Controlling the fluorescence quantum yields of benzothiazole-difluoroborates by optimal substitution

Abstract

Precise tuning of fluoresecence quantum yield, vital for countless applications of fluorophores, remains exceptionally challenging due to numerous factors affecting energy dissipation phenomena often leading to its counterintuitive behavior. In...

Extensive Analysis of the Parameters Influencing Radiative Rates Obtained through Vibronic Calculations

“…Indeed, they are not particularly adequate for modeling highly emissive molecules, as the related simulation times would have to be well beyond the picosecond regime typically applied in surface hopping simulations. Third, static ab initio calculations can also be used to estimate Φ fl . − In this approach, electronic structure calculations, often performed with time-dependent density functional theory (TD-DFT), , have been used to estimate the rates of each of the competitive deactivation processes, typically using remarkable points of the potential energy surface (PES) and/or pathways connecting these points, sometimes combined with the application of variants of Fermi’s Golden rule. This computational approach thus requires making assumptions about the dominant photophysical processes occurring in a given system, but such a rationalized investigation of Φ fl may be of interest to efficiently design new fluorophores of a given family once the main photophysical events have been identified.…”

“…As stated above, in the static computational strategy, the rates of all relevant processes need to be computed separately. For the radiative rate, one can either use the well-known Einstein’s approximation, , though it will fail by design when the oscillator strength ( f ) associated with fluorescence is zero, or apply more refined schemes based on the generating function (GF) method, − such as the thermal vibration correlation function (TVCF) approach, − developed by the Shuai group, , which is a TD Fourier transform implementation that has now become popular in the field. The TVCF approach, described in more detail below, relies on vibronic calculations of the emission spectrum to estimate the k r and has been implemented under various flavors in several codes, e.g., MOMAP, ORCA, and FCclasses .…”

Modeling the Fluorescence Quantum Yields of Aromatic Compounds: Benchmarking the Machinery to Compute Intersystem Crossing Rates

“…A similar outcome was reported before for a series of fluoroborate dyes. 79 Certainly, the compounds possessing smaller FQYs are more prone to yield large deviations (see region below experimental FQY of 0.5 in Figure 5) because of (i) the presence of an additional nonradiative channel (e.g., IC), or (ii) the accumulation and combination of errors potentially have a larger impact than in compounds possessing very large FQYs. In addition, the experimental values for compounds with intermediate FQY values also show some degree of variability, see, e.g., in Table 1 the FQY values for phenanthrene (0.10−0.24) and/or anthracene (0.22−0.36).…”

BF2-Functionalized Benzothiazole Amyloid Markers: Effect of Donor Substituents on One- and Two-Photon Properties

“…To gain systematic knowledge about the relationship between the dye structure, its optical properties, and their modification by binding to amyloids, we investigate three dyes with a weak electron donor located on one or both terminals of the fluorescent core (see Figure ): (1) DA- (( Z )-[(difluoroboryloxy)­phenylmethylene]­(6-methoxy-1,3-benzothiazol-2-yl)­amine), (2) - AD (( Z )-[(difluoroboryloxy)­(4-methoxyphenyl)­methylene]-1,3-benzothiazol-2-ylamine), and (3) DAD (( Z )-[(difluoroboryloxy)­(4-methoxyphenyl)­methylene]­(6-methoxy-1,3-benzothiazol-2-yl)­amine). Using the same benzothiazole core, it was possible to modulate the FQY between 0.4 and 98% by changing the position of the donor and acceptor units only. In the current study, changes in optical properties such as the fluorescence lifetime (τ), FQY, 2PA, 1P, and 2P excited fluorescence upon binding to amyloid fibrils are investigated.…”

“…, and (3) DAD ((Z)-[(difluoroboryloxy)(4-methoxyphenyl)methylene](6-methoxy-1,3-benzothiazol-2-yl)amine). Using the same benzothiazole core, it was possible to modulate the FQY between 0.4 and 98% 25 by changing the position of the donor and acceptor units only. In the current study, changes in optical properties such as the fluorescence lifetime (τ), FQY, 2PA, 1P, and 2P excited fluorescence upon binding to amyloid fibrils are investigated.…”