Conformationally Controlled Electron Delocalization in n-Type Rods: Synthesis, Structure, and Optical, Electrochemical, and Spectroelectrochemical Properties of Dicyanocyclophanesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 7 февраля 2018 г.
Аннотация:A series of dicyanobiphenylcyclophanes 1–6 with various π-backbone conformations and characteristic n-type semiconductor properties is presented. Their synthesis, optical, structural, electrochemical, spectroelectrochemical, and packing properties are investigated. The X-ray crystal structures of all n-type rods allow the systematic correlation of structural features with physical properties. In addition, the results are supported by quantum mechanical calculations based on density functional theory. A two-step reduction process is observed for all n-type rods, in which the first step is reversible. The potential gap between the reduction processes depends linearly on the cos2 value of the torsion angle φ between the π-systems. Similarly, optical absorption spectroscopy shows that the vertical excitation energy of the conjugation band correlates with the cos2 value of the torsion angle φ. These correlations demonstrate that the fixed intramolecular torsion angle φ is the dominant factor determining the extent of electron delocalization in these model compounds, and that the angle φ measured in the solid-state structure is a good proxy for the molecular conformation in solution. Spectroelectrochemical investigations demonstrate that conformational rigidity is maintained even in the radical anion form. In particular, the absorption bands corresponding to the SOMO–LUMO+i transitions are shifted bathochromically, whereas the absorption bands corresponding to the HOMO–SOMO transition are shifted hypsochromically with increasing torsion angle φ.