Themed collection FOCUS: Frontiers in Boron Chemistry

The recent research progress of organic boron-containing thermally activated delayed fluorescence (TADF) materials is reviewed systematically with a focus on the molecular design, photophysical properties and performance of the corresponding OLEDs.

The synthesis and transformation of α-oxylboronates including their C–B bond and C–O bond functionalizations are reviewed.

This review highlights the recent advances in both electrochemical borylation and hydroboration to synthesize organoboron compounds and electrochemical transformation of organoboron compounds to construct carbon–carbon and carbon–heteroatom bonds.

In this review, the most recent development in healable polymers with dynamic B–O links is discussed, taking readers through the concept and features of dynamic B–O linkages to explore their advanced functionalities and emerging applications.

Entrapment of boron(III) in π-conjugated systems causes a strong modification of the observed properties, e.g. optical properties can be realized via post-synthetic reaction with 6.6.6 and 7.6.6 defects precisely incorporated into π-extended motifs.

A copper(I)-catalyzed intermolecular alkylboration of terminal allenes using unactivated alkyl iodides as the carbon electrophiles is reported.

A copper-catalyzed hydroboration of unactivated alkenes using carbonyl as a weak directing group was disclosed with exclusive Markovnikov regioselectivity.

A boryl radical is generated by 4-cyanopyridine and B₂cat₂ and illustrated a ketyl radical by visible light, furtherly reduced unsaturated double bond XO (X = C, N, S). The reaction mechanism is confirmed by spectroscopy and calculation studies.

A formal [4 + 1] cycloaddition reaction of ketiminoboranes with isonitriles is described. This sequential four-component reaction could successfully incorporate HB(C₆F₅)₂, 2,5-dimethylhexa-2,4-diene, nitriles, and isonitriles, into new BN-cycles.

A photocatalytic three-component reaction of alkyltrifluoroborates with two electron-deficient alkenes proceeds in a sequence-selective manner, which can be followed by Wittig olefination to afford γ,δ-unsaturated ketones and esters.

Two o-carborane-based π-conjugated macrocycles were synthesized. Single-crystal structures revealed their micropore characteristics. These macrocycles exhibit aggregation-induced emission and selective identification.

The Matteson homologation is found to be a versatile tool for the stereoselective synthesis of polyunsaturated alkyl boronic esters, which can be used for the construction of five- and six-membered carbocycles via ring-closing metathesis.

The first series of radicals derived from boron-dipyrromethene (BODIPY) and its heavier analogues have been isolated and fully characterized.

The introduction of different donors at the para-carbon position of the BNCz core modulates the predominance of locally excited (LE)/charger transfer (CT) states of the TADF materials to achieve full-color emission.

Aerobic oxidation of organoboron, via uranyl photocatalysis using the principle of indirect single electron transfer, was established under ambient conditions, and afforded multifarious phenols and alcohols, including nine pharmaceuticals.

Cooperative assemblies of amphiphilic boron(III) diketonate compounds, which are found to be driven by the formation of non-covalent π–π and hydrophobic interactions in THF–water solution, result in the construction of nanosheet of lamellar packing.

An alternative method to access 5,10,15-triazatruxene has been developed. The 1,6,11-positions of triazatruxene can further be functionalized to construct a boron difluoride complex with a large Stokes shift.

Presented herein is the discovery of the in situ synthesis of pyrazolylborates. They exhibit great adaptive coordination behaviors in aluminum oxo clusters and further provide a platform for the development of trans-chelating scorpionate analogues.

We synthesized n-type polycyclic aromatic hydrocarbons incorporated with both B ← N and imide units for the first time and examined their optical and electrochemical properties.

A mild and convenient reductive amination protocol for the synthesis of structurally diverse secondary and tertiary amines as well as N-methylated products under metal-free conditions is presented.

An efficient approach to synthesize tetrasubstituted alkenylboronates via a cascade borylation/B–N elimination of propargyl amines and B₂pin₂ is disclosed.

A Cu-catalyzed asymmetric methylboration of 1,2-dihydroquinolines, 2H-chromenes and 2H-thiochromenes providing boryl products bearing two adjacent chiral centers with excellent selectivities, up to 99 : 1 dr and 99.9% ee, has been realized for the first time.

The smallest borafullerene U@C₂₇B has been synthesized using a laser vaporization cluster source. The U atom, placed in the middle of the cage and interacting with all the 28 atoms, is formally described as highly oxidized U(VI).

Two new alkali metal fluorooxoborates, Rb₃B₅O₈F₂ and K_0.6Rb_2.4B₅O₈F₂, were successfully obtained by cation regulation, which exhibit a short UV cutoff edge and an appropriate SHG response.

The direct conversion from boronic esters to the carbonyl groups has been realized herein, via the bromine radical and α-borylalkyl radical under visible light.

Boronic acid (derivatives) activation for the Minisci reaction via dual photoredox/cobalt catalysis in batch and under continuous-flow.

Amorphous CoB nanoarray is a high-efficiency catalyst for electrocatalytic NO₂⁻-to-NH₃ conversion, capable of attaining a large NH₃ yield of 233.1 μmol h⁻¹ cm⁻² and a high faradaic efficiency of 95.2% at −0.7 V in 0.1 M Na₂SO₄ with 400 ppm NO₂⁻.

A rare earth borate fluoride, Sc₂F₂(B₂O₅), displays a deep ultraviolet cutoff edge (<200 nm) and very large birefringence induced by the synergistic effect of B₂O₅ and ScO_nF₂ groups.

An efficient B(9) electrophilic amination of o-carboranes with azodicarboxylates, promoted by a Brønsted acid and HFIP, was developed.

A copper-catalyzed carbonylation process has been developed for the synthesis of diborylated cyclopropanes from both stable internal and terminal aryl olefins in moderate to good yields.

ipso-Hydroxylation of arylboronic acids with Hantzsch ester has been developed. The by-product Hantzsch pyridine was found to promote the reaction in the presence of oxygen under ambient conditions.

Water-soluble photosensitizers based on covalently grafted nitrogen-doped graphene quantum dot–BODIPY for cellular imaging and photodynamic therapy.

A combination of luminescence processes in dual-emission properties by selecting preparation protocols is designed but also temperature-driven switching of luminescence processes in dual-emission properties based on a bis-o-carborane-substituted anthracene triad in crystals.

A convenient method for the synthesis of cyclopropyl boronates via visible-light photoredox-catalyzed borocyclopropanation of alkenes has been established. This protocol is characterized by its wide substrate scope and mild reaction conditions.

Na[o-⁵⁷FESAN] with potential for glioblastoma treatment by Mössbauer effect. Mössbauer spectrum and 2D Fe distribution maps indicate that [o-⁵⁷FESAN]⁻ is present inside U87 cells, a desired target for selective Mössbauer absorption energy deposition.

B(3)-Arylation is unfavorable because the steric repulsion between the substituent group on C(2) and the metal moiety would lead to significant distortion of o-carborane and would result in a higher activation energy for reductive elimination.

Ultrafine dispersed ruthenium nanoparticles on B,N-co-doped carbon nanotubes with simultaneously optimized nanostructures and electronic property were developed to achieve a high catalytic activity for both HER and OER.

Two chiral tetracoordinate organoboranes based on double B←N bridged bipyridine were synthesized via an Et₂AlCl-mediated reaction, and they possess excellent circularly polarized luminescence performance.

The anti-to-Cu 1,2-migration of alkynyl boronates is critical for the 1,1-E-selective difunctionalization of terminal alkynes with CO₂ and organoboranes.

A boron-based organic photocatalyst has been applied in metallaphotoredox catalyzed C–P and C–S bond construction reactions.

The facile deprotonation of fluoroaryl-substituted alkylboranes or alkylboron cations readily leads to anionic boratalkenes or neutral boraalkenes, respectively. These BC double bond systems exhibit an increasing variety of chemical reactivities.

This frontier article summarizes the recent developments in base metal-catalyzed regioselective cage B–H functionalization of carboranes and discusses the related challenging issues.