Charge Assisted H Bonding and Semiconductivity in Cocrystal of Ethane‐1, 2‐diylbis(diphenylphosphine Oxide) and 2 Naphthol

ABSTRACT Organic semiconductors are of great importance because of their low‐cost processing, flexibility, and lightweight nature. We have recently synthesized cocrystal 1 of ethane‐1, 2‐diylbis(diphenylphosphine oxide) and 2‐naphthol which is characterized by NMR and single‐crystal X‐ray diffraction study. Electrical conductivity measurement on a single crystal of 1 showed a semiconductive behavior over the voltage range of ‐15 to +10 V. DFT calculations were performed with structures of 1 with variable phenolic O─H distances. A lower HOMO‐LUMO energy gap was observed in the case of a large O─H distance which is also reflected in the TDDFT by an apparent redshift in the case of the structure with a large phenolic O─H distance. The noncovalent interaction (NCI) plot with the structure of 1 represented the strong charge‐assisted H‐bonding between the O─H of 2‐naphthol and P = O group of ethane‐1, 2‐diylbis (diphenylphosphine oxide) along with the charge transfer band in the EPR spectra.