Abstract Aluminum is the most affluent metal element in many living organisms. However, excessive Al3+ is considered to be harmful for biological activities. In the past decades, many of sensing techniques and probes were widely developed for Al3+ detection. But the low sensitivity and nonquantitative detection still need to be improved. Multi-signal probes may sweep away the obstacle. In this article, a Schiff base based on carbazole and triphenylamine as a multi-signal (colorimetric, absorption and fluorescence) probe was successfully designed, prepared and characterized. This newly designed probe, 4, 4-(9-ethyl-carbazol) methylenimine-triphenylamine(L), exhibited a “turn-on” fluorescence mode for the qualitative and quantitative detection of Al3+. The color of L changes from light yellow to orange, and the limit of detection (LOD) is 2 × 10−6 mol/L. The LODs by absorption and fluorescence methods were found to be 6.7 × 10−7 mol/L and 6.3 × 10−8 mol/L, respectively. The data of the Job’s plot, 1H NMR and LC–MS imply that L will be hydrolyzed in the presence of Al3+, and a new complex is formed based on the carbazole amide molecule and Al3+ to push the “turn-on” fluorescence. Furthermore, the fluorescence image of HeLa cells facilitating intracellular detection of Al3+ was successfully captured by the probe of L.

中文翻译：

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基于新型席夫碱化合物的用于 Al3+ 检测的高选择性比色、吸收和荧光探针

摘要 铝是许多生物体中含量最丰富的金属元素。然而，过量的Al3+被认为对生物活动有害。在过去的几十年中，许多传感技术和探针被广泛开发用于 Al3+ 检测。但灵敏度低和非定量检测仍有待改进。多信号探头可以扫除障碍物。在本文中，成功地设计、制备和表征了基于咔唑和三苯胺作为多信号（比色、吸收和荧光）探针的席夫碱。这种新设计的探针 4, 4-(9-乙基-咔唑) 亚甲基-三苯胺 (L) 表现出一种“开启”荧光模式，可用于 Al3+ 的定性和定量检测。L的颜色由浅黄色变为橙色，检测限 (LOD) 为 2 × 10−6 mol/L。通过吸收法和荧光法测得的 LOD 分别为 6.7 × 10-7 mol/L 和 6.3 × 10-8 mol/L。Job's plot、1H NMR和LC-MS的数据表明L在Al3+存在下会被水解，并基于咔唑酰胺分子和Al3+形成新的复合物以推动“开启”荧光。此外，L.的探针成功捕获了促进细胞内检测Al3+的HeLa细胞的荧光图像。