Avance 2 400 mhz

Manufactured by Bruker

Sourced in United States, Germany

The Avance II 400 MHz is a nuclear magnetic resonance (NMR) spectrometer designed for routine analytical applications. It operates at a frequency of 400 MHz and is capable of performing high-resolution NMR spectroscopy on a variety of samples.

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36 protocols using avance 2 400 mhz

Synthesis and Characterization of Choline Ionic Liquids

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The tested choline ILs were synthesized by mixing choline bicarbonate (Sigma-Aldrich, St. Louis, USA, 80% in H₂O) with carboxylic acids (acetic acid, lactic acid, malonic acid, isovaleric acid, isobutyric acid, 2-methylbutyric acid; all from Sigma-Aldrich, used as received) in aqueous solutions [34 (link)]. The chemical identity of the obtained ILs (for structures, names and abbreviations, see Table 1) was confirmed by ¹H-NMR spectroscopy (Bruker Avance II 400 MHz, Bruker Corporation, Billerica, MA, USA) using D₂O as a solvent. The water content was determined by Karl Fischer’s coulometric titration (Metrohm 756 KF Coulometer, Metrohm AG, Herisau, Switzerland). All ILs were dried under high vacuum and stored in a glovebox under an argon atmosphere (water content below 0.5 ppm) prior to use.

Elhi F., Gantman M., Nurk G., Schulz P.S., Wasserscheid P., Aabloo A, & Põhako-Esko K. (2020). Influence of Carboxylate Anions on Phase Behavior of Choline Ionic Liquid Mixtures. Molecules, 25(7), 1691.

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Synthesis and Characterization of Chiral Compounds

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Unless otherwise noted, the materials were purchased from commercial suppliers and used without further purification. Column chromatography was performed on silica gel (200~300 mesh). Enantiomeric excesses (ee) were determined by HPLC (Agilent, Palo Alto, CA, USA) using the corresponding commercial chiral columns as stated at 25 °C with a UV detector at 254 nm. Optical rotations (JiaHang Instruments, Shanghai, China) were reported as follows:

{[α]}_{D}^{T}

(c g/100 mL, solvent). All ¹H NMR and ¹⁹F NMR spectra were recorded on a Bruker Avance II 400 MHz (Bruker, Karlsruhe, Germany) and Bruker Avance III 600 MHz (Bruker, Karlsruhe, Germany), respectively; (Supplementary Materials) ¹³C NMR spectra were recorded on a Bruker Avance II 101 MHz or Bruker Avance III 151 MHz with chemical shifts reported as ppm (in CDCl₃, TMS as an internal standard). Data for ¹H NMR were recorded as follows: chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t = triplet, m = multiplet, br = broad singlet, dd = double doublet, coupling constants in Hz and integration). HRMS (ESI) was obtained with an HRMS/MS instrument (LTQ Orbitrap XL TM, Agilent, Palo Alto, CA, USA). The absolute configuration of 4 was assigned by the X-ray analysis.

Geng J., Wei X., He B., Hao Y., Qu J, & Wang B. (2023). Desymmetrization of Prochiral N-Pyrazolyl Maleimides via Organocatalyzed Asymmetric Michael Addition with Pyrazolones: Construction of Tri-N-Heterocyclic Scaffolds Bearing Both Central and Axial Chirality. Molecules, 28(11), 4279.

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Synthesis and Characterization of Chitosan-Caffeic Acid Conjugate

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In brief, chitosan (100 mg) was dissolved in degassed MES buffer (pH 5.0, 1 M). Hydrocaffeic acid (50 mg) and DMTMM (74 mg) dissolved in 25 mL of degassed MES buffer (1 M) were added to the chitosan solution. This mixture was kept for 12 h under nitrogen protection at room temperature. The product was purified by dialysis (Cellules Membranes, MWCO: 6–8 kD, SpectraPor, USA) against pH 5.0 HCl solution in deionized water for 72 h and only deionized water for 24 h. Samples were frozen and lyophilized at −80 °C in a freezer for 12 h. Then, the product was stored at −20 °C in a freezer before use. The synthesis of CHI-C was confirmed by using ¹H NMR (Bruker Avance II 400 MHz; Bruker Biospin AG, Fallanden, Switzerland) (Supplementary Fig. 5) and ATR-FTIR (Bruker Optics ALPHA E spectrometer with a universal Zn Se attenuated total reflection accessory in the 400–4000 cm⁻¹; Bruker Biospin AG, Fallanden, Switzerland) (Supplementary Fig. 4).

Xu Y., Rothe R., Voigt D., Hauser S., Cui M., Miyagawa T., Patino Gaillez M., Kurth T., Bornhäuser M., Pietzsch J, & Zhang Y. (2021). Convergent synthesis of diversified reversible network leads to liquid metal-containing conductive hydrogel adhesives. Nature Communications, 12, 2407.

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Stereoselective Synthesis of Fluorinated Molecules

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Unless otherwise noted, materials were purchased from commercial suppliers and used without further purification. Column chromatography was performed on silica gel (200~300 mesh). Enantiomeric excesses (ee) were determined by HPLC (Agilent, Palo Alto, CA, USA) using corresponding commercial chiral columns as stated at 30 °C with UV detector at 254 nm. Optical rotations (JiaHang Instruments, Shanghai, China) were reported as follows:

{[α]}_{D}^{T}

(c g/100 mL, solvent). All ¹H NMR and ¹⁹F NMR spectra were recorded on a Bruker Avance II 400 MHz (Bruker, Karlsruhe, Germany) and Bruker Avance III 600 MHz (Bruker, Karlsruhe, Germany), respectively, ¹³C NMR spectra were recorded on a Bruker Avance II 101 MHz or Bruker Avance III 151 MHz with chemical shifts reported as ppm (in CDCl₃, TMS as an internal standard). Data for ¹H NMR are recorded as follows: chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t = triplet, m = multiplet, br = broad singlet, dd = double doublet, coupling constants in Hz, integration). HRMS (ESI) was obtained with a HRMS/MS instrument (LTQ Orbitrap XL TM, Agilent, Palo Alto, CA, USA). The characterization data is available in Supplementary Material.

Xue A., Wei X., Huang Y., Qu J, & Wang B. (2023). Palladium-Catalyzed Stereoselective Construction of 1,3-Stereocenters Displaying Axial and Central Chirality via Asymmetric Alkylations. Molecules, 28(7), 2927.

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Synthetic Organic Chemistry Characterization

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The reactions were monitored by thin-layer chromatography (TLC) analysis using silica gel (60 F254) plates. Compounds were visualized by UV irradiation. Flash column chromatography was performed on silica gel 60 (230–400.13 mesh, 0.040, 0.063 mm). Melting points (m_p [°C]) were taken on samples in open capillary tubes and are uncorrected. The infrared spectra of compounds were recorded at room temperature on a Thermo Scientific Nicolet IS50 FT-IR. ¹H and ¹³C NMR spectra were recorded on a Bruker Avance II 400 MHz (¹³C, 100 MHz) or on a Bruker Avance DPX 250 MHz (¹³C, 62.9 MHz). Chemical shifts are given in parts per million from tetramethylsilane (TMS) as internal standard. The multiplicities of the spectra are reported as follows: singlet (s), doublet (d), triplet (t), quartet (q), and multiplet (m). Coupling constants (J) are reported in hertz (Hz). High-resolution mass spectra (HRMS) were performed on a Maxis Bruker 4G.

Gambouz K., El Abbouchi A., Nassiri S., Suzenet F., Bousmina M., Akssira M., Guillaumet G, & El Kazzouli S. (2020). “On Water” Palladium Catalyzed Direct Arylation of 1H-Indazole and 1H-7-Azaindazole. Molecules, 25(12), 2820.

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Magnetic Susceptibility of Complex 1

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A Cary 50 ultraviolet–visible (UV–vis) spectrophotometer was used to collect optical spectra. FT-IR spectra were acquired on a Varian 3100 Excalibur Series and a Bruker ATR Alpha P spectrometer. NMR spectra were monitored at 25 °C on a Brüker Avance II 400 MHz instrument and sample peaks were referenced to TMS (CDCl₃). GCMS experiments were performed on an Hewlett-Packard 6890/5973 GCMS. Solution magnetic susceptibility measurements on 1 at 298 K were obtained using the Evans NMR method (39 ) with CDCl₃ containing 5% CH₃CN as the reference. Mass susceptibility, χ_g, was calculated from the following equation:

χ_{g} = \frac{- 3 Δ f}{4 π f m} + χ_{o} [1 + \frac{(d_{o} - d_{s})}{m}]

Where Δf is the frequency shift in Hz of the reference compound, f is the fixed probe frequency of the spectrometer, χ_o is the mass susceptibility in cm³ g⁻¹ of the solvent, m is the mass in g of the complex in 1 mL of solution, and d_o and d_s are the densities of the solvent and solution, respectively.

Banerjee A., Li J., Molenda M.A., Brennessel W.W, & Chavez F.A. (2019). A Biomimetic System for Studying Salicylate Dioxygenase. ACS symposium series. American Chemical Society, 1317(4), 71-83.

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NMR Spectroscopy of Isolated Compounds

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NMR spectra (1D and 2D) of isolated compounds were recorded in CD₃OD (Aldrich, St. Louis, MO, USA) using a Bruker Avance II 400 MHz NMR spectrometers (Bruker, Ettlingen, Germany).

R.i.y.a.n.t.i., Balansa W., Liu Y., Sharma A., Mihajlovic S., Hartwig C., Leis B., Rieuwpassa F.J., Ijong F.G., Wägele H., König G.M, & Schäberle T.F. (2020). Selection of sponge-associated bacteria with high potential for the production of antibacterial compounds. Scientific Reports, 10, 19614.

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General Organic Chemistry Techniques

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All reagents were purchased from
commercial suppliers and used without further purification. Reactions
were carried out in 4 mL screw neck glass vials furnished with screw
caps equipped with poly(tetrafluoroethylene) (PTFE)/rubber septa,
and stir bars under ambient atmosphere unless otherwise noted. Silica
gel 60 Å (40–60 μm, 230–400 mesh) was used
for column chromatography. All NMR spectra were recorded in CDCl₃ using a Bruker AVANCE II 400 MHz or Bruker Avance 500 MHz.
Chemical shifts are given in ppm relative to the residual solvent
peak (¹H NMR: CDCl₃ δ 7.26, ¹³C NMR: CDCl₃ δ 77.16) with multiplicity (br = broad,
s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet),
coupling constants (in hertz), and integration. Kinetic data was analyzed
by Agilent 1260 Infinity Quaternary LC (Eclipse Plus 18C column, 3.5
μm, 4.6 × 100 mm²; UV detector, 265 nm) with
a gradient of acetonitrile and 0.1% formic acid in Milli-Q water at
a flow rate of 1 mL/min. The analytes were calibrated using a five-point
calibration curve with threefold dilution between each sample in the
series. HPLC with a chiral stationary phase was performed on an Agilent
1100 series instrument. High-resolution mass spectrometry analyses
were performed by Thermo Scientific Q Exactive HF Hybrid Quadrupole-Orbitrap
HESI or Bruker microTOF ESI, and low-resolution mass analyses by Bruker
Daltonics amaZon speed no 06052 ESI.

Villo P., Dalla-Santa O., Szabó Z, & Lundberg H. (2020). Kinetic Analysis as an Optimization Tool for Catalytic Esterification with a Moisture-Tolerant Zirconium Complex. The Journal of Organic Chemistry, 85(11), 6959-6969.

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Copolymer Composition Analysis via NMR

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The copolymer
compositions and confirmation that polymer functionalization reactions
were taken to completion was determined using nuclear magnetic resonance
(¹H NMR) using a Bruker AVANCE II 400 MHz spectrometer.
Samples were dissolved in deuterated chloroform (CDCl₃)
or deuterated dimethyl sulfoxide, DMSO-d₆, as the solvent. Determination of copolymer composition via ¹H NMR is described in the Supporting Information.

Peltekoff A.J., Brixi S., Niskanen J, & Lessard B.H. (2021). Ionic Liquid Containing Block Copolymer Dielectrics: Designing for High-Frequency Capacitance, Low-Voltage Operation, and Fast Switching Speeds. JACS Au, 1(7), 1044-1056.

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Characterization of Palladium Nanoparticles

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¹H NMR was acquired on a Bruker Avance II 400 MHz or a Bruker Fourier 300 MHz at 298 K. NMR data was processed using iNMR 3.5.1 software. A residual solvent peak at δ 7.26 ppm was used as an internal reference. JEOL 1200 Ex II transmission electron microscopy (TEM) was used to take TEM images of nanoparticles at 120 keV. TEM samples were prepared by dropping 25 μL of 1 mg PdNP/1 mL THF onto a 400 mesh standard carbon-coated copper grids and allowing the grid to dry in air for 30 min. Images were analysed with Scion Image Beta Release 2 for particle size distribution. Thermogravimetric analysis (TGA) was conducted using a TA instrument SDT Q600 with a flow rate of 100 mL/min of N₂ with heating from room temperature to 900 °C at a heating rate of 20 °C/min.

Maung M.S., Dinh T., Salazar C, & Shon Y.S. (2016). Unsupported Micellar Palladium Nanoparticles for Biphasic Hydrogenation and Isomerization of Hydrophobic Allylic Alcohols in Water. Colloids and surfaces. A, Physicochemical and engineering aspects, 513, 367-372.

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