Highly selective and turn-on fluorescence probe with red shift emission for naked-eye detecting Al3+ and Ga3+ based on metal-organic framework

A novel Zn-II-based metal-organic framework with the formula of {[Zn-2 (BBIP)(2) (NDC)(2)]center dot H2O}(n) (JXUST-5) derived from 3,5-bis(benzimidazol-1-yl)pyridine (BBIP) and 1,4-naphthalenedicarboxylic acid (H2NDC) has been synthesized. The adjacent Zn-II ions are linked through two BBIP ligands to form a [Zn-2(BBIP)(2)] secondary building unit (SBU). The neighbouring SBUs are further connected by NDC2- with mu(2) -eta(1) :eta(1) and mu(2)-eta(1):eta(1):eta(1) bridging modes to form a two-dimensional (2D) framework. Topological analysis shows that JXUST-5 could be simplified as an uninodal fes topology with a point symbol of {4.8(2)}. Furthermore, the 2D framework net could be extended through C-H center dot center dot center dot pi at interaction to form the three-dimensional supramolecular structure. Luminescent experiments suggest that JXUST-5 could selectively and sensitively recognize Al3 + and Ga3+ through fluorescence enhancement effect along with a relatively large red shift. The detection limits for Al3+ and Ga3+ are 0.17 and 0.69 ppm, respectively. Interestingly, the sensing process for both Al3+ and Ga3+ could be directly observed with naked eyes under 365 nm UV lamp. Notably, JXUST-5 could be recycled at least five times as a fluorescent sensor toward Al3+ and Ga3+, which is the second example of turn-on MOF based fluorescent sensor toward Ga3+. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.