<i>trans</i>-Aminoboration across Internal Alkynes Catalyzed by B(C₆F₅)₃ for the Synthesis of Borylated Indoles

We report here a facile B­(C₆F₅)₃ catalyzed <i>trans</i>-aminoboration of internal alkynes, furnishing 3-position borylated indoles at ambient temperature. This reaction proceeds with the breaking of a B–N bond and the formation of N–C and B–C bonds to produce indole and derivatives in one step. It works well for various boron reagents and alkynyl-anilines. The borylated indoles can be further derivatized to give column stable organoboron compounds that can be used for future functionalization

Cascade Dehydrogenative Hydroboration for the Synthesis of Azaborabenzofulvenes

Tandem dehydrogenative hydroboration has been established to be highly effective in the synthesis of BN isosteres of benzofulvene and derivatives. The scope of this synthetic method is applicable to a variety of substrates. Spectroscopic and computational studies indicate that the new azaborabenzofulvenes have similar electronic properties as their carbonaceous analogues

Highly Sensitive Detection of Isomers through Dynamic Reflection Spectroscopy Based on Simple Amorphous Photonic Crystals

Photonic band gaps of photonic crystals (PCs) are related to the effective refractive indices; therefore, it is quite difficult to detect homologues and isomers with similar reflection indices by PCs. Some researchers have tried to use some complex PCs for detecting homologues and isomers. However, there are few reports in trace detection of isomers (cis–trans isomers) and mixed isomers by using simple amorphous photonic crystals (APCs). Herein, dynamic reflection spectrum (DRS) patterns of APCs are obviously different by changing species of compounds, mixtures of two similar isomers, volatility temperatures, and diameters of SiO2. Isomers with a refractive index difference of only 0.001 and their mixtures could be distinguished based on different DRS patterns of simple APCs. For example, the difference in the refractive indices of cis-3-hexene and trans-3-hexene is only 0.001, and the difference of desorption balance time of APCs is 142 s. The method shows high sensitivity detection in isomers and cis–trans isomers

Near-Infrared Electroluminescence Based on Nd-Doped Ga₂O₃ Nanolaminates Fabricated by Atomic Layer Deposition for Optoelectronic Applications

Near-infrared electroluminescence (EL) peaking at 1067 nm is achieved from the devices based on Ga2O3:Nd nanolaminates fabricated by atomic layer deposition on silicon. The emissions originating from intra-4f transitions in Nd3+ ions are activated by both forward and reverse biases, with an external quantum efficiency of ∼1% and the optical power density of 10.5 mW/cm2. The devices operate continuously for more than 4 h and exhibit fluctuant EL emission under alternating-current excitation. Such EL is triggered by the energetic electrons accelerated via interfacial SiOx or Al2O3/TiO2 nanolaminate layers. EL under unidirectional bias is obtained by using a 4 nm interfacial Al2O3 nanofilm that sustains the electric field and energizes injected electrons, demonstrating the acceleration of electrons by high resistance layers and the carrier conduction considering interface energy barrier is indispensable for efficient EL excitation. This work provides innovative nanofilms based on Nd-doped oxides with great potential for applications in Si-based photonics and integrated optoelectronics

Anion Sensing with a Blue Fluorescent Triarylboron-Functionalized Bisbenzimidazole and Its Bisbenzimidazolium Salt

A blue fluorescent <i>p</i>-dimesitylboryl-phenyl-functionalized 1,3-bisbenzimidazolyl benzene molecule (<b>1</b>) has been synthesized in high yield by Stille coupling of bisbenzimidazolyl bromobenzene with <i>p</i>-BMes₂-SnBu₃-benzene. Methylation of <b>1</b> led to the formation of the bisbenzimidazolium salt (<b>2</b>). The utility of both <b>1</b> and <b>2</b> in sensing CN^– and halide (F^–, Cl^–, Br^–, and I^–) was examined, and it was found that only the small fluoride and cyanide anions were able to bind to the boron atom with binding constants in the range of 2.9 × 10⁴ to 5 × 10⁵ M^–1. Computational studies provided insight into the photophysical properties of the molecules and verified that a charge-transfer process is quenched in these “turn-off” molecular sensors

Spiro-BODIPYs with a Diaryl Chelate: Impact on Aggregation and Luminescence

Spiro-BODIPYs with a diaryl chelate unit have been found to form J-aggregates in methanol–water solvent mixture and brightly emissive in the solid state. The diaryl chelate unit has a significant impact on J-aggregates and fluorescence of BODIPYs. Crystal structural analysis reveals that the spiro-structures facilitate J-stacking in the solid state

Spiro-BODIPYs with a Diaryl Chelate: Impact on Aggregation and Luminescence

Spiro-BODIPYs with a diaryl chelate unit have been found to form J-aggregates in methanol–water solvent mixture and brightly emissive in the solid state. The diaryl chelate unit has a significant impact on J-aggregates and fluorescence of BODIPYs. Crystal structural analysis reveals that the spiro-structures facilitate J-stacking in the solid state

Pyridyl Directed Catalyst-Free <i>trans</i>-Hydroboration of Internal Alkynes

We report the first examples of straightforward <i>trans</i>-hydroboration of internal alkynes at room temperature with 9-BBN, producing five-membered BN-heterocycles. Contrary to conventional <i>cis</i>-hydroboration, we demonstrate that the introduction of a pyridyl group switches the stereoselectivity of the reaction. A hydride migration mechanism has been proposed and supported by DFT calculations for the <i>trans</i>-hydroboration. This new hydroboration approach allows facile construction of new blue fluorescent BN-heterocyclic compounds

Understanding and Expanding Zinc Cation/Amine Frustrated Lewis Pair Catalyzed C–H Borylation

[(NacNac)Zn(DMT)][B(C6F5)4], 1, (NacNac = {(2,6-iPr2H3C6)N(CH3)C}2CH), DMT = N,N-dimethyl-4-toluidine), was synthesized via two routes starting from either (NacNac)ZnEt or (NacNac)ZnH. Complex 1 is an effective (pre)catalyst for the C–H borylation of (hetero)arenes using catecholborane (CatBH) with H2 the only byproduct. The scope included weakly activated substrates such as 2-bromothiophene and benzothiophene. Computational studies elucidated a plausible reaction mechanism that has an overall free energy span of 22.4 kcal/mol (for N-methylindole borylation), consistent with experimental observations. The calculated mechanism starting from 1 proceeds via the displacement of DMT by CatBH to form [(NacNac)Zn(CatBH)]+, D, in which CatBH binds via an oxygen to zinc which makes the boron center much more electrophilic based on the energy of the CatB-based LUMO. Combinations of D and DMT act as a frustrated Lewis pair (FLP) to effect C–H borylation in a stepwise process via an arenium cation that is deprotonated by DMT. Subsequent B–H/[H-DMT]+ dehydrocoupling and displacement from the coordination sphere of zinc of CatBAr by CatBH closes the cycle. The calculations also revealed a possible catalyst decomposition pathway involving hydride transfer from boron to zinc to form (NacNac)ZnH which reacts with CatBH to ultimately form Zn(0). In addition, the key rate-limiting transition states all involve the base, thus fine-tuning of the steric and electronic parameters of the base enabled a further minor enhancement in the C–H borylation activity of the system. Outlining the mechanism for all steps of this FLP-mediated process will facilitate the development of other main group FLP catalysts for C–H borylation and other transformations

Resistance Risk and Resistance-Related Point Mutations in Target Protein Cyt b of the Quinone Inside Inhibitor Amisulbrom in Phytophthora litchii

Amisulbrom is a novel quinone inside inhibitor, which exhibits excellent inhibitory activity against phytopathogenic oomycetes. However, the resistance risk and mechanism of amisulbrom in Phytophthora litchii are rarely reported. In this study, the sensitivity of 147 P. litchii isolates to amisulbrom was determined, with an average EC50 of 0.24 ± 0.11 μg/mL. The fitness of resistant mutants, obtained by fungicide adaption, was significantly lower than that of the parental isolates in vitro. Cross-resistance was detected between amisulbrom and cyazofamid. Amisulbrom could not inhibit the cytochrome bc1 complex activity with H15Y and G30E + F220L point mutations in cytochrome b (Cyt b) in vitro. Molecular docking indicated that the H15Y or G30E point mutation can decrease the binding energy between amisulbrom and P. litchii Cyt b. In conclusion, P. litchii might have a medium resistance risk to amisulbrom, and a novel point mutation H15Y or G30E in Cyt b could cause high amisulbrom resistance in P. litchii