The impact of the molecular structure on aggregation and solid state luminescence of 2,3-diarylfumaronitriles

This work focuses on the substituent effect in 2,3-diarylfumaronitriles on the optical properties and intermolecular interactions in the solid state. 2,3-Diarylfumaronitriles show various luminescence behaviour in solution and in the solid state. Aggregation patterns of 2,3-diarylfumaronitriles govern their luminescent properties in the solid state. The weak intermolecular interactions N C center dot center dot center dot N C, C-H center dot center dot center dot Cl, and C-H center dot center dot center dot N C were detected in the X-ray structures of 2,3-diarylfumaronitriles and studied by DFT calculations at the M06-2X/6-311++G(d,p) level of theory and topological analysis of the electron density distribution within the framework of QTAIM method. The estimated strength of these non-covalent bonds is 0.8-1.3 kcal/mol. The orientation of molecules in crystals depends on the substituents in 2,3-diarylfumaronitriles. Distinct molecular orientation and packing arrangements in crystalline 2,3-diarylfumaronitriles ensured perturbed electronic communication amongst the nearest and non-nearest molecules through an interplay of excimer and dipole couplings. As a result, the intermolecular interactions govern the solid state luminescence of molecules. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This work investigates the substituent effect in 2,3-diarylfumaronitriles on optical properties and intermolecular interactions in the solid state. The study reveals that non-covalent bonds, such as N C···N C, C-H···Cl, and C-H···N C interactions, influence the solid-state luminescent properties of molecules, affecting electronic communication between molecules.