Varian 500 mhz

All reagents were purchased from commercial sources and used without further purification. The ¹H and ¹³C-NMR data were obtained Varian 500 MHz (Agilent, Santa Clara, CA, USA) and Bruker Ultrashield Avance 400 (Bruker, Billerica, MA, USA) spectrometers. Thin layer chromatography (TLC) and NMR were used to monitor reactions and determine compound purity. Compounds were purified by silica gel (Sortech, Norcross, GA, USA, 60 Å, 200–500 µm (35 × 70 mesh)) column chromatography or on pre-coated preparative TLC plates (SiliCycle Inc, Quebec City, Canada, 1000 μm, 20 × 20 cm). High-resolution mass spectrometric (HRMS) data was obtained on a Synapt G2 HDMS instrument operated in positive or negative ESI mode. Spectra are provided as supplementary information (Supplementary Figure S1.1a–S1.16b).

Measurements were obtained in a mixture 1/1 of DMSO-d₆ and PBS buffer (pH = 6.8) at 300 K, in 5-mm sample tubes, with a premium shielded Agilent Varian 500 MHz (operating at 500.13 MHz). Complex 3 (5 mg, 6.12 µmol) was dissolved in 250 µL of DMSO-d₆. Ascorbic acid (10 mg, 10 Equiv.) was dissolved in 250 µL of PBS buffer and added to the platinum complex. ¹H NMR spectra were recorded every 7 min for 1 h. After no reduction had taken place initially, the ¹H NMR spectrum was recorded every hour for 4 hours, and finally every 24 h until full reduction of Pt (IV) to Pt (II) and cleavage of the axial ligand was observed after 72 h. Complex 4 (5 mg, 7.19 µmol) was dissolved in 250 µL of DMSO-d₆. Ascorbic acid (12 mg, 10 Equiv.) was dissolved in 250 µL of PBS buffer and added to the solution containing the complex. The¹H NMR spectra were recorded every 7 min for 1 h. After no reduction had taken place initially, the ¹H NMR spectrum was recorded every hour for 2 hours, and finally every 24 h until full reduction of Pt (IV) to Pt (II) and cleavage of the axial ligand was observed after 24 h.

Proton nuclear magnetic resonance (¹H-NMR) analysis was performed using an NMR spectrometer (Varian 500 MHz; Agilent, Santa Clara, CA, USA) with CDCl₃ as the solvent and tetramethylsilane (TMS) as a reference. Differential scanning calorimetry (DSC Q10; TA Instruments, New Castle, DE, USA) was conducted under a nitrogen atmosphere. Approximately 10 mg of the testing sample was sealed in an aluminum pan. The samples were heated from 40 to 250 °C at a heating rate of 10 °C/min. The onset temperature, peak temperature, and enthalpy of the exothermic peak of the cured compositions were recorded. Thermal degradation properties were measured using a thermogravimetric analyzer (TGA, Q500; TA Instruments, New Castle, DE, USA) from 30 to 800 °C at a heating rate of 10 °C/min. Dynamic mechanical analysis (DMA, Q800; TA Instruments, New Castle, DE, USA) was performed at a heating rate of 5 °C/min from −80 to 280 °C with a fixed frequency of 1 Hz in the single cantilever mode. The dimensions of the test species were 17.5 mm (L) × 10.0 mm (W) × 0.5 mm (T). Thermomechanical analysis (TMA, Q400; TA Instruments, New Castle, DE, USA) was conducted at a heating rate of 10 °C/min from 30 to 250 °C, and a force of 0.05 N was applied.