An Uncommon Solvent-Controlled Photochromic Tetraphenylethylene-Based Co-crystal

A co-crystal FJU-182 with a closed cage structure with photochromic phenomenon was formed using a tetraphenylene derivatives 4,4 ',4 '',4 '''-(anthracene-9,10-diylidenebis(methanediyl-ylidene))tetrabenzoic acid self-assembled with 1,3-di(4-pyridyl)propane in a solvent. It was also found that isomorphic crystals grown from different solvents exhibited different fluorescence. The electron paramagnetic resonance and X-ray photoelectron spectroscopy data showed that the photochromic mechanism of crystal FJU-182 was due to photoinduced electron transfer, while the different color change of crystals grown from different solvents was attributed to the size of solvent molecules. The I-V curves of the crystals FJU-182 before and after illumination were also tested, and it was found that the conductivity of the crystals before the color change would be 3-8 times higher than the conductivity of the crystals after the color development. FJU-182 provides a new case for electrochemical devices with photoelectric response.