A sulfur-containing coordination polymer: remarkable heavy metal removal capacities and broad-spectrum antibacterial activities

Coordination polymers (CPs) represent a potentially highly valuable class of materials for next-generation applications in heavy metal removal and as antibacterial agents. Ligands bearing sulfur donors are ideal candidates for the preparation of CPs for these applications since sulfur atom has lone pairs of electrons which could be donated to some metal ions, thereby binding the metals selectively; and it is also effective in disrupting bacterial functioning. Herein, we report, the synthesis of the crystal (1_crys) and the powder (1_powd) forms of the Zn(II)-based CP [Zn(TDPA)₂(TMPy)₂]_n (1) (where TDPA = 3,3-thiodipropionic acid and TMPy = 4,4-trimethylenedipyridine). Structural elucidation of the CPs – 1_crys and 1_powd were undertaken by means of FTIR, TGA and PXRD. The 1_powd was obtained in much higher yields than the 1_crys, and heavy metal removal behavior and antibacterial activity of the former were extensively investigated. Excellent removal capacities of 667 mg/g for Ag(I) and for Pb(II) by 1_powd in single batch studies were observed. Additionally, 1_powd inhibited the growth of six common bacterial strains and showed minimum inhibitory concentrations comparable to reported antibacterial agents. The efficiency of 1_powd for these applications is linked to the sulfur-containing ligand used in the construction of the CP and its polymeric structure. Overall, the ease of preparation, yield, outstanding heavy metal removal capacities and potency in inhibiting bacterial growth offers 1_powd as a highly adaptable and multifunctional material.