Classification of the hydrogen-bonding species in a series of novel hydrazide based azobenzene derivatives investigated by two-dimensional correlation infrared spectroscopy and molecular modeling

Classification of hydrogen-bonding species in a series of novel hydrazide modified p-methoxyazobenzene derivatives, 4-{n-[4-(4-methoxy-phenylazo)-phenoxy]-alkoxy}-benzoic acid hydrazide (Dn, n = 3, 6, 10) are performed in the present study. Temperature-dependent infrared (IR) spectra of Dn have been measured to investigate the thermal stability of the weak intermolecular interactions, such as hydrogen bonding among hydrazide moieties, pi-pi stacking among aromatic groups, and hydrophobic interaction between alkyl chains. In order to reveal the hydrogen bonding formed between NH, NH2, and CONH groups efficiently, two-dimensional (2D) correlation spectra have been constructed in the thermal sensitive spectral regions of (a) 3500-3100 cm(-1) and (b) 1700-1450 cm(-1), separately, and it have also been constructed between these two spectral regions. Based on the experimental data, the ab initio computational models have been developed to the proposed patterns of hydrogen bonding related to intermolecular interactions in Dn. The intermolecular hydrogen bondings and molecular alignments patterns result from both the experimental data and the computational models are performed for D3, D6, and D10, respectively, in the present study.     

Synthesis of ordered spiral and ring-like polypyrrole nanowires in cetyltrimethylammounium bromide crystalline suspension

Spiral dislocation morphology on the surface of cetyltrimethylammounium bromide (CTAB) crystallites has been discovered for the first time. By addition of ammonium peroxydisulfate into CTAB crystalline suspension, a drastic change in the morphology of result crystallites is observed from spiral to two dimensional (2D) islands. The spiral and 2D-island structures of these crystallites could be use as the templates for the synthesis of spiral and ring-like polypyrrole (PPy) nanowires, respectively, via direct chemical oxidative polymerization of pyrrole due to the oxidation reaction occurring preferentially at the steps of these crystallites. The mechanism of adsorption of pyrrole oligomers on the steps of these crystallites is proposed for the growth of PPy spiral and ring-like nanowires.     

Ionic liquids based single drop microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for determination of Co,Hg and Pb in biological and environmental samples

A new method of ionic liquids based cycle flow single drop microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) was proposed for the determination of trace Co, Hg and Pb with 1-(2-pyridylazo)-2-naphthol (PAN) as both extractant and chemical modifier and 1-butyl-3-methylimidazolium hexafluorophosphate as the extraction solvent. Several factors that influence the microextraction efficiency, such as sample pH, sample flow rate, microdrop volume and extraction time, were investigated and the optimized microextraction conditions were established. Co, Hg and Pb in the post-extraction ionic liquids phase were directly determined by ETV-ICP-MS with the use of PAN as chemical modifier. The chemical modification of PAN in ETV-ICP-MS was studied and the factors affecting the vaporization behaviors of target analytes were investigated. Under the optimized conditions, the detection limits of the method were 1.5, 9.8 and 6.7 pg/mL for Co, Hg and Pb, with the relative standard deviations for 0.5 ng/mL (n = 7) of Co, Hg and Pb were 7.7%, 5.2% and 12.0%, respectively. After 10 min of extraction, the enrichment factors were 350 (Co), 50 (Hg) and 60 (Pb). The proposed method was successfully applied to the determination of trace Co, Hg and Pb in human serum and environmental water samples. In order to validate the developed method, a certified reference material of human hair (GBW07601) was analyzed and the determined values were in good agreement with the certified values.     

High Sensitive Electrochemical Detection of Sequence‐Specific DNA Using Low Current Voltammetry

In this article, we report on efforts to construct a high sensitive electrochemical sensor with immobilized sandwich‐type DNA borne ferrocene (Fc) head for sequence‐specific DNA detection using ultramicroelectrode and low current voltammetry. Based on the difference in deformability between the bending rigid complementary DNA double helix and its anomalous flexile mismatches, the fully complementary target can be distinguished from mismatched targets including the single‐base mismatched target. Detection limit estimated as the amount of DNA is observed to be 100 fM via low current voltammetry. The method offers great promise of high sensitivity and selectivity simultaneously for effective gene identification.     

Green and high efficient synthesis of triaza‐benzo[b]fluoren‐6‐one derivatives in water under microwave irradiation

Triaza‐benzo[b]fluoren‐6‐one derivatives were synthesized via the three‐component reaction of aldehyde, cyclohexane‐1,3‐dione compound and 2‐aminobenzimidazole in water under microwave irradiation. The new protocol has the advantages of excellent yield, low cost, reduced environment impact, wide scope and convenient procedure.     

A Mixed Solvothermal Route to Synthesis of Dice‐Like PbS

The authors developed a simple solvothermal route to synthesis of PbS nanocrystals in the mild binary mixed solvent made of diethylenetriamine (DETA) and water. Two kinds of PbS nanostructures (dice‐like and cubic) have been successfully synthesized in the binary mixed solvothermal system at 150 °C by changing the sulfur source. The products were characterized by X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The results show that the as‐prepared dice‐like PbS crystals have a hole on each of their faces. To elucidate the relationship between reaction systems and the morphologies of the final products, the authors also investigated the crystal growth by using different sulfur source. Based on the experimental results, the possible growth mechanism of the dice‐like PbS crystals was proposed.     

Preparation and properties of polyaniline codoped with ionic liquid and dodecyl benzene sulfonic acid or hydrochloric acid

Three nanosized polyaniline (PAn) powders doped with ionic liquid and dodecyl benzene sulfonic acid (DBSA) or hydrochloric acid have been prepared for the first time in an ionic liquid-water emulsion system. The oil-phase ionic liquid is used as both a monomer solvent and doped counterion. The effects of different counterions on the properties (molecular weight, electrical conductivity, glass transition temperature, electrochemical activity) of PAn are investigated. PAn codoped with 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and DBSA shows the highest molecular weight (81 104 g mol^?1), the highest electrical conductivity (1.85 S cm^?1), the lowest glass transition temperature (181°C) and the highest redox reaction current density; PAn doped with an ionic liquid only exhibits the lowest conductivity (0.0018 S cm^?1) and a lower redox reaction current density. PAn codoped with ionic liquid and HCl shows higher conductivity. They also exhibit good electrochemical stability and charge-discharge performance. These indicate that codoping of different counterions under acidic conditions could improve the degree of oxidation and doping ratio of PAn and could result in high electrical conductivity and good electrochemical properties.     

Directed Electron Delivery from a Pb-Free Halide Perovskite to a Co(II) Molecular Catalyst Boosts CO2 Photoreduction Coupled with Water Oxidation

The development of high-performance photocatalytic systems for CO₂ reduction is appealing to address energy and environmental issues, while it is challenging to avoid using toxic metals and organic sacrificial reagents. We here immobilize a family of cobalt phthalocyanine catalysts on Pb-free halide perovskite Cs₂AgBiBr₆ nanosheets with delicate control on the anchors of the cobalt catalysts. Among them, the molecular hybrid photocatalyst assembled by carboxyl anchors achieves the optimal performance with an electron consumption rate of 300±13 μmol g⁻¹ h⁻¹ for visible-light-driven CO₂-to-CO conversion coupled with water oxidation to O₂, over 8 times of the unmodified Cs₂AgBiBr₆ (36±8 μmol g⁻¹ h⁻¹), also far surpassing the documented systems (<150 μmol g⁻¹ h⁻¹). Besides the improved intrinsic activity, electrochemical, computational, ex-/in situ X-ray photoelectron and X-ray absorption spectroscopic results indicate that the electrons photogenerated at the Bi atoms of Cs₂AgBiBr₆ can be directionally transferred to the cobalt catalyst via the carboxyl anchors which strongly bind to the Bi atoms, substantially facilitating the interfacial electron transfer kinetics and thereby the photocatalysis.     

Revealing the CO2 Conversion at Electrode/Electrolyte Interfaces in Li–CO2 Batteries via Nanoscale Visualization Methods

Lithium–carbon dioxide (Li–CO₂) battery technology presents a promising opportunity for carbon capture and energy storage. Despite tremendous efforts in Li–CO₂ batteries, the complex electrode/electrolyte/CO₂ triple-phase interfacial processes remain poorly understood, in particular at the nanoscale. Here, using in situ atomic force microscopy and laser confocal microscopy-differential interference contrast microscopy, we directly observed the CO₂ conversion processes in Li–CO₂ batteries at the nanoscale, and further revealed a laser-tuned reaction pathway based on the real-time observations. During discharge, a bi-component composite, Li₂CO₃/C, deposits as micron-sized clusters through a 3D progressive growth model, followed by a 3D decomposition pathway during the subsequent recharge. When the cell operates under laser (λ=405 nm) irradiation, densely packed Li₂CO₃/C flakes deposit rapidly during discharge. Upon the recharge, they predominantly decompose at the interfaces of the flake and electrode, detaching themselves from the electrode and causing irreversible capacity degradation. In situ Raman shows that the laser promotes the formation of poorly soluble intermediates, Li₂C₂O₄, which in turn affects growth/decomposition pathways of Li₂CO₃/C and the cell performance. Our findings provide mechanistic insights into interfacial evolution in Li–CO₂ batteries and the laser-tuned CO₂ conversion reactions, which can inspire strategies of monitoring and controlling the multistep and multiphase interfacial reactions in advanced electrochemical devices.