Bipyridine‐Appended Cobalt(II) Coordination Polymer Featuring a Pnictogen‐Rich Cyclophosphazene for Visible Light–Driven Dye Degradation

Visible light–driven photocatalysts with high stability and efficient charge transport are highly desirable for sustainable environmental remediation. Herein, we report a cobalt(II)‐based coordination polymer ( PCP‐25 ) assembled from a cyclotriphosphazene‐derived tetracarboxylate linker and 2,2′‐bipyridine ( bpy ) via a solvothermal route. Single‐crystal X‐ray diffraction (SC‐XRD) reveals that PCP‐25 crystallizes as a 1D coordination polymer composed of μ ₄‐carboxylate‐bridged Co(II) nodes, which are further interconnected through pronounced π – π stacking interactions between bpy units to generate a 2D layered network. PCP‐25 exhibits high crystallinity and thermal stability up to 350°C. Optical studies indicate a moderate band gap of 2.47 eV, enabling efficient visible light absorption and charge separation. Significant pollutant conversion was observed under visible light, with PCP‐25 eliminating 94% of MB, 85% of RhB, and 75% of MO over a 90‐min reaction period. Radical trapping and electron paramagnetic resonance (EPR) analyses identify superoxide radicals (O 2 •− ) as the dominant reactive species. Moreover, the catalyst retains over 85% of its initial activity after five cycles, confirming its durability. The combination of pnictogen‐rich cyclophosphazene‐based linkers, redox‐active Co(II) centers, and π ‐conjugated stacking interactions provides an effective strategy for constructing robust coordination polymers for visible light–driven wastewater remediation.