BINDING-PROPERTIES AND CRYSTAL-STRUCTURES OF AZAMACROCYCLES CONTAINING NITROPHENOL SIDE ARMS

Two new azamacrocycles trobenzyl)-4,10-dimethyl-1,4,7,10-tetraazadodec ane (L1) and 1,13-bis(2-hydroxy-5-nitrobenzyl) -4,10-dimethyl-4,7,10, 16-tetramethyl-1,4,7,10,13,16-hexaazaoctadecane (L2) have been synthes ised and characterised. The basicity behaviour has been studied by pot entiometry at 298.1 K in 0.15 mol dm(-3) Me4NCl, by H-1 and C-13 NMR s pectroscopy, as well as by UV-Vis spectroscopy. L1 behaves as a tetrap rotic base in the pH range investigated: log K-1 > 13, log K-2 = 10.59 (1), log K-3 = 7.18(2) and log K-4 = 4.86(2). L2 behaves as a hexaprot ic base: logK(1) = 10.38(2), logK(2) = 9.96(2), logK(3) = 8.29(2), log K(4) = 5.71(2), log K-5 = 4.68(3) and log K-6 = 2.2(1). The influence on the basicity behaviour of the nitrophenolic side arms is discussed. In the case of L2, the equilibria with Cu(II) have been studied by a potentiometric technique. Four main species have been found: the binuc lear species [Cu(2)L2](2+) (log K = 28.7(1)), and three protonated spe cies: [CuH(2)L2](2+), [CuH(3)L2](3+), [CuH(4)L2](4+). For the L1/Cu(II ) system the precipitation of a solid compound prevents the determinat ion of any stability constants, however the coordination behaviour of L1 toward Cu(II) is observed in the crystal structure of [CuL1]ClO4. C rystals of [CuL1]ClO4 are triclinic, space group P (1) over bar, with a = 8.777(3), b=10.744(3), c=15.814(3) Angstrom, alpha = 100.58(2), be ta = 98.47(2), gamma = 101.16(2)degrees, Z = 2, R = 0.070. (C) 1998 El sevier Science S.A. All rights reserved.