*3.1. Materials General Methods*

Gallic acid was purchased from Merck (Darmstadt, Germany) (842649); triethylamine sulfur trioxide adduct (T2136) and triethylamine (TO886) were purchased from TCI (Zwijndecht, Belgium) and Sigma-Aldrich (St. Louis, MO, USA), respectively, while TBA-Br, for ion pair chromatography, was purchased from TCI (MFCD00011633, purity > 99.0%), and solvents were purchased from VWR (Radnor, PA, USA), Biosolve (Dieuze, France) and Honeywell (Seelze, Germany). snSW was collected in the Interdisciplinary Centre of Marine and Environmental Research (CIIMAR, Matosinhos, Portugal), treated with a UV filter and filtered using a 0.45-μm syringe filter. ASW was obtained from sera (sera marin salt, Heinsberg, Germany)—33 g/<sup>L</sup> of sera salt in distilled water.

MW reactions were performed in open glassware vessel reactors in a Milestone Ethos MicroSYNTH 1600 MW (Labstation, ThermoUnicam, Portugal). Thin-layer chromatography (TLC) separations were performed using Merck silica gel 60 (GF254) plates or Macherey–Nagel (Düren, Germany) octadecyl-modified HPTLC silica layers (RP-18 W/UV254). Compounds were visually detected by absorbance at 254 nm and/or 365 nm. Solvents were evaporated using a rotary evaporator under reduced pressure in a Buchi Waterbath B-480 (Flawil, Switzerland). UPW was obtained from the Milli-Q System (Millipore, Darmstadt, Germany).

Infrared spectra for the GAP and GAP–TZA derivative were obtained by FTIR analysis in a Nicolet Magna FTIR 550 Spectrometer coupled with an attenuated total reflectance unit from Smart MiracleTM-Pike Technologies (Fitchurg, WI, USA) with an individual ZnSe crystal. Analyses were performed in the frequency range of 500–4000 cm<sup>−</sup><sup>1</sup> with a 4 cm<sup>−</sup><sup>1</sup> resolution.

1H and 13C (APT) NMR spectra were recorded on a a Bruker Avance 400 spectrometer (Rheinstetten, Germany), operating at 293 K and a frequency of 400.13 MHz for 1H NMR, 100.61 MHz for 13C NMR.

IP-RP-HPLC analyses were performed on a Thermo SCIENTIFIC SpectraSYSTEM (Waltham, MA, USA) equipped with a SpectraSYSTEM UV-8000 diode array detector (DAD), a SpectraSYSTEM P4000 pump and a SpectraSYSTEM AS3000 autosampler, conducted on a Fortis BIO C18 column (Fortis Technologies, 5 μm, 250 × 4.6 mm); the used software was ChromQuest 5.0 ™.
