Synthesis of Two Novels-Shaped Dibenzo[c,l] Chrysene Derivatives, Crystal Structure, and the Evaluation of their Photophysical Properties

Two s-shaped polyaromatic dibenzo[c,l] chrysene derivatives have been synthesized by a two-step process, via. The Wittig reaction, followed by iodine, promoted photocyclization. These molecules have been characterized by H-1 NMR, FAB-MS, and elemental analysis. Further, the molecular structures of 4a and 4b have been confirmed by single crystal X-ray diffraction analysis. The protons located in the cove-regions of molecules 4a and 4b showed downfield shifts of the protons. Molecule 4a crystallized under the monoclinic system with space group C2/c, and the molecule 4b crystallized under the monoclinic system with space group P2(1)/n. Molecules 4a and 4b showed strong absorption maxima wavelengths at 310 nm and 324 nm, respectively. The molar extinctinction coefficients (epsilon) of the compounds 4a and 4b indicated that molecule 4b has a better ability to absorb UV light than molecule 4a. The emission spectra of the molecules 4a and 4b displayed peaks in the region 429-456 nm. The shape of the UV-Visible and Fluorescence spectra of the molecules 4a and 4b look almost identical. However, molecule 4b exhibited better fluorescence intensity than molecule 4a. This may be due to the difference in the substituents of molecules 4a and 4b.