Aggregation behavior and spectroscopic properties of red-emitting distyryl-BODIPY in aqueous solution, Langmuir-Schaefer films and Pluoronic® F127 micelles.

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF2-ms-phenyl-5,5'-bis(4-dimethylaminostyryl)-3,3'-dimethyl-2,2'-dipyrromethene (distyryl-BDP). The particular attention was paid to analysis of high sensitivity of the distyryl-BDP spectral characteristics to the solvent properties, and also the aggregation behavior features both in water-organic media and in mono- and multilayer Langmuir-Schaefer films. We selected the best conditions to obtain the hydrophilic micellar structures of distyryl-BDP with Pluronic® F127 having a high efficiency of dye solubilization. This method increasing the solubility improves the distyryl-BDP transport efficiency in physiological aqueous media. The aqueous solutions of distyryl-BDP-Pl micelles show the intense fluorescence in the phototherapy window region (λfl = 739 nm).

Synthesis and Photochemical Properties of 2,3;5,6-bis(cyclohexano)-BODIPY.

The boron-dipyrromethene (BODIPY) dye containing an annelated cyclohexyl rings at the 2,3 and 5,6-positions of pyrroles has been synthesized and characterized. Photochemical properties of the obtained compound have been investigated in different individual solvents. 2,3;5,6-Bis(cyclohexano)-BODIPY exhibits intense chromophore properties with maximum of S o → S 1 band in the 543-549 nm (A from 66000 to 96000 L/mol·cm). The complex is a fluorophore with a quantum yield up to ~ 100%. The influence of solvent polarity on the spectral properties was evaluated. To better understand the spectroscopic results, quantum chemical calculations were carried out. Photostability of dye was studied.Graphical Abstract.

Influence of structural and solvation factors on the spectral-fluorescent properties of alkyl-substituted BODIPYs in solutions.

The spectral-fluorescent properties of alkyl-substituted BODIPYs 1-5 in organic solvents were investigated. The alkyl-substituted BODIPYs 1-5 exhibit intense chromophoric properties (lgε=4.60-5.00). Relative fluorescence quantum yield of studied compounds reaches 66-100% and weakly dependent on the structural and solvation effects. Introduction of methyl, propyl, amyl and heptyl substituents in the 2,6-positions of the pyrroles the results in a significant red shift (22-29nm) in the electronic absorption and fluorescence spectra.

A New Sensitive and Selective Off-On Fluorescent Zn2+ Chemosensor Based on 3,3',5,5'-Tetraphenylsubstituted Dipyrromethene.

3,3',5,5'-Tetraphenyl-2,2'-dipyrromethene was described as a highly sensitive and selective Off-on fluorescent colorimetric chemosensor for Zn2+ based on the chelation-enhanced fluorescence (CHEF) effect. The reaction of dipyrromethene ligand with Zn2+ induces the formation of the [ZnL2] complex, which exhibits the increasing fluorescence in 120 fold compared with ligand in the propanol-1/cyclohexane (1:30) binary mixture. The Zn2+ detection limit was 1.4 × 10-7 М. The UV-Vis and fluorescence spectroscopic studies demonstrated that the dipyrromethene sensor was highly selective toward Zn2+ cations over other metal ions (Na+, Mg2+, Co2+, Ni2+, Fe3+, Cu2+, Mn2+, Cd2+ and Pb2+), excluding Hg2+.