Varian 500 ms lc ion trap mass spectrometer

The synthesis of the pro-ligand and its Cu(II) and V(V) complexes for this study was performed in open air. Reagents and solvents were used as received commercially, without further purification or drying. CuCl₂·2H₂O and VO(acac)₂ were used as metal precursors for the synthesis of the complexes. Elemental analyses (C, H, and N) were carried out by the Microanalytical Service of the Instituto Superior Técnico. A Bruker Vertex 70 instrument (Bruker Corporation, Ettlingen, Germany) was used for infrared spectra (4000–400 cm⁻¹) analysis in KBr pellets; wavenumbers are in cm⁻¹. The ¹H NMR spectrum of the ligand was recorded on a Bruker Avance II + 400.13 MHz (UltraShield^TM Magnet) spectrometer at room temperature. The internal reference was tetramethyl silane, and the chemical shifts are reported in ppm in the ¹H NMR spectrum. Mass spectra were recorded in a Varian 500-MS LC Ion Trap Mass Spectrometer (Agilent Technologies, Amstelveen, The Netherlands) equipped with an electrospray (ESI) ion source. For electrospray ionization, the drying gas and flow rate were optimized according to the particular sample with 35 p.s.i. nebulizer pressure. Scanning was carried out from m/z 100 to 1200 in methanol solution. The compounds were observed in the positive mode (capillary voltage = 80–105 V).

All synthetic procedures were performed in air. Reagents and solvents were obtained from commercial sources. The organic reactants for the cycloaddition reaction (alkynes and benzyl azide) were further purified prior to use by distillation. DAPTA was synthesized using the published procedure [8 (link),10 (link)]. The ultrasound irradiation was accomplished with a high-intensity ultrasonic probe SONIC VCX 750 (Sonics & Materials Inc., Newtown, CT, USA) model (20 kHz, 750 W) using a titanium horn. Elemental analyses (C, H, and N) were carried out by the Microanalytical service of Instituto Superior Tecnico. ¹H and ³¹P NMR spectra were obtained using a Bruker Advance (Bruker, Billerica, MA, USA) 400 and 500 MHz spectrometers at ambient temperature. Chemical shifts δ are quoted in ppm. ¹H chemical shifts were internally referenced to residual protio-solvent resonance and are reported relative to SiMe₄. ³¹P chemical shifts were referenced to external 85% phosphoric acid. Assignments of ¹H signals rely on COSY experiments. Electrospray mass (ESI-MS) spectra were obtained on a Varian 500-MS LC Ion Trap Mass Spectrometer (Agilent Technologies, Santa Clara, CA, USA) equipped with an electrospray ion source. All compounds were observed in the positive mode (capillary voltage = 80–105 V).