3.1. Materials

2,3,3-Trimethylindolenine, 1,4-Butanesulfone, 4-Hydroxyphenyl boronic acid and 4-Amine-2,2,6,6-tetramethylpiperidinyloxy (4-amine-TEMPO) were purchased from Adamas; Tetrakis (triphenylphosphine) palladium, N,N-Diisopropylethylamine (DIPEA) and anhydrous ethanol were purchased from Sigma. All reactions were monitored by thin-layer chromatography (TLC). Flash chromatography was carried out using silica gel (200–300 mesh). ¹H NMR spectra were recorded with an Agilent 600 MHz with trimethylchlorosilane (TMS) as an internal standard. Mass spectrometry (HRMS) was performed on a Bruker Ultraflextreme MALDI-TOF system or Shimadzu MALDI-7090. Electron paramagnetic resonance (EPR) was tested with Bruker A300-10/12. NIR spectroscopy was performed using a NIR spectrophotometer (Shimadzu, UV-3600). Photoluminescence was determined with a NIR fluorescence spectrometer (Lumina Fluorescence Spectrometer, Thermo Fisher, Waltham, MA, USA).