The heterocyclic probe 3-(1-isoquinolinyl)imidazo[5, 1-a]isoquinoline (IQ) in CH₃OH/HEPES buffer system (5 mM, pH = 7.4, 6:4, v/v), exhibits blue fluorescence (λ_em = 454 nm) upon excitation with 359 nm light. Upon adding Pd²⁺ ion solution, IQ shows “turn-off” response when observed under long UV light. Using IQ bivalent palladium can be detected with a low limit of detection (0.210 μM) within the pH range of 2-8. In the presence of large varieties of metal ion, colorimetric and fluorescence responses did not exhibit any perceptible change. A small change in fluorescence life-time in TRPL study indicates the static nature of quenching. Binding of probe IQ with Pd²⁺ ion can be reversed using Na₂EDTA. Job’s plot and ESI mass spectrometric analysis reveal a 1:1 ratio for binding of IQ with Pd(II) ion. DFT/TDDFT calculations performed on [Pd(IQ)Cl(CH₃CN)]⁺ ion support the experimental findings. Cytotoxic studies showed that probe IQ suppressed the growth of L929 and Hela cells in a dose-dependent manner. Fluorescence imaging in the absence and presence of Pd²⁺ revealed that IQ can be successfully applied on living cells with outstanding sensitivity.

CH ₃ OH / HEPES缓冲液系统（5 mM，pH = 7.4，6：4，v / v）中的杂环探针3-（1-异喹啉基）咪唑啉[5，1- a ]异喹啉（IQ）显示蓝色荧光（λ _EM在用359纳米的光激发= 454纳米）。加入Pd ²⁺离子溶液后，当在长紫外线下观察时，IQ会显示“关闭”响应。使用智商可以在2-8的pH范围内以低检测限（0.210μM）检测二价钯。在存在大量金属离子的情况下，比色和荧光响应未显示任何可察觉的变化。TRPL研究中荧光寿命的微小变化表明淬灭的静态性质。可以使用Na ₂ EDTA逆转探针IQ与Pd ²⁺离子的结合。Job的图和ESI质谱分析显示IQ与Pd（II）离子的结合比例为1：1 。对[Pd（IQ）Cl（CH ₃ CN）] ⁺离子进行的DFT / TDDFT计算支持了实验结果。细胞毒性研究表明探针IQ剂量依赖性地抑制L929和Hela细胞的生长。在不存在和存在Pd ²⁺的情况下进行的荧光成像显示，IQ可以成功地以优异的灵敏度应用于活细胞。