Highly selective imidazole-appended 9,10-<i>N,N′</i>-diaminomethylanthracene fluorescent probe for switch-on Zn²⁺ detection and switch-off H₂PO₄ ^&#x2212; and CN^&#x2212; detection in 80% aqueous DMSO

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>A new imidazole-appended anthracene-based photoinduced electron transfer (PET) probe (<B>P</B>) was designed and synthesized. Probe <B>P</B> detected Zn<SUP>2+</SUP> selectively in an 80% aqueous solution of dimethyl sulfoxide (DMSO) through a switch-on response at pH 7.5 without any interference from other metal ions. Probe <B>P</B> exhibited a moderately strong association constant (<I>K<SUB>a</SUB> </I>) of 1.41×10<SUP>5</SUP> M<SUP>−1</SUP> and associated with Zn<SUP>2+</SUP> ions with 1:1 stoichiometry. The in situ-generated <B>P</B>•Zn<SUP>2+</SUP> (1:1) ensemble detected H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions sequentially through switch-off responses. The selective discrimination of H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions occurred both in the absence and presence of Ca<SUP>2+</SUP> ions at pH 7.5 in a <I>N</I>-2-hydroxyethylpiperazine-<I>N</I>-2-ethanesulfonic acid (HEPES) buffer. The switch-on response was driven by the selective complexation of <B>P</B> with Zn<SUP>2+</SUP> ions, mediated by the combined effects of PET and chelation-induced enhanced fluorescence, resulting in a more structurally rigid complex. Applications of <B>P</B> to real water sample analysis and sequential logic gate operations were demonstrated. The lowest detection limits for Zn<SUP>2+</SUP>, H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP>, and CN<SUP>−</SUP> ions in 80% aqueous DMSO were determined to be 1.0×10<SUP>−9</SUP>, 1.0×10<SUP>−9</SUP>, and 8.0×10<SUP>−9</SUP> M, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Imidazole-appended anthracene probe P for sensing Zn<SUP>2+</SUP> was synthesized. </LI> <LI> Zn<SUP>2+</SUP> ions “<I>switched on</I>” the emission of P in 80% aqueous DMSO. </LI> <LI> In situ generated P-Zn<SUP>2+</SUP> (1:1) ensemble detected H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions sequentially through “<I>switch off</I>” response in the absence and presence of Ca<SUP>2+</SUP> ions respectively. </LI> <LI> Sensing ability of P towards Zn<SUP>2+</SUP> is attributed to PET and CHEF upon complexation. </LI> <LI> Application of P to real water samples and sequential logic gate operations were demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>