Postsynthesis Strategy of Functional Zn-MOF Sensors for the Detection of ClO- and DPA

Active species were introduced into MOFs to prepare multifunctional fluorescent probes by a stepwise postsynthetic modulation strategy. First, two-dimensional HPU-16 (HPU = Henan Polytechnic University; HPU-16 = Zn-(L)(2)(H2O); HL = 2-(5-pyridin-4-yl-5H-[1,2,4]triazol-3-yl)-pyrazine) was transformed into three-dimensional HPU-17 ({Zn-3(L)(2)(btc)(2)(H2O)}(n)) through a crystal dissolution-recrystallization process. Second, linker replacement was used to introduce -NH2 into the HPU-17 to generate functional NH2-HPU-17 via a single-crystal to single-crystal transformation. The functional amino groups caused NH2-HPU-17 to show a significant response to ClO-. Because of the interaction of amino groups and ClO-, the fluorescence of NH2-HPU-17 gradually changed from blue to yellow-green. More interestingly, NH2-HPU-17 could encapsulate Tb3+ and sensitize the visible-emitting characteristic fluorescence of Tb3+ in aqueous solution. Then, newly generated Tb3+@NH2-HPU-17 could serve as an effective probe for the determination of DPA. This work paves a new way for the design and modulation of ratiometric fluorescence probes for the selective and sensitive detection of special molecules.