Structural Tunability on Naphthalimide-Based Dendrimer Gelators via Glaser Coupling Interaction with Tailored Gelation Solvent Polarity and Stimuli-Responsive Properties

Recent Advances in Self-Assembled Naphthalimides: From Molecular Design to Applications

Naphthalimide-based self-assembled materials have gained significant attention in recent years because of their exceptional versatility and wide range of applications, from sensors and electronics to biomedical. Naphthalimides derivatives, with ease of functionalization and robust photophysical properties, became an ideal platform for creating highly ordered self-assembled architectures with tailored functionalities. This review provides an overall understanding of the recent developments in the synthesis and self-assembly of naphthalimide-based materials, focusing on how self-assembly enhances their performance in various applications. The review examines the role of self-assembly in improving these materials' optical, mechanical, and electronic properties, highlighting their use in sensors for detecting gases, volatile organic compounds (VOCs), and amines. Furthermore, the integration of self-assembled naphthalimides in light-emitting devices, energy-harvesting systems, and fluorescence-based imaging demonstrates their potential in both electronic and biological applications. By analyzing recent developments in molecular design, self-assembly strategies, and applications, this review aims to offer insights into how these materials can be optimized for future technological advancements.

Making and Breaking of Gels: Stimuli-Responsive Properties of Bis(Pyridyl-N-oxide Urea) Gelators

The structural modification of existing supramolecular architecture is an efficient strategy to design and synthesize supramolecular gels with tunable and predictable properties. In this work, we have modified bis(pyridyl urea) compounds with different linkers, namely hexylene and butylene, to their corresponding bis(pyridyl-N-oxide urea). The gelation properties of both the parent and the modified compounds were studied, and the results indicated that modification of the 3-pyridyl moieties to the corresponding 3-pyridyl-N-oxides induced hydrogelation. The stability of the parent and modified compounds were evaluated by sol-gel transition temperature (T_gel) and rheological measurements, and single-crystal X-ray diffraction was used to analyze the solid-state interactions of the gelators. The morphologies of the dried gels were analyzed by scanning electron microscopy (SEM), which revealed that the structural modification did not induce any prominent effect on the gel morphology. The stimuli-responsive behavior of these gels in the presence of salts in DMSO/water was evaluated by rheological experiments, which indicated that the modified compounds displayed enhanced gel strength in most cases. However, the gel network collapsed in the presence of the chloride salts of aluminum(III), zinc(II), copper(II), and cadmium(II). The mechanical strength of the parent gels decreased in the presence of salts, indicating that the structural modification resulted in robust gels in most cases. The modified compounds formed gels below minimum gel concentration in the presence of various salts, indicating salt-induced gelation. These results show the making and breaking ability of the gel network in the presence of external stimuli (salts), which explains the potential of using LMWGs based on N-oxide moieties as stimuli-responsive materials.