Quantitative Lattice Energy Analysis of Intermolecular Interactions in Crystal Structures of Some Benzimidazole Derivatives

Gopal Sharma,Rajni Kant

doi:10.13005/ojps05.01-02.08

Abstract

The benzimidazole moiety found in a large number of biologically important drugs has not been completely realized as yet in respect of its strength and directionality of its molecular interactions. To understand the role played by the intermolecular interactions in the benzimidazole derivatives, lattice energy of a series of five important molecules has been computed and results accrued thereof have been discussed. Analysis of molecular packing based on the intermolecular interaction energies suggests existence of different molecular pairs that play an important role in the stabilization of the crystal structures. Interaction energy analysis of such motifs reveals that intermolecular interactions of the type N-H…N and C-H…N happen to be the major contributors to the stabilization of molecular packing in the unit cell. N-H…π and C-H…π type edge-to-face stacking interactions also contribute significantly to the stabilization of crystal packing. The pairs of N-H…N intermolecular hydrogen bonds link the molecules into centrosymmetric dimers making a contribution of -14 to -18.52 kcal/mol towards stabilization, whereas C-H…N bonds link the molecules into dimers in the energy range of -2 to -5 kcal/mol. Additionally, the role of π…π interactions has also been investigated in molecular stabilization.

Highlights

Benzimidazole is an important class of heterocyclic aromatic organic compounds which consists of a benzene ring fused with imidazole ring
As a part of our ongoing research work on the preparation of X-ray diffraction quality single crystals and their structural analysis,[8,9] we have identified a series of five benzimidazole derivatives from CSD.The lattice and cohesive energies of all the molecular pairs were computed by using PIXEL10 software
The maximum stability to the molecular structure occurs with N2-H2A...N1 intermolecular interaction (Motif A, Figure-2)

Summary

Introduction

Benzimidazole is an important class of heterocyclic aromatic organic compounds which consists of a benzene ring fused with imidazole ring. N1 interaction link the molecules into centrosymmetric dimers in the crystal, forming R22(8) ring motif having interaction energy of -18.52 kcal mol-1 with 60% contribution to the net stabilization from Coulombic energy, 25% contribution from Polarization energy and 15% from the dispersive energy, respectively.

Results

Conclusion