Polyoxometalate-phosphonate compounds: Synthesis, structure, photocatalytic and antitumor properties

•Two Strandberg-type polyoxometalate-phosphonate compounds have been synthesized;Compound 2 as catalyst has higher photocatalytic degradation of RhB than 1 due to its larger porosity.•The structure-activity relationships of compounds indicate that the introduction of biz and 3-phosphonopropionic acid into P2Mo5 can make compound 1 better antitumor activities.