Association Complexes of Calix[6]arenes with Amino Acids Explained by Energy-Partitioning Methods

Abstract

Intermolecular complexes with calixarenes are intriguing because of multiple possibilities of noncovalent binding for both polar and nonpolar molecules, including docking in the calixarene cavity. In this contribution calix[6]arenes interacting with amino acids are studied with an additional aim to show that tools such as symmetry-adapted perturbation theory (SAPT), functional-group SAPT (F-SAPT), and systematic molecular fragmentation (SMF) methods may provide explanations for different numbers of noncovalent bonds and of their varying strength for various calixarene conformers and guest molecules. The partitioning of the interaction energy provides an easy way to identify hydrogen bonds, including those with unconventional hydrogen acceptors, as well as other noncovalent bonds, and to find repulsive destabilizing interactions between functional groups. Various other features can be explained by energy partitioning, such as the red shift of an IR stretching frequency for some hydroxy groups, which arises from their attraction to the phenyl ring of calixarene. Pairs of hydrogen bonds and other noncovalent bonds of similar magnitude found by F-SAPT explain an increase in the stability of both inclusion and outer complexes.

Host–Guest Chemosensor Ensembles based on Water-Soluble Sulfonated Calix[n]arenes and a Pyranoflavylium Dye for the Optical Detection of Biogenic Amines

“…Supramolecular chemistry provides a wide range of receptor molecules, particularly macrocycles, that can be used as hosts in a variety of applications, garnering considerable interest from the scientific community. In terms of structural diversity, macrocycles, include cyclodextrins, , cucurbiturils, , crown ethers, cryptands, pillararenes, and calixarenes, , to give some examples. On the other hand, guest molecules are generally small molecules or ions that benefit from the host–guest interactions to improve their stability and bioavailability or even to tune their spectroscopic features, namely, colorimetric and fluorescent properties.…”

Probing the dynamical interaction of the para-sulfonato-calix[4]arene with an antifungal protein

“…The specific interaction with overall positively-charged proteins, like cytochrome-C 8,33,34 , lysozyme 31 and small antifungal proteins (PAF) 35,36 , makes calixarenes ideal ligand host partners 37 in encapsulating positively-charged residues such as lysines and arginines [38][39][40][41] .…”

Hydrogen Bonds

“…An essential area of manifestation of the importance of intermolecular interactions, especially hydrogen bonds, are inclusion complexes based on the guest–host interaction. Masoumifeshani, Chojecki, Rutkowska-Zbik, and Korona use energy partitioning approaches (SAPT, F-SAPT, SSMF3 (i.e., the authors’ modification of SMF)) to systematically characterize interactions in the complexes between amino acids as the potential guests and three calix[6]arene and hexa- p-tert -butylcalix[6]arene conformers as the hosts [ 11 ]. One of the many interesting findings of this study is that the most stable pinched-cone conformer is the one least prone to interact with amino acids.…”