Chemical Reactivity and Quantifying the Intra‐ and Intermolecular Interactions in Zwitterionic Compounds

Abstract

A zwitterionic Schiff base, (E)-2-((2-(1-hydroxyethyl)phenyliminio)methyl-6-methoxyphenolate (L 1 ) was prepared and fully characterized by spectral methods. The crystal structure was determined by using single crystal X-ray diffraction study. Inter and intra-molecular interactions in L 1 and similar zwitterionic Schiff bases (L 2 = (E)-2-(((2hydroxyethyl)iminio)phenyl)methyl-5-(prop-2yn-1-yloxy)phenolate and L 3 = (E)-2-(2-hydroxy-3methoxybenzylideneammonio)-3-(1H-imidazol-3-ium-4-yl) propanoate) have been established via topological analysis by considering the presence of (3,-1) bond critical points (BCP) between the interacting atoms using the approach of QTAIM (Quantum Theory of Atoms In Molecules) with the aid of ADF (Amsterdam Density Functional) 2017 package. Furthermore, Hirshfeld 2D fingerprint plots and 3D deformation densities were used to determine the interactions quantitatively. The L 1 -L 3 forms a six-member pseudo cycle via an intramolecular N-H···O hydrogen bond, and the crystal structure is further stabilized by the presence of p···p stacking interactions. The effect of hydrogen bonding interactions of the molecule on infra red frequencies has been studied using DFTB (Density Functional based Tight Binding) method with ADF. The effect of intermolecular interactions of these compounds towards biomolecules was studied by using Auto Dock Vina and QTAIM analysis.

Small‐Molecule Fluorescent Probe: Ratiometric and Selective Detection of Sodium Ions for Imaging and Solid‐State Sensing Applications

“…The phenolic hydroxyl group is probably deprotanated by acetate anion (CH 3 COO − ) and it becomes phenolate anion (Scheme 2) to neutralize the complex ( NaL ). The observed C2‐O5 bond distance (1.308(2) Å) was also comparable with the previously reported phenolate ions [65–67] . The Na‐O bond distances were observed in the ranges of 2.325(2) to 2.582(2) Å within sodium octahedron, and have average value of 2.428 Å, similar to previously reported values [68–72] .…”

Supramolecular Packing of a Series ofN-Phenylamides and the Role of NH···O═C Interactions

“…The effect of the substituent on a series of N-phenylamides 1− 7 leads to some changes in both the strength of the hydrogen bond energy and crystal packing. The proposed crystallization mechanisms for the compounds were divided into two types, which are two stages (1−6) and stacking of tetramers (7). Compound 2 presented the formation of a 1D portion (chains) in the first stage, where 1 and 3−6 showed the formation of 2D blocks.…”

“…Furthermore, theoretical studies have contributed to the characterization and description of these interactions. The QTAIM (quantum theory of atoms in molecules) analysis is a powerful tool used to analyze the strength of intra-/intermolecular interactions that stabilize crystal structures. , Similarly, the molecular reactivity can be obtained by measuring the molecular electrostatic potential (MEP) based on regions of positive and negative potentials …”

“…The QTAIM (quantum theory of atoms in molecules) analysis is a powerful tool used to analyze the strength of intra-/intermolecular interactions that stabilize crystal structures. 7,8 Similarly, the molecular reactivity can be obtained by measuring the molecular electrostatic potential (MEP) based on regions of positive and negative potentials. 9 In addition to theoretical tools, experimental approaches using 1 H NMR are used to explore interactions, including π•••π or hydrogen bonds, reflecting the aggregation of the molecules in the solution.…”

“…Another data obtained from the overlay of the molecules are the root mean square (RMS) as a measure of the magnitude of the overlay. Compound 1 was used as reference while considering the methyl substituent as a pattern [because the hydrogensubstituted compound (7) has Z′ = 2]. The highest values refer to compounds 3 and 4A because of the twisting of the plane to the opposite direction of the others.…”