Preferential Orientation of Crystals and its Influence on the Emission Wavelength of Acrylonitrile Derivatives Treated with Polar Solvents

Abstract

AbstractPhotoluminescence properties in solid state and its relationship with structural features of prop‐2‐enenitrile derivatives containing any of functional groups 4‐halogenphenyl, phenyl, 4‐dimethylamino, or 4‐diphenylamino are investigated. The compounds show change in color from yellow to orange after treatment with dimethyl sulfoxide or dimethyl formamide. Nevertheless, the single‐crystal X‐ray diffraction for both, the original yellow and the treated orange crystals, does not display any major structural differences. The optical properties are related to the crystal packing and intermolecular interactions such as edge‐to‐face through the vertices of aromatic rings. The last is supported by the behavior of the presence of functional group. The absorption spectrum in solution for all compounds shows two absorption bands with wavelength of maximum absorption around 390–430 nm and at 290–300 nm. Regardless of the crystal type, the maximum emission in solution was between 450–570 nm. In solid state, yellow crystals exhibit an emission in the 500–530 nm range and in the 580–630 nm range for orange crystals. Results suggest that optical properties are strongly dependent on morphology and habit. Powder X‐ray characterization shows a preferential orientation for orange crystals. All compounds are characterized by common spectroscopy techniques, fluorescence, atomic force microscopy and X‐ray diffraction.