Convenient design of anti-wetting nano-Al/WO_(3)metastable intermolecular composites(MICs)with an enhanced exothermic life-span

For solving the dilemma of the short exothermic life-span of WO_(3)based metastable interstitial composites(MICs)with extensive application prospect,this paper has firstly designed the promising antiwetting Al/WO_(3)MICs via electrophoresis assembly of nano-Al and WO_(3)particles fabricated by hydrothermal synthesis method,followed by the subsequent fluorination treatment.A combination of X ray diffraction(XRD),field emission scanning electron microscope(FESEM),energy dispersive X-ray spectroscopy(EDX),and Fourier transform infrared spectroscopy(FT-IR)techniques were utilized in order to characterize the crystal structure,microstructure,and elemental composition distribution of target films after different natural exposure tests.The product with uniform distribution and high purity possesses a high contact angle of~170°and a minute sliding angle of~1°,and displays the outstanding anti-wetting property using droplets with different surface tensions.It also shows great moisture stability in high relative-humidity circumstances after one year of the natural exposure experiment.Notably,the heat output of a fresh sample can reach up to 2.3 kJ/g and retain 96%after the whole exposure test,showing outstanding thermo-stability for at least one year.This work further proposed the mechanism of antiwetting Al/WO_(3)MICs considering the variation tendency of their DSC curve,providing a valuable theoretical reference for designing other self-protected MICs with a long exothermic life-span applied in wide fields of national defense,military industry,etc.

Thermal Stability Improved by π–π Stacking Interactions: Synthesis, Crystal Structure and Thermal Decomposition of Sodium Nitroformate

An energetic salt, sodium nitroformate （NaNF）, was synthesized and characterized by elemental analysis, IR and UV spectra, and its crystal structure was first determined by single crystal X-ray diffraction. The structure exhibits two types of π-π stacking interactions between the nitroformate anions, i e, the parallel-displaced and T-shaped confgurafions. Furthermore, the thermal decomposition mechanism was investigated by DSC, TG-DTG and FTIR techniques. The kinetic parameters of the thermal decomposition were also calculated by using Kissinger＇s and Ozawa-Doyle＇s methods. The results show that NaNF has a good thermal stability, which is attributed to the π-π stacking interactions.

Theoretical Study on the Reaction Mechanism of 2-Methoxybenzaldehyde,4-Bromo-indanone,Malononitrile and Ammonium Acetate One-pot to Form 6-(2-Methoxyphenyl)-2-amino-6-bromo-5H-indeno[1,2-b]pyridine-3-carbonitrile

The reaction mechanism of 2-methoxybenzaldehyde, 4-bromo-indanone, malononitrile and ammonium acetate one-pot to form 6-（2-methoxyphenyl）-2-amino-6-bromo-5 Hindeno[1,2-b]pyridine-3-carbonitrile was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Reaction pathways were investigated in this study. The result indicates that the reaction Re→ TSB1→IMB1→ TSB2→ IMB2→TSB3→IMB3→TSB4→IMB4→TSB5→IMB5→TSB6→IMB6→TSB7→IMB7→ TSB8→IMB8→TSB9→IMB9→P2 is the main pathway, the activation energy of which is the lowest. The dominant product predicted theoretically is in agreement with the experiment results.

Theoretical Studies on the Thermal Decomposition Mechanism of Potassium Nitroformate

The microcosmic reaction mechanism of the thermal decomposition of potassium nitroformate（KNF） has been investigated by density functional theory within the generalized gradient approximation. The geometric structures of reactants, intermediates, transition states, and products are fully optimized. The frequency analysis approves the authenticity of intermediates and transition states. Our results show that there are four feasible reaction pathways. The main pathway of the reaction is KNF → B1 → TSB1 → B2 → TSB2 → B3 → TSB3 → B4 → KNO2 ＋ NO2 ＋ NO ＋ CO, and the energy barrier of the rate-limiting step is 216.30 k J·mol^-1. The dominant products predicted theoretically are KNO2, NO2, NO, and CO, which is in agreement with the experiment.

A New Mn(Ⅱ) Coordination Polymer with a Rare Polyrataxane Topology: Synthesis,Crystal Structure and Luminescent Property

A novel coordination polymer [Mn(bcp)(bib)0.5]n(1, H2 bcp = 1,3-bis(4-carboxyphenoxy)propane and bib = 1,4-bis(imidazol-1-yl)benzene) was synthesized under hydrothermal conditions, and was characterized by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy and powder X-ray diffraction(PXRD).Complex [Mn(bcp)(bib)0.5]n(1) is of triclinic system, space group P1 with a = 7.320(5), b =11.871(5), c = 13.932(5)?,α= 111.125(5)°,β= 99.658(5)°,γ= 101.104(5)°, Z = 2, V= 1070.3(9)?3 Mr = 474.34, Dc = 1.472 g/cm^3, F(000)= 488,μ= 0.660 mm^-1, the final R = 0.0353 and wR =0.0.984 for 4373 observed reflections with I > 2σ(I). Structure analysis reveals that complex 1 displays a rare 2 D + 2 D → 2 D polyrataxane topology. Moreover, the luminescent property for 1 was investigated at room temperature.

Synthesis, Crystal Structure and Catalytic Properties of a Novel Ni(Ⅱ) MOF with a Rare [3+3+3] Nine Fold Interpenetrated Network

Metal-organic frameworks are a sort of rapid development crystal solids,which have greatly attracted a large amount of attention in recent decades.The construction of 3D[Ni(bcp)(bpp)]n(namely complex 1)displays a rare[3+3+3]nine-fold interpenetrated diamond topology,which can be successfully synthesized by a mixed strategy of 1,3-bis(4-carboxyphenoxy)propane(H2bcp)and 1,4-bis(4-pyridylmethyl)piperazine(bpp).The interpenetrated network may be ascribed to these flexible bridging linkers to facilitate the penetration degree.In addition,the resultant sample was adequately characterized by elemental analysis,single-crystal X-ray diffraction,powder X-ray diffraction,and thermal gravimetric analysis.Furthermore,the as-synthesized sample can be used as catalysis for chemical fixation of CO2 and epoxide to carbonate.

Molecular Thermal Motion Modulated Room-Temperature Phosphorescence for Multilevel Encryption

The stimulus-responsive room-temperature phosphorescence(RTP)materials have become an increasingly significant topic in the fields of bioimaging,sensing,and anticounterfeiting.However,this kind of materials is scarce to date,especially for the ones with delicate stimulus-responsive behavior.Herein,a universal strategy for multilevel thermal erasure of RTP via chromatographic separation of host-guest doping RTP systems is proposed.The tunable host-guest systems,matrix materials,heating temperature,and time are demonstrated to allow precise six-level data encryption,QR code encryption,and thermochromic phosphorescence encryption.Mechanistic study reveals that the thermal-responsive property might be attributed to molecular thermal motion and the separation effect of the silica gel,which provides expanded applications of host-guest RTP materials such as cold chain break detection.This work offers a simple yet universal way to construct advanced responsive RTP materials.