Computational Insight into Conformational Rearrangement and Intramolecular-H Bond Analysis of Some Calix[4]Arenes Including Acryloyl Moiety

Abstract

The conformational analyses of Calix[4]arenes reveals four different stable structures (conformations); Cone, Partial Cone, 1,2-Alternate and 1,3-Alternate after employing a density functional theory (DFT) computational analysis. Intramolecular Hydrogen Bonds (IHBs) existing Calixarene core cause Cone conformation, supporting to be the best stable state in 1, 2 and 3 compounds. In addition, one needs Natural Bond Orbital (NBO) analyses of current compounds in order to understand nature of these IHBs. Specifically, it has been shown using NBO that the LP *?? interactions for O???O¯H IHBs and the delocalization LP ? ?* for O¯C=O are the major contributions to energy stabilization. Of all conformers of compound 4, Partial Cone has the lowest energy, which can be attributed to devoid of intramolecular hydrogen bond due to the absence of free phenolic groups.