Coloured aza-cages for lithium encapsulation

The two azacages 1-2,4-dinitrobenzene-7,13-dimethyl-1,4,7,10,13-pentaazabicyclo[5.5.5]eptadecane (1) and 1-2,4-dinitroben-zene-1-2,4-dinitrobenzene-8,14-dimethyl-1,5,8,11,14-pentaazabicyclo [7.5.5]nonadecane (2) have been synthesized by two different synthetic routes. The basicity behavior in mixed water/DMSO solution has been studied by potentiometry (25 degrees C, I = 0.10 mol dm(-3)): logK(1) = 12.76(8), logK(2) = 3.84(5) for (1). The low solubility of (2) prevents the accurate basicity constants determination. Crystals of (2) are monoclinic, space group P2(1)/a, with a = 11.944(3), b = 13.587(6), c = 15.034(4) Angstrom, beta = 90.36(2)degrees and Z = 4; final R = 0.059 (wR(2) = 0.1632) for 1211 unique observed reflections with I > 2 sigma(I), Both cages are able to encapsulate Li+ ion, the Li-7 NMR spectra (CD3OD) of [Li(1)](+) and [Li(2)](+) show sharp signals at 3.52 and 2.50 ppm respectively and indicative of high deshielded cation.