On the molecular and supramolecular properties of N,N′-disubstituted iminoisoindolines: Synthesis, spectroscopy, X-ray structure and Hirshfeld surface analyses, and DFT calculations of two (E)-N,N′-bis(aryl)iminoisoindolines (aryl = 2-tert-butylphenyl or perfluorophenyl)

Abstract

Supramolecular studies of iminoisoindoline-derived compounds have been prompted by their biological and photophysical properties. In this article, we report the synthesis, spectroscopy, X-ray structural characterization, and DFT study of two N,N′-(aryl)-disubstituted 1-iminoisoindolines, namely (E)-N,N′-bis(2-tert-butylphenyl)iminoisoindoline (2-t-BuPhimiso) and (E)-N,N′-bis(perfluorophenyl)iminoisoindoline (F5Phimiso). Our X-ray structural analyses have shown that the isoindoline N2 atom of 2-t-BuPhimiso is slightly pyramidalized whereas the respective atom of F5Phimiso displays the expected trigonal planar geometry. The supramolecular arrangement of 2-t-BuPhimiso comprises one-dimensional chains along the [101] direction formed by CH···πarene interactions, in which the isoindoline ring behaves as a hydrogen-bond donor. For 2-t-BuPhimiso, DFT calculations at the B97-D3/6-311G** level have shown that the dimer formed by this CH···πarene contact displays a binding energy of −12.83 kcal mol−1. Product F5Phimiso assembles in the crystal state through type-I F3 synthons in addition to CH⋯F, C–Fδ–···πF+, and πarene/F–πarene/F stacking interactions. Accordingly, our DFT-D3 calculations have confirmed that these interactions synergistically play a dominating role in the crystal packing of F5Phimiso. Finally, the relative stability of the (Z) and (E) isomers of each product has been evaluated at the DFT level of theory. Our calculations have shown that the (E) forms are the most stable ones.