Bimetal-Organic Frameworks Incorporating Both Hard and Soft Base Active Sites for Heavy Metal Ion Capture

Zhan Shen; Wei-Miao Zhang; Zhen Shan; Shu-Fan Li; Gen Zhang; Jian Su

doi:10.1021/acs.inorgchem.3c04610

Bimetal-Organic Frameworks Incorporating Both Hard and Soft Base Active Sites for Heavy Metal Ion Capture

Inorg Chem. 2024 Apr 26. doi: 10.1021/acs.inorgchem.3c04610. Online ahead of print.

Authors

Zhan Shen¹, Wei-Miao Zhang¹, Zhen Shan¹, Shu-Fan Li¹, Gen Zhang¹, Jian Su^{1

2}

Affiliations

¹ School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
² State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.

PMID: 38668738
DOI: 10.1021/acs.inorgchem.3c04610

Abstract

The design and synthesis of stable porous materials capable of removing both hard and soft metal ions pose a significant challenge. In this study, a novel metal-organic framework (MOF) adsorbent named CdK-m-COTTTB was developed. This MOF material was constructed using sulfur-rich m-cyclooctatetrathiophene-tetrabenzoate (m-H₄COTTTB) as the organic ligand and oxygen-rich bimetallic clusters as the inorganic nodes. The incorporation of both soft and hard base units within the MOF structure enables effective removal of various heavy metal ions, including both soft and hard acid species. In single-component experiments, the adsorption capacity of CdK-m-COTTTB for Pb²⁺, Tb³⁺, and Zr⁴⁺ ions reached levels of 636.94, 432.90, and 357.14 mg·g^-1, respectively, which is comparable to specific MOF absorbents. The rapid adsorption process was found to be chemisorption. Furthermore, CdK-m-COTTTB exhibited the capability to remove at least 12 different metal ions in both separate and multicomponent solutions. The material demonstrated excellent acid-base stability and renewability, which are advantageous for practical applications. CdK-m-COTTTB represents the first reported pristine MOF material for the removal of both hard and soft acid metal ions. This work serves as inspiration for the design and synthesis of porous crystalline materials that can efficiently remove diverse heavy metal pollutants.