The host-guest interactions between ortho- (Ph), pyro- (Pp), and tripolyphosphate (Tr) anions together with ATP (At), ADP (Ad), and AMP (Am) nucleotides and the hexaazamacrocyclic ligand 3,7,11,19,23,27-hexaazatricyclo[27311(13,17)]triaconta- 1(32),13,15,17(34),29(33),30-hexaene (Bn) have been investigated by potentiometric equilibrium methods. Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic attraction between the host and the guest. Formation constants for all the species obtained are reported. The selectivity of the Bn ligand with regard to the phosphate and nucleotide substrates is discussed and illustrated with species distribution diagrams. A comparison of the present results with those obtained for the similar but smaller macrocyclic ligand 3,6,9,17,20,23- hexaazatricyclo[23311(11,15)]triaconta-1(29),11(30),12,14,25,27-hexaene (Bd) is also discussed. It is found that the competition of the Bd and Bn ligands for the formation of ternary species with a specific substrate is strongly dependent on the p[H]. The crystal structure of the compound [(H6Bn)(H2PO4)6]2H2O with empirical formula C28H68N6O26P6 has been solved by means of X-ray diffraction analysis. The compound belongs to the triclinic P1 space group with Z = 1, a = 8892(2) A, b = 9369(4) A, c = 16337(8) A, alpha = 7372(4) degrees, beta = 8301(4) degrees, and gamma = 6481(3) degrees. The phosphate counterions are found to bridge adjacent layers of macrocyclic molecules through an extensive hydrogen-bonding network

The crystal structure of 3,7,11,18,22,26-hexaazatricyclo[26.2.2.2(13,16)]tetratriaconta-1(31),13(34),14,16(33),28(32),29-hexaene hexahydrobromide salt [(H6P3)Br6] has been determined by means of X-ray diffraction analysis. It crystallizes with an additional molecule of ethanol and half a molecule of water per molecule of the hydrobromide P3 ligand. The protonation constants of P3 and its host-guest interactions with monophospate (Ph) and pyrophosphate (Pp) have been investigated by potentiometric equilibrium methods. Ternary complexes are formed in aqueous solution as a result of hydrogen bond formation and Coulombic interactions between the host and the guest; formation constants for all the species obtained are reported and compared with the isomeric 3,7,11,19,23,27-hexaazatricyclo[27.3.1.1(13,17)]tetratriaconta-1(33),13, 15,17(34),29,31-hexaene (Bn) ligand. For the H6P3Pp(2+) those bonding interactions reach a maximum yielding a log KR6 of 5.87. The selectivity of the P3 ligand with regard to the monophosphate and pyrophosphate substrates (S) is discussed and illustrated with global species distribution diagrams showing a strong preference for the latter over the former as a consequence of the much stronger formation constants with pyrophosphate. An analysis of the isomeric effect is also carried out by comparing the P3-S versus Bn-S systems. In the best case, a selectivity of over 88% is achieved for the diphosphate complexation when using the meta isomer over the para, due solely to the size and shape of the receptors cavity.