Penta-coordinated Cr(II) and Cu(II) complexes appended with 4′-(4-quinolyl)-2,2′:6′,2″-terpyridine: Crystal structure, Hirshfeld surface analysis, luminescence and thermal properties

•New penta-coordinated complexes of Cr(II) and Cu(II) based on the terpyridine ligand.•Supramolecular structures through C-H…X (X= N, O, halide) hydrogen bond interaction.•Hirshfeld surface analysis was used to analyze the intermolecular interactions.•Luminescence properties displayed the ligand-based π–π* emission bands in solution.•Thermal decomposition of products showed the formation of corresponding metal oxide.