra units are probed using variable temperature Raman spectroscopy to understand the mechanism of structural phase transitions. These phase transitions are driven by the anomalies of the molecular vibration of sulfate tetrahedra at higher temperatures as revealed from Raman data. Additionally, ionic conductivity measurements also depict these structural phase transitions with a change in slope with an increase in temperature.

A comprehensive study of chiral N-benzylideneaniline analogues for their structural and material properties.

A new crystal polymorph of CTAB–I with smaller unit cell size and reduced cetyl chain mobility is observed. In situ embedding of plasmonic metal nanoparticles into this polymorph is realized leading to materials with strong plasmon–plasmon coupling.

The work carried out by our research group over the last couple of decades in the context of quantitative crystal engineering involves the analysis of intermolecular interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding using experimental charge density methodology is reviewed. The focus is to extract electron density distribution in the intermolecular space and to obtain guidelines to evaluate the strength and directionality of such interactions towards the design of molecular crystals with desired properties. Following the early studies on halogen bonding interactions, several “sigma-hole” interaction types with similar electrostatic origins have been explored in recent times for their strength, origin, and structural consequences. These include interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding. Experimental X-ray charge density analysis has proved to be a powerful tool in unraveling the strength and electronic origin of such interactions, providing insights beyond the theoretical estimates from gas-phase molecular dimer calculations. In this mini-review, we outline some selected contributions from the X-ray charge density studies to the field of non-covalent interactions (NCIs) involving elements of the groups 14–17 of the periodic table. Quantitative insights into the nature of these interactions obtained from the experimental electron density distribution and subsequent topological analysis by the quantum theory of atoms in molecules (QTAIM) have been discussed. A few notable examples of weak interactions have been presented in terms of their experimental charge density features. These examples reveal not only the strength and beauty of X-ray charge density multipole modeling as an advanced structural chemistry tool but also its utility in providing experimental benchmarks for the theoretical studies of weak interactions in crystals.

1,2,3‐triazole system is readily obtained by the click reaction in a facile and regioselective way. Regioselectivity is introduced under Copper(CuAAC), and Ruthenium(RuAAC) catalysed azide‐alkyne cycloaddition reaction furnishing 1,4 and 1,5‐disubstituted triazoles, respectively. These two regioisomeric systems offer discrete physicochemical and medicinal properties based on crucial binding interactions and biocompatibility with the biological targets. In this regard, a comparative investigation on the coumarin‐linked regioisomeric 1,2,3‐triazoles via its crystal structure, Hirshfeld surface analysis, and antitubercular assays and molecular docking are reported. It sheds light on the variation of in vitro antitubercular efficacy against Mycobacterium tuberculosis H ₃₇ Rv followed by molecular docking studies that justify the prominent interactions at the binding site. Further, solid‐state and Hirshfeld surface analysis provided significant crystallographic insights on the critical intermolecular interactions that dictate the crystal packing in these systems. Thus structure‐property correlation for these regioisomeric systems can open new avenues in drug design and discovery.

Amino acid and oxalic acid-based salt-cocrystals have been discovered as non-porous self-assembled HOFs that show efficient proton conductivity under humidified conditions. Promising performance as a membrane in H₂–O₂ fuel cells has been achieved.