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Controlling the selectivity of a detonation initiation reaction of explosive is essential to reduce sensitivity, and it seems impossible to reduce it by strengthening the external electric field. To verify this, the effects of external electric fields on the initiation reactions in NH2NO2∙∙∙NH3, a model system of the nitroamine explosive with alkaline additive, were investigated at the MP2/6-311++G(2d,p) and CCSD(T)/6-311++G(2d,p) levels. The concerted effect in the intermolecular hydrogen exchange is characterized by an index of the imaginary vibrations. Due to the weakened concerted effects by the electric field along the −x-direction opposite to the "reaction axis", the dominant reaction changes from the intermolecular hydrogen exchange to 1,3-intramolecular hydrogen transference with the increase in the field strengths. Furthermore, the stronger the field strengths, the higher the barrier heights become, indicating the lower sensitivities. Therefore, by increasing the field strength and adjusting the orientation between the field and "reaction axis", not only can the reaction selectivity be controlled, but the sensitivity can also be reduced, in particular under a super-strong field. Thus, a traditional concept, in which the explosive is dangerous under the super-strong external electric field, is theoretically broken. Compared to the neutral medium, a low sensitivity of the explosive with alkaline can be achieved under the stronger field. Employing atoms in molecules, reduced density gradient, and surface electrostatic potentials, the origin of the reaction selectivity and sensitivity change is revealed. This work provides a new idea for the technical improvement regarding adding the external electric field into the explosive system. [ABSTRACT FROM AUTHOR]

A sequential multistep reaction toward 5-thio- or 5-selenotriazoles has been established by generation of both copper(I) triazolides and sulfenylating or selenylating agents in situ, starting from elemental sulfur or selenium. This reaction features mild conditions, readily available and broad-scope substrates, good functional group compatibility, high efficiency and regioselectivity, easy operation, and ligand-free CuI. [ABSTRACT FROM AUTHOR]

Synthesis of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane and 1,3,5-trinitro-1,3,5-triazacyclohexane by the Bachmann process leads to a mixture of both. The separation of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane and 1,3,5-trinitro-1,3,5-triazacyclohexane from their mixture is difficult because the sizes and physical properties of these homologous compounds are similar. For this purpose, seven molecularly imprinted polymers have been synthesized for each explosive, and a selective solid-phase extraction procedure has been developed. A molecularly imprinted polymer, synthesized with 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane as the template, methacrylic acid as the monomer and trimethylolpropane trimethacrylate as the cross-linking agent in a molar ratio of 1:8:8 showed the best separation capability. A packed cartridge containing this polymer can be reused for 23 solid-phase extraction cycles without repacking, and the total separation capability toward 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane reached 6.81 mg per gram of polymer. 1,3,5-Trinitro-1,3,5-triazacyclohexane was not detected in the separated 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane by high-performance liquid chromatography and vice versa. This newly developed method had the advantages of high recovery (100%) and purity, environmental friendliness, and room temperature operability. This study showed that some molecularly imprinted polymers that cannot absorb target analytes well in the solvent in which the polymers were polymerized might have high-binding capacity for the analytes and show imprinting effects in other solvents. [ABSTRACT FROM AUTHOR]

Two intermediates, 1,5-dinitroso-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DNDS) and 1-nitroso-3,5,7-trinitro-1,3,5,7-tetraazacyclooctane (MNX), were isolated and characterized in the synthesis of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) from the nitrolysis of 3,7-dinitro-1,3,5,7-tetraazabicyclo[3,3,1]nonane (DPT) for the first time. When the nitrolysis of DPT was slowed down, two intermediates were detected with HPLC. It was proposed that electrophilic NO2+ and NO+ from HNO3 and N2O4 might attack nitrogen atoms at positions 3 and 7 of DPT to form the cations of the intermediates, then nucleophilic H2O attacked the bridge carbon atoms of DPT to produce the intermediates, which were oxidized to form HMX. [ABSTRACT FROM AUTHOR]

N-heterocyclic compounds are key nitration precursors for some high energy density explosives such as 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX). Nitration of 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) yields HMX in high yields and purity. However, the analogue 1,3,5-triacetyl-1,3,5-triazacyclohexane (TRAT) is easily co-produced via the condensation of acetonitrile and 1,3,5-trioxan. To selectively extract TAT from a mixture of TAT and TRAT, the molecular imprinting technology (MIT) was developed in this study. The capacity of the dry polymer is 16 mg g−1 and the recovery surpasses 75 %. [ABSTRACT FROM AUTHOR]

Molecular imprinting has received much attention because of their high selectivity for target molecules. However, the column efficiency of classic molecularly imprinted polymers packed column was unsatisfactory because of poor monodispersion and slow mass transfer. In this study, surface-imprinted silica (SIS) based on metal coordination was prepared and used as stationary phase in HPLC for the separation of hemoglobin (Hb). Iminodiacetic acid (IDA) was used as metal-coordinating monomer and Hb template was anchored by Cu2+on the surface of silica by metal coordination. The silica was coated with a polymer formed by condensation of propyltrimethoxysilane (PTMS) and aminopropyltrimethoxysilane (APTMS). The obtained Hb-SIS were characterized by scanning electron microscope, elemental analysis and Fourier transform infrared spectroscopy. Rapid adsorption kinetics was achieved and the adsorption capacity of SIS was 8-fold higher than that of the nonimprinted silica (NIS). Chromatographic behaviors of Hb and other proteins on Hb-SIS column were investigated. The Hb-SIS column showed good selectivity and outstanding column efficiency (>2 × 104plates m−1) to Hb and can be used for the separation of Hb from a protein mixture containing bovine serum albumin and Cytochrome C. [ABSTRACT FROM AUTHOR]

Dinitro pentamethylene tetramine (DPT) is an important precursor of octogen (cyclotetramethylene tetramine, HMX). This article explores the process of synthesizing DPT by one-pot method to provide a practical basis for improving HMX production through DPT. The urea was used as the original material. Without isolation from intermediates, DPT was obtained by the chemical reaction of nitration, hydrolysis and Mannich condensation. Some factors to affect yield of DPT were investigated, such as dosage of nitric acid, nitration time, hydrolyzation time, dosage of formaldehyde, pH of solution and so on. The optimum conditions of process were determined. With this process, the yield of DPT was advanced up to 65.2%. [ABSTRACT FROM AUTHOR]

The simple protocol allows the direct amination of acetophenone and benzophenone bearing a p-chloro substituent with cyclic secondary amines. [ABSTRACT FROM AUTHOR]

We present two types of two-dimensional (2D) photonic crystals (PC) hydrogel sensors based on glycated albumin (G-alb) as a proof-of-concept for utilizing recognition between G-alb and bacterial cell surface lipopolysaccharides (LPS) to detect and discriminate Gram-negative bacteria. The G-alb functionalized PC-G-alb hydrogel provides recognition of different LPS via hydrogen bonding and can discriminate different Gram-negative bacteria based on their LPS types. The hydrogel delivered LOD of 0.87 ng mL−1 for E.coli LPS, 153 CFU mL−1 for E.coli, 1.22 ng mL−1 for P.aeruginosa LPS and 225 CFU mL−1 for P.aeruginosa. On the other hand, LPS bioimprinted hydrogel (PC-G-alb-LPS imp) provides selective recognition of E.coli LPS with LOD 0.76 ng mL−1 and for E.coli 58 CFU mL−1, via generation of flexible specific cavities for E.coli and its LPS. The two hydrogels showed remarkable recoveries for both LPS and Gram-negative bacteria in the relevant samples of milk, orange juice, river water, and serum with a short response time of 6–12 min. In the binding process, the hydrogels shrink, and 2D PC particle spacing decreases with diffraction shift from green to blue. The diffraction shifts can be visually observed, measured through Debye's diffraction ring diameter by a laser pointer or determined from a spectrometer. Image 1 • G-alb functionalized PC sensor for general recognition of LPS and Gram-negative bacteria and LPS imprinted G-alb PC sensor for selective detection of E.coli LPS and E.coli. • Easy fabrication and detection through naked eye by diffraction rings and color changes. • Molecular docking to investigate the sensing mechanism. • Sensing application in milk, river water, orange juice, and serum samples as a proof of point-of-care testing. [ABSTRACT FROM AUTHOR]