Temperature-controlled synthesis and luminescent properties of two novel coordination polymers modeled by hexa-carboxylate ligand derived from cyclotriphosphazene

Abstract

Solvothermal reactions of hexakis(4-formylphenoxy)cyclotriphosphazene (H(6)L1) with Cd(NO(3))(2)·4H(2)O in H(2)O/DMF under different synthesis temperatures produced two new compounds, namely, {[Cd(3)(C(42)H(24)O(18)P(3)N(3)) (H(2)O)(7)]·xGuest}(n) (1), and {[Cd(2)(C(42)H(24)O(18)P(3)N(3)) (H(2)O)(2)]·xGuest}(n) (2). Compound 1 exhibits a novel 3D framework adopting 2,4,6-connected 3-nodal topology with the point (Schläfli) symbol {4(4)·6(2)}{4(5)·6(2)·8(8)}{4} constructed from the joint of neutral Cd(2) SBUs, mono-Cd ions and L1 ligands. Compound 2 reveals a 2D crystal structure exhibiting a 3,6-connected 2-nodal kgd topology with the point (Schläfli) symbol {4(3)}(2){4(6)·6(6)·8(3)} constructed from the connection of Cd centers and L1 ligands. In these two compounds, the ligands L1 are fully deprotonated, whose six extended carboxyl arms connect six different/same metallic nodes to form high dimensional frameworks. The variable reaction temperature must be responsible for the higher coordination number and versatile coordination modes of carboxylates in 1 compared to the ones in 2, resulting in the formation of a distinct crystal structure. In the solid state, both complexes are photoluminescent (LMCT) at room temperature.