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1. Fluorinated Boron Nitride Quantum Dots: A New 0D Material for Energy Conversion and Detection of Cellular Metabolism

   https://doi.org/10.1002/ppsc.201800346  

   Radhakrishnan, Sruthi; Park, Jun Hyoung; Neupane, Ram; de los Reyes, Carlos A.; Sudeep, Parambath M.; Paulose, Maggie; Martí, Angel A.; Tiwary, Chandra Sekhar; Khabashesku, Valery N.; Varghese, Oomman K.; et al (December 2018, Particle & Particle Systems Characterization)

   Abstract Quantum dots encompass a broad spectrum of optical, catalytic, and electrochemical properties bringing in novel applications in catalysis, imaging, displays, and optoelectronics. Herein, the unanticipated broad‐spectrum light absorption and high fluorescence quantum yield in fluorinated boron nitride (FBN) quantum dots are discussed. A heterostructure of FBN quantum dots with a wide‐bandgap semiconductor, titania nanotube arrays, exhibits high photocatalytic activity as evidenced by high external quantum efficiency extending from ultraviolet to green region of the solar spectrum (≈24% at 400 nm). The high activity is confirmed using photoelectrochemical hydrogen evolution experiments. Further, it is demonstrated that high fluorescence quantum yield could be tapped for the detection of glycolytic activity in cancer cells compared to normal cells. This finding could shift the paradigm of molecular detection using quantum dots. The 0D structure and the gap states introduced through fluorination are believed to be responsible for these unprecedented characteristics of boron nitride. 

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2. Fluorinated peptide biomaterials

   https://doi.org/10.1002/pep2.24184  

   Sloand, Janna N.; Miller, Michael A.; Medina, Scott H. (July 2020, Peptide Science)

   Abstract Fluorinated compounds, while rarely used by nature, are emerging as fundamental ingredients in biomedical research, with applications in drug discovery, metabolomics, biospectroscopy, and, as the focus of this review, peptide/protein engineering. Leveraging the fluorous effect to direct peptide assembly has evolved an entirely new class of organofluorine building blocks from which unique and bioactive materials can be constructed. Here, we discuss three distinct peptide fluorination strategies used to design and induce peptide assembly into nano‐, micro‐, and macro‐supramolecular states that potentiate high‐ordered organization into material scaffolds. These fluorine‐tailored peptide assemblies employ the unique fluorous environment to boost biofunctionality for a broad range of applications, from drug delivery to antibacterial coatings. This review provides foundational tactics for peptide fluorination and discusses the utility of these fluorous‐directed hierarchical structures as material platforms in diverse biomedical applications. 

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3. A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

   https://doi.org/10.1002/poc.4115  

   Ghosh, Goutam; Greer, Alexander (August 2020, Journal of Physical Organic Chemistry)

   Abstract With interests in alkoxy radical formation on natural and artificial surfaces, a physical‐organic study was carried out with a Hammett series of triaryl phosphites (p‐MeO, H,p‐F, andp‐Cl) to trap adsorbed alkoxy radicals on silica nanoparticles. A mechanism which involves PhC (Me)₂O• and EtO• trapping in a cumylethyl peroxide sensitized homolysis reaction is consistent with the results. Thep‐F phosphite was able to indirectly monitor the alkoxy radical formation, and³¹P NMR readily enabled this exploration, but other phosphites of the series such as thep‐MeO phosphite were limited by hydrolysis reactions catalyzed by surface silanol groups. Fluorinated silica nanoparticles helped to suppress the hydrolysis reaction although adventitious water also plays a role in hindering efficient capture of the alkoxy radicals by the phosphite traps. 

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4. First synthesis of 2D materials by hypergolic reactions and evaluation of their dispersions for ink formulation: hexagonal boron nitride and fluorinated carbon nanosheets

   https://doi.org/10.1088/2053-1591/ad2d42  

   Chalmpes, Nikolaos; Bourlinos, Athanasios B; Alsmaeil, Ahmed Wasel; Aljarrah, Abdulaziz S; Salmas, Constantinos E; Karakassides, Michael A; Giannelis, Emmanuel P (March 2024, Materials Research Express)

   Abstract Hypergolic reactions have emerged as a new synthetic approach enabling the rapid production of a diverse set of materials at ambient conditions. While hypergolic reactions bear several similarities to the well-established flame spray pyrolysis (FSP), the former has only recently been demonstrated as a viable approach to materials synthesis. Here we demonstrate a new pathway to 2D materials using hypergolic reactions and expand the gallery of nanomaterials synthesized hypergolically. More specifically, we demonstrate that ammonia borane complex, NH₃BH₃, or 4-fluoroaniline can react hypergolically with fuming nitric acid to form hexagonal boron nitride/fluorinated carbon nanosheets, respectively. Structural and chemical features were confirmed with x-ray diffraction, infrared, Raman, XPS spectroscopies and N₂porosimetry measurements. Electron microscopy (SEM and TEM) along with atomic force microscopy (AFM) were used to characterize the morphology of the materials. Finally, we applied Hansen affinity parameters to quantify the surface/interfacial properties using their dispersibility in solvents. Of the solvents tested, ethylene glycol and ethanol exhibited the most stable dispersions of hexagonal boron nitride (h-BN). With respect to fluorinated carbon (FC) nanosheets, the suitable solvents for high stability dispersions were dimethylsulfoxide and 2-propanol. The dispersibility was quantified in terms of Hansen affinity parameters (δ_d,δ_p,δ_h) = (16.6, 8.2, 21.3) and (17.4, 10.1, 14.5) MPa^1/2for h-BN and FC, respectively. 

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5. Superhard Boron-Rich Boron Carbide with Controlled Degree of Crystallinity

   https://doi.org/10.3390/ma13163622  

   Chakrabarty, Kallol; Chen, Wei-Chih; Baker, Paul A.; Vijayan, Vineeth M.; Chen, Cheng-Chien; Catledge, Shane A. (August 2020, Materials)

   null (Ed.)

   Superhard boron-rich boron carbide coatings were deposited on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) under controlled conditions, which led to either a disordered or crystalline structure, as measured by X-ray diffraction. The control of either disordered or crystalline structures was achieved solely by the choice of the sample being placed either directly on top of the sample holder or within an inset of the sample holder, respectively. The carbon content in the B-C bonded disordered and crystalline coatings was 6.1 at.% and 4.5 at.%, respectively, as measured by X-ray photoelectron spectroscopy. X-ray diffraction analysis of the crystalline coating provided a good match with a B50C2-type structure in which two carbon atoms replaced boron in the α-tetragonal B52 structure, or in which the carbon atoms occupied different interstitial sites. Density functional theory predictions were used to evaluate the dynamical stability of the potential B50C2 structural forms and were consistent with the measurements. The measured nanoindentation hardness of the coatings was as high as 64 GPa, well above the 40 GPa threshold for superhardness. 

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