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1. Photochemically and Thermally Generated BN-Doped Borafluorenate Heterocycles via Intramolecular Staudinger-Type Reactions

   https://doi.org/10.1021/acs.inorgchem.3c02284  

   Tra, Bi Youan; Molino, Andrew; Hollister, Kimberly K.; Sarkar, Samir Kumar; Dickie, Diane A.; Wilson, David J.; Gilliard, Robert J. (January 2023, Inorganic Chemistry)

   A series of BN-incorporated borafluorenate heterocycles, bis(borafluorene-phosphinimine)s (11–15), have been formed via intramolecular Staudinger-type reactions. The reactions were promoted by light or heat using monodentate phosphine-stabilized 9-azido-9-borafluorenes (R3P-BF-N3; 6–10) and involve the release of dinitrogen (N2), migration of phosphine from boron to nitrogen, and oxidation of the phosphorus center (PIII to PV). Density functional theory (DFT) calculations provide mechanistic insight into the formation of these compounds. Compounds 11–15 are blue emissive in the solution and solid states with absolute quantum yields (ΦF) ranging from 12 to 68%. 

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2. MIDA‐ and TIDA‐Boronates Stabilize α‐Radicals Through B−N Hyperconjugation

   https://doi.org/10.1002/anie.202309566  

   LaPorte, Antonio J.; Feldner, Jack E.; Spies, Jan C.; Maher, Tom J.; Burke, Martin D. (October 2023, Angewandte Chemie International Edition)

   Abstract Multifunctional organoboron compounds increasingly enable the simple generation of complex, Csp³‐rich small molecules. The ability of boron‐containing functional groups to modify the reactivity of α‐radicals has also enabled a myriad of chemical reactions. Boronic esters with vacant p‐orbitals have a significant stabilizing effect on α‐radicals due to delocalization of spin density into the empty orbital. The effect of coordinatively saturated derivatives, such as N‐methyliminodiacetic acid (MIDA) boronates and counterparts, remains less clear. Herein, we demonstrate that coordinatively saturated MIDA and TIDA boronates stabilize secondary alkyl α‐radicals via σ_B‐Nhyperconjugation in a manner that allows site‐selective C−H bromination. DFT calculated radical stabilization energies and spin density maps as well as LED NMR kinetic analysis of photochemical bromination rates of different boronic esters further these findings. This work clarifies that the α‐radical stabilizing effect of boronic esters does not only proceed via delocalization of radical character into vacant boron p‐orbitals, but that hyperconjugation of tetrahedral boron‐containing functional groups and their ligand electron delocalizing ability also play a critical role. These findings establish boron ligands as a useful dial for tuning reactivity at the α‐carbon. 

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3. Non-Carbon 2D Materials-Based Field-Effect Transistor Biosensors: Recent Advances, Challenges, and Future Perspectives

   https://doi.org/10.3390/s20174811  

   Sedki, Mohammed; Chen, Ying; Mulchandani, Ashok (September 2020, Sensors)

   null (Ed.)

   In recent years, field-effect transistors (FETs) have been very promising for biosensor applications due to their high sensitivity, real-time applicability, scalability, and prospect of integrating measurement system on a chip. Non-carbon 2D materials, such as transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), black phosphorus (BP), and metal oxides, are a group of new materials that have a huge potential in FET biosensor applications. In this work, we review the recent advances and remarkable studies of non-carbon 2D materials, in terms of their structures, preparations, properties and FET biosensor applications. We will also discuss the challenges facing non-carbon 2D materials-FET biosensors and their future perspectives. 

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4. Azaphosphinines and their derivatives

   https://doi.org/10.1039/d3cs00737e  

   McNeill, J Nolan; Bard, Jeremy P; Johnson, Darren W; Haley, Michael M (December 2023, Chemical Society Reviews)

   Six-membered heterocycles containing one phosphorus and one nitrogen atom, known as azaphosphinines, have existed in the shadows of their single heteroatom-containing analogues for almost 150 years. Despite this, recent chemistry has seen a rapid increase in publications concerning this uncommon scaffold. Azaphosphinines exist in one of six isomers—there are three possible orientations of the pnictogen atoms and in each of these, the phosphorus is in one of two valences (PIII vs. PV). This review aims to outline and inform on the synthesis and applications of all six isomers. PV–oxo azaphosphinines are of particular interest to this review as many of the discussed heterocycles either form as the pentavalent species directly or oxidize to this over time. In very recent years the published applications of azaphosphinines have blossomed into subjects spanning several fields of chemistry such as asymmetric catalysis, supramolecular association, cellular imaging, and medicinal chemistry. 

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5. Comparison of Hall Mobility and Carrier Density of Thin Black Phosphorus Exfoliated from Bulk Crystals Provided by Various Vendors

   Katie Welch; Mahmudul Hasan Doha; Zachary P. Uttley; Arash Fereidouni; Abayomi Omolewu; Jose Santos; Magda El-Shenawee; and Hugh O. H. Churchill (July 2022, Digest IEEE Antennas and Propagation Society International Symposium)

   IEEE (Ed.)

   In this project, Hall bar devices with black phosphorus (BP) as the semiconductor layer were fabricated to measure the Hall mobility and carrier density of exfoliated BP flakes obtained from bulk crystals acquired from various commercial sources. Black phosphorus is proposed as an alternative material for terahertz photoconductive antennas (PCAs) from the standard GaAs or InGaAs PCAs that are currently available commercially. Black phosphorus is an anisotropic material with a reported Hall mobility over three times greater than GaAs, but our preliminary testing of BP PCAs has shown dramatic differences of electrical properties between black phosphorus sourced from three different vendors. To determine the best quality black phosphorus source, Hall bar devices containing 40 nm BP flakes were used to measure the carrier mobility of the semiconductor. A Hall bar device is created by layering a 40nm BP flake underneath a hexagonal boron-nitride (hBN) flake, all on top of gold contacts in a Hall bar arrangement fabricated on a high-resistivity silicon substrate. The hBN acts as a passivation layer for the BP so that it may be safely removed from the glove box without damage. The Hall mobility of the material from different sources ranges from around 100 cm2/Vs to 1600 cm2/Vs, with only one source showing promising, high mobility results. This study allows BP with optimized electrical properties to be incorporated into THz PCAs for characterization via THz time domain spectroscopy. 

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