Ready Access to Molecular Rotors Based on Boron Dipyrromethene Dyes-Coumarin Dyads Featuring Broadband Absorption

Abstract

Herein we report on a straightforward access method for boron dipyrromethene dyes (BODIPYs)-coumarin hybrids linked through their respective 8- and 6- positions, with wide functionalization of the coumarin fragment, using salicylaldehyde as a versatile building block. The computationally-assisted photophysical study unveils broadband absorption upon proper functionalization of the coumarin, as well as the key role of the conformational freedom of the coumarin appended at the meso position of the BODIPY. Such free motion almost suppresses the fluorescence signal, but enables us to apply these dyads as molecular rotors to monitor the surrounding microviscosity.

A Ratiometric Afterglow Response of Aluminium Ions in Methanol‐Water

“…A Salicylimine‐linked rhodamine 1 was prepared via the condensation of hydrazine rhodamine dye 2 [36] and (3‐formyl‐4‐hydroxyphenyl)boronic acid [37] in 40% yield (Scheme 1). The structural assignment was based on analytical data (See Supporting Information).…”

3-(3-Bromophenyl)-7-acetoxycoumarin

“…For this reason, we report herein a bifunctional coumarin containing two sites that can be easily modified. In the prepared compound, bromine at position 3 of the phenyl substituent can be altered by several different reactions, e.g., by Suzuki cross coupling [8] for C-C bond formation, via the Miyaura reaction for borylation [9], or through catalytic C-N cross-coupling, such as the Ullman reaction or Buchwald-Hartwig reaction [10]. The acetoxy group at position 7 can be deprotected into a hydroxyl group, which can also be further altered by several different reactions, e.g., esterification.…”