Two three-dimensional mixed-ligated cobalt phosphonate coordination polymers: Syntheses, crystal structures and magnetic properties

•Two new mixed-ligated cobalt phosphonates 1 and 2 incorporating both 5-phosphonatophenyl-1,2,4-tricarboxylic acid and N-donor co-linkers were synthesized successfully.•Both coordination polymers show 3D framework structure composed of cobalt clusters and organic ligands.•Powder X-ray diffraction, thermal stability, IR spectroscopies and magnetic properties have been studied.•The antiferromagnetic interactions are dominated in compound 1, while the weak ferromagnetic exchange couplings are observed in compound 2.