Synthesis, crystal structure and spectroscopic investigations of heteronuclear Co(III)/Cu(II), Co(III)/Cd(II) and Fe(III)/Cd(II) 3D coordination polymers with 4-(2-aminoethyl)pyridine

•The cyanide complexes of transition metals with 4-(2-aminoethyl)pyridine were synthesized and investigated.•The crystal structures of the complexes have been determined by the single crystal x-ray diffraction (SC-XRD) patterns.•In complex 1, the intermolecular O–H∙∙∙N, N–H∙∙∙N, N–H∙∙∙O and C–H∙∙∙N hydrogen bonds and CN∙∙∙π and π∙∙∙π interactions play a crucial role in the architecture of 3D network.•The intermolecular CN∙∙∙π interaction between cyanide ligand and pyridine ring of the 4aepy ligand is the most striking feature of complex 1.•Heterometallic complexes 2–3 have 3D coordination polymers.