Chiroptical Inversion Induced by Rotation of a Carbon–Carbon Single Bond: An Experimental and Theoretical Study

Abstract

We propose a new strategy to construct chiral molecular switches with highly reversible and sensitive chiroptical responses to variations in the external environment. Its fundamental concept involves a stimuli-triggered exchange of two conformations presenting significantly different chiroptical properties through the rotation of a carbon-carbon single bond, as demonstrated by chiral Schiff bases s-1, s-2, and a salicylamide analogue s-3. Upon addition of base in solution, the circular dichroism (CD) spectra of these molecular switches displayed unique changes featuring an inversion of the Cotton effect's signs, and the original CD profiles can be recoverd by acidification. Various spectroscopic studies as well as the conformational analysis combining with TDDFT computations allowed clear elucidation of the chiroptical inversion mechanism. It is expected that this kind of chiroptical switches is of great interest for molecular recognition, chemosensing, and the construction of molecular-scale devices. Furthermore, the present study indicates that the use of the conformational transition about a single bond may serve as the basis for designing chiroptical inversion systems.

Investigation of the Effect of Some Optically Active Imine Compounds on the Enzyme Activities of hCA‐I and hCA‐II under In Vitro Conditions: An Experimental and Theoretical Study

“…The synthesized compounds were already reported in the literature so only 1H NMR results of these compounds were taken, and the results obtained were consistent with the literature and confirmed the structures of compounds. Experimental NMR results of all compounds were provided as the Supporting Information.…”

“…The Schiff base was characterized by elemental analysis, FT‐IR, and 1 H NMR techniques. The results of the experimental characterization of this compound, which are presented in the literature , are as follows: melting point: 82–85°C, yield (%): 906.. Found: mass spectrum (LC/MS‐MS): m/z 226 [M + 1] + Calcd. For C 15 ONH 15 ; 225 g/mol.…”

“…In this study, four optically active Schiff bases, which are well known but no theoretical studies or enzyme inhibition/activation studies were conducted, were synthesized and their inhibition and activation effects on human CA I and II enzymes were investigated. In addition, each compound was optimized by the density functional theory (DFT) method and B3LYP/6‐311+G(2d,p) basis set using Gaussian 09 software package, and theoretical 1 H NMR shift values were calculated.…”

Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels

“…Ling et al. proposed a new strategy to construct reversible chiroptical inversion induced by rotation around a carbon–carbon single bond . On addition of a base in solution, the circular dichroism (CD) spectra of these molecular switches displayed unique changes with an inversion of the Cotton effect signs, and the original CD profiles could be recovered by acidification.…”

Supramolecular Chirality in Dynamic Coordination Chemistry

“…such as small organic molecules [13][14][15][16][17][18][19], polymers [20][21][22][23], metamaterials [24], and assemblies [25][26][27][28], have been developed for chirality induction and switching in response to external stimuli, more sophisticated systems are required to mimic natural systems.…”