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

Two novel coordination polymers were synthesized through the reaction of the Hpcpa 2- ligand (H 3 pcpa = N -(4-carboxyphenyl)oxamic acid) with cadmium(II) and lead(II) metal ions, yielding [Cd 2 (Hpcpa) 2 (H 2 O) 6 ] n & sdot; H 2 O ( 1 ) and [Pb(Hpcpa)(H 2 O)] 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)(H 2 O) 3 ]<middle dot>0.5H 2 O} n and {[Gd 2 (Hpcpa) 3 (H 2 O) 5 ]<middle dot>H 2 O} 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.