The observed self-assembly was rationalized by quantum chemical calculations showing a unique charge distribution in its anionic form, with a gradient of charge yielding a neat molecular in-plane electric dipole momentum, which transforms out-of-plane after surface deposition due to twisted → folded conformational change and to partial charge transfer from Au(111). Intermolecular van der Waals interactions and antiparallel trapezoidal shape fitting lead to the formation of an optimal dense on Au(111) two-dimensional assembly of this new compound.