Azole-Fused High-Energy Heterocycles: A Decade of Synthetic Innovation and Structure–Property Insights (2015–2025)

As modern weaponry and equipment evolve, there is an increasing demand for more powerful, less sensitive, and environmentally benign energetic materials. Fused heterocycle-based energetic materials, large conjugated systems composed of two or more rings that share adjacent atoms, exhibit superior thermal stability and higher density than their monocyclic and bridged analogs. Meanwhile, similar to cage heterocyclic rings, the fused structures generally possess higher heats of formation and elevated ring-strain energies, which enhance detonation performance. In addition, the fused backbones offer versatile modification sites, enabling researchers to balance energy and stability by introducing different functional groups. This review summarizes the research progress on 97 energetic fused heterocyclic compounds from the Web of Science (WOS) and Scopus databases since 2015 and presents their molecular design strategies, synthesis methods, and detonation properties. Furthermore, the major challenges are associated with the design of complex fused-ring frameworks and the large-scale preparation. This review highlights the insightful future research directions, particularly the development of universal synthesis strategies and the exploration of AI-driven automated design.