Content area
Abstract
This study describes the synthesis of N,N'-dinitroethylene diamine (EDNA) co-crystals, coordination polymers and organic salts to determine the feasibility and potential use as energetic materials by exploiting intermolecular motifs and functional groups.
A variety of co-crystals of EDNA using the aromatic diamine co-formers; 4,4'-bipyridyl (CC-1), 1,2-di(4-pyridyl)ethylene (CC-2) and 4,4'-azopyridine (CC-3) were synthesized using literature methods exploiting the moderate N—H...N(py) type hydrogen bond. Four coordination polymers of EDNA were synthesized by established literature methods requiring the deprotonation of EDNA and the consequent addition of the divalent metals; Co(II) [MS-1], Ni(II) [MS-2], Cu(II) [MS-3] and Sr(II) [MS-4]. Finally, two organic salts of EDNA were synthesized using the basic, short chained alkyl diamines; propane-1,3-diamine (OS-1) and butane-1,4-diamine (OS-2).
All compounds were then characterized by IR spectroscopy, single crystal X-ray diffractometry, thermal analyses such as differential scanning calorimetry and thermogravimetric analysis.
The use of the N—H...N(py) hydrogen bond has been successfully exploited in the formation of co-crystals. The importance of π-π, anion-π, lp-π interactions in the driving of packing arrangement have been observed. An overall decrease in energetic and thermal properties was reported when non-energetic co-formers, due to a higher carbon content, are used in the synthesized co-crystals.
The synthesized coordination polymers all resulted in increased crystallographic densities, oxygen balance values and thermal decomposition values, apart from MS-3, which had a lower decomposition value (162 °C).
The resulting organic salts all displayed increased thermal decomposition temperatures along with slightly lowered energetic properties due to increased carbon content.
Flame tests were carried out, classifying the newly formed products as either explosives, propellants or pyrotechnics, with results being that all compounds could potentially be used as propellants and MS-4 as a potential pyrotechnic.
