Assembly of peptide–thiophene conjugates: the influence of peptide content and location

Biomolecule-directed self-assembly of π-conjugated oligomers has attracted great attention in the past decade. In this contribution, two conjugates composed of quaterthiophene and tetrapeptide (Gly-Val-Gly-Val) were synthesised, namely peptide–thiophene–peptide (PTP) and thiophene–peptide–thiophene (TPT), to investigate the influence of peptide content ratio and its location in the molecular structures on the nanostructures and properties of the assemblies. Both conjugates formed organogels consisting of left-handed twisted nanostructures; however, anti-parallel β-sheets were observed in PTP while parallel β-sheets were obtained for TPT, although in both cases oligothiophenes adopted an H-like stacking mode. Obvious solvent-induced supramolecular chirality inversion from the oligothiophene segment was observed for PTP while such phenomenon was not clear for TPT. PTP and TPT gels also showed different stabilities towards temperature increase, as evidenced by variable-temperature circular dichroism study. From the data, it is suggested that the rational design of the location and ratio of peptide plays a key role in constructing materials with determined properties based on peptide–thiophene conjugates.     

A Photo-Responsive Organogel Based on Pyrene-Substituted Acylhydrazone Derivative

A new simple pyrene-substituted acylhydrazone derivative, 4-(3,4-dioctyloxy) phenyl-1-pyrene acylhydrazone (PAH-8), was designed and synthesized. The PAH-8 can form thermo-reversible organogel in DMSO, and shows gelation-induced enhanced fluorescence emission. Xerogel exhibits ribbon-like fibrous aggregates with widths of 0.5-1 μm. The PAH-8 organogel indicates photo-responsive behaviors due to the trans-cis isomerizations of -C=N- bond upon exposure to visible or UV light. Upon visible light irradiation, the partial trans-cis isomerization of the -C=N- bond causes the fiber morphology to disappear, resulting in gel-sol transition, whereas the PAH-8 organogel exhibits few photoisomerizations from trans to cis transition without breakage of the gel state upon UV light irradiation.     

Versatile light‐responsive organogels: Evaluation of their dye releasing and photoinitiation behaviors

Light‐responsive crosslinked structures were prepared by a straightforward quaternization strategy using chloride functional polystyrene copolymers and commercially available Michler's ketone with varying feed ratios. Resulting organogels demonstrated excellent solvent absorption and their swelling characteristics were altered by UV‐light irradiation. According to scanning electron microscope images, UV‐illuminated samples showed an obvious photodecomposition, which enhanced their solvent uptake capacity with increase of UV exposure. Additionally, release behavior of eosin Y as a model compound was determined by UV–vis and fluorescence spectrometers. Achieved photoactive gels were also employed as the reusable heterogeneous initiators for photoinduced free‐radical polymerization of methyl methacrylate. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1275–1282     

Swelling and Network Parameters of 1-Hexadecene-Co-Trimethylolpropane Distearate Monoacrylate Sorbers

Linear and crosslinked copolymers with different compositions of 1-hexadecene and trimethylolpropane distearate monoacrylate monomers were synthesized and evaluated for oil-absorbency application. Different concentrations of ethylene glycol diacrylate (EGDA) and ethylene glycol dimethacrylate (EGDMA) crosslinkers were used. The concentration of both crosslinkers was varied from 0.5% to 2%. Copolymer compositions were determined from ¹H NMR spectroscopy. Monomer reactivity ratios were calculated using Fineman-Ross and Kelen-Tudos techniques at low conversions. The oil absorbency and swelling rate constant were measured and influenced mainly by the degree of crosslinking and the hydrophobicity of copolymer units. The final equilibrium oil content, volume fraction of polymer and swelling capacity were determined at 298 K. The effective crosslinking density V_e, theoretical crosslink density V_t, the average molecular weight between the crosslinks M_c and the polymer-toluene interaction parameter χ were determined from swelling measurements. The efficiencies of EGDA and EGDMA crosslinking agents toward copolymers were determined.     

Organogelators based on the norbornane scaffold

Using the rigid norbornane scaffold, a series of low-molecular-weight organogelators has been synthesised and evaluated. Three separate compounds (16, 19 and 20) were identified as organogelators in three aromatic organic solvents (PhMe, anisole and o-xylene). The formation of fibrillar assemblies at nanometre level was confirmed using atomic force microscopy and transmission electron microscopy.     

Synthesis and characterization of a novel two-component organogelator based on ion-bonded discotic complex

A novel ion-bonded discotic complex was prepared from 2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)triphenylene (HDTP) and 4′-dodecyloxybiphenyl-4-carboxylic acid (DBC) by ionic self-assembly (ISA) route and characterized by Fourier transform infrared (FTIR) spectrum. We found that the complex can self-assemble into stable gels in aromatic hydrocarbons. Nanofibers with diameters of 50–130 nm were observed in the gels by transmission electron micrograph (TEM). The FTIR data in conjunction with UV–vis and fluorescence spectra suggested that the aggregation of the complex into elongated fibers in solution was induced by a directional extended network of hydrogen bonds and π–π interactions. Based on the experiment analysis, we proposed a tentative model of the self-assembly of this two-component gel-phase material.     

Microsphere-to-nanotube transition via in situ sonication triggered in a supramolecular self-assembly system based on triphenylamine derivative

A new gelator 1 containing triphenylamine was designed and synthesized, and formed stable gel in ethyl acetate. The self-assembly process of molecule 1 was thoroughly investigated. The solid microsphere structure formed in gel 1 could be turned into nanotube in the transition process of gel to gel via sonication. At the same time, the intermolecular hydrogen bond of self-assembly system was obviously enhanced under sonication. The XRD and water contact angle experiments results of xerogel 1 before and after sonication showed great difference. The hydrophobicity of xerogel 1 film was obviously decreased with the change of contact angle from 142° to 129° after sonication at 100 W for one minute. From the results, it was possible that the solid microsphere was re-dissolved and further reassembled into nanotube. To our knowledge, it was the first example that the solid sphere structure was changed into nanotube in self-assembly system via sonication.     

Generation of low-molecular-weight organic compounds in water by titania photocatalyst under UV-Vis light radiation

We attempted to develop a new type titania photocatalyst that, when activated, responded in not only the ultraviolet rays region but also visible light radiation region by the new titania photocatalyst with the zirconia and nitrogen simultaneously introduced in the titania lattice. The decomposition performance of the standard organic compound in water by this new type titania photocatalyst nanoparticle was compared with the conventional type under both the ultraviolet ray and visible light radiation conditions. It was suggested that the low-molecular-weight organic compounds were also generated from the organic compound in water by the new type titania photocatalyst activities under the visible light radiation.