From Structural Stabilization to Photochemical Activation: Hydrogen-Bond Interactions Govern Nonequilibrium Reactivity

Understanding how hydrogen-bond interactions govern nonequilibrium photochemical reactivity is essential for controlling the stability and functionality of molecular crystals. Using crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as a representative molecular crystal, we investigate the microscopic origin of its anomalous photosensitivity. We find that decomposition is initiated by coupled proton–electron dynamics, which drive directional charge redistribution along amino-nitro hydrogen-bond motifs. The resulting enhancement of donor–acceptor polarization destabilizes the aromatic π-framework, induces anisotropic structural deformation, and ultimately promotes bond-selective molecular dissociation. This electronically directed pathway is fundamentally distinct from thermally activated decomposition and provides a microscopic explanation for the longstanding stability–sensitivity paradox of TATB. Our findings establish a structure-dynamics-reactivity relationship linking hydrogen-bond-assisted proton–electron coupling to bond-selective photochemistry, providing a mechanistic framework for understanding and controlling nonequilibrium reactivity in molecular crystals.