pH-induced structural variations of two new Mg(II)-PDA complexes: experimental and theoretical studies

•pH-dependent Mg(II) complexes with 2,6-pyridine dicarboxylic acid•Exploration of noncovalent interactions in building supramolecular assembly•Bader's theory of Atoms-in-Molecules (AIM) to characterize the noncovalent interactions•Theoretical Noncovalent interaction (NCI) plot index for further characterization PH-dependent reaction between 2,6-pyridine dicarboxylic acid (PDA) and Mg(NO3)2 in water results in the formation of two new complexes (1) and (2). The grown complexes are characterized through single-crystal X-ray diffraction analyses. The structural investigations exhibit that the hydrogen bonds and lone-pair···π interactions stabilize the crystal structure of the complex (1) whereas complex (2) is stabilized through hydrogen bonds only. The noncovalent interactions have been characterized using Bader's theory of “atoms in molecules” (AIM). The nature of these interactions have been studied using atoms in molecules topological analysis. Topological analysis of intermolecular interactions at their bond critical points revealed that all of the interactions are of closed-shell interactions. The “noncovalent interaction” (NCI) plot index has been performed to characterize the noncovalent interactions of the structures discussed in this study.