Solid State and Structural Chemistry Group

Indian Institute of Science Education and Research Mohali

The group is focused to design and synthesize new organic and related materials with desirable properties and biological activities involving various active functional groups and with special emphasis on halogens. The influence of various functional groups and halogens in altering the structural aspects and properties of small organic molecules are analyzed 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 deals with the in-depth understanding of various strong and weak interactions in the solid state and applying them to build 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.
 
 

We are focused in the direction of crystallization of drugs and pharmaceuticals for higher solubility and better bio-availability. We work on various 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.

The understanding of weak intermolecular forces is incomplete without quantitative analysis of the interactions. To gain quantitative understanding of weak intermolecular interactions we utilize computational packages like Gaussian 09, Crystal Explorer, PIXELC, AIM2000, Crystal 14. We use Material Studio for the prediction of crystal structures of small molecules.
 

Intermolecular interactions are also studied using the high resolution single crystal X-ray diffraction data by analyzing the experimental charge densities (using both XD and MoPro) to understand the nature, strength and directionality of various strong and weak interactions in the solid state. Theoretical charge density analyses using Crystal 14 is done to verify the experimental multipole model with the theoretically calculated structure factors.
 

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 can be used to study cocrystallization of a pair of small organic molecules as well.