We have examined the reactions of 1,3-disubstituted isobenzofurans with the fullerene C60 in the context of an approach to open a large orifice on the fullerene framework. A variety of substituted isobenzofurans (6a-h), generated from the reaction of 1,4-substituted 1,4-epoxynaphthalenes 3a-h with 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (4a) or 1,2,4,5-tetrazine (4b), were added to C60 to afford the Diels-Alder adducts 7a-h. The thermal stability of these adducts toward retro-Diels-Alder fragmentation differs greatly in solution from that in the solid state. In solution, the relatively facile retro-Diels-Alder fragmentation of monoadducts 7a and 7c, to give C60 and the free isobenzofurans 6a and 6c, have rate constants (and activation barriers) of k=9.29x10(-5) s-1 at 70 degrees C (Ea=32.6 kcal mol-1) and k=1.36x10(-4) s-1 at 40 degrees C (Ea=33.7 kcal mol-1), respectively, indicating that the addition of isobenzofurans to C60 is readily reversible at those temperatures. In the solid state, thermogravimetric analysis of adduct 7a indicates that its decomposition occurs only within the temperature range of 220-300 degrees C. As a result, these compounds can be stored at room temperature in the solid state for several weeks without significant decomposition but have to be handled within several hours in solution.

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U.S. Army ARDEC has been examining a novel pyroelectric-type material developed by Digital Solid State Propulsion, LLC for its unique combustion properties and insensitivity. This unique ECEM is formed using an ionic liquid oxidizer and polymer fuel, via sol-gel processes and is quite dense, making it very suitable for energetic applications in both the civilian and military fields. This ECEM is completely insensitive to the application of impact, flame, friction, and shock threats. Once a power of the required voltage is applied, the baseline ECEM rapidly initiates combustion with H2O, CO2, and N2 formed as the only major gas phase products produced. Initial testing of ECEM in perforated pipes appears promising as indicated by uniform ignition along the entire length of the test assembly.

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