Geometric Change of a Thiacalix[4]arene Supramolecular Gel with Volatile Gases and Its Chromogenic Detection for Rapid Analysis

New Class of Supramolecular Bowl-Shaped Columnar Mesogens Derived from Thiacalix[4]arene Exhibiting Gelation and Organic Light-Emitting Diodes Applications

A new class of blue light-emitting bowl-shaped mesogens with the thiacalix[4]arene core appended with 1,3,4-thiadiazole derivatives having peripheral alkoxy side chains have been synthesized and well characterized. The liquid crystalline behavior of present synthesized derivatives was examined by optical polarizing microscopy, differential scanning calorimetry, and X-ray diffraction studies. It was observed that these thiacalix[4]arene derivatives were capable of stabilizing the observed Col_h phase with a higher temperature range. The cone-shaped thiacalix[4]arene-based liquid crystals with peripheral alkoxy side chains able to pack into the columns with enriched intermolecular interactions and thermal behavior. All derivatives showed blue luminescence in solution, solid thin-film, and gelation state. The hexagonal columnar phase and emissive nature of thiadiazole-based thiacalixarene compounds having xerogel behavior make them favorable in the application of emissive electronic display devices. The electrochemical properties of these thiacalixarene-based compounds demonstrate the effect of alkyl side chain on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels and also exhibited lower electron band gaps. The electroluminescence behavior of the compound 10c was examined as emissive layers in the fabrication of organic light-emitting diodes.

A temperature-responsive supramolecular hydrogel: preparation, gel-gel transition and molecular aggregation

In this study, a novel supramolecular hydrogel, abbreviated as AGC16/NTS, was designed and constructed by the molecular self-assembly of a cationic gemini surfactant, 1,3-bis(N,N-dimethyl-N-cetylammonium)-2-propylacrylatedibromide (AGC16), and an anionic aromatic gelator, trisodium 1,3,6-naphthalenetrisulfonate (NTS). The AGC16/NTS hydrogel was able to form in a mass ratio range of AGC16 and NTS from 20 : 1 to 10 : 1. It was interestingly found that AGC16/NTS exhibited two phase transitions (gel-to-gel and gel-to-sol) observed by visual and rheological measurements during the heating process, which is rarely reported in the previous literature reports of hydrogels prepared using low molecular weight gelators. Cryogenic scanning electron microscopy (cryo-SEM), fluorescence emission spectroscopy and X-ray diffraction (XRD) were used to investigate the temperature-responsive properties and molecular self-assembly mechanism of the hydrogel AGC16/NTS. During the gel-to-gel transition process, the temperature-responsive changes in the visual appearance of AGC16/NTS (turbid to transparent) were clearly observed. Compared with the transparent gel, the turbid gel possesses higher mechanical strength and a much more compact network mophology due to stronger intermolecular hydrophobic association beetween gelators. The molecular self-assembly modes for the two different hydrogel states (turbid and transparent gel) were proposed, helping to further understand the hydrogel transition mechanisms at a molecular level.

Elastomeric PDMS Planoconvex Lenses Fabricated by a Confined Sessile Drop Technique

The ubiquity of high quality smartphones at affordable prices not only accelerated the social penetration in the global population but also promoted nontraditional usage of smartphones as point-of-care medical diagnostic devices, sensors, and portable digital microscopes. This paper reveals a simple, rapid, cost-effective, and template-free technique for mass-scale production of an elastomeric PDMS (ePDMS) planoconvex lens capable of converting a smartphone into a portable digital microscope. By taking advantage of the resistance to spreading of liquid by a sharp edge, highly stable spherical cap of viscous liquid PDMS (lPDMS) on a smooth PMMA circular disk was fabricated. The axisymmetric spreading of lPDMS under the gravitational force and interfacial tension force enable the formation of spherical cap with a certain radius of curvature. A thermal treatment at 80 °C for 30 min cured the spherical cap lPDMS into a bubble-free ePDMS planoconvex lens. Lenses with focal lengths of 55.2-3.4 mm could be reproducibly fabricated by adjusting the volume of dispensed lPDMSs and diameter of PMMA disks. High-resolution panoramic microscope images without a distortion of small cylindrical object could be constructed on-the-fly using the imbedded smartphone app. Applications of the smartphone digital microscope equipped with an ePDMS planoconvex lens for imaging of micro printings, gun shot residues, cylindrical objects, and bullet toolmarks were explored.

Calix[4]arene-based low molecular mass gelators to form gels in organoalkoxysilanes

Organoalkoxysilanes-based molecular gels for melting-free deposition molding, potential smart materials for 3D printing.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

Structural Diversity and Fluorescence Regulation of Three ZnII Coordination Polymers Assembled from Mixed Ligands Tectons

By adopting a mixed-ligand strategy, three ZnII coordination polymers were prepared by hydrothermal reactions of zinc(ii) acetate with flexible 1,2-phenylenediacetic acid (H2phda) combining with three nitrogen-rich tectons namely, [Zn2(phda)2(bpo)2]n·2H2O (1), [Zn(phda)(pytz)]n (2), and [Zn(phda)(bib)]n·H2O (3) (where bpo = 2,5-bis(4-pyridyl)-1,3,4-oxadiazole, pytz = 3,5-di(4-pyridyl)-1,2,4-triazole, and bib = 1,4-bis(imidazol-1-yl)benzene). The single-crystal X-ray diffraction patterns reveal that the three compounds contain metal(ii)-carboxylate chains further extended by such nitrogen-rich co-ligands to afford a vast diversity of structures from two-dimensional (2D) stepwise grids (1), 2D double layers (2), to three-dimensional (3D)→3D 4-fold interpenetrating diamondoid networks. Furthermore, the structural differences in these complexes are primarily affected by the introduction of N-donor ancillary co-ligands so that their solid-state photoluminescence properties exhibit various emission spectra. Especially, compound 3 shows a guest-sensitive luminescence behaviour, which may be useful in applications as guest sensors.

Vapochromism associated with the changes in the molecular arrangement of organic crystals

Exposure of yellow anhydrate organic crystals to water vapor gave red hydrate crystals with significant changes in the molecular arrangement.