Difluoroboron β-diketonate dye with intense red/near-infrared fluorescence in solutions and solid states

Difluoroboronβ-diketonate(BF2bdk)complexes have attracted much attention due to their outstanding photophysical properties.However,BF2bdk with near-infrared fluorescence usually suffer from emission quenching in solid state due to theπ-πstacking in aggregation.Herein,we report a BF2bdk dye exhibiting donor-acceptor(D-A)structure with the difluoroboron moiety acting as the electron acceptor and the aminonaphthalene as the electron donor.It processes intense molar extinction coefficient,large Stokes shift and strong fluorescence in red/NIR region in both solution and aggregations.It was used for NIR imaging in living cells.

An overview on AIEgen-decorated porphyrins:Current status and applications

One of the major obstacles of porphyrins is the aggregation-caused quenching(ACQ)of photoluminescence due to the strong intermolecularπ–πinteraction of the planar porphyrin core in the solid state.However,ACQ leads to the nonradiative deactivation of the photoexcited states which results in short-lived charge-separated states and thus low photoluminescence and singlet quantum yields.This phenomenon would limit the utilization of porphyrins in near-infrared fluorescent bioimaging,photodynamic therapy,photocatalytic hydrogen evolution,electrochemiluminescence,and chiroptical applications.Hence,to address the ACQ property of porphyrins and enhance the performance of the above applications,a limited number of AIEgen-decorated porphyrins have been designed,synthesized,and tested for their applications.It has been found that the introduction of AIEgens,such as tetraphenylethylene,diphenylacrylonitrile,(3,6-bis-(1-methyl-4-vinylpyridinium)-carbazole diiodide,and iridium motif into the porphyrin core,transformed the porphyrins from ACQ to aggregation-induced emission(AIE)in their solid state due to the reduced strong intermolecularπ–πstacking of porphyrins.Consequently,such porphyrins containing AIE features are employed as potential candidates in the above-mentioned applications.In this review,we summarize the AIEgen-decorated porphyrins which have been published to date,and also discuss the benefits of converting porphyrins from ACQ to AIE for enhanced performance within each application.As far as we know,there is no review that summarizes the structures and applications of AIEgen-decorated porphyrins to date.Therefore,we presume that this review would be helpful to design more efficient AIEgen-decorated porphyrins for a wide range of applications in the future.

Synthesis and Spectral Properties of 4-（2,5-Dimethoxyphenyl- methelene）-2-phenyl-5-oxazolone （DMPO）

An interesting flourophore, 4-（2,5-dimethoxyphenylmethelene）-2-phenyl-5-oxazolone （DMPO） was synthesized by mixing an equivalent molar quantity of hippuric acid and 2,5-dimethoxybenzaldehyde in acetic anhydride in the presence of anhydrous sodium acetate. The absorption and fluorescence characteristics of 4-（2,5-dimethoxy-phenyl- methelene）-2-phenyl-5-oxazolone （DMPO） were investigated in different solvents. DMPO dye exhibits red shift in both absorption and emission spectra as solvent polarity increases, indicating change in the dipole moment of mole- cules upon excitation due to an intramolecular charge transfer interaction. The fluorescence quantum yield depends strongly on the properties of the solvents, which was attributed to positive and negative solvatokinetic effects. A crystalline solid of DMPO gave strong excimer like emission at 630 nm due to the excitation of molecular aggregates. This is expected from the idealized crystal structure of the dye that belongs to the B-type class of Steven＇s Classifica- tion. DMPO displayed fluorescence quenching by triethylamine via nonemissive exciplex formation.