4-(3-oxo-1,3-dihydroisobenzofuran-1-yl)aminobenzoic acid and its complexes: Synthesis, crystal structures, theoretical calculations and in vitro and in silico antibacterial properties

•4-(3-oxo-1,3-dihydroisobenzofuran-1-yl)aminobenzoic acid were prepared as a new ligand.•The crystal structure of new ligand and its metal complexes were characterized.•Antibacterial effects of these compounds were evaluated as in vitro and in silico.•The compounds were found to have significant antibacterial effect on K. pneumoniae. The current study outlines the syntheses of a new ligand 4-(3-oxo-1,3-dihydroisobenzofuran-1-yl)aminobenzoic acid (1) and its cobalt and nickel complexes [tetramethanolbis(4-(3-oxo-1,3-dihydroisobenzofuran-1-yl)aminobenzoato)cobalt(II) (2) and tetramethanolbis(4-(3-oxo-1,3-dihydroisobenzofuran-1-yl)aminobenzoato)nickel(II) (3). Their structures were established using FT-IR, elemental analysis, and UV–Vis, and also their molecular and crystal structures were clarified by single crystal X-ray diffraction technique. They belong to the monoclinic system P21/n (for 1) and C 2/c (for 2 and 3) space groups with a = 12.2557 (5) Å, b = 5.8164 (3) Å, c = 17.7583 (6) Å, β = 94.202 (3)°, Z = 4 and V = 1262.48 (9) Å3 (for 1), a = 32.9005 (8) Å, b = 6.8552 (3) Å, c = 15.5507 (5) Å, β = 109.183 (3)°, Z = 4 and V = 3312.6 (2) Å3 (for 2) and a = 32.9604 (6) Å, b = 6.8265 (2) Å, c = 15.5949 (4) Å, β = 109.382 (3)°, Z = 4 and V = 3310.06 (14) Å3 (for 3). In the crystal structures of the ligand (1) and its complexes (2 and 3), the N–H···O, O–H···O, and C–H···O hydrogen bonds link the molecules, enclosing R22(8), R22(22) and R22(26) ring motifs, into three-dimensional architectures. The weak C–H···π interaction (in 1) and the π…π interactions between the five-membered rings of the neighboring molecules with centroid to centroid distances of 3.8302 (10) Å (in 2) and 3.8441 (11) Å (in 3) further consolidate the crystal packings. Hirshfeld surface analyses further revealed the prevailing significance of π…π and H-bonding contacts. It indicates that the most important contributions for the crystal packings are from H…H (50.9%), H…O/O…H (22.8%), and H…C/C…H (14.7%) (for 2), and from H…H (50.9%), H…O/O…H (22.5%) and H…C/C…H (14.9%) (for 3). Hydrogen bonding and Van der Waals contacts are the dominant interactions in the crystal packings. Moreover, the optimized molecular structures, using density functional theory (DFT) at the B3LYP/6–311G(d,p) level, were compared with the experimentally determined ones. The HOMO–LUMO energy gaps were determined and the molecular electrostatic potential (MEP) surfaces were calculated at the B3LYP/6–31 G level to predic