2.1.1. Synthesis of [L1]2n[Pb2Cl6]n∞·nH2O (**1**)

FA solution was prepared by dissolving paraform (0.13 g, 4.5 mmol) in 10 mL boiling deionized water in a 50 mL conic flask. After cooling at r.t., solid Ea·HCl (0.39 g, 4 mmol) was introduced into the FA solution, which was stirred vigorously at r.t. for half an hour. Then, the pale-yellow solution was filtered and left open overnight. The next day, 2-PCA (0.38 mL, 4 mmol) was added and the solution was kept stirring for 1 h while getting brownish. A subsequent dropwise addition of Pb(NO3)2 (0.33 g, 1 mmol) dissolved in DMF (5 mL) induced the precipitation of a small amount of a yellow residue. The mixture was kept stirring for another hour, then filtered and the brown solution was allowed to stand at r.t. Colourless needles of **1** suitable for X-ray crystallography were formed within a few days after addition of <sup>i</sup> PrOH (2 mL). The crystals were filtered off, washed with <sup>i</sup> PrOH and finally dried in air. Yield based on Pb(NO3)2: 47%. FT–IR (ν, cm−1): 3400vs, 3116s, 3072, 3060, 2954, 2928, 2880, 1654, 1560, 1544, 1508, 1448, 1384, 1350, 1328, 1258, 1224, 1150s, 1132, 1076, 946, 922, 880, 796s, 750, 666, 636, 428. 1H NMR (400 MHz, DMSO-*d*6): δ (ppm) 10.01 (s, 1H, =N–CH=N–), 8.79 (d, *J* = 7.0 Hz, py), 8.32 (s, 1H, =C=CH−N–), 7.87 (d, *J* = 9.2 Hz, 1H, py), 7.26 (dd, *J* = 9.1, 6.7 Hz, 1H, py), 7.16 (dd, *J* = 9.9, 3.8 Hz, 1H, py), 5.23 (s, 1H, OH), 4.67 (m, 2H, CH2), 3.92 (m, 2H, CH2). Analysis calculated for C18H24Cl6N4O3Pb2 (971.49): C, 22.25; H 2.49; N 5.77%. Found: C 22.39; H 2.28; N 5.52%.
