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1. Successive carbene insertion into 9-phenyl-9-borafluorene

   https://doi.org/10.1039/c9dt01032g  

   Bartholome, Tyler A.; Bluer, Kristen R.; Martin, Caleb D. (May 2019, Dalton Transactions)

   The reactions of 9-phenyl-9-borafluorene with trimethylsilyldiazomethane in a 1 : 1 and 1 : 2 stoichiometry furnished the corresponding BC 5 and BC 6 heterocycles via the formal insertion of one and two carbene units. 

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2. Synthesis of 9-borafluorene analogues featuring a three-dimensional 1,1′-bis( o -carborane) backbone

   https://doi.org/10.1039/c8cc10087j  

   Yruegas, Sam; Axtell, Jonathan C.; Kirlikovali, Kent O.; Spokoyny, Alexander M.; Martin, Caleb D. (January 2019, Chemical Communications)

   The synthesis of [1,1′-bis( o -carboranyl)]boranes was achieved through the deprotonation of 1,1′-bis( o -carborane) reagents followed by salt metathesis with ( i Pr) 2 NBCl 2 . X-ray crystallography confirms planar central BC 4 rings and Gutmann–Beckett studies reveal an increase in Lewis acidity at the boron center in comparison to their biphenyl congener, 9-borafluorene. 

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3. 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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4. Study the Use of Activated Carbon and Bone Char on the Performance of Gravity Sand-Bag Water Filter

   https://doi.org/10.3390/membranes11110868  

   Fung, Eric; Johnson, Ken I.; Li, Wenqi; Borges, William; Chi, Kai; Sharma, Sunil K.; Madan, Yogita; Sharma, Priyanka R.; Hsiao, Benjamin S. (November 2021, Membranes)

   In this study, granulated activated charcoal (GAC) and bio charcoal (BC) is used as a filler in P3 biosand bag filter to study their filtration performance against a range of fluoride impurities from 1–1400 mg/L. A set of experiments are done to analyze the filtration efficiency of the sandbag filter against fluoride impurities after incorporating different amounts (e.g., 0.2, 2 kg) and a combination of GAC and BC. A combination of filler GAC and BC (1 kg each) have exhibited excellent results with 100% fluoride removal efficiency against 5 mg/L fluoride impurities for an entire experimental time of 165 min. It is because of the synergetic effect of adsorption caused by the high surface area (739 m2/g) of GAC and hydroxyapatite groups in BC. The data from remediation experiments using individual GAC and BC are fitted into the Langmuir and Freundlich Isotherm Models to check their adsorption mechanism and determine GAC and BC’s maximum adsorption capacity (Qm). The remediation data for both GAC and BC have shown the better fitting to the Langmuir Isotherm Model with a high R2 value of 0.994 and 0.970, respectively, showing the excellent conformity with monolayer adsorption. While the GAC and BC have presented negative Kf values of −1.08 and −0.72, respectively, for Freundlich Model, showing the non-conformity to multilayer adsorption. The Qm values obtained from Langmuir Model for GAC is 6.23 mg/g, and for BC, it is 9.13 mg/g. The pH study on adsorption efficiency of individual GAC and BC against 5 mg/L of fluoride impurities indicates the decrease in removal efficiency with an increase in pH from 3 to 9. For example, BC has shown removal efficiency of 99.8% at pH 3 and 99.5% at pH 9, while GAC has exhibited removal efficiency of 96.1% at pH 3 and 95.9% at pH 9. Importantly, this study presents the significance of the synergetic application of GAC and BC in the filters, where GAC and BC are different in their origin, functionalities, and surface characteristics. 

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5. Salt- and pH-induced swelling of a poly(acrylic acid) brush via quartz crystal microbalance w/dissipation (QCM-D)

   https://doi.org/10.1039/c9sm01289c  

   Hollingsworth, Nisha R.; Wilkanowicz, Sabina I.; Larson, Ronald G. (October 2019, Soft Matter)

   We infer the swelling/de-swelling behavior of weakly ionizable poly(acrylic acid) (PAA) brushes of 2–39 kDa molar mass in the presence of KCl concentrations from 0.1–1000 mM, pH = 3, 7, and 9, and grafting densities σ = 0.12–2.15 chains per nm 2 using a Quartz Crystal Microbalance with Dissipation (QCM-D), confirming and extending the work of Wu et al. to multiple chain lengths. At pH 7 and 9 (above the p K a ∼ 5), the brush initially swells at low KCl ionic strength (<10 mM) in the “osmotic brush” regime, and de-swells at higher salt concentrations, in the “salted brush” regime, and is relatively unaffected at pH 3, below the p K a , as expected. At pH 7, at low and moderate grafting densities, our results in the high-salt “salted brush” regime ( C s > 10 mM salt) agree with the predicted scaling H ∼ Nσ +1/3 C s −1/3 of brush height H , while in the low-salt “osmotic brush” regime ( C s < 10 mM salt), we find H ∼ Nσ +1/3 C s +0.28–0.38 , whose dependence on C s agrees with scaling theory for this regime, but the dependence on σ strongly disagrees with it. The predicted linearity in the degree of polymerization N is confirmed. The new results partially confirm scaling theory and clarify where improved theories and additional data are needed. 

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