Unusually high fluorescence quantum yield of a homopolyfluorenylazomethine – towards a universal fluorophore

Abstract

The absolute fluorescence quantum yield (Φfl) of a polyfluorenyl azomethine homopolymer was measured as a function of solvent polarity. The solvent induced and temperature dependent fluorescence of the homopolymer were also investigated and they were compared to the corresponding monomer and copolymer. The Φfl of the homopolymer was consistent (45-70%), regardless of solvent polarity with Stokes shifts up to 7460 cm(-1) in ethanol. In contrast, the Φfl of its corresponding monomer decreased from 60% in ethanol to 1% in toluene, whereas a Φfl < 5% for its analogous copolymer was measured. Moderate fluorescence yields (Φfl ≈ 25%) were also possible in thin film when co-depositing the homopolymer with PMMA. Cryofluorescence was used to probe the excited state deactivation modes. Deactivation by internal conversion was found to compete with fluorescence. The fluorescence deactivation pathways of the homopolymer and its corresponding monomer could be suppressed at 77 K, resulting in fluorescence turn-on. Both fluorophores were found to detect nitroaromatics.

A redox-mediator pathway for enhanced multi-colour electrochemiluminescence in aqueous solution

“…Low temperature PL spectra were obtained using 5 mM metal complex in an ethanol : methanol (4 : 1) mixture that was cooled to 85 K using an OptistatDN Variable Temperature Liquid Nitrogen Cryostat equipped with custom-made quartz sample holder. 54 The temperature of 85 K was used to avoid damage to the spectroscopic cuvettes which occurred at 77 K. 55 We previously found no signicant difference in l max in the spectra of [Ru(bpy) 3 ] 2+ and Ir(ppy) 3 measured at these two temperatures under these instrumental conditions. 54 All PL emission spectra were corrected for the change in instrumental sensitivity over the wavelength range by multiplication with correction curves established using a quartz halogen tungsten lamp.…”

CdS Nanoplates Modification as a Platform for Synthesis of Blue-Emitting Nanoparticles

“…It is possible that the defect-free NP surface obtained during consecutive forward and reverse phase transfer is responsible for such exceptional optical properties [ 16 ]. This value of PL QY is e.g., much higher than for most of the blue emitting organic fluorophores [ 17 ].…”

A conceptual framework for the development of iridium(iii) complex-based electrogenerated chemiluminescence labels

“…For the low temperature emission spectra, the complexes were prepared at 5 μM in ethanol : methanol (4 : 1) and cooled to 85 K using an OptistatDN Variable Temperature Liquid Nitrogen Cryostat equipped with custom-made quartz sample holder. The low temperature spectra were collected at 85 K to avoid damage to the spectroscopic cuvettes near 77 K observed during our previous study17 and by others 57. No significant difference in the λ max for metal complexes such as [Ru(bpy) 3 ] 2+ and Ir(ppy) 3 between 77 K and 85 K was observed under these instrumental conditions 30.…”