Iron 3 chloride tetrahydrate

Iron (II) chloride hexahydrate (97%), iron (III) chloride tetrahydrate (98%), hydrochloric acid (36.5–38.0%), and hydroxylamine hydrochloride (98%) were purchased from Sigma Aldrich (Saint Louis, MO, USA). Sodium hydroxide (pure p.a., 98.8%), tetrachloroauric (III) acid (99.995% trace metals basis), and Arabic gum (powder) were bought from Avantor Performance Materials Poland S.A. (Gliwice, Poland). Essential oil used as a component of the reaction environment of Fe₃O₄@Au nanoparticles was bought in AromaLab (Warsaw, Poland).

For the syntheses, all chemicals were used without further purification. Iron(II) chloride tetrahydrate (≥ 99%), iron(III) chloride tetrahydrate (99%), oleic acid (90%), chloroform (≥ 99%), cetyltrimethylammonium bromide (CTAB, ≥ 98%), ammonium hydroxide solution (≥ 25% NH₃ in water), tetraethyl orthosilicate (TEOS, ≥ 99%) ethyl acetate (99.8%), (3-aminopropyl)triethoxysilane (APTES, 99%), acetonitrile (ACN, ≥ 99.9%) were purchased from Sigma-Aldrich Corporation (München, Germany). Poly(ethylene glycol) monomethylether (1kmPEG, M_w: 1000 g/mol) was purchased from TCI Europe N.V. (Zwijindrecht, Belgium), tosylchloride (98%), dichlorodimethylsilane (98%) was purchased from abcr GmbH (Karlsruhe, Germany). Tetrahydrofuran (99.8%) was purchased from Acros Organics (Geel, Belgium), dichloromethane (DCM, ≥ 99.9%) was purchased from Honeywell GmbH (Seelze, Germany), MgSO₄ (99%) was purchased from ThermoFisher (Kandel) GmbH (Kandel, Germany), tris(hydroxypyridinone)maleimide (THP-Mal) was purchased from CheMatech (Dijon, France). Silica gel impregnated glass fiber (ITLC-SG) chromatography plates were obtained from Merck (Darmstadt, Germany). The permanent block neodymium magnet that was used in the experiments was purchased from K&J Magnetics, Inc., USA (type: BX066, material: NdFeB, Grade N42, B_rmax: 13,200 Gauss, B_Hmax: 42 MGOe).