Paul Eshani, Raza Rameez, Dhara Subrata Ranjan, Baildya Nabajyoti, Ghosh Kumaresh
Department of Chemistry, University of Kalyani Kalyani 741235 India
RSC Adv. 2024 Oct 17;14(45):32759-32770. doi: 10.1039/d4ra05503a.
Herein, we report the synthesis, characterization, supramolecular gelation and multiple applications of 6-aminocoumarin-derived Schiff bases 1 and 2. Both Schiff bases underwent gelation in DMF-HO (2 : 1, v/v), DMSO-HO (2 : 1, v/v) and dioxane-HO (2 : 1, v/v) involving weak forces. Furthermore, the gels were stable and exhibited good viscoelastic properties. The storage modulus (') of each gel was considerably higher than its loss modulus (''). The higher value of the crossover point and lower value of tan for the gel of Schiff base 2 compared to the gel of Schiff base 1 demonstrated the better gelation behaviour of 2 than that of 1 in DMF-HO (2 : 1, v/v). Further, iodo-analogue 2 exhibited cross-linked helical morphology, whereas non-iodo analogue 1 exhibited long chain fibrous morphology, as observed FESEM. These differences in morphology and viscoelastic behaviors were attributed to the iodo group present in 2, which influenced its aggregation involving halogen bonding. To demonstrate their application, the DMF-HO (2 : 1, v/v) gels of both 1 and 2 recognized CN over a series of other anions by exhibiting a gel-to-sol phase change. Besides anion sensing, gels 1 and 2 selectively detected Fe and Cu ions over other metal ions a gel-to-gel colour change. Finally, CN-treated solutions of 1 and 2 allowed the successful detection of CO by the naked eye. Moreover, the detection was possible using a test-kit method.
在此，我们报告了6-氨基香豆素衍生的席夫碱1和2的合成、表征、超分子凝胶化及多种应用。两种席夫碱在DMF-H₂O（2∶1，v/v）、DMSO-H₂O（2∶1，v/v）和二氧六环-H₂O（2∶1，v/v）中通过弱作用力发生凝胶化。此外，这些凝胶稳定且表现出良好的粘弹性。每种凝胶的储能模量（G'）显著高于其损耗模量（G''）。与席夫碱1的凝胶相比，席夫碱2的凝胶具有更高的交叉点值和更低的tanδ值，这表明在DMF-H₂O（2∶1，v/v）中，2的凝胶化行为比1更好。此外，如场发射扫描电子显微镜（FESEM）观察到的，碘代类似物2呈现交联螺旋形态，而非碘代类似物1呈现长链纤维形态。形态和粘弹性行为的这些差异归因于2中存在的碘基团，它影响了其涉及卤键的聚集。为了展示它们的应用，1和2的DMF-H₂O（2∶1，v/v）凝胶通过呈现凝胶-溶胶相变，在一系列其他阴离子中识别CN⁻。除了阴离子传感外，凝胶1和2在其他金属离子中选择性地检测Fe³⁺和Cu²⁺，表现为凝胶-凝胶颜色变化。最后，用CN⁻处理的1和2的溶液能够通过肉眼成功检测CO₂。此外，使用测试试剂盒方法也可以进行检测。
