Dr. A. R. Choudhury
Assistant Professor , Chemical Sciences

Major Research Themes:

Synthesis, characterization and structural analyses and understanding of strong and weak hydrogen bonds:
We are focused to design and synthesize new materials with desirable properties for enhanced biological activities involving various functional groups including halogens. The influence of various functional groups and halogens in altering the structural aspects of small organic molecules are analysed and understood utilizing both single crystal and powder X-ray diffraction as the major techniques with the additional support from various spectroscopic techniques (FTIR, NMR) and other thermal methods (TGA, DSC). The structure-property relationship is achieved through suitable correlation between the structural analyses and theoretical calculations using ab-initio computations.

Crystal engineering and Polymorphism:
Crystal engineering deals with the in-depth understanding of various strong and weak interactions in the solid state and applying them in building suitable supramolecular assemblies for desired properties. Polymorphism in small organic and inorganic materials are useful in various fields such a pharmaceutical chemistry, opto-electronic devices, magnetic materials etc. Understanding of the kinetics and thermodynamics behind the crystal nucleation and growth for various polymorphs of a given compound is a challenging task and is one of the major areas of our research.

Pharmaceutical cocrystallization and formulation of drugs:
Our research is also focused in the direction of crystallization of drugs and pharmaceuticals for higher solubility and better bio-availability. We work on a number of different classes (antibiotic, antifungal, anti-depression etc.) of widely used drugs to modify their formulations for higher solubility, better intrinsic dissolution rates to achieve higher bio-availability. We also concentrate in generating different polymorphic modifications of these drugs and pharmaceuticals to produce a new crystalline form with better physical properties and higher chemical stability.

Computational analyses of weak interactions and crystal structure prediction:
We also work on computational aspects related to weak interactions observed in the solid state using various computational methods using Gaussian09 and AIM2000 in the gas phase and using Crystal14 in the periodic systems in the solid state. We use Material Studio for the prediction of crystal structures of small molecules.

Experimental and theoretical charge density studies:
Using high resolution single crystal X-ray diffraction data, we analyse experimental charge densities (using both XD and MoPro) in order to understand the nature, strength and directionality of various strong and weak interactions in the solid state. Theoretical charge density analyses are also done to compare the experimental multipole model with the theoretically calculated charge density distribution using Crystal14.

In situ crtystallization of low melting materials:
The crystallization and structural analyses of the materials which are liquid below 30 oC is a challenging task. Crystallization and structure elucidation of very low melting materials are routinely carried out in our laboratory using Optical Heating and Crystallization Device (OHCD). This technique helps us to crystallize low melting natural products, low melting small organic compounds for their structure determination. The same technique is used to study cocrystallization of a pair of small organic molecules as well.

Selected Publications

• Das, D.; Choudhury, A. R. Water-assisted ground state intra-molecular proton transfer in 2,5-dihydroxy-substituted azobenzenes: experimental and computational studies. CrystEngComm, 21, 2373-2380,2019.
  
  
• Joshi, M.; Choudhury, A. R. Salts of Amoxapine with Improved Solubility for Enhanced Pharmaceutical Applicability. ACS Omega, 3, 2406-2416, 2018.
  
  
• Dhingra, S.; Barman, D. J.; Yadav, H. R.; Eyyathiyil, J.; Bhowmik, P.; Kaur, P.; Adhikari, D.; Choudhury, A. R. Structural and computational understanding of weak interactions in “bridge-flipped” isomeric tetrafluoro-bis-benzylideneanilines. CrystEngComm,  20, 716-727, 2018.
  
  
• Mondal, P. K.; Yadav, H. R.; Choudhury, A. R.; Chopra, D. Quantitative Characterization of supramolecular synthons involving fluorine atoms in the crystal structures of di- and tetra fluorinated benzamides. Acta Cryst. B., 73, 805-819, 2017.
  
  
• Yadav, H. R.; Choudhury A. R. Can C—H···F—C hydrogen bonds alter crystal packing features in the presence of N—H···O=C hydrogen bond?. J. Mol. Struct, 1150, 469-480, 2017.
  
  
• Kaur, G.; Singh, S.; Sreekumar, A.; Choudhury, A. R. The evaluation of the role of C‒H···F hydrogen bonds in crystal altering the packing modes in the presence of strong hydrogen bond. J. Mol. Struct. 1106, 154-169, 2016.
  
  
• Dev, S.; Maheswari, S.; Choudhury, A. R. Insight in the C-H...F-C hydrogen bond: Cambridge Structural Database Analyses and Computational Studies. RSC Adv., 5, 26932-26940, 2015.
  
  
• Kaur, G.; Choudhury, A. R. A comprehensive understanding of the synthons involving C–H⋯F–C hydrogen bond(s) from structural and computational analyses. CrystEngComm. 17, 2949-2963, 2015.
  
  
• Choudhury, A. R.; Yufit, D. S.; Howard, J. A. K. In situco-crystallization of cresols with aniline and fluoroanilines: subtle interplay of strong and weak hydrogen bonds. Z. Kristallogr. 229, 625-634, 2014.
  
  
• Kaur, G.; Choudhury, A. R. Understanding of the Weak Intermolecular Interactions Involving Halogens in Substituted N‑Benzylideneanilines: Insights from Structural and Computational Perspectives. Cryst. Growth Des. 14, 1600-1616, 2014.
  
  
• Karanam, M.; Choudhury, A. R. Study of Halogen-Mediated Weak Interactions in a Series of Halogen-Substituted Azobenzenes. Cryst. Growth Des. 13, 4803-4814, 2013.
  
  
• Karanam, M.; Choudhury, A. R. Structural Landscape of Pure Enrofloxacin and Its Novel Salts: Enhanced Solubility for Better Pharmaceutical Applicability. Cryst. Growth Des. 13, 1626-1637, 2013.
  
  
• Kaur, G.; Panini, P.; Chopra, D.; Choudhury, A. R. Structural Investigation of Weak Intermolecular Interactions in Fluorine Substituted Isomeric N‑Benzylideneanilines. Cryst. Growth Des. 12, 5096-5110, 2012.
  
  
• Karanam, M.; Dev, S.; Choudhury A. R. New Polymorphs of Fluconazole: Results from Cocrystallization Experiments. Cryst. Growth Des. 12, 240-252, 2012
  
  
• Aitipamula, S.; Banerjee, R.; Bansal, A. K.; Biradha, K.;  Cheney, M. L.; Choudhury, A. R.; Desiraju, G. R.; Dikundwar, A. G.; Dubey, R.; Duggirala, N.; Ghogale, P. P.; Ghosh, S.; Goswami, P. K.; Goud, N. R.; Jetti, R. K. R.; Karpinski, P.; Kaushik, P.; Kumar, D.; Kumar, V.; Moulton, B.; Mukherjee, A.; Mukherjee, G.; Myerson, A. S.; Puri, B.; Ramanan, A.; Rajamannar, T. Reddy, C. M.; Hornedo, N. R-.; Rogers, R. D.; Guru Row, T. N.; Sanphui, P.; Shan, N.; Shete, G.; Singh, A.; Sun, C. C.; Swift, J. A.; Thaimattam, R.; Thakur, T. S.; Thaper, R. K.; Thomas, S. P.; Tothadi, S.; Vangala, V. R.; Variankaval, N.; Vishweshwar, P.; Weyna, D. R.; Zaworotko, M. J. Polymorphs, Salts, and Cocrystals: What’s in a Name?. Cryst. Growth Des., 12, 2147-2152, 2012.