Characterization of Supramolecular (H₂O)₁₈ Water Morphology and Water-Methanol (H₂O)₁₅(CH₃OH)₃ Clusters in a Novel Phosphorus Functionalized Trimeric Amino Acid Host

Abstract

Phosphorus functionalized trimeric alanine compounds (l)- and (d)-P(CH(2)NHCH(CH(3))COOH)(3) 2 are prepared in 90% yields by the Mannich reaction of Tris(hydroxymethyl)phosphine 1 with (l)- or (d)- Alanine in aqueous media. The hydration properties of (l)-2 and (d)-2 in water and water-methanol mixtures are described. The crystal structure analysis of (l)-2.4H(2)O, reveals that the alanine molecules pack to form two-dimensional bilayers running parallel to (001). The layered structural motif depicts two closely packed monolayers of 2 each oriented with its phosphorus atoms projected at the center of the bilayer and adjacent monolayers are held together by hydrogen bonds between amine and carboxylate groups. The water bilayers are juxtaposed with the H-bonded alanine trimers leading to 18-membered (H(2)O)(18) water rings. Exposure of aqueous solution of (l)-2 and (d)-2 to methanol vapors resulted in closely packed (l)-2 and (d)-2 solvated with mixed water-methanol (H(2)O)(15)(CH(3)OH)(3) clusters. The O-O distances in the mixed methanol-water clusters of (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH (O-O(average) = 2.857 A) are nearly identical to the O-O distance observed in the supramolecular (H(2)O)(18) water structure (O-O(average) = 2.859 A) implying the retention of the hydrogen bonded structure in water despite the accommodation of hydrophobic methanol groups within the supramolecular (H(2)O)(15)(CH(3)OH)(3) framework. The O-O distances in (l)-2.3H(2)O.CH(3)OH and (d)-2.3H(2)O.CH(3)OH and in (H(2)O)(18) are very close to the O-O distance reported for liquid water (2.85 A).

Formation of Two‐Dimensional Supramolecular Icelike Layer Containing (H2O)12 Rings

“…However, understanding the growth of larger water clusters and how the clusters link to form a large network is still challenging, though some polymeric water phases consisting of basic water tetramer and hexamer subunits have been reported. [8][9][10][11] Very recently, two 2D water/ice layers containing large 12- [12] or 18-membered [13] water rings have been observed in solid states, which provide novel structural aspects of water and new insights into water with implications in biological environments. In this context, we describe two 1D and 2D water morphologies observed in the supramolecular solid-state complexes bpedo·2 H 2 O (1) and bpedo·5 H 2 O (2; bpedo = trans-bis(4-pyridyl)ethylene dioxide).…”

Helix inside a Helix: Encapsulation of Hydrogen‐Bonded Water Molecules in a Staircase Coordination Polymer

“…[2] As hydrogen bonds and other noncovalent interactions are the main driving forces behind this self-assembly process, supramolecular chemistry is now in a phase of characterizing and understanding various hydrogen-bonded water clusters in the form of hexamers, [3,4] octamers, [5,6] decamers, [7] (H 2 O) 15 (CH 3 OH) 3 clusters [8] and one-dimensional (1D) infinite water chains [9,10] in diverse environments of various crystal hosts. Zeolite-like 3D network structures with chiral channels filled with highly ordered water molecules are well known.…”

Modification of 2D Water That Contains Hexameric Units in Chair and Boat Conformations—A Contribution to the Structural Elucidation of Bulk Water

“…[1][2][3] The need for detailed knowledge of the hydrogen bonding and the rearrangement dynamics between water molecules distributed in two and three dimensions arises from the fact that these processes rule the anomalous physical and chemical properties of liquid and solid water, [3,4] the processes that occur at the ice-liquid, ice-air and liquid-air interfaces [10][11][12] as well as the interaction between water and solutes. [11] From an experimental point of view, so far a significant progress has been made with respect to the structural characterization of discrete small [1-3, 9, 13-15] and mediumsized [16][17][18] water clusters (H 2 O) n (n = 2-100) as well as the characterization of 1D aggregates such as chains and tapes. [19][20][21] However, only disperse information is available on 2D layers, [9,[19][20][21][22][23][24][25][26][27][28][29] Many of these layers are sandwich inclusion structures, in which the 2D water sheets are composed either of puckered edge-sharing pentameric clusters or result from the combination of cyclic tetrameric, pentameric, hexameric and/or (very rarely) larger clusters.…”