The solvothermal reaction of [tris-(4-carboxylphenyl)phosphineoxide] (H3TPO) with UO2(NO3)2·6H2O in DMF affords a uranium-based chiral, microporous, metal-organic framework compound [(CH3)2NH2][UO2(TPO)]·4DMF·12.5H2O (SCU-3) that exhibits the highest void volume (68.8%) and second-harmonic generation (SHG) efficiency (1.54 KDP) for an actinide compound reported to date. The combination of large channels and the coordination capabilities of P=O moieties in the structure enables SCU-3 to capture large amounts of Th(iv) from aqueous solutions, providing a new strategy for preparing heterobimetallic 5f/5f compounds, and may lead to applications in nuclear waste management.