Light‐controlled 1D to 2D 2,3‐Diaminophenazine Self‐assembly Transformation on Cu(111) Surface

Controlled molecular self-assembly enables precise engineering of nanomaterials with programmable dimensionality and functionality. Conventional thermal-driven approaches, however, often struggle to achieve structural complexity due to weak intermolecular interactions and entropy-driven disorder at elevated temperatures. Here, we introduce a light-controlled methodology to realize a dimensionality transformation of carbon nitride-based architectures on a Cu(111) surface, bypassing the limitations of thermal processing. By applying ultraviolet (UV) light irradiation, we achieve the controlled conversion of 1D self-assembled nanoribbons of 2,3-diaminophenazine (DAP), a carbon nitride precursor, into ordered 2D extended frameworks. This light-driven 1D-to-2D structural evolution starkly contrasts with thermal treatments, which exclusively produce disordered aggregates under comparable conditions. Remarkably, this transformation proceeds without requiring light-reactive chemicals, underscoring the unique capability of UV light to direct molecular reorganization at interfaces. The work establishes a paradigm for manipulating nanoscale dimensionality in carbon nitride systems, circumventing conventional entropy limitations and offering a versatile platform for designing advanced 2D functional materials with applications in photocatalysis, nanoelectronics, and surface-supported molecular engineering.