Effects of Nitro-Substitution on the Spectroscopic and Self-Assembly Properties of BODIPY Dyes.

A series of boron dipyrromethene (BODIPY) dyes were nitrated in high yields using nitronium tetrafluoroborate at positions 2, 3, and 2,6 of the BODIPY core. This method allows for the regioselective nitration of the pyrrolic positions under milder conditions than previously reported methods. The photophysical properties and electronic transitions of these BODIPYs were investigated by using UV-vis spectroscopy, fluorescence spectroscopy, and density-functional theory (DFT) calculations.

8()-Pyridyl-BODIPYs: Effects of 2,6-Substitution with Electron-Withdrawing Nitro, Chloro, and Methoxycarbonyl Groups.

The introduction of electron-withdrawing groups on 8()-pyridyl-BODIPYs tends to increase the fluorescence quantum yields of this type of compound due to the decrease in electronic charge density on the BODIPY core. A new series of 8()-pyridyl-BODIPYs bearing a 2-, 3-, or 4-pyridyl group was synthesized and functionalized with nitro and chlorine groups at the 2,6-positions. The 2,6-methoxycarbonyl-8-pyridyl-BODIPYs analogs were also synthesized by condensation of 2,4-dimethyl-3-methoxycarbonyl-pyrrole with 2-, 3-, or 4-formylpyridine followed by oxidation and boron complexation.

A Comparison of the Photophysical, Electrochemical and Cytotoxic Properties of -(2-, 3- and 4-Pyridyl)-BODIPYs and Their Derivatives.

Boron dipyrromethene (BODIPY) dyes bearing a pyridyl moiety have been used as metal ion sensors, pH sensors, fluorescence probes, and as sensitizers for phototherapy. A comparative study of the properties of the three structural isomers of -pyridyl-BODIPYs, their 2,6-dichloro derivatives, and their corresponding methylated cationic pyridinium-BODIPYs was conducted using spectroscopic and electrochemical methods, X-ray analyses, and TD-DFT calculations. Among the neutral derivatives, the and isomers showed the highest relative fluorescence quantum yields in organic solvents, which were further enhanced 2-4-fold via the introduction of two chlorines at the 2,6-positions.