A Simple Route of Printing Explosive Crystalized Micro-Patterns by Using Direct Ink Writing

The production of energetic crystalized micro-patterns by using one-step printing has become a recent trend in energetic materials engineering. We report a direct ink writing (DIW) approach in which micro-scale energetic composites composed of 1,3,5-trinitro-1,3,5-triazinane (RDX) crystals in selected ink formulations of a cellulose acetate butyrate (CAB) matrix are produced based on a direct phase transformation from organic, solvent-based, all-liquid ink. Using the formulated RDX ink and the DIW method, we printed crystalized RDX micro-patterns of various sizes and shapes on silicon wafers. The crystalized RDX micro-patterns contained single crystals on pristine Si wafers while the micro-patterns containing dendrite crystals were produced on UV-ozone (UVO)-treated Si wafers. The printing method and the formulated all-liquid ink make up a simple route for designing and printing energetic micro-patterns for micro-electromechanical systems

Modulating Energetic Characteristics of Multicomponent 1D Coordination Polymers: Interplay of Metal-Ligand Coordination Modes

The energetic properties of multicomponent explosive materials can be altered for high detonation capabilities and minimized safety risk by changing their building components. We synthesized energetic coordination polymers (ECPs) using a 5,5'-bis(tetrazole)-1,1'-diolate linker and a N,N-dimethylacetamide (DMA) solvent, together with Cu and Mn metal cations. The new compounds, ECP-1 and ECP-2, contain two different types of 1D chain structures, straight and helical. We have conducted comprehensive studies on these ECP structures, energetic properties, and sensitivity and found excellent insensitivity owing to the long chain-to-chain distances created by the DMA solvent molecules. The results indicate that the metals as well as solvents used are crucial components influencing both the structure and energetic properties

Correlation between Functionality Preference of Ru Carbenes and exo/endo Product Selectivity for Clarifying the Mechanism of Ring-Closing Enyne Metathesis

Functionality preferences of metathesis Ru carbenes to various alkenes and alkynes with electronic and steric diversity were determined by using time-dependent fluorescence quenching. The functionality preferences depend not only on the properties of multiple bonds but also on the ligands on Ru. There was a good correlation between functionality preference and the metathesis reaction outcome. The correlation between functionality preference and exo/endo product ratio offers a solution to resolve the mechanistic issue related with alkene- vs alkyne-initiated pathway in ring-closing enyne metathesis. The correlation indicates the preference is likely to dictate the reaction pathway and eventually the outcome of the reaction. The Ru catalyst favoring alkyne over alkene provides more endo product, indicating that the reaction mainly initiates at the alkyne. By changing the substitution pattern, the preference can be reversed to give an exclusive exo product.1110sciescopu

Tetrazole-Based Energetic Metal-Organic Frameworks: Impacts of Metals and Ligands on Explosive Properties

New energetic materials are required to compensate for the shortcomings of the current ones. Especially secondary explosives are the ones with low-sensitivity, while maintaining energetic performance similar to those of primary ones, and particularly useful when safety must be ensured. Herein, we report two energetic metal-organic frameworks (eMOFs), eMOF-1, [Mn-5(mtz)(6.1)(atz)(2.9)(NO3)] (mtz=5-methyltetrazole, atz=5-aminotetrazole) and eMOF-2, [Cu(mtz)(2)], both of which have unique detonation and sensitivity properties. In particular, eMOF-1, firstly reported here, shows better energetic performance when compared with the previously reported material, Cd-based mtz MOF, an isostructural series. In addition, eMOF-2 synthesized in water shows a great detonation performance, whereas isotopological Zn-based mtz MOF did not show a meaningful performance as an explosive. Therefore, such reticular approach, i. e. replacing metal ions or ligands in isostructural frameworks, can be quite effective for the development of a new breed of energetic materials

Correlation between Functionality Preference of Ru Carbenes and <i>exo</i>/<i>endo</i> Product Selectivity for Clarifying the Mechanism of Ring-Closing Enyne Metathesis

Functionality preferences of metathesis Ru carbenes to various alkenes and alkynes with electronic and steric diversity were determined by using time-dependent fluorescence quenching. The functionality preferences depend not only on the properties of multiple bonds but also on the ligands on Ru. There was a good correlation between functionality preference and the metathesis reaction outcome. The correlation between functionality preference and <i>exo</i>/<i>endo</i> product ratio offers a solution to resolve the mechanistic issue related with alkene- vs alkyne-initiated pathway in ring-closing enyne metathesis. The correlation indicates the preference is likely to dictate the reaction pathway and eventually the outcome of the reaction. The Ru catalyst favoring alkyne over alkene provides more <i>endo</i> product, indicating that the reaction mainly initiates at the alkyne. By changing the substitution pattern, the preference can be reversed to give an exclusive <i>exo</i> product