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Photoresponsive self-assembling process of rod-coil amphiphiles with spiropyran units was investigated, and achieved visual recognition of copper ions.

Self-assembled nanomaterials composed of amphiphilic oligomers with functional groups have been applied in the fields of biomimetic chemistry and on-demand delivery systems. Herein, we report the assembly behavior and unique properties of an emergent n-shaped rod-coil molecule containing an azobenzene (AZO) group upon application of an external stimulus (thermal, UV light). The n-shaped amphiphilic molecules comprising an aromatic segment based on anthracene, phenyl linked with azobenzene groups, and hydrophilic oligoether (chiral) segments self-assemble into large strip-like sheets and perforated-nanocage fragments in an aqueous environment, depending on the flexible oligoether chains. Interestingly, the nano-objects formed in aqueous solution undergo a morphological transition from sheets and nanocages to small one-dimensional nanofibers. These molecules exhibit reversible photo- and thermal-responsiveness, accompanied by a change in the supramolecular chirality caused by the conformational transitions of the rod backbone. The architecture of n-shaped amphiphilic molecules with a photosensitive group makes them ideal candidates for intelligent materials for applications in advanced materials science.

The aggregation-induced emission (AIE) effect is an important feature for luminescence studies, which can offer a broader range of applications for fluorescent materials. Herein, we report the morphological control and photoproperties of amphipathic propeller-shaped rod–coil molecules based on a benzene-1,3,5-tricarboxamide (BTA) unit, which restricts the intramolecular rotation and leads to the AIE effect during the self-assembly process. Investigations on the assembly of these molecules have revealed that tetragonal perforated lamella, hexagonal columnar, body-centered tetragonal micellar, and hexagonal close-packed nanostructures were spontaneously formed in the solid-state. In the solution-state, these molecules assemble into nanosheet-like aggregates, bowl-like objects, and spherical nanoparticles, respectively. The morphology of the molecular aggregates can be controlled by modifying the molecular chain length or introducing lateral methyl groups in the coil chain. Notably, these molecular assemblies exhibit strong AIE phenomena in a mixed THF/H2O solution and can be used as smart soft materials due to the restriction of their intramolecular motion.

COVID-19 is a rapidly evolving emergency, for which there have been no specific medication found yet. Therefore, it is necessary to find a solution for this ongoing pandemic with the aid of advanced pharmaceutics. What is proposed as a solution is the repurposing of FDA approved drug such as niclosamide (NIC) having multiple pathways to inactivate the SARS-CoV-2, the specific virion that induces COVID-19. However, NIC is hardly soluble in an aqueous solution, thereby poor bioavailability, resulting in low drug efficacy. To overcome such a disadvantage, we propose here an oral formulation based on Tween 60 coated drug delivery system comprised of three different mesoporous silica biomaterials like MCM-41, SBA-15, and geopolymer encapsulated with NIC molecules. According to the release studies under a gastro/intestinal solution, the cumulative NIC release out of NIC-silica nanohybrids was found to be greatly enhanced to ~97% compared to the solubility of intact NIC (~40%) under the same condition. We also confirmed the therapeutically relevant bioavailability for NIC by performing pharmacokinetic (PK) study in rats with NIC-silica oral formulations. In addition, we discussed in detail how the PK parameters could be altered not only by the engineered porous structure and property, but also by interfacial interactions between ion-NIC dipole, NIC–NIC dipoles and/or pore wall-NIC van der Waals in the intra-pores of silica nanoparticles., Graphical abstract Image 1

The nanostructure and morphology of mesoporous carbon obtained from a newly designed porous geopolymer template were characterized by low-voltage high-resolution scanning electron microscopy. The present porous carbon exhibited a large specific surface area and pore volume, resulting in a high CO2 uptake capacity.

We demonstrate humidity-responsive structural colors with ultrafast rise and recovery times of 20 and 36 ms from a random arrangement of amorphous titania microspheres. A large fraction of the amorphous titania microsphere is shown to be nanoporous, permitting significant changes to the effective permittivity upon water uptake and thereby altering its scattering cross section. Individually, the microspheres are indistinguishable by scattered light in dry and humid environments, but collectively display color contrast in both environments as the incoherent scattering from each particle allows the individual scattering cross sections to be summed in the far-field, exposing smoothly varying spectral features unique to the humidity environment. Time-resolved humidity response measurements of the microspheres show ultrafast response times due to the fast diffusion dynamics of water molecules in the titania nanoporous network. Absence of spatial ordering among microspheres for generating color also facilitates the fabrication of a simple binary humidity-responsive display, optimized in speed and signal at only a monolayer coverage of particles. As the sensing relies on changes in the scattering cross-section, signal detection can be performed using a monochromatic light source that demands little power (30 μW in our demonstration). Such results suggest intriguing possibilities for realizing cheap, simple, ultrafast and power-efficient colorimetric humidity sensors using structural colors from disordered systems.

The Ga/Zn oxynitride solid solution [(GaN)1–x(ZnO)x] is one of the promising visible light harvesting photocatalysts for overall water splitting. A series of (GaN)1–x(ZnO)x (0.11 ≤ x ≤ 0.33) compounds are synthesized by calcining the carbonate-type Zn/Ga-LDH precursor with and without sodium carbonate flux at 850 °C for 8–14 h under a NH3 gas flow. The solid solutions without flux are determined to be low in crystallinity, but platelike morphology with preferred orientation could be observed. On the other hand, those with flux turn out to be better in crystallinity, and eventually exhibit significantly higher photocatalytic activity for overall water splitting under visible light irradiation than those without flux. In addition, the band gap energies can also be engineered from 2.57 to 2.72 eV by changing a synthetic parameter such as nitridation time. It is, therefore, suggested that the present new approach can offer new opportunities for designing the next generation of photocatalytic systems.

Single particle Mie calculations of near micron-sized TiO2 particles predict strong light scattering dominating the visible range that would give rise to a white appearance. We demonstrate that a polydisperse collection of these “white” particles can result in the generation of visible colors through ensemble scattering. The weighted averaging of the scattering over the particle size distribution modifies the sharp, multiple, high order scattering modes from individual particles into broad variations in the collective extinction. These extinction variations are apparent as visible colors for particles suspended in organic solvent at low concentration, or for a monolayer of particles supported on a transparent substrate viewed in front of a white light source. We further exploit the color variations on optical sensitivity to the surrounding environment to promote micron-sized TiO2 particles as stable and robust agents for detecting the optical index of homogeneous media with high contrast sensitivities. Su...

Hexagonal and wormhole-type mesoporous geopolymers were developed by controlling the concentration of a structure directing agent (cetrimonium bromide, CTAB) with fixed ratios of Si/Al, KOH/(Si + Al), and H2O/(Si + Al), and their detailed porous structures were confirmed by TEM, N2 adsorption–desorption and X-ray diffraction measurements. The as-prepared geopolymers were then used as templates to replicate porous carbons with various structures and porosities for CO2 adsorption. To understand the correlation between the CO2 adsorptivity and porous structures, we tuned the porosity of the geopolymer-templated carbons by modifying the structures of the geopolymers. The porous carbons obtained from the hexagonal-type porous geopolymers were found to be composed of the aggregates of carbon nanowires exhibiting large particles, while those obtained from the wormhole-like porous geopolymers were determined to be wormhole type as well, as evidenced by TEM and X-ray diffraction studies. According to the CO2 adsorption isotherms of the porous carbons, the aggregates of carbon nanowires exhibited the highest CO2 adsorptivity due to their highest microporosity and largest specific surface area.

Disordered photonic systems as observed in iridescent insects and flowers introduces new pathways for realizing cost-effective and scalable structural colors. In this work, we present a fast-colorimetric humidity sensor derived from a disordered arrangement of polydisperse nanoporous titania microspheres. The sensor relies on changes in the total scattering of the microspheres upon variations in the surrounding humidity. The incoherent scattering from each particle allows the sum of the individual cross sections to determine the total scattering cross section, which converts the individual noisy spectra to a smoothly varying spectrum that gives rise to a saturated color.[1] We show that because the titania microspheres is highly porous with 1~2 nm-sized nanopores, water can diffuse into the particle interior via intracrystalline dynamics, thereby changing the effective permittivity and consequently the scattered color at ultra-fast speeds (sub 50ms). Our results provide a practical route toward achieving cheap, simple, scalable, ultrafast colorimetric humidity sensors using structural colors from disordered nanoporous microspheres [2]. [1] Alam, A-M; Baek K; Son J; Pei Y-R; Kim D-H; Choy J-H; and Hyun J-K. Generating Color from Polydisperse, Near Micron-Sized TiO2 Particles, ACS Appl. Mater. Interfaces, 2017, 9 (28), 23941– 23948 [2] M-Noor, S; Jang, H ; Baek K; Pei Y-R; Alam, A-M; Kim,Y.H; Kim, I.S; Choy, J.H and Hyun J-K. Ultrafast humidity-responsive structural colors from disordered nanoporous titania microspheres. Submitted (2019)

The nanostructure and morphology of mesoporous carbon obtained from a newly designed porous geopolymer template were characterized by low-voltage high-resolution scanning electron microscopy. The present porous carbon exhibited a large specific surface area and pore volume, resulting in a high CO2 uptake capacity.

A novel efficient and safe methodology to sanitize algae in natural water without secondary pollution is developed by fabricating floating graphene-inorganic hybrid films. Two kinds of floating freestanding hybrid films of layered titanate-graphene with efficient algae-killing functionality are fabricated by vacuum-assisted filtration of mixed colloidal suspensions of reduced graphene oxide (rG-O) nanosheets and exfoliated layered titanate nanosheets. Both the titanate nanosheets with lepidocrocite- and trititanate-type structures form homogeneous colloidal mixtures and hybrid freestanding films with rG-O nanosheets. The incorporation of a layered titanate nanosheet enhances the algae-killing activity of the graphene freestanding film, highlighting the beneficial role of photocatalytically-active titanate nanosheet. In comparison to the trititanate nanosheet, the lepidocrocite-type titanate nanosheet is more effective as a building block for enhancing the algae-killing activity of graphene film and for forming a novel nanoblade structure on the surface of the graphene film. The observed high sterilization functionality of the present layered titanate-graphene hybrid films is attributable to both the formation of the novel sharp nanoblade structure and the photocatalytic activity of layered titanate. The present result underscores that hybridization between graphene and photocatalytically-active inorganic nanosheets can provide a powerful way to explore pollution-free recoverable matrix efficient for removing harmful microorganisms in natural water. Refereed/Peer-reviewed

Single particle Mie calculations of near micron-sized TiO

In this review, an attempt is made to calculate one-dimensional (1-D) electron density profiles from experimentally determined (00l) XRD intensities and possible structural models as well in an effort to understand the collective intracrystalline structures of intercalant molecules of two-dimensional (2-D) nanohybrids with heterostructures. 2-D ceramics, including layered metal oxides and clays, have received much attention due to their potential applicability as catalysts, electrodes, stabilizing agents, and drug delivery systems. 2-D nanohybrids based on such layered ceramics with various heterostructures have been realized through intercalation reactions. In general, the physico-chemical properties of such 2-D nanohybrids are strongly correlated with their heterostructures, but it is not easy to solve the crystal structures due to their low crystallinity and high anisotropic nature. However, the powder X-ray diffraction (XRD) analysis method is thought to be the most powerful means of understanding the interlayer structures of intercalant molecules. If a proper number of well-developed (00l) XRD peaks are available for such 2-D nanohybrids, the 1-D electron density along the crystallographic c-axis can be calculated via a Fourier transform analysis to obtain structural information about the orientations and arrangements of guest species in the interlayer space. Refereed/Peer-reviewed

Correction for ‘Water-floating nanohybrid films of layered titanate–graphene for sanitization of algae without secondary pollution’ by In Young Kim et al., RSC Adv., 2016, 6, 98528–98535.