Fluorophore Ligand Doping in Metal–Organic Nanotubes

Anisotropic fluorescent materials, such as surface-functionalized carbon nanotubes and organic crystals, show promise in sensing and signal detection but suffer from lack of tunability and ease of synthesis. In contrast, metal–organic nanotubes (MONTs) offer structural flexibility akin to MOFs since they are synthesized in the same manner. While a few fluorescent MONTs have been reported, their emission arises from ligand-to-metal charge transfer or second harmonic generation, neither of which takes advantage of their ability to employ designer ligands. Herein, a new fluoranthene-core di-1,2,4-triazole ligand with sky blue emission has been synthesized for fluorescent MONTs. Fluorescent MONTs were successfully synthesized by doping small amounts (1–10%) of the fluoranthene ligand into an isostructural silver MONT reaction. These fluorescent MONTs were characterized by single-crystal X-ray diffraction, PXRD, and NMR spectroscopy following acid digestion, which quantified the amount of fluoranthene dopant. Notably, the fluorophore can even be added postsynthetically after the MONTs are already synthesized, demonstrating ligand exchange.