Unveiling interfacial interaction between antimony oxyanions and boehmite nanorods: Spectroscopic evidence and density functional theory analysis.

In natural environments, the fate and migratory behavior of metalloid contaminants such as antimony (Sb) significantly depend on the interfacial reactivity of mineral surfaces. Although boehmite (γ-AlOOH) is widely observed in (sub)surface environments, its underlying interaction mechanism with Sb oxyanions at the molecular scale remains unclear. Considering Sb-contaminated environmental conditions in this study, we prepared boehmite under weakly acidic conditions for use in the systematic investigation of interfacial interactions with Sb(III) and Sb(V). The as-synthesized boehmite showed a nanorod morphology and comprised four crystal facets in the following order: 48.4% (010), 27.1% (101), 15.0% (001), and 9.5% (100). The combined results of spectroscopic analyses and theoretical calculations revealed that Sb(III) formed hydrogen bonding outer-sphere complexation on the (100), (010), and (001) facets and that Sb(V) preferred to form bidentate inner-sphere complexation via mononuclear edge-sharing configuration on the (100), (001), and (101) facets and binuclear corner-sharing configuration on the (010) facet. These findings indicate that the facet-mediated thermodynamic stability of the surface complexation determines the interaction affinity toward the Sb species. This work is the first to document the contribution of boehmite to (sub)surface media, improving the ability to forecast the fate and behavior of Sb oxyanions at mineral-water interfaces.

Chiroptical Synaptic Heterojunction Phototransistors Based on Self-Assembled Nanohelix of π-Conjugated Molecules for Direct Noise-Reduced Detection of Circularly Polarized Light.

High-performance chiroptical synaptic phototransistors are successfully demonstrated using heterojunctions composed of a self-assembled nanohelix of a π-conjugated molecule and a metal oxide semiconductor. To impart strong chiroptical activity to the device, a diketopyrrolopyrrole-based π-conjugated molecule decorated with chiral glutamic acid is newly synthesized; this molecule is capable of supramolecular self-assembly through noncovalent intermolecular interactions. In particular, nanohelix formed by intertwinded fibers with strong and stable chiroptical activity in a solid-film state are obtained through hydrogen-bonding-driven, gelation-assisted self-assembly. Phototransistors based on interfacial charge transfer at the heterojunction from the chiroptical nanohelix to the metal oxide semiconductor show excellent chiroptical detection with a high photocurrent dissymmetry factor of 1.97 and a high photoresponsivity of 218 A W-1 . The chiroptical phototransistor demonstrates photonic synapse-like, time-dependent photocurrent generation, along with persistent photoconductivity, which is attributed to the interfacial charge trapping. Through the advantage of synaptic functionality, a trained convolutional neural network successfully recognizes noise-reduced circularly polarized images of handwritten alphabetic characters with better than 89.7% accuracy.

Dimensional Control of Highly Anisotropic and Transparent Conductive Coordination Polymers for Solution-Processable Large-Scale 2D Sheets.

Controlling the dimensional aspect of conductive coordination polymers is currently a key scientific interest. Herein, solution-based dimension control strategies are proposed for copper chloride thiourea (CuCl-TU) coordination polymers that enable centimeter-scale, 2D nanosheet formation for use as transparent electrodes. Despite the wide bandgap of CuCl-TU polymers (4.33 eV), through polaron-mediated electron transfer, the electrical conductivity of the 2D sheet at room temperature is able to reach 4.45 S cm-1 without intentional doping. This leads to a highly anisotropic electronic conductivity of up to the order of ≈103 differences, depending on the material orientation. Furthermore, by substituting alternative thiourea candidates, it is demonstrated that it is possible to predesign CuCl-TU structures with the desired functionality, stability, and porosity through dimensional control. These findings provide a blueprint to design next-generation transparent conducting materials that can operate at room temperature, thereby expanding their applicability to different fields.

Reverse shape selectivity of hexane isomer in ligand inserted MOF-74.

Separation of linear, mono-branched, and di-branched isomers is critically important in the petrochemical industry. In this computational study, we demonstrate that the ligand inserted Mg-MOF-74 structure leads to a reverse selectivity effect (i.e. phenomenon that preferentially allows larger species molecules to permeate in a gas mixture) of hexane isomers in the resulting material. Molecular dynamics simulations suggest that strong confinement of the di-branched hydrocarbons in the small pores lead to reverse selectivity. Over a magnitude difference in diffusivity between linear alkanes and their di-branched isomers was observed, clearly showing the steric effects imposed by the pore structure.

Ultra-dense (~20 Tdot/in2) nanoparticle array from an ordered supramolecular dendrimer containing a metal precursor.

The fabrication of an ultra-dense, highly periodic nanoparticle array from a soft template is one of the most important issues in the fields of material science and nanotechnology. To date, block copolymer (BCP) structures have been primarily used as templates for fabricating highly periodic nanoparticle arrays with high areal densities. Herein, we demonstrate for the first time the use of a supramolecular dendrimer assembly for the formation of a highly ordered nanoparticle array with a high areal density of ~20 Tdot/in2, four times larger than that of the currently reported BCP-based nanoparticle arrays. By the simple thermal annealing of a dendrimers containing a metal precursor between two flat, solid substrates, a hexagonal array of small gold nanoparticles (with a diameter of ~1.6 nm and center-to-center distance of ~5.3 nm), oriented normal to the bottom, was achieved. Density functional theory calculations demonstrated that the gold cation strongly bound to the head group of the dendrimer. This structure served as a building block for self-assembly into a stable cylindrical structure. We anticipate that this study will lead to the creation of a large family of supramolecular dendrimers that can be utilized as soft templates for creating periodic, ultra-dense nanoparticle arrays.

Polyelemental Nanolithography via Plasma Ion Bombardment: From Fabrication to Superior H2 Sensing Application.

The development of complex nanostructures containing a homo- and heteromixture of two or more metals is a considerable challenge in nanotechnology. However, previous approaches are considerably limited to the number of combinations of metals depending on the compatibility of elements, and to the complex shape control of the nanostructure. In this study, a significant step is taken toward resolving these limitations via the utilization of a low-energy argon-ion bombardment. The multilayer films are etched and re-sputtered on the sidewall of the pre-pattern, which is a secondary sputtering phenomenon. In contrast to the precursor mixing method, most metallic combinations can be fabricated. The degree of mixing is tuned by the control of the sequence and thickness of multilayers. In addition, the feature shape and dimensions are controlled by changing the pre-pattern or by controlling the ion-beam angle. Using this method, the shortest response time (2 s to 1% H2 ) in comparison with those of Pd-based H2 sensors reported previously and a limit of detection below 1 parts per million (ppm) for Pd/Au and Pd/Pt bimetallic line arrays are achieved. This study is expected to realize a family of polyelements that can be used in various applications.

Pore dilatation increases the bicarbonate permeability of CFTR, ANO1 and glycine receptor anion channels.

KEY POINTS: Cellular stimuli can modulate the ion selectivity of some anion channels, such as CFTR, ANO1 and the glycine receptor (GlyR), by changing pore size. Ion selectivity of CFTR, ANO1 and GlyR is critically affected by the electric permittivity and diameter of the channel pore. Pore size change affects the energy barriers of ion dehydration as well as that of size-exclusion of anion permeation. Pore dilatation increases the bicarbonate permeability (P HC O3/ Cl ) of CFTR, ANO1 and GlyR. Dynamic change in P HC O3/ Cl may mediate many physiological and pathological processes. ABSTRACT: Chloride (Cl(-) ) and bicarbonate (HCO3 (-) ) are two major anions and their permeation through anion channels plays essential roles in our body. However, the mechanism of ion selection by the anion channels is largely unknown. Here, we provide evidence that pore dilatation increases the bicarbonate permeability (P HC O3/ Cl ) of anion channels by reducing energy barriers of size-exclusion and ion dehydration of HCO3 (-) permeation. Molecular, physiological and computational analyses of major anion channels, such as cystic fibrosis transmembrane conductance regulator (CFTR), anoctamin-1(ANO1/TMEM16A) and the glycine receptor (GlyR), revealed that the ion selectivity of anion channels is basically determined by the electric permittivity and diameter of the pore. Importantly, cellular stimuli dynamically modulate the anion selectivity of CFTR and ANO1 by changing the pore size. In addition, pore dilatation by a mutation in the pore-lining region alters the anion selectivity of GlyR. Changes in pore size affected not only the energy barriers of size exclusion but that of ion dehydration by altering the electric permittivity of water-filled cavity in the pore. The dynamic increase in P HC O3/ Cl by pore dilatation may have many physiological and pathophysiological implications ranging from epithelial HCO3 (-) secretion to neuronal excitation.