Mono‐Bisthienylethene Ring‐Fused versus Multi‐Bisthienylethene Ring‐Fused Photochromic Hybrids

Novel bisthienylethene‐based tetraazaporphyrin and phthalocyanine hybrids (BTE–TAPs) were prepared as photo‐switching molecules. All new compounds were characterized by mass spectrometry (MS), ¹H NMR spectroscopy, elemental analysis, UV‐vis absorption, and luminescence spectroscopy. All BTE–TAP compounds undergo open‐to‐closed and closed‐to‐open ring photoisomerizations in different quantum yields by irradiation with 365 nm or 730 nm light. The near‐IR luminescence of the hybrids can be regulated in a reversible manner by the photoisomerization of the bisthienylethene moiety. These compounds are useful as fluorescent probes and as non‐destructive readouts for erasable memory media. The phosphorescent BTE–TAP–Pt^II complex was also prepared, and its photochromism and changes in phosphorescence in a polycarbonate film were studied. These properties could give rise to other practical uses of BTE–TAP hybrids.