Chain-like uranyl-coordination polymer as a bright green light emitter for sensing and sunlight driven photocatalysis

Abstract

A new uranyl-coordination polymer (UCP) has been solvothermally synthesized employing succinic acid and 1,10-phenanthroline (phen) as ligands. The obtained compound with the formula [(UO₂)₂(phen)(succ)_0.5(OH)(O)₄(μ₃-O)(H₂O)]·H₂O (UNSL-1) is classified as 1D chains showing I⁰O¹ connectivity. Also, the asymmetric unit is composed of two hepta-coordinated uranyl centers: U1 is surrounded by five oxygen atoms from succinate, while U2 is surrounded by two nitrogen atoms from phen and three oxygen atoms from succinate ([U1O₇] and [U2N₂O₅]). The secondary-building unit (SBU) is composed of a sharing edge tetrameric cluster linked with a succinate ligand in the [−1 0 1] direction. Besides, the chains are reinforced by π–π stacking interactions between the aromatic rings of the phen molecules to conform a 2D supramolecular arrangement. Moreover, photoluminescence experiments show strong green emission consistent with uranyl crystalline materials. Photophysical characterization was completed via low-temperature measurements (77 K) and recording the decay emission for calculating the lifetime (τ_obs) value. Regarding its multifunctional properties, a cation-sensing performance was achieved showing selective quenching toward iron ions in aqueous media. Finally, UNSL-1 was tested as an efficient water photocatalyst for dye degradation under simulated sunlight irradiation, exhibiting promising results for organic-pollutant water remediation.