Unprecedented alpha-substituted BOPHY dyes via a key 3,8-dichloroBOPHY intermediate

© 2017 We present a high-yielding synthesis for 3,8-dichloroBOPHY. Starting from unsubstituted pyrrole, this α-halogenated fluorophore was obtained in 51% yield. Subsequent functionalization via nucleophilic substitutions with O, N and S-nucleophiles was achieved in yields up to 88%. Stille and Sonogashira coupling reactions led to red-shifted chromophores. The absorption maxima of the synthesized dyes vary from 442 to 545 nm, with emission maxima ranging from 474 to 612 nm and quantum yields of fluorescence in solution from <1% to 100%.status: publishe

The BOPHY fluorophore with double boron chelation: Synthesis and spectroscopy

© 2018 Elsevier B.V. In this review, the literature on the new fluorophore BOPHY is covered. This doubly boron-centered fluorophore resembles the well-studied BODIPY, but has its own characteristics, both in synthesis and spectroscopy. The general synthesis and properties of this fluorophore, the possibilities for postmodifications, the literature on aromatic ring-fused BOPHYs and boron substitution are discussed.status: publishe

Radical C-H Arylation of the BODIPY Core with Aryldiazonium Salts: Synthesis of Highly Fluorescent Red-Shifted Dyes

We describe herein the first radical C-H arylation of BODIPY dyes. This novel, general, one-step synthetic procedure uses ferrocene to generate aryl radical species from aryldiazonium salts and allows the straightforward synthesis of brightly fluorescent (Φ>0.85) 3,5-diarylated and 3-monoarylated boron dipyrrins in up to 86 % yield for a broad range of aryl substituents. In this way, new and complex dyes with red-shifted spectra can be easily prepared.status: publishe

Synthesis and characterization of novel axially chiral beta-linked 1,2,3-triazolyl porphyrins

© 2018 Elsevier Ltd The regioselective synthesis of novel 1,5- and 1,4,5-substituted 1,2,3-triazoles linked to the β-position of 5,10,15,20-tetraphenylporphyrins and their zincated derivatives were achieved via an organocatalytic multicomponent reaction, starting from easily available β-formyl 5,10,15,20-tetraphenylporphyrin, nitroalkanes and benzyl azide, in moderate yields. The properties of these new β-linked 1,2,3-triazolyl porphyrins were investigated and atropoisomerism was observed. The rotational stability of these β-linked triazolylporphyrins, deduced by 1H NMR, was calculated and all newly synthesized compounds were further characterized by UV-VIS spectroscopy and high resolution mass spectroscopy.status: publishe

Thiocyanation of 3-substituted and 3,5-disubstituted BODIPYs and its application for the synthesis of new fluorescent sensors

© 2018 Elsevier Ltd Interest in BODIPYs (acronym of boron dipyrromethene) has skyrocketed in recent decades, mainly due to their favourable photophysical properties and the wide range of functionalization methods reported for these organic fluorescent dyes. In this context, a simple and straightforward method for the direct thiocyanation of 1,3,5,7-tetramethy-BODIPYs using ammonium thiocyanate and oxone was recently reported as an alternative for the preparation of thiocyanated and thioalkylated BODIPYs. Herein, we performed the thiocyanation of 3-substituted and 3,5-disubstituted BODIPY dyes, which were synthesized from the nucleophilic substitution of halogenated precursors with morpholine, propanethiol and sodium methoxide. There was a direct relation between the electron-donating character of the substituent and the yields of the thiocyanated BODIPYs, which gives support to a mechanism based on the electrophilic substitution by a thiocyanogen species formed in situ. Spectroscopic and photophysical characterization of these new fluorophores was performed and included bidimensional NMR, UV/vis absorption, fluorescence emission and fluorescence quantum yields. The photophysical properties are highly dependable on the structural features of each dye. While 3-morpholino-8-phenyl BODIPYs are virtually non-fluorescent, the fluorescence quantum yields of 3-(4-methoxybenzylamino)-8-methyl BODIPYs were close to 0.9. The thiocyanation of BODIPYs can result in interesting photophysical shifts that can be explored in the fine-tuning of fluorescent sensors. We also report the results of a preliminary qualitative analysis that indicates interesting bathochromic or hypsochromic shifts on the absorption and fluorescence emission spectra when some of the highly emissive dyes were treated with strong acid.status: publishe

Radical CH Alkylation of BODIPY Dyes Using Potassium Trifluoroborates or Boronic Acids

A one-step synthetic procedure for the radical C-H alkylation of BODIPY dyes has been developed. This new reaction generates alkyl radicals through the oxidation of boronic acids or potassium trifluoroborates and allows the synthesis of mono-, di-, tri-, and tetraalkylated fluorophores in a good to excellent yield for a broad range of organoboron compounds. Using this protocol, multiple bulky alkyl groups can be introduced onto the BODIPY core thus creating solid-state emissive BODIPY dyes.status: publishe

Thiocyanation of BODIPY dyes and their conversion to thioalkylated derivatives

A high-yielding method for the direct thiocyanation of BODIPY dyes is described. In 1,3-dimethyl BODIPYs, the thiocyanato group adds at position 2, whereas the insertion occurs at position 5 in 3-amino BODIPYs. The transformation of the thiocyanato group enables the synthesis of thioalkylated BODIPYs. 2-Thioalkylated BODIPYs and 3-thiocyanato-5-piperidino BODIPYs exhibit interesting spectroscopical features. Hence, the described synthetic methodology can be used for the photophysical tuning of BODIPY dyes.crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Lucas Cunha Dias de Rezende (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: The accepted version of this article will be made freely available in the Chemical Sciences Article Repository after a 12 month embargo period history: Received 12 March 2015; Accepted 23 April 2015; Accepted Manuscript published 23 April 2015; Advance Article published 6 May 2015; Version of Record published 19 May 2015status: publishe

Acid-Sensitive BODIPY Dyes: Synthesis through Pd-Catalyzed Direct C(sp3)_H Arylation and Photophysics

A novel palladium-catalyzed direct C(sp3 )-H arylation of the methyl group at the 8-position of BODIPY by bromoarenes was established. A deprotonative cross-coupling process was supposed to be involved in the reaction. This approach allowed us to attach electron-donating/withdrawing, halogen substituted aryls and a heteroaryl with a yield running from 55 to 99 %. Novel pH sensors, which in the absence of acid showed the occurrence of photoinduced electron transfer, were synthesized by attaching dimethylaniline to the methyl at the C8-position of BODIPY. The reference compounds with dimethylaniline directly attached to the C8-position were also synthesized and besides photoinduced electron transfer also showed a charge-transfer emission. Their photophysical properties were investigated by steady-state fluorescence, time-correlated single-photon counting and femtosecond fluorescence up-conversion. Time-dependent density functional (TD-DFT) electronic-structure calculations on the properties of the excited states corresponding to local excitation of the BODIPY core and to charge transfer were conducted. Upon addition of trifluoroacetic acid in toluene and ethanol, the partial fluorescence intensity recovery was at least an order of magnitude more efficient with the newly synthesized sensors compared to the traditional reference sensors. The improved sensitivity of these novel BODIPY-based pH sensors was attributed to less efficient proton-coupled electron transfer of the protonated species.status: publishe