ABSTRACT
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.
ABSTRACT
A photolytically generated ruthenium hydride species catalyzing a free radical cyclization reaction was developed. As the new methodology ensures reproducibility of the free radical reaction of trialkyltin hydrides and a fast hydrogen transfer to the radical intermediates, the methodology provides fast quenching of radical intermediates and thus suppresses rearrangement of radical intermediates before the hydride quench. By offering new reactivity and selectivity to the trialkyltin hydride mediated free radical cyclization reactions, the methodology will find wide range of applications in organic synthesis.
ABSTRACT
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.
ABSTRACT
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.