meso-Methyl Amination of BODIPYs by Regiospecific Cross Dehydrogenative Coupling via Direct C(sp3)-N(sp3) Bond Formation

Herein, we report a direct meso-methyl amination of BODIPY dyes by C(sp3)-N(sp3) bond formation using PIDA as an oxidant with a wide range of aliphatic secondary amines. This metal free cross dehydrogenative coupling reaction is regiospecific at the meso-methyl position of BODIPY in the presence of C1, C3, C5, and C7 methyl groups. Detailed nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and X-ray crystallographic studies were performed to establish the reaction mechanism and the regiospecificity of the reaction. Finally, the photophysical and electrochemical properties of the newly synthesized dyes were evaluated and rationalized.

A Practical and Modular Method for Direct C-H Functionalization of the BODIPY Core via Thianthrenium Salts

Direct structural modification of small-molecule fluorophores represents a straightforward and appealing strategy for accessing new fluorescent dyes with desired functionalities. We report herein a general and efficient visible-light-mediated method for the direct C-H functionalization of BODIPY, an important fluorescent chromophore, using readily accessible and bench-stable aryl and alkenylthianthrenium salts. This practical approach operates at room temperature with extraordinary site-selectivity, providing a step-economical means to construct various valuable aryl- and alkenyl-substituted BODIPY dyes. Remarkably, this protocol encompasses a broad substrate scope and excellent functional-group tolerance, and allows for the modular synthesis of sophisticated symmetrical and asymmetrical disubstituted BODIPYs by simply employing different combinations of thianthrenium salts. Moreover, the late-stage BODIPY modification of complex drug molecules further highlights the potential of this novel methodology in the synthesis of fluorophore-drug conjugates.

One-Pot Access to Ethylene-Bridged BODIPY Dimers and Trimers through Single-Electron Transfer Chemistry

A Cu(I)-promoted oxidative dimerization of BODIPY dyes was developed to give a series of α,α- ethylene-bridged BODIPY dimers and trimers for the first time. This methodology does not need harsh conditions but relies on the singlet-electron-transfer process between alkylated BODIPYs and Cu(I) salt to generate BODIPY-based radical species, which undergo a selective radical homocoupling reaction. Moreover, these resultant dimers and trimers showed high attenuation coefficients, small line widths of the absorption and emission, and intense fluorescence.

Direct sulfonylation of BODIPY dyes with sodium sulfinates through oxidative radical hydrogen substitution at the α-position

A series of α-sulfonated BODIPYs were efficiently synthesized from sodium sulfinates via a radical process, and were demonstrated as new fluorescent probes for selective biothiol detection.

Cross-dehydrogenative coupling involving benzylic and allylic C–H bonds

Benzylic and allylic C–H bonds are coupled with C(sp)–H, C(sp²)–H and C(sp³)–H bonds in a straightforward and high atom-economic manner.

Highly regioselective α-formylation and α-acylation of BODIPY dyes via tandem cross-dehydrogenative coupling with in situ deprotection

A metal-free C-H formylation and acylation of BODIPY dyes using a variety of dioxolane derivatives as aldehyde equivalents is reported, providing a postfunctionalization method for controllable synthesis of BODIPYs with carbonyl groups at 3,5-positions via a radical process. The photophysical properties of resultant dyes from this efficient one-pot, chemo- and site-selective transformation have been studied.

β-AlkenylBODIPY Dyes: Regioselective Synthesis via Oxidative C-H Olefination, Photophysical Properties, and Bioimaging Studies

A series of 2-alkenyl- and 2,6-dialkenylboron dipyrromethene (BODIPY) derivatives were synthesized through Pd(II)-catalyzed regioselective and stereoselective oxidative C-H olefination in one step. The 2-alkenyl BODIPY derivative further reacted with various amines regioselectively at the 5-position through direct oxidative nucleophilic substitution. The photophysical properties of the 2-alkenyl- and 2,6-dialkenyl-substituted BODIPYs were investigated, which showed great potential in fluorescent bioimaging.

Transition-metal-free regioselective cross-coupling of BODIPYs with thiols

Transition-metal-free, regioselective C–H/S–H cross-couplings of BODIPYs with thiols provides structurally diverse thiolated BODIPYs via a radical pathway.

Development of BODIPY dyes with versatile functional groups at 3,5-positions from diacyl peroxides via Cu(ii)-catalyzed radical alkylation

A Cu(ii)-catalyzed, α-regioselective C–H alkylation of BODIPY with alkyl diacyl peroxides provides structurally diverse alkylated BODIPYs via a radical pathway.

Unveiling the Photophysical Properties of Boron Heptaaryldipyrromethene Derivatives

Increased interest has been devoted to the discovery of multifunctional materials with desirable properties, as continuous performance enhancement of various devices mainly depends on high-performance materials. Now, density functional theory has become a powerful tool to design new materials and rationalize experimental observations. In this work, we explored the photophysical properties origin of chiral boron heptaaryldipyrromethene (heptaaryl-BODIPY), which has charming optoelectronic properties. At the same time, we designed the other five compounds on the basis of heptaaryl-BODIPY. The simulated electronic absorption and emission spectra of heptaaryl-BODIPY are in agreement with experimental ones, allowing us to reliably assign its electronic transition property. The designed compound 6 shows remarkably large first hyperpolarizability value up to 82.78×10^-30  esu. For this kind of compounds, their NLO response values associate with not only position but also electronic nature of substituent groups. Moreover, electron reorganization energies of compounds 1-4 are comparable to tris(8-hydroxyquinolinato)aluminium(III) which is a typical electron transport material. Intriguingly, the studied compounds are the excellent fluorescent probe materials from the standpoint of large Stokes shift and high emission efficiency. Our work enables an opportunity for understanding the relationship between microelectronic structure and macroscopic performance of BODIPY derivatives.

Synthesis, structure and photophysical properties of dibenzofuran-fused boron dipyrromethenes

Regioselective functionalization of core per-substituted boron dipyrromethenes (BODIPYs) has been achieved efficiently based on tetrabromoBODIPY, which affords a series of dibenzofuran-fused chromophores, via a regioselective nucleophilic substitution reaction followed by direct palladium-catalyzed two-fold intramolecular ring fusion. These rigid dibenzofuran-fused BODIPYs showed impressive photophysical properties such as clearly red-shifted absorption and emission bands, enhanced absorption coefficients upon and intense fluorescence (close to unity).

I2-Catalyzed intramolecular dehydrogenative aminooxygenation of alkynes to acylated imidazo[1,2-a]pyridines and indolizines

An efficient and green protocol for the construction of acylated imidazo[1,2-a]pyridines and indolizines via intramolecular dehydrogenative aminooxygenation of alkynes has been developed.

Copper-catalyzed α-benzylation of BODIPYs via radical-triggered oxidative cross-coupling of two C–H bonds

An oxidative cross-dehydrogenative coupling of BODIPYs with toluene and it derivatives has been developed, allowing for the facile synthesis of a broad range of structurally diverse α-benzylated BODIPYs with high solid-state fluorescence.

Copper(ii)-promoted oxidative C–H/C–H cross-coupling for rapid access to aza-BODIPY-indole derivatives with broad optical absorption

The absorption band of aza-BODIPY is remarkably broadened by coupling with indoles via a concise and inexpensive approach.