Recurrent supramolecular scenarios within complex 3-D hydrogen bond networks derived from organic ammonium salts of (4-amino-1hydroxybutylidine)-1,1-bisphosphonic acid
Journal Publication ResearchOnline@JCUAbstract
Reactions of (4-amino-1-hydroxybutylidine)-1,1-bisphosphonic acid (alendronic acid = LH5) with organic amines or diamines in a 1 : 2 or 1 : 1 ratio in aqueous solution gave a range of nine new compounds of the general formula [(RN)H](2).LH3] or [(R'N)H-2].LH3]. Crystal structures are reported for: (i) [enH(2)].LH3]center dot 2.H2O) 1; (ii) [MeenH(2)].LH3]center dot 3.H2O) 2; (iii) [Me(2)enH(2)].LH3]center dot 3.5.H2O) 3; (iv) [Et(2)enH(2)].LH3]center dot 2.H2O) 4; (v) [cdaH(2)].LH3]center dot 3.H2O) 5; (vi) [xdaH(2)].LH3]center dot 4.H2O) 6; (vii) [odaH(2)].LH3]center dot 2.H2O)center dot 0.5.EtOH) 7; (viii) [PheaH](2).LH3]center dot 2.H2O) 8; (ix) [melH](2).LH3]center dot 7.H2O)9 (en = H2N.CH2)(2)NH2; Meen = Me(H)N(CH2)(2)NH2; Me(2)en = Me(H)N.CH2)(2)N(H)Me; Et(2)en = Et2N(CH2)(2)NH2; cda = trans-rac-1,2-C6H10.NH2)(2); xda = m-C6H4.NH2)(2); oda = H2N.CH2)(8)NH2; Phea = 2-Ph(CH2)(2)NH2; mel = 1,3,5-C3N3(NH2)(3)). Each structure displays numerous hydrogen bond interactions between bisphosphonate anions, the (alkyl) ammonium cations and water molecules resulting in 3-D network materials. Compounds 1, 7 and 8 display identical 2-D sheets composed of [LH3] (2-)anions and water molecules approximately 12 A thick and pillared by the [enH(2)] (2+) or [onH(2)] (2+) cations or a double layer of [PheaH](+) cations. A similar pillared structure is also observed in compound 9 where the 2-D anion layers are separated by regions of hydrogen bonded and p-stacked [melH]+ cations. The anion layer, although similar to that of compounds 1, 7 or 8, contains a significantly higher proportion of water molecules. The substituted ethylene diamine derivatives 2, 3, and 4 also display a consistent (but not identical) set of flat 2-D sheets of [LH3](2-)anions and water molecules, with the organic diammonium cations and further water molecules sandwiched in between. In contrast to the above lamella type structures, the cda and xda derivatives, 5 and 6, comprise tessellated columns of anion and cations. A consistent feature of all the above structures is the head-to-tail arrangement of [LH3](2-)anions held by strong, charge assisted, N(H)...O hydrogen bonds.
Journal
CrystEngComm
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Volume
19
ISBN/ISSN
1466-8033
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Issue
37
Pages Count
11
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Publisher
Royal Society of Chemistry
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DOI
10.1039/c7ce01034f