2 research outputs found
Oxidation of Porphyrins in the Presence of Nucleophiles: From the Synthesis of Multisubstituted Porphyrins to the Electropolymerization of the Macrocycles
International audienc
Polymorphism, Mechanofluorochromism, and Photophysical Characterization of a Carbonyl Substituted Difluoroboron-β-Diketone Derivative
Difluoroboron-β-diketones
are known to exhibit very promising
mechanochromic luminescence but a greater understanding of these materials
and their mechanoresponsive properties is still desirable. Here we
demonstrate that a combination of spectroscopic and physicochemical
techniques is necessary to understand the variation of solid-state
fluorescence observed under mechanical stress and thermal annealing.
For this study, we decided to focus on a new fluorescent compound
showing a polymorphic behavior. Our investigation on the mechanofluorochromic
properties is based on a thorough spectroscopic study (steady-state
and time-resolved) on powder samples and thin films deposited on paper
and coverglass substrates. Three different states were identified:
two crystalline states (a stable green-emissive and a metastable yellow-emissive
one) and an amorphous phase (yellow orange emission). The detailed
photophysical properties highlight the dynamic excimer formation processes,
which can take place in the yellow-emissive crystalline and amorphous
states, along with the effect of the substrate on the thin films composition.
These results were confirmed by studying the thermal annealing process
with a combined AFM and fluorescence microscope. The switching between
these states under mechanical and thermal treatments underlies the
fluorescence color changes