title: Two 3D Cd(II) Metal-Organic Frameworks Linked by Benzothiadiazole Dicarboxylates: Fantastic S@Cd6Cage, Benzothiadiazole Antidimmer, and Dual Emission.
abstract: On the basis of the same benzothiadiazole (BTD) ligand 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H2L), two new isomers of three-dimensional (3D) BTD-derived Cd(II) metal-organic frameworks 1-2 {[S@Cd6L6]·xH2O}nwere obtained by the different solvothermal reactions, which were structurally similar. Surprisingly, structural analyses reveal that in 1 or 2, one free sulfur atom was fixed in a Cd(II) cluster cage by strong intermolecular interaction to form the secondary building unit (SBU) S@Cd6. Each SBU S@Cd6is connected by six L2-ligands and further extended into the 3D porous framework. In this work, the BTD antidimmer was evidenced by structural analysis and photophysical study. Furthermore, either 1 or 2 showed the uncommon dual emission, while only one emission was observed in the solution of ligand H2L. The dual-emission mechanism was also realized by the structural analysis and photophysical study. Interestingly, although there is slight difference in structure (regular octahedral cage in 1 and slightly distorted octahedral cage in 2), the changes in N2adsorption capability and photophysical performance between 1 and 2 are obvious, where 2 shows smaller Brunauer-Emmett-Teller surface area, broader absorption of antidimmer, and longer dual-emission lifetimes. Interestingly, either 1 or 2, the dual emission was clearly red-shifted by increasing the solvent polarity or the acidity of ambience, respectively.
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University , Henan 450001, P. R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University , Henan 450001, P. R. China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Han
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University , Henan 450001, P. R. China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Tong
authors.affiliation: Center for Advanced Materials Research, Zhongyuan University of Technology , Zhengzhou 450007, P. R. China.
authors.forename: Chao
authors.initials: C
authors.lastname: Huang
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University , Henan 450001, P. R. China.
authors.forename: Jie
authors.initials: J
authors.lastname: Ding
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University , Henan 450001, P. R. China.
authors.forename: Hongwei
authors.identifier: http://orcid.org/0000-0003-4762-0920
authors.initials: H
authors.lastname: Hou