Solvothermal synthesis and crystal structures of two Holmium(III)-5-Hydroxyisophthalate entangled coordination polymers and theoretical studies on the importance of π•••π stacking interactions

•Two new Holmium CPs 1 and 2, containing 5-hydroxyisophthalate linker have been synthesized and characterized.•Both the CPs show 1D linear ladder shaped extension with the linkage having the backbone of hip2− moieties. 1 is mononuclear and 2 is isophthalate bridged tetranuclear structure.•Hydrogen bonding in both the CPs 1 and 2 contribute to the extensive 3D supramolecular framework.•DFT studies reveal the existence of strong antiparallel and parallel stacking interactions in 1 and 2, respectively. Two new Ho(III)-5-hydroxyisophthalates with the formulae; {[Ho(hip)(H2O)5].(NO2).H2O}n (1) and {[Ho4(hip)4(H2O)20].2(hip2−).8H2O}n (2) were solvothermally synthesized by self-assembly of Ho(III)-nitrate with rigid 5-hydroxyisophthalic acid (H2hip) linker. The coordination polymers (CPs) 1 and 2 crystallize in monoclinic P21/c and P21/n space groups, respectively. Both the CPs 1 and 2, shows 1D linear ladder shaped extension with the linkage having the backbone of hip2− moieties. In the both CPs 1 and 2, the Ho centers are nine coordinated. In CP 1, Ho shows distorted tricapped trigonal prismatic geometry while in CP 2, four Ho centres display three different geometries (monocapped square antiprismatic geometry around Ho1 and Ho3; distorted tricapped trigonal prismatic geometry around Ho2 and; distorted monocapped square antiprismatic geometry around Ho4). The organic linker hip2− exhibits only one coordination mode (μ2-κO,O:κO,O). Theoretical calculations have been performed to analyze the antiparallel and parallel π stacking interactions observed in the solid-state structures of coordination polymers1 and 2, respectively. The DFT study is focused on the energetic features of the π-stacking, the influence of the ligand coordination to Ho upon the π-stacking strength and their characterization by the noncovalent interaction plot (NCIplot) index computational tool. [Display omitted]