C. Bazzicalupi, A. Bencini, A. Bianchi
Jul 1, 1994
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Influential Citations
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Journal
Supramolecular Chemistry
Abstract
Abstract The synthesis and characterization of the two macrobicycles 10-methyl-4,15-dioxo-1,7,10-triaza[5.5.5]cycloheptadecane (1) and 27,32-dimethyl-4,10,16,22-tetraoxa-1,7,13,19,27,32-hexaazatricyclo-[17.5.5.57,13]tetratriacontane (2) is reported. The basicity behaviour in aqueous solution have been studied by potentiometry (25°C, I = 0.15 mol dm−3) and NMR spectroscopy (1H and 13C). Compound 1 behaves as diprotic base (log K1 = 11.46(9), log K2 = 5.40(9)), while compound 2 behaves as a pentaprotic base (log K1 = 11.1(1), log K2 = 10.85(9), log K3 = 4.72(9), log K4 = 2.76(9), log K5 = 2.54(9)). NMR experiments indicate most of the stepwise protonation sites. Crystals of [H1][BPh4] are monoclinic, space group P21/n, with a = 11.532(2), b = 20.538(2), c = 13.974(2) A, β = 90.32(1)° and Z = 4; final R value of 0.085 (Rw = 0.080) for 1253 unique observed reflections with I < 4σ(I). The structure shows that the molecule adopts a fairly regular square pyramidal shape with N(1), N(2), O(1) and O(2) forming the...