Duong Duc La

Aggregation-induced emission of a star-shape luminogen based on cyclohexanehexone substituted with AIE active tetraphenylethene functionality

We describe a rigid star-shaped luminogen (HTCA) of cyclohexanehexone bearing six tetraphenylethene moieties, which exhibited strong aggregation-induced emission (AIE) characteristics. The twisting amplitude and steric hindrance of the TPE units were found to play a crucial role in their aggregated nano- to micro-structures. Interestingly, HTCA exhibits reversible piezofluorochromic behaviour through grinding which is reversed by treatment with solvents resulting in a cycle that can be repeated several times.

Solvophobic control aggregation-induced emission of tetraphenylethene-substituted naphthalene diimide via intramolecular charge transfer

Two new tetraphenylethene-core-substituted naphthalene diimides (TPE-cNDI) were synthesized through linking one and two TPE, where TPE acts both as an electron-donor for ICT and also display the characteristic of AIE effect, i.e. is non-emissive in solution but has enhanced red-emission in both the aggregated and the solid state with high quantum efficiency. Furthermore, both the derivatives self-assembled into variety of nano- to micro-structures via solvophobic control.

Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

Nanostructured charge transfer complex of CuTCNQF4 for efficient photo-removal of hexavalent chromium

The high toxicity of hexavalent chromium warrants the development of efficient catalysts that could reduce chromium into relatively non-toxic trivalent chromium species. Pristine charge transfer complexes of the MTCNQ family (M = Cu or Ag; TCNQ = 7,7,8,8-tetracyanoquinodimethane) have previously failed to catalyse the reduction of Cr6+ to Cr3+. We demonstrate that due to the outstanding electron transfer properties of one of the fluorinated derivatives of MTCNQ, i.e., 7,7,8,8-tetracyano-2,3,5,6-tetraflouroquinodimethane (CuTCNQF4), it is able to catalyse the reduction of hexavalent chromium in aqueous solution at room temperature. We further demonstrate that the semiconducting nature of these organic charge transfer complexes allows CuTCNQF4 to act as an outstanding material for the reductive photo-removal of hexavalent chromium under UV photoexcitation conditions. Such materials are likely to play an important role in photoactive electron transfer reactions.

Construction of a highly efficient near-IR solid emitter based on naphthalene diimide with AIE-active tetraphenylethene periphery

Tetraphenylethene-core-substituted naphthalene diimide (TTPEcNDI) shows distinct near-IR optical properties and aggregation induced emission phenomena. Furthermore, TTPEcNDI aggregated into a variety of supramolecular assembled structures via solvophobic control such as hollow spheres, bundles of fibrils and leaf-like structures with controlled dimensions. The present study can be applied to more elaborate supramolecular structures for the development of near-IR solid emitter luminescent nanomaterials for electronic applications.

Effect of Amide Hydrogen Bonding Interaction on Supramolecular Self-Assembly of Naphthalene Diimide Amphiphiles with Aggregation Induced Emission

Abstract In the present work, two new naphthalene diimide (NDI) amphiphiles, NDI‐N and NDI‐NA, were successfully synthesized and employed to investigate their self‐assembly and optical properties. For NDI‐NA, which contains an amide group, aggregation‐induced emission enhancement (AIEE) was demonstrated in the presence of various ratios of methylcyclohexane (MCH) in chloroform, which led to the visual color changes. This new amide‐containing NDI‐NA amphiphile formed nanobelt structures in chloroform/MCH (10:90, v/v) and microcup‐like morphologies in chloroform/MCH (5:95, v/v). The closure of these microcups led to the formation of vesicles and microcapsules. The structural morphologies gained from the solvophobic control of NDI‐NA were confirmed by various complementary techniques such as infrared spectroscopy, X‐ray diffraction, and scanning and transmission electron microscopy. In the absence of the amide moiety in NDI‐N, no self‐assembly was observed, indicating the fundamental role of H‐bonding in the self‐association process.

Tetraphenylethylene-Based AIE-Active Probes for Sensing Applications

This Review provides a comprehensive analysis of recent development in the field of aggregation-induced emission (AIE)-active tetraphenylethylene (TPE) luminophores and their applications in biomolecular science. It begins with a discussion of the diverse range of structural motifs that have found particular applications in sensing, and demonstrates that TPE structures and their derivatives have been used for a diverse range of analytes such as such as H+, anions, cations, heavy metals, organic volatiles, and toxic gases. Advances are discussed in depth where TPE is utilized as a mechanoluminescent material in bioinspired receptor units with specificity for analytes for such as glucose or RNA. The rapid advances in sensor research make this summary of recent developments in AIE-active TPE luminophores timely, in order to disseminate the advantages of these materials for sensing of analytes in solution, as well as the importance of solid and aggregated states in controlling sensing behavior.

Chiral Assembly of AIE-Active Achiral Molecules: An Odd Effect in Self-Assembly†

The induction of chirality in supramolecular structures through hierarchical self-assembly of achiral compounds and the control of their handedness are closely related to the evolution of life and the chiral amplification found in nature. Herein, it is shown that the combination of achiral tetraphenylethylene, an aggregation-induced emission (AIE)-active luminophore bearing four alkyl chains with an odd or even number of carbon atoms via an amide linkage in the molecular structure allows the induction and control of supramolecular chirality in well-defined helical superstructures by controlling the solvent composition and polarity. In particular, right-handed supramolecular structures were produced for an even number of carbon atoms in the alkyl chains, whereas an odd number led to the assembly of left-handed superstructures. The twisted superstructure was visualised by SEM, and circular dichroism was used to observe chirality in the assembly. These controlled assemblies of AIE-active molecules are of potential practical value, such as templates for helical crystallisation, catalysis and formation of chiral mechanochromic luminescent superstructures.

Cyanopyridone flanked the tetraphenylethylene to generate an efficient, three-dimensional small molecule non-fullerene electron acceptor

Herein we report the design, synthesis and characterization of a novel material, (5Z,5′Z,5′′Z,5′′′E)-5,5′,5′′,5′′′-(((ethene-1,1,2,2-tetrayltetrakis(benzene-4,1-diyl))tetrakis(thiophene-5,2-diyl))tetrakis(methanylylidene))tetrakis(4-methyl-1-octyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile) (TPE-CP4), which was generated using a combination of tetraphenylethylene and cyanopyridone functionalities. The tetraphenylethylene unit was terminally functionalized with cyanopyridone in order to generate a three-dimensional molecular architecture. The new material TPE-CP4 was produced via a Knoevenagel condensation reaction and was found to be highly soluble in a variety of common organic solvents, such as chloroform and o-dichlorobenzene. TPE-CP4 exhibited promising optoelectronic properties and energy levels complementing those of the conventional donor polymers poly(3-hexylthiophene) [P3HT] and Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) [PTB7]. Due to its optoelectronic properties, solubility and good film forming capability, TPE-CP4 was incorporated as an n-type semiconducting component along with the commercially available P3HT and PTB7 as the p-type semiconductors in BHJ photovoltaic devices. TPE-CP4 performed very well with both of the donor polymers and afforded 6.02% and 6.72% power conversion efficiencies with P3HT and PTB7, respectively. Not only is TPE-CP4 the first reported example combining tetraphenylethylene and cyanopyridone structural units, but the device performance indicates that it is an efficient non-fullerene acceptor.

Fabrication of a GNP/Fe–Mg Binary Oxide Composite for Effective Removal of Arsenic from Aqueous Solution

Graphene nanoplates (GNPs) can be used as a platform for homogeneous distribution of adsorbent nanoparticles to improve electron exchange and ion transport for heavy-metal adsorption. In this study, we report a facile thermal decomposition route to fabricate a graphene-supported Fe–Mg oxide composite. The prepared composite was characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. Batch experiments were carried out to evaluate the arsenic adsorption behavior of the GNP/Fe–Mg oxide composite. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, in which the sorption kinetics of the arsenic adsorption process by the composite was found to be pseudo-second-order. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled-column filter test. The GNP/Fe–Mg oxide composite exhibited significant fast adsorption of arsenic over a wide range of solution pHs, with exceptional durability and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solutions.