A phosphorescent copper(i) coordination polymer with sodium 3,5-dimethyl-4-sulfonate pyrazolate

Abstract

A phosphorescent copper(I) coordination polymer with the sodium salt of 3,5-dimethyl-4-sulfonate pyrazole (HL_Na) has been prepared and structurally characterized. The presence of the SO₃Na substituent in position 4 of the pyrazole ring led to a 3D polymeric species in which an organic/inorganic/organic sandwich motif is observed and repeated along the a axis through zig-zag chains of linear coordinated Cu(I) ions. The inorganic core of the sandwich consists of a trapezoidal grid of Na-ions interconnected by μ-(κO;κ²-O′,O′′)-bridging sulfonates and bridging water molecules; H-bonds can be also found between water molecules and SO₃⁻ groups. In the solid state, the copper derivative showed an interesting phosphorescent behavior when irradiated with UV light, with a yellow emission (570 nm) and a good absolute quantum yield (Φ_PL = 0.44), together with a remarkable Stokes shift of 2.50 eV.