Abstract
Metal-organic frameworks (MOFs) based on 9,10-diphenylanthracene-derived ligands had been reported to exhibit upconverted fluorescence through triplet-triplet annihilation. We found that zirconium MOFs based on 9,10-diphenylanthracene can also give upconverted fluorescence via two-photon absorption without adding a triplet photosensitizer when a femtosecond pulsed laser is used as the excitation source. By tuning the synthetic condition, we obtained nanoscale MOFs of UiO structure in both octahedral and hexagonal nanoplate shapes, as well as a hexagonal nanoplate of MOFs of hcp-UiO structure and two-dimensional metal-organic layers. All of them, as well as a homogeneous solution of the 9,10-diphenylanthracene ligand, exhibit upconverted fluorescence upon excitation using a laser pulse of 60 fs with a pulse energy of ∼1.1 × 106 nJ/cm2 (unfocused). Moreover, we observed different emission spectra by two-photon excitation compared to those by one-photon excitation, which indicates access to a unique initial excited state via two-photon excitation. This phenomenon is not observed for a homogeneous solution of the ligand. These nanoscale MOFs may find application in two-photon fluorescence imaging.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.