Solvation-Enhanced Intermolecular Charge TransferInteraction in Organic Cocrystals: Enlarged C–C Surface CloseContact in Mixed Packing between PTZ and TCNB

摘要

The mixed π–π packing of the donor (D) and acceptor (A) molecules is the highlighting feature of the intermolecular interactions following charge transfer (CT) issues in organic cocrystal systems. There is an inverse relationship between the D–A interplanar distance and the intermolecular CT interaction. However, the D–A C–C surface close contact (relative areas) on the intermolecular CT interactions in organic cocrystal systems is rarely investigated. Herein, we designed and constructed a novel cocrystal and its solvate cocrystal. The structural and electrostatic potential analyses suggest that the solvation destroys the N–H···N hydrogen bond interaction between phenothiazine (PTZ) and 1,2,4,5-tetracyanobenzene (TCNB), which causes the TCNB molecules to have a 90° rotation along the normal axis of the PTZ plane. Thus, the D–A C–C surface close contact is enlarged, strengthening the intermolecular π–π stacking interactions and intermolecular CT interaction between PTZ and TCNB, which are further evidenced by theabsorption and Raman spectroscopic analyses. This study provides rareevidence of the enlarged C–C surface close contact in the mixedpacking between D and A that greatly contributes to the intermolecularCT interaction in a D–A cocrystal system. It also providesa deeper understanding of the role of solvation in the structure–propertyrelationship of organic cocrystal materials.