Investigating Solid-State Luminescent Properties of New Cadmium(II) and Lead(II) Oxamato-Based Coordination Polymers

Abstract

Two novel coordination polymers were synthesized through the reaction of the Hpcpa^2- ligand (H₃pcpa = N-(4-carboxyphenyl)oxamic acid) with cadmium(II) and lead(II) metal ions, yielding [Cd₂(Hpcpa)₂(H₂O)₆]_n·H₂O (1) and [Pb(Hpcpa)(H₂O)]_n (2). Structural analysis by single-crystal X-ray diffraction revealed that 1 consists of one-dimensional zigzag polymeric chains, while 2 is a three-dimensional polymer network. Additionally, investigations of their optical properties were carried out in a comparative study involving the previously reported pcpa-based coordination polymers {[Zn(Hpcpa)(H₂O)₃]·0.5H₂O}_n and {[Gd₂(Hpcpa)₃(H₂O)₅]·H₂O}_n], called here as 3 and 4, respectively. Under 330 nm excitation wavelength, all compounds exhibited broad emission bands spanning from 350 to 650 nm. Particularly, 1 and 3 displayed notable external quantum yields of 15.4 and 12.8%, respectively, highlighting their potential in luminescent applications.

Keywords:
coordination polymers; luminescence; oxamato