Synthesis, Characterization, and Properties of Phthalimide-Fused Phenanthrenone

The synthesis, characterization, and properties of phthalimide-fused phenanthrenone (<b>PIP</b>) and its dicyano derivative (<b>PIPCN</b>) are reported in this study. A three-step synthetic route was established for the preparation of <b>PIP</b>. Single-crystal X-ray diffraction revealed <b>PIP</b>'s rigid π-conjugated framework and significant intermolecular interactions. Systematic UV-vis absorption spectra and DFT calculations demonstrated that the dicyano group in <b>PIPCN</b> enhances intramolecular charge transfer effects, resulting in lower LUMO energy levels compared to classical imide units such as naphthalene diimide (NDI) and perylene diimide (PDI). Furthermore, Z-scan experiments highlighted <b>PIPCN</b>'s pronounced third-order nonlinear optical properties. These findings demonstrate that <b>PIP</b> and <b>PIPCN</b> are promising candidates for applications in organic electronics and nonlinear optical materials.