Water Tape Research Articles

Experimental and Computational Investigations of Supramolecular Interactions in Cd(II)–Organic Hydrate: Catalytic Applications in the Knoevenagel Condensation Reaction under Solvent‐Free Conditions

AbstractA dinuclear cadmium(II) complex, [Cd2(Hhqc)2(H2O)4] (H3hqc=4,8‐dihydroxyquinoline‐2‐carboxylic acid) was synthesized and characterized by single crystal X‐ray diffraction studies, elemental analyses and thermo‐gravimetric studies. The metal centers are found to be six coordinated with distorted pentagonal pyramidal geometry around them. The complex shows few significant intermolecular hydrogen bonding interactions to produce a three dimensional supramolecular network comprising of T8(2) water tapes. Besides these non‐covalent interactions few other supramolecular interactions are also involved within the molecular dimer like π⋅⋅⋅π stacking, Cd⋅⋅⋅π etc. They have been analyzed using DFT calculations, MEP surface analyses and NCI plot index analyses. The detailed study highlights the complex interplay of π‐stacking, H‐bonding, and spodium interactions in stabilizing the dimers of complex, which providing precious insights into their energetic and structural characteristics. Further more, the catalytic efficiency of the synthesized complex has been investigated as an effective heterogeneous catalyst in the Knoevenagel condensation reactionunder solvent‐free conditions.

Water-Stable, Eight-electron Acceptor Drives Anion⋅⋅⋅Water Assisted Tunable Ionic Self-Assembly and Proton Conduction.

Organic π-scaffolds are being envisaged for new-age electron- and ion-responsive materials that can accumulate electrons as well as transport proton. However, such systems are extremely rare as electron-deficient scaffolds are unstable in aqueous solution. Here we detail the synthesis of a water-stable core-naphthalenediimide-nitrobenzyl-viologen based tetra-cation, which accumulates up to eight-electrons within an exceptionally narrow potential window of +0.05 V and -1.12 V. The supramolecular interactions and the ensuing ionic framework are tunable based on the three anions, e. g., Cl-, Br- and PF6 -, that are investigated in this work. The ionic framework is formed and supported by a range of H-bonds, in which, the nitro benzyl groups act as pillars connecting the 1D water-tapes and the halide anions. The water molecules are hydrogen-bonded with the halide anions and bestow a facile pathway for the proton conduction, with proton conductivity up to 3.19×10-3 S cm-1. In contrast, the ionic assembly formed by the lipophilic PF6 - anions do not host the water tapes and consequently the proton conductivity is found to be four orders of magnitude lower. This is a unique example, whereby proton conductivity is realized and is tunable within a highly electron-deficient, eight-electron acceptor, water-stable ionic supramolecular system.

Front Cover: Supramolecular Assemblies and Reversible De‐/ Rehydration in One‐Dimensional Dimethyltin Carboxylates (Eur. J. Inorg. Chem. 13/2022)

The Front Cover shows the synthesis of one-dimensional ladder-like structures of dimethyltin carboxylates in an aqueous medium and highlights the role of chelating 2,2'-bipyridine to control the dimensionality in the presence of 1,2,4,5-benzenetetracarboxylate ligand. The structures reveal supramolecular assemblies formed by the inclusion of infinite water tapes [T4(0)A1] or the organic hydrate (bipy⋅6H2O). The study is a manifestation of reversible single crystal to single crystal structural transformation from P21/c to P212121 upon dehydration with conformational changes in the macrocycles. More information can be found in the Research Article by R. Shankar and co-workers.

Supramolecular Assemblies and Reversible De‐/ Rehydration in One‐Dimensional Dimethyltin Carboxylates

AbstractThe study presents the synthesis and structural aspects of a new family of dimethyltin carboxylates, [(Me2Sn)2(btec)(bipy)(H2O)] ⋅ 4H2O (1), [Me2Sn(btec)0.5(bipy)]2 ⋅ H2O (2), [Me2Sn(btec)0.5(bipy)] ⋅ 3H2O ⋅ 0.5bipy (3) and [Me2Sn(btec)0.5(phen)] (4) derived from 1,2,4,5‐benzenetetracarboxylic acid (H4btec). The structure in each case adopts a one‐dimensional motif featuring ditin macrocycles with 2,2'‐bipyridine (bipy) or 1,10‐phenanthroline (phen) acting as the chelating ligand. For 1, the lattice water molecules in association with the framework form infinite T4(0)A(1) water chains. The organic hydrate, bipy ⋅ 6H2O in 3 adopts a layered structure comprising T4(2)6(2) water tapes and trans‐bipy. Dehydration of 2 to 2 a results in crystal structure transformation from centrosymmetric P21/c (in 2) to chiral P212121 space group and reveals conformational changes in the ditin macrocycles from chair to boat form. The reversibility of this transformation has been supported by TGA, PXRD, and single‐crystal X‐ray studies.

Isolation, Morphotyping, Molecular Characterization and Prevalence of Free-Living Amoebae from Different Water sources in Makkah city, Saudi Arabia

Free-living amoebae (FLA) are protozoa that can be found in a wide range of habitats around the world. Some species have been found to be pathogenic to humans in addition to their normal distribution. There is no research on the prevalence of FLA in various water sources in Makkah city that we are aware of. The aim of this study was to investigate the prevalence of FLA from various water sources in a different part of the city. A total of 86 water samples were processed and cultured with Escherichia coli overlay on non-nutrient agar medium (NNA). Microscopic examination was used to examine the samples. Fifty (58.1%) of the 86 samples tested were positive for FLA. Amoebae identified by morphology belonging to the genus Acanthamoeba were 30 (34.9%) and that belonging to the genus Naegleria, were 20 (23.3%). Among the positive cases, 100% of ponds, 80% of air conditioner exhaust, 50% of water fountains and tape water filters, 40% of swimming pools and 33.3% of stored tanks. The absence of FLA in the examined wells was a striking feature. Polymerase chain reaction (PCR) on DNA showed a 229-bps fragment using Nelson primers and a 500-bps fragment using Acanthamoeba genus-specific primer pair JDP1/JDP2. In conclusion, Acanthamoeba spp. was the most predominant type of free-living amoeba and more prevalent in ponds water absent in wells as shown by culture, microscopy and PCR.

Synthesis and crystal structure of catena-poly[[hexa-aqua{μ3-2-[bis-(carboxyl-atometh-yl)amino]-terephthalato}dicobalt(II)] penta-hydrate] containing water tapes and penta-mers.

The title coordination polymer, {[Co2(C12H7NO8)(H2O)6]·5H2O} n , was crystallized at room temperature from an aqueous solution of 2-aminodi-acetic terephthalic acid (H4adtp) and cobalt(II) nitrate. The asymmetric unit consists of one adtp4- ligand, one and two half CoII ions, six water ligands coordinated to CoII ions and five uncoordinated water mol-ecules. Two of the cobalt cations lie on centres of inversion and are coordinated in octa-hedral O2(OH2)4 environments, whereas the other adopts a slightly distorted octa-hedral NO3(OH2)2 environment. The crystal structure contains parallel stacked, one-dimensional zigzag chains, {[Co2(C12H7NO8)(H2O)6]} n , which assemble into a three-dimensional supra-molecular architecture via networks of hydrogen bonds involving the coordinated and free water mol-ecules. One-dimensional 'water tapes' are formed, containing alternating six-membered and twelve-membered rings of water mol-ecules, together with water penta-mers, in which a central uncoordinated water mol-ecule is hydrogen bonded to two coordinated and two free water mol-ecules in a tetra-hedral arrangement.

Utilization of White Glutinous Rice Fermentation as A Coagulant of Natural Rubber Latex

Clumping is one of the important stages in the processing of latex. This stage is the first step to produce a coagulum. The purpose of this study was to determine the potential of white sticky water tape as a latex coagulant and determine the effect of white sticky water tape on the speed of clumping, color, pH, texture, levels of latex dry rubber. Tests were carried out in 4 treatments, namely R0: 1 ml of 10% formic acid solution added to 100 ml of latex; R1: 1 ml of water tape is added in 100 ml of latex; R2: 5 ml of water tape is added in 100 ml of latex; R3: Water tape as much as 10 ml was added to 100 ml of latex Then the latex parameters were observed including clumping speed, pH, texture, color and levels of dry rubber (KKK). The results of this study indicate that the administration of white sticky tape water does not reduce the pH of the latex to the isoelectric point 4.7. Nevertheless latex clumping still occurs. This is thought to be due to the alcohol content in the white sticky water tape. Based on observations, the R2 treatment is the best treatment that produces a slippery and hard coagulant texture similar to the R0 (formic acid) treatment. Whereas the latex texture in R1 and R3 treatments is softer. The addition of white sticky tape water coagulant produces latex color to milky white while formic acid produces white-yellowish color. The R2 treatment had an average KKK 41.63% lower than using formic acid, which was R0 45.96%. Although the white sticky tape water coagulant has not been able to meet the KKK quality standards of 20%.

Rapid Performance Evaluation of Water Supply Services for Strategic Planning

The assessment of existing water supply services was carried out through selected performance indicators with the aim of using that data in future for strategic planning of urban Mardan. The key performance indictors studied were selected to assess both the quantity and quality of water. The quality of water was assessed by turbidity, pH, and E-coli tests for samples collected at the start, middle, and tail end of the distribution system. The quantity of water supplied was measured by calculating discharges from water tapes at the three selected locations in the distribution system. A total of thirty samples were collected from ten union councils out of fourteen covering urban Mardan. A number of issues are highlighted in the overall water supply infrastructure and short, mid, and long term remedial measures are recommended. The results are presented in the form of an interactive map using Google Earth and VBA based dynamic database. It was found that the overall quality of water is generally acceptable for drinking. However, the presence of bacteria is an issue in many cases which needs to be resolved. A significant decrease in discharge is observed in the distribution systems away from the source due to leakages and illegal connections. A comprehensive overhaul of both management and infrastructure is required for sustainable and satisfactory level of services.

Nitroaromatic detecting zinc cyclohexyldicarboxylate coordination polymers with a long spanning dipyridyl tethering ligand

Four new divalent zinc coordination polymers containing a dianionic cyclohexyldicarboxylate and the long-spanning pillaring dipyridyl ligand bis(4-pyridylmethyl)piperazine (bpmp) have been prepared and structurally characterized via single-crystal X-ray diffraction. Significant structural and topological diversity across the series is evident. {[Zn2(cis-12cdc)2(bpmp)]·6H2O}n (1, cis-12cdc = cis-1,2-cyclohexanedicarboxylate) shows a coordination polymer layer motif with embedded paddlewheel {Zn2(OCO)4} dinuclear units and T6(4)4(4) classification water tapes. Using cis-1,2-cyclohex-4-enedicarboxylate (cis-12chedc) afforded [Zn2(cis-12chedc)2(bpmp)(H2O)2]n (2), which manifests a simple yet unusual (6)(648.10) topology. [Zn2(cis-13cdc)2(bpmp)]n (3, cis-13cdc = cis-1,3-cyclohexanedicarboxylate) displays sawtooth (4,4) coordination polymer layers, while [Zn2(trans-14cdc)2(bpmp)]n (4, trans-14cdc = trans-1,4-cyclohexanedicarboxylate) shows a 3D system of coordination polymer networks with 3-fold interpenetrated 41263pcu topology. The layered phases 1–3 showed capability for the detection of small quantities of nitrobenzene in ethanol suspension.

Five new cobalt(II) complexes based on indazole derivatives: synthesis, DNA binding and molecular docking study

Five cobalt(II) complexes based on 1H-indazole-3-carboxylic acid (H2L), [Co(phen)(HL)2]·2H2O (1), [Co(5,5′-dimethyl-2,2′-bipy)(HL)2] (2), [Co(2,2′-bipy)2(HL)2]·5H2O (3), [Co2(2,9-dimethyl-1,10-phen)2(L)2] (4) and [Co2(6,6′-dimethyl-2,2′-bipy)2(L)2]·H2O (5) (2,2'-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized and structurally characterized by elemental analyses, IR and UV-vis spectroscopies and single-crystal X-ray crystallography. The results indicate that 1–3 possess mononuclear Co(II) structures, while 4 and 5 exhibit binuclear structure. 1D water tape which is linked by the multiple hydrogen bonds was embedded in the 3D motif of complex 3. Complexes 4 and 5 show two orthogonal planes of motif that was constituted by phen/2,2′-bipy and indazole acid, respectively. The intermolecular interactions including hydrogen bonding and π-π stacking interactions are stabilizing these complexes. The interactions of the synthesized complexes with calf-thymus DNA (CT-DNA) have been investigated by UV-vis absorption titration, ethidium bromide displacement assay and viscosity measurements. The results reveal that the complexes could interact with CT-DNA via a groove binding mode. Their behavior rationalization was further theoretically studied by molecular docking.

The State of Water Supply and Sanitation in Government Primary Schools in Dares Salaam Region a Case of Kinondoni Municipality

This paper sets out to assess the state of water supply and sanitation in government primary schools in Kinondoni Municipality. It based on data collected in 2013. A cross-sectional study design was adopted, collecting data through the use of questionnaire, in-depth interviews and observation from ten public primary schools in the study area. Statistical Package for social science (SPSS) was used to clean and analyse the data collected. The study found out that there is inadequate and unreliable water supply, water storage facilities and shortage of functioning hand-washing facilities. The available sanitation facilities are poorly utilized due to various reasons including pupils’ background personal hygiene, sanitation technology, pupils’ population, lack of hygiene education and school weakness in implementing School Water, Sanitation and Hygiene (SWASH) guideline. The study concludes that although the government primary schools in Kinondoni Municipality own a variety of water sources and sanitation facilities, generally there is inadequate coverage of water and sanitation facilities in primary schools. Also the SWASH guidelines did not specify who is to be responsible for the maintenance costs, awareness creation to teachers, parents, and pupils as well cultural aspect on the use of SWASH facilities were not considered. To increase water reliability at schools, multiple sources (water tape and deep wells) could be the best solution. Parents and pupils should be involved in SWASH program awareness and consider economic (maintenance costs) and cultural appropriateness, also to avoid punishing pupils by using toilet cleaning at schools.

1,8‐Naphthyridinecarbaldehydes and Their Methyl‐Substituted Precursors: Synthesis, Molecular Structures, Supramolecular Motifs and Trapped Water Clusters

1,8‐Naphthyridinecarbaldehydes bearing chlorine, pyrrolidinyl, piperidinyl or morpholinyl groups, were synthesised by oxidation of their methyl‐substituted precursors. The prepared carbaldehydes represent valuable starting materials for the construction of systems that are useful for supramolecular and medicinal chemistry. Single‐crystal X‐ray diffraction studies of four carbaldehydes and six methyl derivatives provided interesting information about the supramolecular motifs in the crystal structures of solvent‐free and solvated naphthyridines. The formation of interesting water clusters, for example, T4(2) water tape, was observed in the case of 7‐methyl‐2‐(piperidin‐1‐yl)‐1,8‐naphthyridine as well as in the crystal structure of a by‐product 7‐(morpholin‐1‐yl)‐1,8‐naphthyridine‐2‐carboxylic acid. Knowledge of the detailed structural properties of water clusters is of great research interest to a broad range of scientific disciplines.

Copper(II) complex derived from axial chiral heterocyclic spiro ligand: Crystal structure, characterization and SOD activity

A new Cu(II) coordination polymer (1) constructed from an axially chiral heterocyclic spiro ligand, 2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-dicarboxylic acid (H2L) and 1,3-bis(4-pyridyl)propane (bpp), has been prepared and characterized by single-crystal X-ray diffraction analysis, infrared spectra (IR), elemental analysis, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Structural analysis shows that 1 features a 2D undulated layer of rhombic meshes with (4, 4) topology. Interestingly, a 1D wave-like water tape formed by the cyclic centrosymmetric chairlike octamer water clusters (H2O)8 are observed between the 2D sheets. Furthermore, the experimental data and computational studies of superoxide dismutase (SOD) activity of H2L and 1 were investigated.

Supramolecular isomers, water clusters and solvent-mediated transformations in a series of lanthanide MOFs

A series of Lanthanide MOFs of hydromuconic acid (H2hymuc) with cations of different size (La3+, Ce3+, Gd3+, Y3+) were generated at room temperature, pH = 5.5–5.8, using water as solvent. Two microporous genuine supramolecular isomers were found for the larger cations (La3+, Ce3+) sustained either by discrete (H2O)18 clusters or by infinite water tapes, consisting of fused tetramers, pentamers and hexamers. The smaller cations (Gd3+, Y3+) produced a 2D phase, considered as catenane isomer of previously published lanthanide MOFs with adipic acid. MOFs obtained with Ce3+, Gd3+and Y3+ undergo irreversible solvent-mediated transformation, yielding isomorphous 3D two-fold interpenetrated MOFs. The close structural similarity between the 2D phase and the 3D interpenetrated one indicated a possible mechanism for this transformation.

Thermal Hydraulic Modeling and Analysis of Fusion Reactors Plasma Facing Components Using Alumina Nanofluids

Damage to plasma facing components (PFC) due to high intense energy deposition during tokamak plasma instabilities is still considered one of the most serious and unresolved problem for the fusion reactors. Key plasma facing components as the divertor and the entire first wall during off-normal operations are generally subjected to high rate of deposition of energy, neutrons, and radiation leading generally to structural catastrophic failures including burnout of coolant tubes. The use of alumina nanofluids applied to future fusion reactors is proposed to, at least, mitigate some of the problems described providing better thermal performance during off-normal events. A 1D heat transfer model using the characteristics of alumina nanoparticles dispersed in common water is presented. Heat transfer of alumina nanofluid is modeled. Results obtained are critically compared with other well-known computer packages and experiments used to predict the coolant heat removal capabilities during longer quasi-steady state plasma instabilities events. Enhancements produced by the use of alumina nanoparticles are evident. Comparisons with both pure water and swirl tape inserts are carried out and critical heat flux (CHF) conditions are predicted showing good agreement with both published numerical and experimental data.

Structural diversity of a series of urea-based coordination complexes: from water tapes, water-sulfate chains, to supramolecular structures

[Hg2(L1)2I4] (1), [Cd2(L1)2I4] (2), {[Cd(L1)2(SO4)(H2O)]·4H2O}n (3), {[Zn2(L2)2(Cl)4]·0.5H2O} (4), {[Cu2(L2)2(SO4)2(H2O)4]·2.5H2O} (5), and {[Cd(L2)2(SO4)(H2O)]·3H2O}n (6), based on N–(3–picolyl)–N′–(3–pyridyl)urea (L1) or N–(4–picolyl)–N′–(3–pyridyl)urea (L2), have been synthesized and characterized by elemental analyses, IR spectra, single-crystal and powder X-ray diffraction, and thermogravimetric analyses. Complexes 1 and 2 are isomorphous and feature similar rectangular metal organic loops, which were further extended into 2-D supramolecular structures through hydrogen bonds. Complex 3 possesses a 2-D sql sheet, and the channels between the neighboring sheets are filled with lattice water molecules, which formed a 1-D water tape. Complex 4 also exhibits a rectangular metal organic loop and a 3-D supramolecular structure with the help of hydrogen bonding interactions. Complex 5 also possesses a metal organic loop, and the water molecules interacted with sulfates, constructing a 1-D water–sulfate tube. Complex 6 features a 1-D loop polymeric chain. Moreover, the solid state luminescences of 1–4 and 6 have been investigated.

Control of dimensionality and topology in nickel and cobalt coordination polymers containing adamantane-based dicarboxylate and long-spanning dipyridyl ligands

Hydrothermal reaction of a metal nitrate, an adamantane-based dicarboxylic acid, and a long-spanning dipyridyl ligand produced six coordination polymers that were structurally characterized by single-crystal X-ray diffraction. [Ni2(adc)2(μ-H2O)(4-bpfh)2]n (1, adc=1,3-adamantanedicarboxylate, 4-bpfh=bis(4-pyridylformyl)homopiperazine) displays 1D coordination polymer ribbons based on [Ni2(OCO)2(μ-H2O)] dimeric units. {[Ni(adc)(4-bpfp)2(H2O)2]·H2O}n (2, 4-bpfp=bis(4-pyridylformyl)piperazine) shows a simple stacked (4,4) layer structure. {[Ni2(adc)2(3-bpmp)2(H2O)2]·15H2O}n (3, 3-bpmp=bis(3-pyridylmethyl)piperazine) also possesses stacked (4,4) grids, but with two different types of infinite water tapes in the interlamellar regions. {[Ni2(adc)2(4-bpmp)2(H2O)2]·3H2O}n (4, 4-bpmp=bis(4-pyridylmethyl)piperazine) again exhibits (4,4) layers, but with two-fold 2D+2D→2D parallel interpenetration. [Co(adc)(4-bpmp)]n (5) displays carboxylate bridged {Co2(OCO)2} cluster units pillared by adc and 4-bpmp ligands into an 8-connected 42464bcu topology. Use of the longer 1,3-adamantanediacetate (ada) ligand afforded {[Ni2(ada)2(4-bpmp)2(H2O)]·2H2O}n (6), which possesses dinuclear {Ni2(OCO)2(μ-H2O)} cluster units linked into [Ni2(ada)2(H2O)] ribbons, further connected by 4-bpmp ligands into a rare 6-connected self-penetrated 4867msw net. Variable temperature magnetic studies were undertaken in cases where dimeric units were evident; antiferromagnetic coupling was observed for 1 and 5, while ferromagnetic coupling with low temperature spin canting was observed for 6. Thermal properties of all new materials were also investigated.

Experimental and computational crystal structure landscape study of nigerloxin: a fungal metabolite from Aspergillus niger

The crystal structure landscape for the bioactive fungal metabolite, nigerloxin, has been explored in the present study using a combined experimental and computational approach. Two new solvate forms of nigerloxin, have been identified from crystallization screening experiments. Additionally, a crystal structure prediction (CSP) study of nigerloxin anhydrate and monohydrate forms has been performed in the study. A comparison of the radical scavenging properties of nigerloxin and related β-hydroxy-γ-pyrone analogues have been performed with the help of bond dissociation enthalpy (BDE) and HOMO–LUMO energy gap computations, which indicate the lowest BDE and HOMO–LUMO gaps for nigerloxin. Various growth units present in the experimental and predicted crystal structures were identified using the supramolecular synthon approach and were utilized in the identification of the most probable crystal growth pathways available for nigerloxin. A total of twelve distinct crystal growth pathways were identified for nigerloxin anhydrate from the CSP based crystal structural landscape study. The 1-D nigerloxin water tape synthon (1HA) was identified as the most frequently observed growth unit in the predicted structures and was also found present in the two experimental solvate forms. The higher order supramolecular constructs derived from the synthon 1HA were identified as the most probable crystal growth pathways for the nigerloxin monohydrate.

Guest water-controlled reversible crystalline-to-amorphous transition and concomitant fluorescence shift in a polar open coordination polymer

This work presents a polar porous coordination polymer with new topological prototype, named {[Zn(ndca)(bpp)]·(H2O)5}n (H2ndca=5-norbornene-2,3-dicarboxylic acid and bpp=1,3-bis(4-pyridyl) propane). Each the borehole-shaped linear channel is encapsulated with one spiral water tape built by alternate array of the quadrangular and hexagon water clusters. The crystals display a reversible crystal-to-amorphous transformation through subtly manipulating over the evacuation and uptake of the guest water tapes confined in the channels upon performing the dehydrated-rehydrated process and I2-exchanged experiment. The results show that the polar crystalline structure is stabilized by the well-orientated H-bonds between the host framework and guest water tape, which are also responsible for the prefect host-guest chiral matching. The most distinguished feature for this material is attribuated to the reversible crystalline-to-amorphous phase transition that is accompanied with a significant fluorescence shift by 31nm, implying its great potential in fluorescence sensing of the environment humidity.

Transepidermal water loss and tape stripping in minipig skin

Transepidermal water loss and tape stripping in minipig skin