Drx 500 nmr spectrometer

The samples were dissolved in the deuterated solvent acetone-d₆ and put into a 5 mm NMR tube. All experiments were performed on a Bruker DRX-500 NMR spectrometer (Bruker, Rheinstetten, Germany), operating at a frequency of 500 MHz for ¹H NMR observation, and 125 MHz for ¹³C NMR observation (at room temperature). The 2D NMR experiments included heteronuclear single-quantum correlation (HSQC) and heteronuclear multiple-bond correlation (HMBC). NMR spectra were carefully processed with the TOPSPIN2.1® software (Bruker). The spectra recorded in acetone-d₆ were referenced to the solvent signal at δ_H 2.05 ppm and δ_C 29.92 ppm.

PVC was obtained from Petkim Petrokimya (Istanbul, Turkey). The tin reagents; namely triphenyltin chloride (Ph₃SnCl; 95%), dibutyltin oxide (Bu₂SnO; 98%), dibutyltin dichloride (Bu₂SnCl₂; 96%), and dimethyltin dichloride (Me₂SnCl₂; 97%) were purchased from Merck (Gillingham, UK). The electronic spectra (200–900 nm) was measured in dimethylformamide (1 × 10⁻³ M) using a Shimadzu-160 spectrophotometer (Shimadzu, Kyoto, Japan). FTIR spectra (400–400 cm⁻¹) using a KBr disc technique were recorded on a Shimadzu FTIR 8300 spectrophotometer (Shimadzu, Tokyo, Japan). ¹H (500 MHz) and ¹³C NMR (125 MHz) spectra were recorded in DMSO-d₆ using a Bruker DRX500 NMR spectrometer (Bruker, Zürich, Switzerland). Energy dispersive X-ray (EDX) images were captured using a Bruker XFlash 6 10 (Bruker, Tokyo, Japan) and the microscopic images were captured by a Meiji Techno Microscope (Meiji Techno, Tokyo, Japan). The field emission scanning electron microscope (FESEM) images (15 kV) were captured by a TESCAN-MIRA3 system (TESCAN, Kohoutovice, Czech Republic). A Veeco atomic force microscope (AFM) (Veeco Instruments Inc., Plainview, NY, USA) was used to capture AFM images. An accelerated weather-meter QUV tester (Q-Panel Company; Homestead, FL, USA) was used to irradiate PVC films using UV light (λ_max = 365 nm; light intensity = 6.43 × 10⁻⁹ ein dm⁻³s⁻¹) at 25 °C.

7-Methylxanthine was identified and quantified using the same HPLC system as described above. A ThermoScientific Hypersil BDS C18 HPLC column (4.6 mm inner diameter x 150 mm length) was used as the stationary phase. A mobile phase of 7.5:92.5:0.5 (vol/vol/vol) methanol-water-acetic acid at a flow rate of 0.5 mL/min. Purity of the 7-methylxanthine was confirmed using HPLC and NMR (Figs. S5 and S6). The NMR results were obtained from the NMR facility in the Chemistry Department of the University of Alabama. The spectrum was recorded in DMSO-d₆ with a Bruker DRX 500 NMR spectrometer at 299 K. The chemical shifts were relative to DMSO-d₆ using the standard δ notation in parts per million.

600 μL of serum with 70 μL D₂O and 1 mM sodium 2-trimethylsilylpropionate (TMSP) was used as internal reference in a 5 mm NMR tube at room temperature and data acquisition was carried out.
For NMR data collection, one-dimensional ¹HNMR spectra were acquired on a Bruker DRX-500 NMR spectrometer operating at 500.13 MHZ and Carr-Purcell-Meiboom-Gill (CPMG) 90-(t-180-tn-acqusition) (τ = 200, n = 100) pulse sequence as described earlier.
Analysis of data and pattern recognition were performed using Chenomix 6.4 software.