Lathe A. Jones

Tetraphenylethene-Based Star Shaped Porphyrins: Synthesis, Self-assembly, and Optical and Photophysical Study

Supramolecular self-assembly and self-organization are simple and convenient ways to design and create controlled assemblies with organic molecules, and they have provoked great interest due to their potential applications in various fields, such as electronics, photonics, and light-energy conversion. Herein, we describe the synthesis of two π-conjugated porphyrin molecules bearing tetraphenylethene moieties with high fluorescence quantum yield. Photophysical and electrochemical studies were conducted to understand the physical and redox properties of these new materials, respectively. Furthermore, these derivatives were used to investigate self-assembly via the solvophobic effect. The self-assembled aggregation was performed in nonpolar and polar organic solvents and forms nanospheres and ring-like nanostructures, respectively. The solution based aggregation was studied by means of UV-vis absorption, emission, XRD, and DLS analyses. Self-assembled ring-shape structures were visualized by SEM and TEM imaging. This ring-shape morphology of nanosized macromolecules might be a good candidate for the creation of artificial light-harvesting nanodevices.

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.

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.

pH-Dependent self-assembly of water-soluble sulfonate-tetraphenylethylene with aggregation-induced emission

Abstract The fabrication of well-defined nanostructures with luminescent properties in the solid or aggregated state is of intense interest due to their applications in nano- and biotechnology. We report the synthesis of water-soluble tetraphenylethylene bearing four sulfonate groups as a sodium salt (Su-TPE), and investigations concerning its AIE characteristics by the addition of organic solvent into the aqueous solution, which is the reverse procedure to conventional AIE-active TPE derivatives. The resultant compound is weakly emissive in pure water, however, emits strongly upon addition of THF solvent (with THF fraction > 60%). The emission properties and the morphologies of the aggregates were greatly dependent upon the solution pH. Su-TPE self-assembled into variety of structures in water/THF mixture with pH control, for the first time. Well-defined uniform nanorods with a width of about 200 nm and a length of up to 10 μm were obtained at solution pH of 1. The Su-TPE showed very good mechanochromic properties were observed during the process of grounding and fuming.

Graphene-Supported Spinel CuFe2O4 Composites: Novel Adsorbents for Arsenic Removal in Aqueous Media

A graphene nanoplate-supported spinel CuFe2O4 composite (GNPs/CuFe2O4) was successfully synthesized by using a facile thermal decomposition route. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Electron Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the prepared composite. The arsenic adsorption behavior of the GNPs/CuFe2O4 composite was investigated by carrying out batch experiments. Both the Langmuir and Freundlich models were employed to describe the adsorption isotherm, where the sorption kinetics of arsenic adsorption by the composite were found to be pseudo-second order. The selectivity of the adsorbent toward arsenic over common metal ions in water was also demonstrated. Furthermore, the reusability and regeneration of the adsorbent were investigated by an assembled column filter test. The GNPs/CuFe2O4 composite exhibited significant, fast adsorption of arsenic over a wide range of solution pHs with exceptional durability, selectivity, and recyclability, which could make this composite a very promising candidate for effective removal of arsenic from aqueous solution. The highly sensitive adsorption of the material toward arsenic could be potentially employed for arsenic sensing.

N-Methylation of macrocyclic hexaaminecobalt(III) complexes

Reaction between formaldehyde and the pendant arm macrocyclic complex (trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)cobalt(III) [CoL1]3+ yielded the diimine derivative trans-6,13-dimethyl-6,13-bis(methyleneamino)-1,4,8,11-tetraazacyclotetradecane (L3) as its cobalt(III) complex. Reduction of the imines has been achieved with NaBH4 and the meso and rac cobalt(III) complexes of trans-6,13-dimethyl-6,13-bis(methylamino)-1,4,8,11-tetraazacyclotetradecane (L5) have been prepared. Crystal structures of the macrocyclic complexes [CoL1][ClO4]3, [CoL3][ClO4]3 and meso-[CoL5][ClO4]3·2H2O were determined and some unusual structural, spectroscopic and electrochemical variations observed going from the parent hexaamine [CoL1]3+ to [CoL3]3+ (diimine) and ultimately to [CoL5]3+ (bis-N-methylated hexaamine).

The sensitivity of donor – acceptor charge transfer to molecular geometry in DAN – NDI based supramolecular flower-like self-assemblies

A charge-transfer (CT) complex self-assembled from an electron acceptor (NDI-EA: naphthalene diimide with appended diamine) and an electron donor (DAN: phosphonic acid-appended dialkoxynapthalene) in aqueous medium. The aromatic core of the NDI and the structure of DAN1 were designed to optimize the dispersive interactions (π-π and van der Waals interactions) in the DAN1–NDI-EA self-assembly, while the amino groups of NDI also interact with the phosphonic acid of DAN1 via electrostatic forces. This arrangement prevented crystallization and favored the directional growth of 3D flower nanostructures. This molecular geometry that is necessary for charge transfer to occur was further evidenced by using a mismatching DAN2 structure. The flower-shaped assembly was visualized by scanning electron and transmission electron microscopy. The formation of the CT complex was determined by UV-vis and cyclic voltammetry and the photoinduced electron transfer to produce the radical ion pair was examined by femtosecond laser transient absorption spectroscopic measurements.

Tetraphenylethene Derivatives: A Promising Class of AIE Luminogens—Synthesis, Properties, and Applications

To overcome the aggregation-caused quenching (ACQ) effect in the aggregated state new photoluminescent materials are required. Among planar aromatic molecules, naphthalene, anthracene, phenanthrene, fluoranthene, fluorine, pyrene, perylene, carbazole, triphenylamine, fluorescein, phenothiazine, cyanine, diketopyrrolopyrrole, perylene diimide, naphthalene diimide, and porphyrins have all been used for a range of important applications; however, they suffer from the ACQ effect. In 2001, a new phenomenon was described—so called aggregation-induced-emission (AIE), where typically small organic molecules, which are weak emitters when fully dissolved in solvents such as toluene, THF, and chloroform, become highly luminescent in the supramolecular aggregated state, as well as in solid films. Among the AIE-active luminophores developed, tetraphenylethene (TPE) derivatives have attracted significant attention due to their weak intermolecular interactions and excellent solubility in organic solvents, with a structure that is susceptible to functionalization on the planar phenyl groups, which may lead to AIE activity. In this chapter, we described in detail the synthesis, properties, and applications of AIE-active TPE derivatives.

Fabrication of diverse nano-architectures through the self-assembly of a naphthalene diimide derivative bearing four carbamates

A naphthalene diimide (NDI) derivative bearing four carbamate groups (coded as: W2) was synthesised using a multistep strategy, and utilizing solvophobic effects, the self-assembly of this molecule was studied using solvent mixtures. Self-assembly led to a variety of controllable morphologies of supramolecular structures on both the micro and nanoscale. Nanobelts, nanospheres, nano-corals, microflowers and nanograss-like morphologies were obtained in DMF, MCH, CHCl3, THF, water and MeOH solvent mixtures. UV-vis absorption, fluorescence emission spectroscopy, FT-IR and XRD gave insight into the mode of aggregation of W2 in various solvents. The polarity of the solvent mixtures used directed the self-organisation of W2 by driving the π–π stacking interaction between NDI cores, and the H-bonding between the carbamate moieties. Our studies show that the solvent polarity guides the self-assembly process during solvent evaporation leading to the formation of supramolecular nano- and microstructures under ambient conditions.

Modulating interleaved ZnO assembly with CuO nanoleaves for multifunctional performance: Perdurable CO2 gas sensor and visible light catalyst

Herein, we report the preparation of well characterized hierarchical CuO/ZnO heterostructures and demonstrate the versatility of this composite as a CO2 gas sensor and a visible light catalyst for methylene blue (MB) degradation. 3D hierarchical ZnO spheres were decorated with CuO nanoleaves to form the interleaved p-CuO/n-ZnO hetero-surfaces. Subsequently, silver (Ag) functionalized composites were tested for their sensitivity and selectivity towards CO2 gas as a core application. The nanostructured Ag@CuO/ZnO composite demonstrated an improved sensor response of 34% at 320 °C with response/recovery times of 76 and 265 s compared to the CuO/ZnO composite and control samples. Additionally, the Ag@CuO/ZnO composite displayed excellent recovery (97%), repeatability (96%), accuracy (86%), and lower baseline drifts with a co-efficient of variation (COV) of 4.5% measured over an extended period of 40 days towards 1000 ppm CO2 gas for 10 individually tested sensors. In a parallel application as a photocatalyst, the CuO/ZnO composite was observed to degrade 98% methylene blue in 180 min with the first order rate constant (κapp) found to be 6- and 75-fold greater, respectively, when compared to the ZnO and CuO samples under visible light irradiation. The gas sensing mechanism substantiated from in situ diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) confirmed the formation of copper carbonate in the presence of CO2. Interleaved assembly ensured the high mobility of electron–hole pairs with concerted efforts from a high effective surface area, multi-interleaved p/n nano-interfaces and the catalytic role of Ag. The confluence of these factors resulted in an improved CO2 sensor response and photocatalytic performance.