Huligujje Sruthi, Duraisamy Dinesh Kumar, Shanmugam Ganesh, Deshpande Abhijit P
Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
Organic & Bioorganic Chemistry Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai 600020, India.
Langmuir. 2025 Aug 19;41(32):21435-21444. doi: 10.1021/acs.langmuir.5c02025. Epub 2025 Aug 8.
Organogels are soft materials that have been gaining increased attention due to their wide range of applications in various fields. While the gelation of several organic solvents has been successfully achieved using polymer and low molecular weight (LMW) gelators, forming gels of dimethyl sulfoxide (DMSO) remains challenging due to its high polarity and its ability to disrupt hydrogen bonding. This is particularly challenging because LMW gelators primarily rely on intermolecular hydrogen bonding along with hydrophobic interactions for gelation. In this study, we demonstrate that the bifunctionalization of l-lysine with fluorenylmethoxycarbonyl and palmityl groups at the N and N amino groups of l-lysine (FmKPal) respectively, induces organogelation in neat DMSO. Notably, the minimum gelation concentration (MGC) of FmKPal in DMSO is as low as 0.2 wt %, which is significantly lower than the typical 1-2 wt % observed for most LMW organogelators. This low MGC classifies FmKPal as a "super" organogelator. Electron microscopy reveals a nanofibrillar network formed through the self-assembly of FmKPal, resulting in a stable gel. Various biophysical characterizations indicate that aromatic π-π and hydrophobic interactions drive the self-assembly of the FmKPal. Interstingly, despite DMSO's hydrogen bond-disrupting nature, intermolecular hydrogen bonding between the carbamate and amide groups of FmKPal remains intact. This preservation is likely due to the synergistic effects of aromatic π-π and hydrophobic interactions. Furthermore, blending the FmKPal DMSO gel with lubricant oil retained the gel behavior, highlighting its potential for oil-based applications. The current finding of DMSO gelation by an LMW gelator provides additional insights into supramolecular gel formation and offers a lead for designing similar gelators with broader applications such as lubrication and related fields.
有机凝胶是一种软材料，因其在各个领域的广泛应用而受到越来越多的关注。虽然使用聚合物和低分子量（LMW）凝胶剂已成功实现了几种有机溶剂的凝胶化，但由于二甲基亚砜（DMSO）的高极性及其破坏氢键的能力，形成DMSO凝胶仍然具有挑战性。这尤其具有挑战性，因为LMW凝胶剂主要依靠分子间氢键以及疏水相互作用来实现凝胶化。在本研究中，我们证明，分别在L-赖氨酸的N和N'氨基上用芴甲氧羰基和棕榈酰基对L-赖氨酸进行双官能化（FmKPal），可在纯DMSO中诱导有机凝胶化。值得注意的是，FmKPal在DMSO中的最低凝胶化浓度（MGC）低至0.2 wt%，这明显低于大多数LMW有机凝胶剂通常观察到的1-2 wt%。这种低MGC将FmKPal归类为“超级”有机凝胶剂。电子显微镜显示通过FmKPal的自组装形成了纳米纤维网络，从而产生了稳定的凝胶。各种生物物理表征表明，芳香族π-π和疏水相互作用驱动了FmKPal的自组装。有趣的是，尽管DMSO具有破坏氢键的性质，但FmKPal的氨基甲酸酯和酰胺基团之间的分子间氢键仍然完好无损。这种保留可能是由于芳香族π-π和疏水相互作用的协同效应。此外，将FmKPal DMSO凝胶与润滑油混合保留了凝胶行为，突出了其在油基应用中的潜力。目前关于LMW凝胶剂使DMSO凝胶化的发现为超分子凝胶形成提供了更多见解，并为设计具有更广泛应用（如润滑及相关领域）的类似凝胶剂提供了线索。
