Effects of Heavy Iodine Atoms and π‐Expanded Conjugation on Charge Transfer Dynamics in Carboxylic Acid BODIPY Derivatives as Triplet Photosensitizers

Abstract

Borondipyrromethene (BODIPY) chromophores are composed of a functional-COOH group at meso position with or without a biphenyl ring, and their compounds with heavy iodine atoms at À 2, À 6 positions of the BODIPY indacene core were synthesized. The photophysical properties of the compounds were studied with steady-state absorption and fluorescence measurements. It was observed that the absorption band is significantly red-shifted, and fluorescence signals are quenched in the presence of iodine atoms. In addition to that, it was indicated that the biphenyl ring does not affect the spectral shifting in the absorption as well as fluorescence spectra. In an attempt to investigate the effect of π-expanded biphenyl moieties and heavy iodine atoms on charge transfer dynamics, femtosecond transient absorption spectroscopy measurements were carried out in the environment of the tetrahydrofuran (THF) solution.Based on the performed ultrafast pump-probe spectroscopy, BODIPY compounds with iodine atoms lead to intersystem crossing (ISC) and ISC rates were determined as 150 ps and 180 ps for iodine BODIPY compounds with and without πexpanded biphenyl moieties, respectively. According to the theoretical results, the charge transfer in the investigated compounds mostly appears to be intrinsic local excitations, corresponding to high photoluminescence efficiency. These experimental findings are useful for the design and study of the fundamental photochemistry of organic triplet photosensitizers.

Electrochemical Diselenation of BODIPY Fluorophores for Bioimaging Applications and Sensitization of 1O2

“…Despite the tendency of TD-DFT to overestimate transition energies, the bathochromic effect induced by diselenide substitution is qualitatively captured. As previously discussed, and supported by existing literature, [24] the S 0 !S 1 transitions in BODIPYs are typically attributed to 1 π-π* transition characterized by minimal charge transfer, typical for HOMO-LUMO (HÀ L) transitions. The NTO analysis depicted in Figure 3 aligns with this picture.…”

Nonlinear optical response of silver trimer adsorbed para-aminobenzoic acid: A DFT study

“…However, the sharp peak of the absorption of PABA+Ag 3 was observed around 390 nm. The drastic shift in the maximum absorption wavelength of the complex was due to the maximum absorption wavelength of Ag nanoparticles around 400 nm which was observed in a lot of experimental studies previously [45,46]. Thus, taking the maximum wavelength of Ag nanoparticles into consideration, the Ag 3 trimer considered in the present study which has a maximum absorption wavelength of 417 nm can be considered as a nanoparticle.…”

Engineering Metal Halide Perovskite Nanocrystals with BODIPY Dyes for Photosensitization and Photocatalytic Applications

“…The BDP absorption maximum (506 nm) was close to that of the NC exciton, as shown in Figure b, in contrast to that of I2-BDP, with an absorption maximum at 540 nm, as shown in Figure c. Thus, the iodine substituents of I2-BDP produced a significant effect on the absorption properties of NC@I2-BDP, , namely, a redshift of the peak at ca. 50 nm, thus improving the dye light absorption in the visible window.…”