Carbazole-Derived Amphiphile-Based AIEgen: Detection of Nitro-Antibiotics and Water-Repelling Surfaces

We have designed three amphiphilic substituted urea compounds with varying chain lengths. These hydrophobic amphiphiles displayed aggregation-induced emission on solvent switching. The aggregates were further detailed by microscopy. The hydrophobicity of these AIEgens has been used to create water-repelling fluorescent surfaces. The AIEgen via the photoinduced electron transfer-mediated mechanism has been applied in the detection of nitroantibiotics. The analytical utility of the AIEgen is being demonstrated concerning the detection of nitroantibiotics in biofluids.

Chiral Naphthalenediimides with High-Efficiency Fluorescence and Circularly Polarized Luminescence in the Solid State for the Application in Organic Optoelectronics

Naphthalenediimides (NDIs) have been extensively studied due to their tunable luminescent properties. However, generally, the monomers or aggregates of non-core substituted NDIs exhibit low fluorescence quantum yields (Φ_FL <10 %) in the solid state, which limit their applications as light-emitting materials and render their chiral species unsuitable for circularly polarized luminescence (CPL). Herein, a series of non-core substituted chiral NDIs that exhibit high luminous efficiencies (Φ_FL up to 56.8 % for racemate and 36.5 % for enantiomer) and a strong CPL behavior in the solid state is reported. These significant improvements are attributed to the unique molecular conformation of the chiral NDIs and the formation of distinctive discrete dimers. The structures of the NDIs were significantly simpler and more accessible than those of other NDIs. The findings evidence that non-core substituted NDIs can exhibit strong fluorescence in the solid state and provide a new pathway to improve photophysical properties of NDIs.

Mimicking the Natural World with Nanoarchitectonics for Self-Assembled Superstructures

Scientists are often inspired by nature, where naturally occurring morphologies, such as those that resemble animals and plants, can be created in the lab. In this review, we have provided an overview on complex superstructures of animals, plants and some similar shapes from the natural world. We begin this review with a discussion about the formation of various animal-like shapes from small organic molecules and polymers, and then move onto plants and other selected shapes. Literature surveys reveal that most of the polymers studied tend to form micellar structures, with some exceptions. Nevertheless, small organic molecules tend to form not only micellar structures but also other animal shapes such as worms and caterpillars. These superstructures tend to have high surface areas and variable surface morphology, making them very useful material for applications in various field such as catalysis, solar cells, and biomedicine, amongst others.

Tuning of energy levels, transport properties and device performance of naphthalenediimide derivatives by introduction of Michael addition reaction

NDI derivatives have been synthesized via Michael addition reaction with uplifted HOMO–LUMO energy levels and strong CT interaction in MA products generally not achieved by simple imide-N substitutions.

Direct Visualization of Chiral Amplification of Chiral Aggregation Induced Emission Molecules in Nematic Liquid Crystals

Chiral amplification in liquid crystals (LCs) is a well-known strategy. However, current knowledge about the underlying mechanism was still lacking; in particular, how it was realized at the nano scale still remained to be revealed. Here, we provide systematical exploration of chiral amplification of chiral aggregation induced emission (AIE) molecules in LCs from direct visualization of their co-assemblies at the nano scale to theoretical calculation of the molecular packing modes on a single molecular level. Using AFM imaging,we directly visualized the co-assembly formed by chiral AIE molecules/LCs at the nano scale: the chiral AIE molecules self-assembled into helical fibers to serve as the helical template for LCs to bind, while the LCs helically bound to the helical fibers to form the co-assembly, giving the morphology of pearled necklaces or thick rods. Theoretical calculation suggested that chiral AIE molecules were packed into left-handed helical fibers with a large volume of empty space between neighboring molecules, which provided the binding cites for LCs. Structural analysis showed that the π-π stacking between aromatic groups from LCs and TPE groups and the σ-π hyperconjugation between LC aromatic groups and cholesterol aliphatic groups play an important role in stabilizing the binding of LCs in the confined space on the surface of the helical assemblies.

Lipase sensing by naphthalene diimide based fluorescent organic nanoparticles: a solvent induced manifestation of self-assembly

The precise control of supramolecular self-assembly is gaining utmost interest for the demanding applications of manifested nano-architecture across the scientific domain. This study delineates the morphological transformation of naphthalene diimide (NDI) derived amphiphiles with varying water content in dimethyl sulfoxide (DMSO) and the selective sensing of lipase using its aggregation-induced emission (AIE) properties. To this end, NDI-based, benzyl alcohol protected alkyl chain (C1, C5, and C10) linked amphiphilic molecules (NDI-1,2,3) were synthesized. Among the synthesized amphiphiles, benzyl ester linked C5 tailored naphthalene diimide (NDI-2) exhibited AIE with an emission maximum at 490 nm in a DMSO-water binary solvent system from fw = 30% and above water content. The fibrous morphology of NDI-2 at fw = 30% got gradually transformed to spherical aggregated particles along with steady increment in the emission intensity upon increasing the amount of water in DMSO. At fw = 99% water in DMSO, complete transformation to fluorescent organic nanoparticles (FONPs) was observed. Microscopic and spectroscopic techniques demonstrated the solvent driven morphological transformation and the AIE property of NDI-2. Moreover, this AIE of NDI-2 FONPs was employed in the selective turn-off sensing of lipase against many other enzymes including esterase, through hydrolysis of a benzyl ester linkage with a limit of detection 10.0 ± 0.8 μg L-1. The NDI-2 FONP also exhibited its lipase sensing efficiency in vitro using a human serum sample.

Supramolecular fibrous gels with helical pitch tunable by polarity of alcohol solvents

A sugar-based, low-molecular-weight gelator 16AG, can gelatinize primary alcohols by forming supramolecular fibers. We obtained non-helical, tape-like fibers in methanol and ethanol but helical fibers in alcohols with at least three carbons. The pitch of the helical fibers became shorter with increasing carbon number.

Chloride-promoted self-assembly and photoluminescence of naphthalene diimides tethered to polyacetylene

A novel polyacetylene containing naphthalene diimides (NDIs) in the side chains is sensitive to Cl̄ by structural transformation of the polymer backbone and the NDI aggregates along with turning fluorescence emission on.

Chirality reversal, enhancement and transfer by pH-adjusted surfactant assembly

The controllable chirality reversal and enhancement at a supramolecular level is crucial for the synthesis and applications of circularly active materials, which has been achieved by a pH-adjusted amphiphilic chiral surfactant assembly approach, and reveals the relationship between the chirality behavior and its assembly morphology in a non-covalent interaction regime and its ability to transfer chirality from chiral molecules to achiral ones under appropriate conditions.

Photoluminescence Quenching of a Novel Electroconductive Poly(propylene thiophenoimine)-co-Poly(ethylenedioxy thiophene) Star Copolymer

A generation 1 poly(propylene thiophenoimine)-co-poly(ethylenedioxy thiophene) (G1PPT-co-PEDOT) star copolymer, which exhibits a strong optical absorption over a broad range in the ultraviolet–visible (UV-Vis) region and with good electro/conductive properties, was chemically prepared for the first time. Synthesis of the star copolymer, G1PPT-co-PEDOT was confirmed by spectroscopic studies. Indeed, the disappearance of the very high intensity bands, C–H bending at α-position (687 cm⁻¹), and C=N stretching (1620 cm⁻¹) in the Fourier transform infrared spectroscopy (FTIR) of G1PPT-co-PEDOT, which were initially present in the spectrum of the thiolated starting material, G1PPT, confirmed copolymerization. Furthermore, a large bathochromic shift in the onset wavelength of the UV-Vis absorbance spectra from 367 nm in G1PPT to 674 nm in G1PPT-co-PEDOT further attests of successful copolymerization. The electrochemical analysis of G1PPT-co-PEDOT achieved a highest occupied molecular orbital (HOMO) energy level value of 5.3 eV, which is reminiscent of the value for an ideal electron-donor material. Photoluminescence quenching of up to 82% was observed in solution blends of the G1PPT-co-PEDOT star copolymer and N,N′-diisopropyl naphthalene diimide (NDI). This demonstrates the occurrence of photoinduced intermolecular charge transfer (PICT) from the electron-donating G1PPT-co-PEDOT to the electron accepting NDI, a good property, beneficial for optoelectronic and photovoltaic applications.

Azine based AIEgens with multi-stimuli response towards picric acid

Selective detection of picric acid using AIEgens via fluorescence enhancement and quenching in the monomer and aggregated from respectively.

Al3+ triggered aggregation induced emission of an anthracence based azine derivative in SDS medium

Single crystal X-ray structurally characterized anthracene appended unsymmetrical azine derivative, viz. 4-(anthracen-9-ylmethylene-hydrazonomethyl)-2-methoxy-phenol (L5) shows Al³⁺ assisted aggregation induced emission in SDS medium.