Lead 2 nitrate

Pyrogallol (C₆H₃(OH)₃, > 99%), sodium citrate hydrate (C₆H₅Na₃O₇·2H₂O, > 99%), polyvinpyrrolidone (PVP, > 99%), methanol (CH₃OH, > 99.8%), sodium hydroxide (NaOH, > 97%), potassium hydroxide (KOH, > 85%), lead (II) nitrate (Pb(NO₃)₂, > 99.9%), and nitric acid (HNO₃, 69%) were purchased from Wako Pure Chemical Industries, Ltd. All chemical were used as received without further purification. Deionized water with a specific resistance of 18.2 MΩ cm was obtained by reverse osmosis followed by ion exchange and filtration.

Citric acid was supplied by TCI. Thiourea, DMF, 2-amino-3-chloro-1,4-napthoquinone, disodium anthraquinone-1,5-disulfonate, silver nitrate (AgNO₃), cadmium nitrate (Cd[NO₃]₂·4H₂O), cobalt(ii) chloride (CoCl₂·6H₂O), nickel(ii) nitrate (Ni[NO₃]₂·6H₂O), and lead(ii) nitrate (Pb[NO₃]₂), and zinc nitrate (Zn[NO₃]₂·6H₂O) were purchased from Fujifilm Wako Chemicals. Copper(ii) perchlorate (Cu[ClO₄]₂·6H₂O), iron(iii) chloride (FeCl₃·6H₂O), and manganese(ii) chloride (MnCl₂·4H₂O) were purchased from Kishida chemicals. Next, iron(ii) chloride (FeCl₂·4H₂O) was supplied by Kanto chemicals. Dichloromethane (CH₂Cl₂), methanol (MeOH), ethyl acetate (EtOAc), and diethyl ether (Et₂O) were purchased from Fujifilm Wako Chemicals. Water used in the present study was purified by a Milli-Q Integral 3 (Merck) with a resistivity of greater than 18.2 MΩ cm.