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Herein, we report a quantum chemistry investigation of the interaction between µ-truxinic acid, referred to as TXA0, and Y+ (Y = Li, Na, K) and Z− (Z = F, Cl, Br) ions using M06-2X, B3LYP and ω B97XD functionals in conjunction with the 6–31 + + G(d,p), aug-cc-pVDZ(-X2C) and 6–311 + + G (d, p) basis sets. Our computations suggest that Y+ cations can bind to TXA0 through several combinations of cation...O and cation-π interactions, while Z− anions generally establish anion...H–O contacts. Predicted binding energies at the M06-2X/6–311 + + G(d,p) level range between − 26.6 and − 70.2 kcal/mol for cationic complexes and − 20.4 and − 62.3 kcal/mol for anionic ones. As such, TXA0 appears as an amphoteric molecule with a slight preference for electrophilic (cation... O) attacks. Furthermore, the most favourable binding site for cations allows for the formation of O...cation...O interactions where the cation is trapped between O37 and O38 atoms of TXA0. Anions do not behave uniformly towards TXA0: while the fluoride anion F− induces the deprotonation of TXA0, Br− and Cl− do not. All of these structural insights are supported by topological calculations in the context of the quantum theory of atoms in molecules (QTAIM). Finally, SAPT0 analyses suggest that TXA0...Y+ and TXA0...Z− complexes are mainly stabilized by electrostatic and inductive effects, whose combined contributions account for more than 60 percent of the total interaction energy. [ABSTRACT FROM AUTHOR]

The ambident reactivity of small-sized XAHs (X=H, F, Cl, Br, CH3, and A=S, Se, Te) molecules towards the imidazole molecule (IMZ) has been investigated using wave function (MP2) and Density Functional Theory (B3LYP, B3LYP-D3). Molecular electrostatic potentials (MEPs) and frontier molecular orbitals of monomers are computed to rationalise the regioselectivity of IMZ towards XAHs. The chemical bonding of each complex is described in the framework of the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) paradigms. The symmetry-adapted perturbation theory (SAPT) is employed to assess the physical nature of the interactions. Our findings suggest that XAHs mainly bind to IMZ through H-bonding and chalcogen-bonding interactions of weak to moderate strength, with binding energies ranging from −3.1 to −17.6 kcal/mol at the MP2/aug-cc-pVDZ(-PP) level. Topological QTAIM descriptors reveal all H-bonds between IMZ and XAHs to be purely noncovalent contacts, while chalcogen bonds of halogenated XAHs (X = F, Cl, Br) show a partial covalent character. SAPT2 calculations indicate that both H-bonded and chalcogen-bonded complexes are mainly stabilised by electrostatic interactions. Insights drawn from this study are expected to constitute the bedrock for further investigations about noncovalent interaction between middle to big-sized chalcogen-containing molecules and imidazole derivatives. [ABSTRACT FROM AUTHOR]