A new compound (1) formed by two antiparallelly disposed tetracyano thienoquinoidal units has been synthesized and studied by electrochemistry, UV/Vis-NIR, IR, EPR, and transient spectroscopy. Self-assembly of 1 on a Au(111) surface has been investigated by scanning tunneling microscopy. Experiments have been rationalized by quantum chemical calculations. 1 exhibits 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-surface two-dimensional assembly of 1.
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A Trapezoidal Octacyanoquinoid Acceptor Forms Solution & Surface Products by Antiparallel Shape Fitting with Conformational Dipole Momentum Switch, Juan Casado, Samara Medina Rivero, Javier Urieta-Mora, Agustín Molina-Ontoria, Cristina Martín-Fuentes, Jose Ignacio Urgel, María Zubiria-Ulacia, Vega Lloveras, David Casanova, Jose Ignacio Martinez, Jaume Veciana, David Ecija, Nazario Martín, Angew. Chem. Int. Ed., DOI: 10.1002/anie.202104294 (2021)