A new class of laser dyes, 2-oxa-bicyclo[3.3.0]octa-4,8-diene-3,6-diones, with unity fluorescence yield

Abstract

A new class of highly fluorescent dyes, 4,8-diphenyl-2-oxa-bicyclo[3.3.0]octa-4,8-diene-3,6-diones (1a-c), have been synthesized, they all exhibit unity fluorescence quantum yield and short radiative lifetime (< 4 ns) in common organic solvents and have demonstrated remarkable amplified spontaneous emission with a gain efficiency of > 10.

Carbon Nanomaterials for Biological Imaging and Nanomedicinal Therapy

“…For biomedical imaging, we have covered a broad range of optical and nonoptical imaging applications using carbon nanomaterials, with a focus on NIR-II fluorescence imaging with SWCNTs. The NIR-II fluorescence emission of SWCNTs under excitation in the visible and NIR-I windows is unique to SWCNTs, and has not been found with any other materials or molecules until more recently. ,, Although all other carbon nanomaterials than SWCNTs only have fluorescence emission in the conventional spectral regions, the resistance to photobleaching makes them more durable fluorescent labels than organic fluorophores for long-term in vitro and in vivo imaging and tracking experiments, despite their lower fluorescence quantum yields than regular fluorophores such as quantum dots and organic dyes. − Besides fluorescence imaging, graphitic carbon nanomaterials such as CNTs and graphene also have Raman signatures that support resonant Raman spectroscopy and imaging, and their extremely large Raman scattering cross sections owing to resonant Raman scattering process make them equally promising Raman probes as SERS nanoparticles for in vitro and in vivo biomedical imaging. ,, All carbon nanomaterials with optical absorbance at certain wavelengths should theoretically be imaged with transient absorption microscopy and photoacoustic imaging, while their large surface area also allows for loading other imaging contrast agents for X-ray CT, MRI, PET, and SPECT imaging modalities.…”