Xinhua Cao

Strong Blue Emissive Supramolecular Self-Assembly System Based on Naphthalimide Derivatives and Its Ability of Detection and Removal of 2,4,6-Trinitrophenol

Two simple and novel gelators (G-P with pyridine and G-B with benzene) with different C-4 substitution groups on naphthalimide derivatives have been designed and characterized. Two gelators could form organogels in some solvents or mixed solvents. The self-assembly processes of G-P in a mixed solvent of acetonitrile/H2O (1/1, v/v) and G-B in acetonitrile were studied by means of electron microscopy and spectroscopy. The organogel of G-P in the mixed solvent of acetonitrile/H2O (1/1, v/v) formed an intertwined fiber network, and its emission spectrum had an obvious blue shift compared with that of solution. By contrast, the organogel of G-B in acetonitrile formed a straight fiber, and its emission had an obvious red shift compared with that of solution. G-P and G-B were employed in detecting nitroaromatic compounds because of their electron-rich property. G-P is more sensitive and selective toward 2,4,6-trinitrophenol (TNP) compared with G-B. The sensing mechanisms were investigated by 1H NMR spectroscopic experiments and theoretical calculations. From these experimental results, it is proposed that electron transfer occurs from the electron-rich G-P molecule to the electron-deficient TNP because of the possibility of complex formation between G-P and TNP. The G-P molecule could detect TNP in water, organic solvent media, as well as using test strips. It is worth mentioning that the organogel G-P can not only detect TNP but also remove TNP from the solution into the organogel system.

Steric-Structure-Dependent Gel Formation, Hierarchical Structures, Rheological Behavior, and Surface Wettability.

A series of bicholesteryl-based gelators with different central linker atoms C, N, and O (abbreviated to GC, GN, and GO, respectively) have been designed and synthesized. The self-assembly processes of these gelators were investigated by using gelation tests, field-emission scanning electron microscopy, field-emission transmission electron microscopy, UV/Vis absorption, IR spectroscopy, X-ray diffraction, rheology, and contact-angle experiments. The gelation ability, self-assembly morphology, rheological, and surface-wettability properties of these gelators strongly depend on the central linker atom of the gelator molecule. Specifically, GC and GN can form gels in three different solvents, whereas GO can only form a gel in N,N-dimethylformamide (DMF). Morphologies from nanofibers and nanosheets to nanospheres and nanotubes can be obtained with different central atoms. Gels of GC, GN, and GO formed in the same solvent (DMF) have different tolerances to external forces. All xerogels gave a hydrophobic surface with contact angles that ranged from 121 to 152°. Quantum-chemical calculations indicate that the GC, GN, and GO molecules have very different steric structures. The results demonstrate that the central linker atom can efficiently modulate the molecular steric structure and thus regulate the supramolecular self-assembly process and properties of gelators.

Superhydrophobic surface formation and modulation in a biphenyltetracarboxylic dianhydride derivative self-assembly system via changing alkyl chain lengths

A series of organogelators (C4, C6, C12 and C18) based on biphenyltetracarboxylic dianhydride derivative were designed and synthesized. The organogels could be obtained via self-assembly of the biphenyltetracarboxylic dianhydride derivatives in some frequently-used solvents. The organogels were thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-vis and fluorescence spectra, contact angle. Interestingly, superhydrophobic surface was formed via the self-assembly of compound C12 in petroleum ether and exhibited the lotus-effect. The surface wettability could be modulated via changing alkyl chain lengths. The π–π stacking and van der Waals force were possible the main driving forces for gel formation. This gel system held promise for soft materials application in upscale superhydrophobic surface materials.

Organogel of fluorescein-based derivative formation in the selected pH value

In this work, film structure was obtained by self-assembly of fluorescein derivative via sol–gel process. The self-assembly structure and the formation mechanism had been studied and certified by scanning electron microscopy, IR, UV–vis, fluorescence and X-ray diffraction experiment data. The UV–vis absorption and emission spectra of the compound 1 were changed with the change of the pH value in the solution state. This gelator had certain selectivity for pH value and formed gels.

New cholesterol-based gelator with orotate unit

A new cholesterol-based gelator with orotate unit (cholesterol orotate) was synthesised. The morphology and structure of the gels were investigated by scanning electron microscopy and powder X-ray diffractions. It is observed that the addition of melamine modulated the supramolecular self-assembly and aggregation mode, which originated from the intermolecular non-covalent interactions, as revealed by FT-IR and UV–vis absorption spectra.

Regulation gel formation, hierarchical structures and surface wettability via isomeride effect in supramolecular organogel system

A new serial of gelators with two cholesteryl groups based on o-phenylenediamine, m-phenylenediamine and p-phenylenediamine were synthesized, and their organogelation ability was evaluated. We found that G-o could form gels in DMF, DMSO and ethyl acetate, G-m and G-p could only gel DMF and 1,4-dioxane. The organogels were thoroughly characterized using various microscopic techniques including field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Vis spectrum, FT-IR spectrum and contact angle. The gelation ability, morphology, self-assembly mode and materials surface wettability all could be tuned via isomeride effect in self-assembly system. Interestingly, superhydrophobic surface was formed via the self-assembly of compound G-p in 1,4-dioxane and exhibited very high adsorption capacity for water. This gel system provided new method for modulation self-assembly process in supramolecular field.

Electrochemical Determination of Glucose in Human Serum Utilizing a Novel Nanocomposite Composed of Copper Nanoparticles in a Hollow Carbon Shell

A novel nanocomposite composed of copper nanoparticles encapsulated in a hollow carbon shell was prepared. The thin, porous carbon shell ensured efficient mass and electron transport and provided a confined environment for electrochemical reactions. The Cu@C nanocomposite exhibited favorable electrocatalytic activity toward glucose and superior electrochemical sensing performance toward glucose, with a low limit of detection (1 µM) and a wide linear dynamic range (0.0–6.1 mM). Good selectivity, reproducibility, and stability were obtained. The application of the sensor for the determination of glucose in human serum demonstrated its use for practical analysis.

Organogel formation based on bis-urea derivative

In this work, a new gelator containing urea group was synthesised which had excellent gelation ability and could form organogel in 12 frequently used solvents. Varisized fibre structures were obtained by self-assembly via sol-gel process. The self-assembly structure and the formation mechanism had been studied and certified by scanning electron microscopy, UV–vis, IR and XRD experiment data. The ‘H-aggregate’ self-assembly mode was adopted in organogel system. H-bonding and π–π stacking were the main driving force for the organogel formation. The self-assembly structures could be adjusted by the solvents.

Formation of hydrophobic surface using a bis-urea derived organogel

A bis-urea derived gelator 1 was synthesised with a high yield via a simple organic reaction. The gelator could form organogel in four kinds of solvents. The organogels obtained from four kinds of solvents were systematically investigated by FESEM, UV–Vis, PL, IR, XRD and water contact angle experiments. It was interesting that the self-assembly process of gelator 1 could be tuned by solvents. The film structure and fibre were formed in different solvents. At the same time, the different morphologies all displayed hydrophobicity. Especially, the contact angle of the fibre obtained from organogel in DMF was up to 147°. This research would provide a good pattern for preparation of a special hydrophobic surface through supramolecular self-assembly.