Issue 35, 2018

Adaptive responses of sterically confined intramolecular chalcogen bonds

Abstract

The responsive behavior of an entity towards its immediate surrounding is referred to as an adaptive response. The adaptive responses of a noncovalent interaction at the molecular scale are reflected from its structural and functional roles. Intramolecular chalcogen bonding (IChB), an attractive interaction between a heavy chalcogen E (E = Se or Te) centered sigma hole and an ortho-heteroatom Lewis base donor D (D = O or N), plays an adaptive role in defining the structure and reactivity of arylchalcogen compounds. In this perspective, we describe the adaptive roles of a chalcogen centered Lewis acid sigma hole and a proximal Lewis base (O or N) in accommodating built-in steric stress in 2,6-disubstituted arylchalcogen compounds. From our perspective, the IChB components (a sigma hole and the proximal Lewis base) act in synergism to accommodate the overwhelming steric force. The adaptive responses of the IChB components are inferred from the observed molecular structures and reactivity. These include (a) adaptation of a conformation without IChBs, (b) adaptation of a conformation with weak IChBs, (c) twisting the skeletal aryl ring while maintaining IChBs, (d) ionization of the E–X bond (e.g., X = Br) to relieve stress and (e) intramolecular cyclization to relieve steric stress. A comprehensive approach, involving X-ray data analysis, density functional theory (DFT) calculations, reaction pattern analysis and principal component analysis (PCA), has been employed to rationalize the adaptive behaviors of IChBs in arylchalcogen compounds. We believe that the perception of ChB as an adaptive/stimulus responsive interaction would profit the futuristic approaches that would utilise ChB as self-assembly and molecular recognition tools.

Graphical abstract: Adaptive responses of sterically confined intramolecular chalcogen bonds

Supplementary files

Article information

Article type
Perspective
Submitted
29 Apr. 2018
Accepted
24 Jūl. 2018
First published
25 Jūl. 2018
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2018,9, 7027-7042

Adaptive responses of sterically confined intramolecular chalcogen bonds

K. Selvakumar and H. B. Singh, Chem. Sci., 2018, 9, 7027 DOI: 10.1039/C8SC01943F

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