BODIPY Fluorophore Toolkit for Probing Chemical Reactivity and for Tagging Reactive Functional Groups

Abstract

The photophysical and synthetic studies of new tether‐functionalized boron dipyrromethene (BODIPY) fluorophores as probes for chemical reactions are described. These compounds differ from typically reported probes in that they provide a way to tag and indicate chemical reactions without chemical transformation of the BODIPY core itself; instead the dyes are spectators. The introduction and modification of the tether has expanded the available chemistry and yet these new BODIPY derivatives have similar photophysical properties to their parent substrates. As a result of the chemistry enabled by these probes, a single step of a multistep metal‐catalyzed reaction was revealed by a change in the fluorescence resonance energy transfer (FRET) signal. The fundamental knowledge of quantum yield, FRET efficiencies, and reagent compatibility is critical to enabling the broader application of fluorescent probes to study chemical reaction mechanisms by cutting‐edge microscopy techniques.

Single-Polymer–Particle Growth Kinetics with Molecular Catalyst Speciation and Single-Turnover Imaging

“…As part of these full studies, interrogating polynorbornene and polydicyclopentadiene with combined ex situ characterization by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) and in situ by fluorescence microscopy differentiated the presence of catalysts in all their potential (off cycle) forms from their activity, overcoming a specific version of the long-standing analytical challenge in the speciation study of molecular catalysts. Finally, single-turnover enyne metathesis 25 reactions at individual molecular catalysts were imaged, which are only the second type of reaction imaged at the single-turnover level at individual molecular catalysts. The impact of these additional studies is to (1) build a physical model for the time-resolved and timevariable catalytic behavior, (2) to demonstrate differentiation between presence of a molecular metal complex (likely including speciation between active and inactive material) and its catalytic turnover reactivity (arising solely from active material), and (3) to establish additional strategies for the field of mechanistic chemistry in order to access unique (that is, subensemble) information with sensitivity and time resolution at molecular catalysts under synthetically relevant conditions.…”

Two-color emissive probes for click reactions

“…2 On the other hand, such two-color emissive, reactive probes can act as ''molecular chameleons'' and represent one approach to visualize single-molecule chemistry on a microscopic scale. 31,32,[36][37][38][39] Consequently, the reactive group has to be part of the chromophoric system by changing its size (participant approach). 37 As any conjugated ring system, i.e.…”

“…here the triazole after the click reaction, is oriented perpendicular to the chromophore plane when in the meso position and thus not conjugated to the latter, fluorescence shifts will be very small or even hypsochromic. 34,36,40 Derivatisation of the positions 1 (gamma), 2 (beta) and 3 (alpha) (Scheme 1) should therefore induce a presumably bathochromic change in the wavelength. 25,34 Accordingly we first investigated the most suitable position on an unsymmetrical BODIPY core for reaction monitoring (Scheme 1).…”

Preference of Ruthenium-Based Metathesis Catalysts toward Z- and E-Alkenes as a Guide for Selective Reactions to Alkene Stereoisomers

“…However, efficient methods enabling the selective reaction for each stereoisomer have been scarcely developed due to the lack of a guide regarding the selectivity of catalysts toward each stereoisomer. Herein, we present the preference of Ru-based metathesis catalysts for each stereoisomer, determined by a method using the principle of fluorescence resonance energy transfer (FRET) − as a guide for the selective reaction to each stereoisomer (Figure ). We demonstrate that this guide is indeed consistent with the selectivity of catalysts toward alkene stereoisomers in the olefin metathesis reaction of diene substrates possessing combinations of Z/ E -alkenes.…”