Coordination Polymerization of Metal Azides and Powerful Nitrogen-Rich Ligand toward Primary Explosives with Excellent Energetic Performances

Abstract

Advancement in explosive systems toward miniaturization and enhanced safety has prompted the development of primary explosives with powerful detonation performance and relatively low sensitivities. Energetic coordination polymers (ECPs) as a new type of energetic materials have attracted wide attention. However, regulating the energetic characters of ECPs and establishing the relationship between structure and energetic property remains great challenges. In this study, two isomorphic 2D π-stacked solvent-free coordination polymers, [M(N 3 ) 2 (atrz)] n (M = Co 1, Cd 2; atrz = 4,4′-azo-1,2,4-triazole), were hydrothermally prepared and structurally characterized by X-ray diffraction. The two compounds exhibit reliable stabilities, remarkable positive enthalpies of formation, and prominent heats of detonation. The enthalpy of formation of 1 is 4.21 kJ•g −1 , which is higher than those of all hitherto known primary explosives. Repulsive steric clashes between the sensitive azide ions in 1 and 2 influence the mechanical sensitivities deduced from the calculated noncovalent interaction domains. The two energetic π-stacked ECPs 1 and 2 can serve as candidates for primary explosives with an approved level of safety.

Coexistence of Spin Canting and Metamagnetism in a One-Dimensional Mn(II) Compound Bridged by Alternating Double End-to-End and Double End-On Azido Ligands and the Analog Co(II) Compound

“…Coordination compounds with azide ligand have been studied for decades, not only for their potential use as detonation agents or explosives [1][2][3][4][5], but also because of the intrinsic properties of N 3 − as a "pseudo halogen" [6,7] and as a subject of magnetism [8]. Many studies of stable azide coordination compounds have been reported, and the Cambridge Structural Database (2020 release) contains over 5000 items having at least one coordinated azide ligand [9].…”

A green metal-free fused-ring initiating substance

“…Looking back upon the historical development of lead-free primary explosives (see Table 1 ), both inorganic energetic metal complexes and organic explosive substances have been explored 4 – 17 . For most metal-based primary explosives, either perchlorate (ClO 4 − ) or heavy metals (Co, Ni, Cu, Zn, Cd, Hg, etc.)…”

Framework-Interpenetrated Nitrogen-Rich Zn(II) Metal–Organic Frameworks for Energetic Materials

“…The Δ c H value of 1 is greater than those of most previously reported 3D energetic MOFs, such as [Cu 3 (MA) 2 (N 3 ) 3 ] (CuMAA, MA = melamine) (−9.73 kJ/g), Cd 3 (atz) 4 (N 3 ) 2 (CdatzA = Cd 3 (atz) 4 (N 3 ) 2 , Hatz = 3-amino-1,2,4-triazole) (−8.561 kJ/g), (Et 4 N)­[Cd 6 Br 5 (ATZ) 8 ]·H 2 O (CdATZ, HATZ = 5-aminotetrazolate, Et = ethyl) (−6.672 kJ/g), CoBTA (−5.92 kJ/g) (CoBTA = [Co 9 (BTA) 10 (HBTA) 2 (H 2 O) 10 ] n (H 2 BTA = N , N ′-bis­(1 H -tetrazole-5-yl)-amine)), and comparable to that of the recently reported mixed-ligand 2D energetic MOFs, [Co­(N 3 ) 2 (atrz)] n (−11.939 kJ/g) and [Cd­(N 3 ) 2 (atrz)] n (−10.745 kJ/g) (atrz = 4,4′-azo-1,2,4-triazole). The nitrogen content and calculated density (ρ) of [Co­(N 3 ) 2 (atrz)] n are 63.81% and 2.094 g/cm 3 , respectively, and those of [Cd­(N 3 ) 2 (atrz)] n are 53.99% and 2.282 g/cm 3 , respectively . In 2011, Yang’s group prepared a one-dimensional N-rich mixed-ligands Zn­(II)-based compound [Zn­(N 2 H 4 ) 2 (N 3 ) 2 ] n (ZnHA) (N% = 65.6%).…”