The present article delineates the formation of green fluorescent organic nanoparticle through supramolecular aggregation of naphthalene diimide (NDI)-based, carboxybenzyl-protected, l-phenylalanine-appended bola-amphiphile, NDI-1. The amphiphilic molecule is soluble in DMSO, and, with gradual addition of water within the DMSO solution, the amphiphile starts to self-assemble via H-type aggregation to form spherical nanoparticles. These self-assembly of NDI-1 in the presence of a high amount of water exhibited aggregation-induced emission (AIE) through excimer formation. Notably, in the presence of 99% water content, the amphiphile forms spherical aggregated nanoparticles as confirmed from microscopic investigations and dynamic light scattering study. Interestingly, the emission maxima of molecularly dissolved NDI-1 (weak blue fluorescence) red-shifted upon aggregation with increase in water concentration and led to the formation of green-emitting fluorescent organic nanoparticles (FONPs) at 99% water content. These green-emitting FONPs were utilized in cell imaging as well as for efficient transportation of anticancer drug curcumin inside mammalian cells.

In this article, we have designed L-aspartic acidlinked naphthalene diimide (NDI)-based amphiphilic molecules having a benzyl ester group at both the terminals with varying substituents (NAB-1−5). The substituent was judiciously modified from an electron-withdrawing group (EWG) like nitrobenzene to an electron-donating group (EDG), methoxybenzene, and finally to an extended aromatic residue (naphthalene) to regulate the π-electron density at the terminal of NDI derivatives. All of the synthesized NDI derivatives were molecularly dissolved in dimethyl sulfoxide (DMSO), and with an increase in the water content within the DMSO solution, the NDI derivative starts to get selfassembled through J-aggregation at and above 40% water content. Self-assembled spherical organic nanoparticles formed in 99% water in DMSO (f w = 99%) were characterized by microscopic studies. All of the NDI derivatives showed very weak emission in the molecularly dissolved state (DMSO). Aggregation-induced emission (AIE) was observed for the NDI derivatives (except NAB-1) at the self-assembled state through excimer formation. Upon excitation at 350 nm, the emission maxima of these NDI-based AIE luminogens (AIE-gens) (NAB-2−5) get red shifted from 463 to 588 nm upon altering the substitution from EWG to EDG at the donor site. Inclusion of proper donor−acceptor moieties in the molecular backbone of the self-assembling unit can govern the AIE in combination with the intramolecular charge-transfer process. Consequently, the emission color of these AIE-gens (NAB-2−5) gets tuned from cyan blue to faint green to strong green and finally to bright orange. The tunable aggregation-induced multicolor emission was investigated by different spectroscopic techniques. These cytocompatible, multicolor-emitting fluorescent organic nanoparticles were utilized for bioimaging applications.

Hydrophobic end-modulated l-phenylalanine-containing triethylene glycol monomethyl ether tagged neutral hydrogelators (1-4) are developed. Investigations determine the gelators' structure-dependent inclusion of carbon nanomaterials (CNMs) in the self-assembled fibrillar network (SAFIN). The gelators (1, 3, and 4) can immobilize water and aqueous buffer (pH 3-7) with a minimum gelator concentration of 10-15 mg mL(-1). The hydrophobic parts of the gelators are varied from a long chain (C-16) to an extended aromatic pyrenyl moiety, and their abilities to integrate 1 D and 2 D allotropes of carbon (i.e., single-walled carbon nanotubes (SWNTs) and graphene oxide (GO), respectively) within the gel are investigated. Gelator 1, containing a long alkyl chain (C-16), can include SWNTs, whereas the pyrene-containing 4 can include both SWNTs and GO. Gelator 3 fails to incorporate SWNTs or GO owing to its slow rate of gelation and possibly a mismatch between the aggregated structure and CNMs. The involvement of various forces in self-aggregated gelation and physicochemical changes occurring through CNM inclusion are examined by spectroscopic and microscopic techniques. The distinctive pattern of self-assembly of gelators 1 and 4 through J- and H-type aggregation might facilitate the structure-specific CNM inclusion. Inclusion of SWNTs/GO within the hydrogel matrix results in a reinforcement in mechanical stiffness of the composites compared with that of the native hydrogels.

The objective of this feature article is to coalesce our recent advancements on different expressions of tailor-made supramolecular self-assemblies and to explore them as a function of molecular architecture. In the last decade, we have developed a library of elegant and simple functional amphiphilic small molecules, which have very interesting abilities to form diverse manifestations of supramolecular self-assemblies such as micelles, reverse micelles, vesicles, fibers, supramolecular gels, and so on. Each of the expressions of the self-aggregated structures has its individual prominence and finds important applications in the fields of chemistry, physics, biology, and others. In this feature article, the major emphasis is mostly on how to attain precise control over the development of various well-defined supramolecular self-assemblies through the judicious design of low-molecular-weight amphiphiles. By tuning only the functional moieties of the amphiphilic structure, diverse supramolecular architectures can be constructed with task-specific applications. We expect that this article will provide a general and conceptual demonstration of various approaches to the development of different functional supramolecular systems and their prospective applications in numerous domains.

Supramolecular self-assembly of low molecular mass amphiphiles is of topical interest with the urge to achieve precise control over the formation of various self-aggregated structures. Particularly, fabrication of multifarious nanostructures from single molecular backbone would be highly advantageous for task specific applications of the self-aggregates. To this end, the present study reports the solvent triggered evolution of hierarchical self-assembled structures of cholesterol based glucose appended amphiphiles and the pathway of structural transition. The amphiphiles formed bilayered vesicles in water and gels in different organic solvents. In DMSO-water solvent mixture, it showed gradual transition in the morphology of self-aggregates from vesicle-to-fiber and intermediate morphologies depending on the solvent compositions. Microscopic and spectroscopic investigations showed that morphological transformation took place through fusion, elongation and twisting of self-aggregates owing to the reorganization of the amphiphiles (H-type to J-type) in varied solvent polarity. Moreover, sheetlike molecular organization originating from hydrogen bonding and solvophobic interaction played a vital role in the formation of nanoribbons that led to the formation of gel fibril network. This study endows a new strategy to develop solvent induced multistructured self-aggregates from a single molecular scaffold, unraveling the route of forming hierarchical self-assembly.