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  • 1
    ISSN: 1572-8854
    Keywords: 1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane ; 2,5-pyridinedicarboxylic acid ; 2,2′-dithiosalicylic acid ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A 1:2:2 complex of 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane with 2,5-pyridinedicarboxylic acid and water (1) and its 1:1:1.75 complex with 2,2′-dithiosalicylic acid and water (2) have been obtained and characterized by x-ray diffraction. C26H40N4O14 (1), triclinic, $$P\bar 1$$ , a = 9.574(1) Å, b = 9.632(1) Å, c = 9.723(1) Å, α = 112.70(1)°, β = 91.07(1)°, γ = 115.45(1)°, V = 728.35(13) Å3, Z = 1. C26H39.5N2O9.75S2 (2), M = 600.22, triclinic, $$P\bar 1$$ , a = 10.492(1) Å, b = 10.945(1) Å, c = 14.535(2) Å, α = 102.74(1)°, β = 109.08(1)°, γ = 90.68(1)°, V = 1532.2(3) Å3, Z = 2. In complex 1, both N-atoms of the macrocyclic ring are protonated. The following types of H-bonding have been found: (1) between protonated aza groups of the macrocycle and ionized carboxylic groups; (2) between the protonated aza groups and N-atoms of the pyridine nuclei (D–A distance slightly exceeds 3 Å); (3) between water molecules and C=O groups of the non-ionized carboxylic groups; and (4) between the nonionized and ionized groups of the carboxylic acid. The above interactions give rise to the formation of a developed supramolecular network in the crystals of 1. In complex 2, despite the presence of several types of hydrogen bonds involving the aza crown, 2,2′-dithiosalicylic acid and water, the aromatic anions are H-bound only to the two other components, and not to each other. The H-bonds found in complex 2 are between (1) one of the protonated aza groups and water, (2) protonated aza groups and O-atoms of the ionized carboxylic groups, (3) water molecule and carboxylic O-atom, (4) water molecule and sulfur atom, and (5) water molecule and O-atom of diaza-18-crown-6.
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  • 2
    ISSN: 1572-8854
    Keywords: 5,7-Dioxo-1,4,8,11-tetraazacyclotetradecane ; 2,6-dihydoxyanthraquinone ; hydrogen bonding ; supramolecular network
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A complex of 5,7-dioxo-1,4,8,11-tetraazacyclotetradecane (dioxocyclam) and 2,6-dihydoxyanthraquinone (anthraflavic acid) has been obtained. The complex (crystals grown from water-ethanol solution) has a stoichiometry dioxocyclam-anthraflavic acid 1:1:5. C31H32N4O8, chemical formula weight 588.61, triclinic, P − 1, a = 10.542(3) Å, b = 11.936(2) Å, c = 12.206(2) Å, α = 104.00(1)°, β = 92.68(2)°, γ = 103.64(2)°, V = 1439.4 (5) Å3, Z = 2, Dx = 1.358 g cm−3. Only one of the two amine N-atoms of the macrocycle is protonated due to very weak acidic properties of 2,6-dihydoxyanthraquinone. Due to the rather poor quality of the crystals and structure refinement, reliable determination of H-bonds is complicated. Nevertheless, several types of H-bonding responsible for the formation of a developed supramolecular network can be suggested: between the protonated amino groups and macrocycle's C=O moieties; between non-protonated amino groups and macrocycle's C=O moieties; between protonated and non-protonated amino groups; between the amide NH and C=O groups of anthraflavic acid; and between protonated and deprotonated hydroxy groups of the acid. Two types of anthraflavic components can be distinguished in the lattice: those having a parallel orientation with respect to the macrocyclic fragments and forming hydrogen bonds with the latter, and those lying in an approximately perpendicular plane and not involved in H-bonding with the macrocycles.
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