Water Tetramer Research Articles

Self-assembly of ordered water tetramers in an encapsulated [Br(H2O)12]− complex

An unanticipated anion-water cluster is assembled by one bromide and three highly-ordered "water tetramers" within the cavity of a receptor, providing a perfect C(3) symmetric propeller-shaped bromide-water cluster of [Br(H(2)O)(12)](-).

A novel T4(1)6(1) water tape encapsulated in a (3,3)-connected 2D copper metal–organic framework

A (3,3)-connected 2D copper coordination polymer {[Cu(abit)(NO3)]·5H2O}n (1) containing a novel T4(1)6(1) water tape consisting of chair-shaped water hexamer with two dangling water molecules and uudd configuration of tetramer water that share one water molecule between the adjacent rings has been synthesized and characterized by single crystal X-ray diffraction analysis.

Characterization of a well-resolved acyclic methanol(water)5 heterohexamer in the solid state

Abstract A novel (CH3OH)(H2O)5 binary cluster is trapped in a photoluminescent silver(I) coordination polymeric host, [Ag2(bpp)2(H2O)(ssa)·4H2O·CH3OH]n (1, bpp = 1,3-bis(4-pyridyl)propane, H2ssa = 5-sulfosalicylic acid). The heterohexamer can be viewed as either a D5 water pentamer with a dangling methanol molecule or a combination of D4 tetrameric water and methanol–water heterodimer. This well-resolved heterohexamer may behave as a useful model helping us to further understand phase behavior of binary methanol–water system. The luminescent behavior of 1 was also discussed.

An unprecedented T4(1)4(2)5(2) water topology

Abstract Herein, a special water cluster was observed in a metal-organic framework, namely [Zn(μ-(H2O)2)(L)(BDC)]·5H2O (1, L = 2-(pyridine-4-yl)-1H-benzo[d]imidazole, H2BDC = terephthalic acid). In this ice-like water cluster, tetramer water clusters are combined together by sharing one corner to give rise to the T4(1) water structure, while the pentamer water clusters are located on two sides of this T4(1) water chain by sharing two edges with two tetramer water clusters, thus resulting in the overall T4(1)4(2)5(2) water topology.

A discrete water hexamer with a new planar tetrameric water moiety trapped in the crystal host of [Ag(azelate)(4,4′-bipyridine)]·(H2O)3

Abstract The ultrasonic reaction of Ag2O, bipy and H2aze gave rise to a novel Ag(I) mixed-ligand coordination polymer, namely [Ag(aze)(bipy)]·(H2O)3 (1) (bipy = 4,4′-bipyridine, H2aze = azelaic acid). In 1, Ag(I) ions are linked by bipy and aze ligands to form a single two-dimensional (2D) undulated net with a (6,3) topology, incorporating Ag6(bipy)4(aze)2 windows of 22.58 × 11.06 A based on Ag⋯Ag distances. A pair of identical 2D single nets are interconnected via π⋯π stacking and unsupported Ag⋯Ag interactions to generate a 2D double-layered net. A discrete water hexamer composed of a new planar tetrameric water ring and two pendent water molecules is perpendicularly located in each hydrophilic cavity of the 2D bilayer and acts as a ‘glue’ to assemble adjacent 2D double-layered nets into a three-dimensional (3D) structure.

Different water clusters dependent on long-chain dicarboxylates in two Ag(I) coordination polymers: Synthesis, structure and thermal stability

Two mixed-ligand Ag(I) coordination polymers (CPs), [Ag 2(bipy) 2(sub)·5H 2O] n ( 1), [Ag 2(bipy) 2(aze)·3H 2O] n ( 2), (bipy = 4,4′-bipyridine, H 2sub = suberic acid, H 2aze = azelaic acid) have been synthesized and structurally characterized by elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis, and single crystal X-ray diffraction. Both 1 and 2 are two-dimensional (2D) sheets based on infinite [Ag(bipy)] n double chain incorporating Ag⋯Ag interactions. Interestingly, two different water clusters are encapsulated in the voids between the sheets of 1 and 2. For 1, one water decamer (H 2O) 10 based on a cyclic water tetramer was hydrogen-bonded with the host 2D sheet. While, one water hexamer (H 2O) 6 also based on a cyclic water tetramer was observed in 2. Comparing the experimental results, it is comprehensible that the dicarboxylates play a crucial role in the formation of the different water clusters. Moreover, the thermal stabilities of them were also discussed.

Cation-templated 2-D Mn(II)–oxalate framework with an acyclic tetrameric water cluster

The single-crystal X-ray structure of a cation-templated manganese–oxalate coordination polymer [NH(C2H5)3][Mn2(ox)3] · (5H2O)] (1) is reported. In 1, triethylammonium cation is entrapped between the cavities of 2-D honeycomb layers constructed by oxalate and water. The acyclic tetrameric water clusters and discrete water assemble the parallel 2-D honeycomb oxalate layers via an intricate array of hydrogen bonds into an overall 3-D network. The magnetic susceptibility, with and without the water cluster, are reported with infrared and EPR studies.

Generation of Zwitterionic Water Channels: Biszwitterionic Imidazolium Carboxylates as Hydrogen-Bonding Acceptors

Organic crystals containing several types of water channels are generated by clipping water molecules with biszwitterionic imidazolium carboxylates as hydrogen-bonding acceptors. The types of water channels to be generated depend on the size and the shape of the aromatic spacers tethered with two imidazolium carboxylates moieties. Clusters of water tetramers and dimers were obtained from imidazolium carboxylates with phenylene (1) and naphthalene (2) linkers, respectively. The latter showed pseudopolymorphism, affording layers of water hexamers. Imidazolium carboxylate possessing biphenylene linker (3) afforded channels of discrete water tetramers.

Two novel polyoxotantalates formed by Lindqvist-type hexatantalate and Copper-amine complexes

Two novel polyoxotantalate derivatives, {[Cu(1,3-dap)2]2[Cu(1,3-dap)(H2O)]2[Ta6O19]}·8H2O (1) and [Cu(en)2]4[Ta6O19]·14H2O (2) (1,3-dap = 1,3-diaminopropane, and en = ethylenediamine), which are constructed from the Lindqvist-type [Ta6O19]8− anion and copper–amine complexes, have been synthesized and characterized by elemental analyses, IR, XPS, TGA and single-crystal X-ray diffraction. In compound 1, each [Ta6O19]8− anion is bound to four copper fragments via the surface bridging oxygen atoms to form a neutral tetrasupported Lindqvist structure, which is further connected by water trimer via hydrogen-bonds to yield a one-dimensional (1D) supramolecular chain. In compound 2, the [Ta6O19]8− anions are linked together via the hydrogen bonds and Cu⋯O weak interaction to form an infinite 1D supramolecular chain, which is further connected to each other via hydrogen bonds with the cyclic water tetramer to yield a two-dimensional (2D) supramolecular network.

Energetic and fragmentation stability of water clusters (H 2O) n, n = 2–30

Ab initio calculations have been performed to study the structural trend, energetic stability, and fragmentation behavior of water clusters (H 2O) 2–30. We show that as size increases, the cluster structures evolve from a mono-ring motif to multi-ring and ring-stacking motifs, and then to stuffed cage structures. We also show that losing water molecules one-by-one is the most favorable fragmentation channel with a dissociation energy of ∼11.53 kcal/mol. Small water clusters such as water dimer, trimer, and tetramer, can also be observed in the fragmentation products since they often appear in the second best fragmentation channel.

Carbophosphazene-Based Multisite Coordination Ligands: Metalation Studies on the Pyridyloxy Carbophosphazene, [NC(NMe2)]2[NP(p-OC5H4N)2

The pyridyloxycarbophosphazene, [NC(NMe2)]2[NP(p-OC5H4N)2] (L), reacted with Cd(OAc)2·4H2O to afford a rail-road-like double-strand coordination polymer, [{Cd(CH3COO)2(L)}(CH3OH)(H2O)2]n (1). The c...

A Discrete Spirocyclic (H2O)9 Cluster and 1D Novel Water Chain with Tetrameric and Octameric Clusters in Cationic Hosts

Two mixed-ligand Ag(I) coordination polymers (CPs), [Ag2(bpp)2(suc)·12H2O]n (1) and [Ag2(bpe)2(suc)·9H2O]n (2) (where bpp = 1,3-bis(4-pyridyl)propane, bpe = 1,3-bis(4-pyridyl)ethane, and H2suc = succinic acid), have been synthesized and structurally characterized. Both structures consist of cationic layers with Ag···π interacted chains of alternating metal and bis(pyridyl) ligands. The noncoordinated succinate (suc2−) in 1 or 2 serves as an anionic template driving surrounding water molecules to aggregate into an ordered 2D water-suc anionic layer. The interlamellar anions and cationic layers are stacked through weak electrostatic interaction and hydrogen bonds. One novel 1D water chain constructed from alternating water tetramer with uudd configuration and rare octamer exists in the anionic layer of 1. Each octameric water cluster consists of a pair of fused hexameric water clusters, and each water hexamer assumes a rare bag-shaped conformation. A discrete spirocyclic nonameric water cluster featuring two vertex-sharing pentamers, which shows a similar structure to organic hydrocarbon spiro[4.4] nonane, was observed in 2. All water clusters have not been structurally documented so far and illustrate new modes of supramolecular association of water molecules. What is more important is that the present observations demonstrate that the spacer length of N-donor ligands has a significant influence on the final formation of water aggregates.

Protonated 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine and its Fe(II) bischelates: Syntheses and molecular structures

Compounds of the molecular formulae, [ LH 3](NO 3) 3 ( 1), [Fe( LH) 2](PF 6) 4·5H 2O ( 2), [Fe( L) 2][Fe( L)( LH)](PF 6) 5·H 2O ( 3), [Fe( L) 2][Fe( L)( LH)](BF 4) 5·2H 2O ( 4) and [Fe( L) 2](Cr 2O 7)·6H 2O ( 5) have been synthesized using 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine ( L). The molecular structures of all the compounds were determined. The Fe(II) complexes are high spin in nature at room temperature and upon cooling a gradual spin-transition is observed. Among 1– 5, hydrogen-bonding, π···π, and anion···π interactions as well as water tetramer and pentamer are present in the molecular packing.

One 1D T4(0)A(0) water tape embedded in a 1D Cu(II) coordination polymer with 1,3-bis(4-pyridyl)propane

The reaction of Cu(OH) 2 ( in situ synthesized from CuCl 2·2H 2O and NaOH), bpp and H 2ox gave rise to a novel Cu(II) coordination polymer under ultrasonic irradiation at ambient temperature, namely [Cu(bpp)(ox)(H 2O)·5H 2O] n ( 1) (bpp = 1,3-bis(4-pyridyl)propane, H 2ox = oxalic acid). In the complex 1, Cu(II) cations are bridged by bpp ligands to form a one-dimensional (1D) infinite wave-like polymeric chain. The coordinated ox 2− anions and water molecules interact with each other by six different hydrogen-bonding motifs and extend the 1D polymeric chain into a two-dimensional (2D) bilayer pattern. Of further interest, one 1D T4(0)A(0) water tape consisting of alternate cyclic water tetramers resides in the channel structure of 1.

Varying structural motifs in oxyanions (NO3−, CO32−) and phenoxyacetate (PhOAc−) bridged coordination polymers derived from alkoxo-bridged dicopper building blocks with {Cu2O2} core

The oxyanions (NO3−, CO32−) and phenoxyacetate (PhOAc−) bridged three 1D-coordination polymeric chains, {[Cu2(μ-hep)2(μ-NO3)]2}n (1), {[Cu2(μ-hep)2(H2O)2]·2H2O(μ-CO3)}n (3) and {[Cu2(μ-hep)2(μ-PhOAc−)]2}n (2) (hep-H = 2-(2-hydroxyethyl)pyridine) have been synthesized. In 1–3 the alkoxide bridged dicopper building units, [Cu(μ-hep)]2 with Cu2O2 core, are linked via the respective anions. Detailed structural analysis reveals that in 1 or 2, two units of NO3− (1) or PhOAc− (2), respectively, bind with the four copper ions in two adjacent alkoxide bridged dimeric units in head-to-head and tail-to-tail fashion and the same binding mode continues along the polymeric chain. This in effect yields a 12-membered metallacyclic ring in between two dimeric core units. However, in 3 only one CO32−group bridges the two copper centres associated with the two neighbouring alkoxide bridged dimeric units in head-to-tail mode which in turn forms a zig-zag polymeric chain. Two coordinated and two lattice water molecules from two adjacent polymeric layers in the structure of 3 form water tetramers. Furthermore, the interaction of water tetramer with the uncoordinated –CO group of the bridging CO32− develops an additional zig-zag chain which is being trapped between the two outer zig-zag coordination polymeric chains in 3. The polymeric chains in 1–3 further develop a 2D-network pattern via an extensive non-covalent hydrogen bonding as well as C–H⋯π and π⋯π interactions.

Confinement of unprecedented tetrahedral water tetramers inside 1D hydrophobic channels of metal–organic framework hosts

Two NbO frameworks are constructed by the reaction of Co(OAc)2·4(H2O)/Zn(OAc)2·2(H2O) with 1-(4-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione in the ratio of 1:2, in which they are isostructural and the NbO net exhibits a two-fold interpenetration featuring hexameric 1D channels. Theses channels are occupied by unprecedented tetrahedral tetramer water clusters.

Supramolecular networks constructed by cationic copper(II) complexes incorporating hybrid water–anionic polymeric assemblies

Two complexes, [Cu2(TFSA)(2,2′-bpy)4] · TFSA · 8H2O (1) and {[Cu(4,4′-bpy)(H2O)2] · TFSA · 6H2O} n (2) (H2TFSA = tetrafluorosuccinic acid, 2,2′-bpy = 2,2′-bipyridine, and 4,4′-bpy = 4,4′-bipyridine), have been synthesized and structurally characterized by X-ray structural analyses. Complex 1 is a binuclear molecule bridged by TFSA ligands; 2 is a 1-D chain bridged by 4,4′-bpy ligands. The asymmetric units of the two complexes are composed of cationic complexes [Cu2(TFSA)(2,2′-bpy)4]2+ (1) and [Cu(4,4′-bpy)(H2O)2]2+ (2), free TFSA anion, and independent crystallization water molecules. A unique 2-D hybrid water–TFSA anionic layer by linkage of {[(H2O)8(TFSA)]2−} n fragments consisting of 1-D T6(0)A2 water tape and TFSA anionic units by hydrogen bonds in 1 was observed. Unique 2-D hybrid water–TFSA anionic layer generated by the linkage of {[(H2O)6(TFSA)]2−} n fragments consisting of cyclic water tetramers with appended water molecules and TFSA anionic units, and 1-D metal–water tape [Cu–H2O ··· (H2O)6 ··· H2O−] n in 2 were found. 3-D supramolecular networks of the two complexes consist of cationic complexes and water–TFSA anionic assemblies connected by hydrogen bonds.

Calculated Nuclear Magnetic Resonance Parameters for Multiproton-Exchange and Nonbonded-Hydrogen Rotation Processes in Cyclic Water Clusters

In this work we report, for the first time, calculations of nuclear magnetic resonance parameters for the processes of multiproton-exchange and nonbonded-proton rotations in small, cyclic water clusters. The simultaneous proton exchange induces a large decrease in the oxygen shielding constants in both clusters, with a mean value of -52.6 ppm for the water trimer and -50.1 ppm for the water tetramer. The (1(h))J(OH) coupling constant between an oxygen nucleus and exchanging proton decreases (in absolute value) along the path, changes sign, finally reaching a value of 5-7 Hz. The changes in the NMR parameters induced by the nonbonded proton rotations are smaller. The calculated dependencies of the intermolecular spin-spin coupling constants upon rotation reveal that the largest changes are expected for the couplings transmitted through the hydrogen bond between the rotating and neighboring molecule which acts as a proton donor. The symmetry-adapted perturbation theory (SAPT) interaction energy calculations for each dimer forming the water trimer have allowed us to relate a strength of interactions within pairs of water molecules with coupling constant values. The predicted maximal values of the interaction-energy terms (energetically unfavorable orientations of the constituent dimers) along paths correlate with the extremal values of the spin-spin coupling constants, which mostly correspond to the maximal couplings along pathways.

Structure of a cyclic water tetramer in a nucleotide crystal host and a hypothetical model for water cluster growth

Structure of a cyclic water tetramer in channels (pores) formed by self-assembly of N6-methyl-5′-AMP·Na2 molecules is described and a hypothetical model is proposed for growth of water clusters.

Electron Capture Dynamics of a Water Molecule Connected to a Cyclic Water Trimer: A Direct Ab Initio MD Approach

Electron capture dynamics of the water tetramer (H(2)O)(n) (n = 4) have been investigated by means of a full-dimensional direct ab initio molecular dynamics (MD) method at the MP2/6-311++G(d,p) level. Two structural conformers (branched and cyclic forms of the water tetramer) were examined as neutral water tetramers. The structure of the branched form is that a dangling water molecule binds to the ring composed of a cyclic water trimer. In the case of electron capture of the branched form, first, an excess electron was trapped by the dangling water molecule. Next, rotation of the water molecule located in the ring occurred rapidly, while a hydrogen bond of the ring was broken. The branched structure was gradually changed to a linear one. This change was caused by the increase of the dipole moment of the neutral water tetramer oriented toward the excess electron. The time scale of hydrogen bond breaking and solvation of the excess electron were estimated to be 100 and 400 fs, respectively. In the case of the cyclic water tetramer, a planar structure was only changed to a slight bent form. The mechanism of electron capture of the water tetramer (mainly the branched form) was discussed on the basis of theoretical results.