Understanding of Förster Resonance Energy Transfer (FRET) in Ionic Materials

Abstract

Herein, an ionic material (IM) with Förster Resonance Energy Transfer (FRET) characteristics is reported for the first time. The IM is designed by pairing a Nile Blue A cation (NBA+) with an anionic near-infrared (NIR) dye, IR820−, using a facile ion exchange reaction. These two dyes absorb at different wavelength regions. In addition, NBA+ fluorescence emission spectrum overlaps with IR820− absorption spectrum, which is one requirement for the occurrence of the FRET phenomenon. Therefore, the photophysical properties of the IM were studied in detail to investigate the FRET mechanism in IM for potential dye sensitized solar cell (DSSCs) application. Detailed examination of photophysical properties of parent compounds, a mixture of the parent compounds, and the IM revealed that the IM exhibits FRET characteristics, but not the mixture of two dyes. The presence of spectator counterion in the mixture hindered the FRET mechanism while in the IM, both dyes are in close proximity as an ion pair, thus exhibiting FRET. All FRET parameters such as spectral overlap integral, Förster distance, and FRET energy confirm the FRET characteristics of the IM. This article presents a simple synthesis of a compound with FRET properties which can be further used for a variety of applications.

Electron‐Donating and Electron‐Withdrawing Subunit Effects on Coumarin‐BODIPY Dyads: Optical and Electrochemical Properties and Molecular Interactions

“…FT-IR spectra were recorded on the Perkin Elmer Spectrum 100 FT-IR Spectrometer with ATR capability. 1 H-NMR, 13 C-NMR, 11 B-NMR, and 19 F-NMR spectra were recorded on Bruker Avance III 500 spectrometer in deuterated chloroform (CDCl 3 ). Electronic absorption spectra (UV-Vis) were recorded on Shimadzu UV-2450 UV-Visible Spectrophotometer.…”

“…Furthermore, according to classical FRET theory, the donor structure must have a high quantum yield (Φ) to enhance the process efficiency [7,8] . This critical mechanism, which is located between two interacting fluorophores, is used in a variety of advanced applications, including (bio)sensors, energy harvesting, and light‐emitting diodes [9–12] …”

“…[7,8] This critical mechanism, which is located between two interacting fluorophores, is used in a variety of advanced applications, including (bio)sensors, energy harvesting, and light-emitting diodes. [9][10][11][12] BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is a highly versatile fluorophore that exhibits a high absorption coefficient, thermal and photochemical stability, high fluorescence quantum yield, and spectral properties that can be tuned to the near-infrared (NIR) region through structural modifications. [13][14][15] A typical BODIPY chromophore center's absorption and emission wavelengths range from 470 to 530 nm.…”

Cationic Porphyrin-Based Ionic Nanomedicines for Improved Photodynamic Therapy

“…Previous work by our research lab has shown the possibility of FRET mechanism in IMs/INMs upon removing spectator ions . Therefore, the FRET phenomenon in [Porph]­[IR783] IMs and INMs was investigated in three different solvents (ethanol, water, and PBS) and details of the spectra are provided in Figure S18.…”

“…Previous work by our research lab has shown the possibility of FRET mechanism in IMs/INMs upon removing spectator ions. 41 Therefore, the FRET phenomenon in [Porph][IR783] IMs and INMs was investigated in three different solvents (ethanol, water, and PBS) and details of the spectra are provided in Figure S18. The high spectral overlap integral (J(λ)) value (Table 2) obtained using eq S1 in the SI supports the possibility of energy transfer from porphyrin to IR783.…”