Oxyethylated Fluoresceine—(thia)calix[4]arene Conjugates: Synthesis and Visible-Light Photoredox Catalysis in Water–Organic Media

Abstract

Fluorescent derivatives attract the attention of researchers for their use as sensors, photocatalysts and for the creation of functional materials. In order to create amphiphilic fluorescent derivatives of calixarenes, a fluorescein derivative containing oligoethylene glycol and propargyl groups was obtained. The resulting fluorescein derivative was introduced into three different (thia)calix[4]arene azide derivatives. For all synthesized compounds, the luminescence quantum yields have been established in different solvents. Using UV-visible spectroscopy, dynamic light scattering, as well as transmission and confocal microscopy, aggregation of macrocycles was studied. It was evaluated that calixarene derivatives with alkyl substituents form spherical aggregates, while symmetrical tetrafluorescein-containing thiacalix[4]arene forms extended worm-like aggregates. The macrocycle containing tetradecyl fragments was found to be the most efficient in photoredox ipso-oxidation of phenylboronic acid. In addition, it was shown that in a number of different electron donors (NEt3, DABCO and iPr2EtN), the photoredox ipso-oxidation proceeds best with triethylamine. It has been shown that a low molecular weight surfactant Triton-X100 can also improve the photocatalytic abilities of an oligoethylene glycol fluorescein derivative, thus showing the importance of a combination of micellar and photoredox catalysis.

Visible Light‐Induced Metal‐free Arylation of Coumarin‐3‐carboxylates with Arylboronic Acids

“…[14] Upon excitation, fluorescein dye, i. e. rose bengal reacts with boronic acids as their redox potential lies within the range of photocatalyst. [15] A diverse range of boronic acids have been used as a source of aryl free radicals due to their low toxicity, sensible cost, ease of preparation and reasonable stability (Figure 2). [16]…”

“…Initially, we attempted the site‐selective photoarylation of coumarin‐3‐carboxylate using a photocatalyst based on fluorescein dye instead of transition metal photocatalysts [14] . Upon excitation, fluorescein dye, i. e. rose bengal reacts with boronic acids as their redox potential lies within the range of photocatalyst [15] . A diverse range of boronic acids have been used as a source of aryl free radicals due to their low toxicity, sensible cost, ease of preparation and reasonable stability (Figure 2).…”

Photochromic Azobenzene Inverse Opal Film toward Dynamic Anti-Fake Pattern

“…Functional fluorescent materials have aroused extensive research interest due to their promising applications in light-emitting devices [1,2], biological imaging [3,4], and catalysis [5,6]. Among these materials, azobenzene mesogens, as a conventional emitting organic material, have attracted attention for their reversible photo-isomerization effect [7,8].…”