Soft Materials Research Laboratory, Department of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Simrol, Indore, 453552, India.
Indian Institute of Technology, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India.
Chem Asian J. 2020 Oct 1;15(19):3020-3028. doi: 10.1002/asia.202000630. Epub 2020 Sep 2.
A fluorescent metallogel (2.6 % w/v) has been obtained from two non-fluorescent components viz. phenyl-succinic acid derived pro-ligand H PSL and LiOH (2 equiv.) in DMF. Li ion not only plays a crucial role in gelation through aggregation, but also contributed towards enhancement of fluorescence by imposing restriction over excited state intramolecular proton transfer (ESIPT) followed by origin of chelation enhanced fluorescence (CHEF) phenomenon. Further, the participation of CHEF followed by aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) in the gelation process have been well established by fluorescence experiments. Transmission electron microscopy (TEM) analysis disclosed the sequential creation of nanonuclei followed by nanoballs and their alignment towards the generation of fibers of about 3, 31 and 40 nm diameter, respectively. The presence of a long-range fibrous morphology inside the metallogel was further attested by scanning electron microscopy (SEM). Rheological studies on the metallogel showed its true gel-phase material nature. Nyquist impedance study shows a resistance value of 7.4 kΩ for the metallogel which upon applying ultrasound increased to 8.5 kΩ, while an elevated temperature of 70 °C caused reduction in the resistance value to 4.8 kΩ. The mechanism behind metallogel formation has been well established by using FTIR, UV-vis, SEM, TEM, PXRD, H NMR, fluorescence and ESI-MS.
一种荧光金属凝胶（2.6%w/v）是由两个非荧光组件即苯琥珀酸衍生的前配体 H PSL 和 LiOH（2 当量）在 DMF 中获得的。Li 离子不仅通过聚集在凝胶化中起着至关重要的作用，而且通过对激发态分子内质子转移（ESIPT）施加限制，也有助于增强荧光，随后产生螯合增强荧光（CHEF）现象。此外，通过荧光实验充分证实了 CHEF 与聚集猝灭（ACQ）和聚集诱导发光（AIE）在凝胶化过程中的参与。透射电子显微镜（TEM）分析揭示了纳米核的顺序形成，然后是纳米球，以及它们对齐以分别生成约 3、31 和 40nm 直径的纤维。扫描电子显微镜（SEM）进一步证明了金属凝胶中存在长程纤维形态。对金属凝胶的流变学研究表明其具有真正的凝胶相材料性质。奈奎斯特阻抗研究显示金属凝胶的电阻值为 7.4kΩ，施加超声后增加到 8.5kΩ，而 70°C 的高温会将电阻值降低至 4.8kΩ。通过使用 FTIR、UV-vis、SEM、TEM、PXRD、H NMR、荧光和 ESI-MS，已经很好地确立了金属凝胶形成的机制。
