Unravelling the Importance of H bonds, σ–hole and π–hole‑Directed Intermolecular Interactions in Nature

Abstract

The field of intra- and intermolecular interactions has
received a major boost in the past one decade. Significant advances
in both instrumentation (for experimental purposes) and computational
resources (development of theoretical models) have provided strong
impetus to this area of research. The understanding of the nature, energetics
and the topological characteristics of these interactions are the
driving forces which govern intermolecular recognition. This is strongly
dependent on the state of aggregation of the substance. The environment
(solid, liquid and gas) plays an extremely crucial and subtle role
in deciphering the mechanism via which molecules interact with each
other. In the past two decades, there has been rigorous development in
the understanding of strong hydrogen bonds. The focus has now shifted
towards the quantitative assessment of weak intermolecular interactions,
of the type C–H···X (X = F in particular), X···X, X(lp)···π along with
σ–hole-directed intermolecular interactions involving tetrels, chalcogens,
pnictogens, halogens and the aerogens. In addition, there is increasing
evidence for the assessment of the relevance of π–hole-based interactions
in tetrels, chalcogens, and pnictogens as well. The current perspective
highlights the importance of the above-mentioned interactions
and their associated electronic features. This has strong implications
in the area of materials and related applied sciences with relevance
towards the technological applications of these interactions in terms of
understanding structure–property correlation in the mechanical, optical
and electrical properties of matter.