Tetrabutylammonium Fluoride Research Articles

High-performance carbon nanotube field-effect transistors with electron mobility of 39.4 cm2V−1s−1 using anion–π interaction doping

Single-walled carbon nanotube (SWNT) is desirable next generation semiconductor for flexible, transparent and even stretchable with exceptional electrical characteristics. Here, high-performance n-type semiconducting SWNT field-effect transistors (s-SWNT-FETs) are achieved by chemical doping using anion-π interaction between SWNT and anion of tetrabutylammonium fluoride (TBAF) salt. The Fermi level (EF) of SWNT shifts to the conduction band edge with increasing dopant concentration. The doped s-SWNT-FETs exhibit significant improvement in electron mobility (39.4 cm2V−1s−1) with high current on/off ratio (>104) compared to those of un-doped device. The doping using anion–π interaction leads to populate electron density of channel and reduces both channel and contact resistance by 99.0% and 99.6%. Excess carriers introduced by the doping compensate traps by shifting the EF toward conduction band edge. The doped device showed improved current stability after 10 h of bias stress test, while the current of undoped FET decreased by 40.4%. Finally, flexible FETs with TBAF doped s-SWNT network are demonstrated on polyethylene naphthalate substrate and show stable operation after 2000 times bending test.

CO2 conversion to formamide using a fluoride catalyst and metallic silicon as a reducing agent

Metallic silicon could be an inexpensive, alternative reducing agent for CO2 functionalization compared to conventionally used hydrogen or hydrosilanes. Here, metallic silicon recovered from solar panel production is used as a reducing agent for formamide synthesis. Various amines are converted to their corresponding amides with CO2 and H2O via an Si-H intermediate species in the presence of a catalytic amount of tetrabutylammonium fluoride. The reaction system exhibits a wide substrate scope for formamide synthesis. Spectroscopic analysis, including in situ Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N2 adsorption/desorption analyses, and isotopic experiments reveal that the fluoride catalyst effectively oxidizes Si atoms on both surface and interior of the powdered silicon particles. The solid recovered after catalysis contained mesopores with a high surface area. This unique behavior of the fluoride catalyst in the presence of metallic silicon may be extendable to other reductive reactions, including those with complex substrates. Therefore, this study presents a potential strategy for the efficient utilization of abundant resources.

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C-Si bond functionalization.

3-Silylated furfurals, readily prepared in three steps from biomass-derived furfural and 5-methylfurfural, are converted into 3-silylated 2-furyl carbinols upon condensation with organomagnesium or organolithium reagents. The hydroxy unit of the carbinol adducts can be exploited to promote C3(sp2)–Si bond functionalization through intramolecular activation. Two approaches were contemplated for this purpose. Activation by alkoxides of the C3–SiEt3 or C3–SiMe2t-Bu bonds was ineffective. Conversely, treatment of the C3-benzyldimethylsilyl-appended derivatives with tetrabutylammonium fluoride led to cyclic siloxanes, which revealed to be competent donors for copper-catalyzed cross-coupling reactions, such as arylation reactions catalyzed by Pd2(dba)3/CuI, as well as allylation and methylation reactions catalyzed by CuI⋅PPh3. C3-Benzyldimethylsilyl-appended furfurals are thus introduced as versatile platforms, providing a modular access to 3-substituted 2-furyl carbinols from renewable feedstock.

Development of novel multi-selective slurry with mechanically driven etching for through silicon via chemical mechanical polishing

As a new generation of semiconductor chips such as 3D integration has been developed, the circuit becomes diverse and fine with the composition of various materials. In this study, the novel multi-selective slurry was developed to control each material removal of SiO2, Si3N4, and Cu films respectively. The material removal rate (MRR) of SiO2 was chemically controlled using tetrabutylammonium fluoride (TBAF), in which the addition of 0.5 mM of TBAF increases the MRR of only SiO2 film by 16 times larger than pristine silica slurry without any side effect on the MRR of other materials. The MRR of the Si3N4 wafer was mostly influenced by mechanical abrasion owing to the solid contents. The MRR of the Cu wafer was adjusted by varying the amount of benzotriazole added as an inhibitor. Because each additive affected the material removal only for the target film, the MRR for various materials could be selectively adjusted. Finally, the dishing or protrusion of Cu pad in through-silicon via (TSV) could be controlled in a nanometer scale by using a fabricated multi-selective slurry. In addition, a completely flat surface was obtained when TSV wafer was polished by the selectivity of 1:1:1 on Si3N4, SiO2, and Cu films.

A Mild‐Stimuli‐Responsive Fluorescent Molecular System Enables Multilevel Anti‐Counterfeiting and Highly Adaptable Temperature Monitoring

AbstractSmart luminescent materials with tangible and reversible responses to external stimuli have gained popularity for multiple applications. However, impracticable stimuli and less adaptability render them unfit for real‐life applications. Here, a proton competitive binding‐based molecular system is reported, which demonstrates, both in solution and solid state, remarkable responses toward light illumination and temperature variation. Small change in solvent composition could result in remarkable variation in measurable temperature range at least from −80 to 60 °C. Combination of light illumination and temperature change enables multilevel anti‐counterfeiting, as well as construction of easy‐to‐use and high‐resolution liquid thermometers. The key components in the concerned molecular system are a newly designed fluorophore, NI‐CBN, a four‐coordinated boron derivative of naphthalimide (NI), and an organic fluoride salt that is tetrabutylammonium fluoride (TBAF). Reaction between NI‐CBN and TBAF yields a dynamic fluorophore, NI‐CBN‐F, which shows remarkable color change to the stimuli via proton migration between the imine group in NI‐CBN and the fluoride anion of the salt. Such responses enable the aforementioned advanced anti‐counterfeiting and visible temperature monitoring.

Visible-Light-Induced [4+1] Cyclization-Aromatization of Acylsilanes and α,β-Unsaturated Ketones

Visible-Light-Induced [4+1] Cyclization-Aromatization of Acylsilanes and α,β-Unsaturated Ketones

Design, Synthesis, and Applications of ortho -Sulfur Substituted Arylphosphanes

Design, Synthesis, and Applications of <i>ortho</i> -Sulfur Substituted Arylphosphanes

Multiple Stimuli-Responsive Supramolecular Gel Formed from Modified Adenosine.

Urea derivatives 1 and 2, synthesized from adenosine, were designed as low-molecular-weight gelators. Hydrophobic groups have been introduced into all or part of the hydroxy groups of the hydrophilic ribose moiety of 1 and 2 to control the solvophilicity of the molecules and their aggregates. Compound 2 selectively formed supramolecular gels in halogenated solvents such as chloroform and 1,2-dichloroethane. The supramolecular gel of 2 and chloroform was thermally stable and its gel-to-sol phase transition temperature was higher than the boiling point of chloroform. The physical properties of the supramolecular gel were investigated by determining its viscoelastic properties using a rheometer. The supramolecular gel realized multiple stimuli-responsive reversible gel-sol phase transitions. The supramolecular gel showed reversible phase transition by repeated warming-cooling cycles accompanying with the gel-sol transitions. The supramolecular gel could undergo five repeated mechano-responsive gel-sol transitions. Gel-to-sol phase transition could also be achieved by adding various anions to the supramolecular gel, such as tetrabutylammonium fluoride. Regelation was realized by adding boron trifluoride etherate to the fluoride ion containing sol. Addition of methanol to the supramolecular gel also induced gel-to-sol phase transition. Regelation was realized by adding molecular sieves 4 Å to the suspension.

Synthesis and antifungal activity of slow-release pyridinylcarbonyl chitooligosaccharide copper complexes

Copper fungicides are fungicides have a wide application, but their toxicity to plant growth and the damage they cause to the environment cannot be ignored. As such, the novel, low toxicity biogenic copper fungicide has strong industrial application prospects. Herein, pyridinylcarbonyl chitooligosaccharide ligands (pCOSx) and their copper complexes (pCOSx-Cu) were synthesized. The results showed that a p-π-π conjugated system was formed in pCOSx, resulting in the formation of a slowly dissociated coordination bond between the nitrogen atom of pyridyl and Cu2+ in pCOSx-Cu. The cumulative release rate of Cu2+ is positively correlated with the electron donating ability of pyridyl. Compared with the commercial copper fungicide thiodiazole‑copper, pCOSx-Cu exhibited better antifungal activity, lower phytotoxicity and better biocompatibility. This work demonstrated that it was feasible to construct a conjugated system in a chitooligosaccharide copper complex to improve slow-release performance, which laid a foundation for the in-depth study of green copper fungicides. Chemical compoundsChitooligosaccharide (PubChem CID: 3086191); Nicotinoyl chloride hydrochloride (PubChem CID: 88438); Isonicotinoyl chloride hydrochloride (PubChem CID: 12262826); 2-chloronicotinoyl chloride (PubChem CID: 2774541); Trimethylchlorosilane (PubChem CID: 6397); Tetrabutylammonium fluoride (PubChem CID: 2724141); Copper (II) acetate monohydrate (PubChem CID: 165397).

A C 54 B 2 Polycyclic π-System with Bilayer Assembly and Multi-Redox Activity

A C ₅₄ B ₂ Polycyclic π-System with Bilayer Assembly and Multi-Redox Activity

SN2 versus E2 reactions in a complex microsolvated environment: theoretical analysis of the equilibrium and activation steps of a nucleophilic fluorination.

The reactivity of the fluoride ion towards alkyl halides is highly dependent on the solvating environment. In polar aprotic solvents with large counter-ions is highly reactive and produces substantial E2 product, whereas in polar protic solvents leads to slow kinetics and high selectivity for SN2 reactions. The use of a more complex environment with stoichiometric addition of tert-butanol to acetonitrile solvent is able to module the reactivity and selectivity of tetrabutylammonium fluoride (TBAF). In the present work, we have performed a detailed theoretical analysis of this complex reaction system by density functional theory, continuum solvation model, and including explicit tert-butanol molecules. A kinetic model based on the free energy profile was also used to predict the reactivity and selectivity. The results indicated that the TBAF(tert-butanol) complex plays the key role to increase the SN2 selectivity, whereas higher aggregates are not relevant. The E2 product is formed exclusively via free TBAF, because the solvating tert-butanol in the TBAF(tert-butanol) complex inhibits the E2 pathway. Our analysis suggests that diols or tetraols could produce an improved selectivity.

Palladium-Catalyzed One-Step Synthesis of Stereodefined Difunctionalized Glycals

Palladium-Catalyzed One-Step Synthesis of Stereodefined Difunctionalized Glycals

Polymerizations of 2-(Trimethylsilyl)ethanesulfonyl-activated aziridines

A novel N-sulfonyl aziridine, N-((2-(trimethylsilyl)ethyl)sulfonyl)-2-methyl-aziridine (SES-MeAz) was synthesized, and its controlled anionic ring-opening polymerization to form poly(SES-MeAz) studied. The desulfonylation of poly(SES-MeAz)s can be achieved under mild conditions, with tetrabutylammonium fluoride (TBAF) to form polypropylene imine (PPI), although purification of the PPI was not completely successful. The block copolymer p(pTs-MeAz)-b-p(SES-MeAz), (pTs-MeAz = N-para-tosyl-2-methyl-aziridine) was prepared by a sequential polymerization. The desulfonylation of the block copolymer is the first example of the selective removal of a sulfonyl protecting group from a poly(sulfonylazirdine) block copolymer and this is the first formation of a polysufonylaziridine-block-polypropylene imine copolymer. Three-armed star-shaped poly(SES-MeAz)s were also successfully synthesized and exhibited improved solubility compared with linear poly(SES-MeAz)s.

Hexafluoroisobutylation of enolates through a tandem elimination/allylic shift/hydrofluorination reaction.

The isobutyl side chain is a highly prevalent hydrophobic group in drugs, and it notably constitutes the side chain of leucine. Its replacement by a hexafluorinated version containing two CF3 groups may endow the target compound with new and advantageous properties, yet this modification remains overlooked due to the absence of a general and practical synthetic methodology. Herein, we report the first general method to introduce the hexafluoroisobutyl group into ketoesters, malonates, 1,3-diketones, Schiff base esters and malononitrile. We demonstrated that the reaction occurs through an elimination/allylic shift/hydrofluorination cascade process which efficiently overcomes the usual fluoride β-elimination observed with α-CF3-vinyl groups. We showed that with alkali metal bases, a pentafluorinated alkene is obtained predominantly, whereas the use of tetrabutylammonium fluoride (TBAF) allows hydrofluorination to occur. This tandem process represents a conceptually new pathway to synthesize bis-trifluoromethylated compounds. This methodology was applied to the multigram-scale synthesis of enantiopure (S)-5,5,5,5′,5′,5′-hexafluoroleucine.

Friedel–Crafts Addition of Indoles to Nitrones Promoted by Trimethylsilyl Trifluoromethanesulfonate

N-Alkylindoles undergo Friedel-Crafts addition to aryl and secondary alkyl nitrones in the presence of trimethylsilyl trifluoromethanesulfonate and trialkylamine to produce 3-(1-(silyloxyamino)alkyl)indoles. Spontaneous conversion to bisindolyl(aryl)methanes, which is thermodynamically favored for nitrones derived from aromatic aldehydes, is suppressed under the reaction conditions. The silyloxyamino group can be deprotected with tetrabutylammonium fluoride to yield hydroxylamines.

In Situ Perovskitoid Engineering at SnO2 Interface toward Highly Efficient and Stable Formamidinium Lead Triiodide Perovskite Solar Cells.

The black-phase formamidinium lead triiodide (α-FAPbI3) perovskite has turned out to be one of the most efficient light harvesting materials. However, the phase stability of FAPbI3 is a long-standing issue. Herein, we introduce a layer of tetrabutylammonium fluoride (TBAF) on SnO2, which would form an in situ layer of TBAPbI3 perovskitoid at the SnO2/FAPbI3 interface by interacting with PbI2. The results show that this strategy could improve the conductivity of SnO2, passivate the defects in perovskite, improve the phase stability of α-FAPbI3, and retard the nonradiative recombination in the device. As a result, we obtain a champion device with a power conversion efficiency of 23.1% under AM 1.5 G illumination of 100 mW/cm2. The unencapsulated devices can maintain excellent stability under illumination, thermal stress, and humidity conditions, respectively.

Synthesis, antimicrobial/radical scavenging, and in‐silico investigations of a novel class of 4‐[(4′‐hydroxymethylphenyl)‐1H‐1′,2′,3′‐triazol‐1‐yl‐methyl]‐2H‐chromen‐2‐ones

AbstractReaction of 4‐[(4′‐trimethylsilyl‐1H‐1′,2′,3′‐triazol‐1‐yl)methyl]‐2H‐chromen‐2‐ones with benzaldehyde and tetra‐n‐butylammonium fluoride (TBAF) in THF yielded ten novel coumarinyl‐ triazoyl‐ phenyl methanol derivatives in 88%–97% yields. The in‐vitro antibacterial, antifungal, and radical scavenging activities reveal three of the compounds possess good biological activity. In‐silico computational investigations with the most active ligands have indicated that molecules behave as potent antibacterial inhibitors.

A New Strategy for the Preparation of E Isomers of Hydrazones and Anil‐Like Compounds: Thermally Stimulated Isomerization of Z Isomers of Anions

AbstractA new, simple method for the preparation of E‐isomers of hydrazones and anil‐like compounds from Z‐isomers of these compounds has been developed. In DMF, the Z‐isomers of these compounds in the presence of tetrabutylammonium fluoride (TBAF) or tetrabutylammonium acetate (TBAA) gave the corresponding N anions of the Z‐isomers, which are isomerized to the N anions of the E‐isomers even at room temperature. Upon addition of a protic solvent (H2O, or CH3OH) to this reaction mixture, the N anion of the E‐isomer was immediately quantitatively converted to the E‐isomer of the corresponding nonionic compound, which can be readily isolated by methods commonly used in the synthesis.

Metal‐free Nucleophilic α‐Azidation of α‐Halohydroxamates with Azidotrimethylsilane

AbstractA mild and metal‐free synthetic method for α‐azido carbonyl derivatives via the nucleophilic α‐azidation of α‐halohydroxamates have been established. The reactions of trimethylsilyl azide with various α‐mono‐ and disubstituted azaoxyallyl cations, generated in situ from α‐halohydroxamates, afforded a wide range of hindered mono‐ and dialkyl α‐azido carbonyl derivatives in good yields in the presence of tetrabutylammonium fluoride as a catalyst.

Media‐Driven Pd‐Catalyzed Reaction Cascades with 1,3‐Diynamides Leading Selectively to Either Indoles or Quinolines

AbstractDivergent Pd‐catalyzed reaction cascades with various 1,3‐diynamides yielding either 2‐amino‐3‐alkynylindoles or 2‐amino‐4‐alkenylquinolines were established. Omitting or adding TBAF (tetrabutylammonium fluoride) to the reaction of N,N‐(2‐iodophenyl)(4‐toluenesulfonyl)‐1,3‐diynamides with secondary or primary amines in the presence of KOH in THF and catalytic amounts of Pd(PPh3)4 completely changed the outcome of the reaction. In the absence of TBAF, 2‐amino‐3‐alkynylindoles were the sole products, while the presence of TBAF switched the product formation to 2‐amino‐4‐alkenylquinolines. Deuterium labeling proceeded selectively at the C3 and C11 positions of the 2‐amino‐4‐alkenylquinoline products and this suggests the unprecedented formation of [4]cumulenimines from 1,3‐diynamides as reactive key intermediates.