“…Previous experimental and theoretical studies indicate that there is a several-ten wavenumber difference between water tetramer and other clusters (Tables S5 and S6). − The frequencies of the tetramer structure in different environments (including hydrophobic CCl 4 and hydrophobic ion tags) all fall in the range of 3360–3440 cm –1 . , Therefore, the peaks observed at ∼3397 cm –1 in the ssp spectrum and at ∼3381 cm –1 in the ppp spectrum most likely arise from cyclic water tetramer. Such assignment can be further confirmed by the spectral profiles given by previous theoretical calculations which show that only the calculated spectrum for the cyclic water tetramer structure looks like the ppp spectrum in Figure a.…”
Hydrophobic-like water monolayers have been predicted at the metal and some polar surfaces by theoretical simulations. However, direct experimental evidence for the presence of this water layer at surfaces, particularly at biomolecule and polymer surfaces, is yet to be validated at room temperature.Here we observe experimentally that an ordered molecular water layer is present at the hydrophobic fluorinated polymer such as polytetrafluoroethylene (PTFE) surface by using sum frequency generation vibrational spectroscopy. The macroscopic hydrophobicity of PTFE surface is actually hydrophilic at the molecular level. The macroscopically hydrophobic character of PTFE is indeed resulting from the hydrophobicity of the ordered twodimension (2D) water layer, in which cyclic water tetramer structure is found. The water layer at humidity of ≤40% has a vibrational relaxation time of 550 ± 60 fs. The vibrational relaxation time in the frequency range of 3200−3400 cm −1 shows remarkable difference from the interfacial water at the air/H 2 O interface and the lipid/H 2 O interface. No discernible frequency dependence of the vibrational relaxation time is observed, indicating the homogeneous dynamics of OH groups in the water layer. These insights into the water layer at the macroscopically hydrophobic surface may contribute to a better understanding of the hydrophobic interaction and interfacial water dynamics.
“…Previous experimental and theoretical studies indicate that there is a several-ten wavenumber difference between water tetramer and other clusters (Tables S5 and S6). − The frequencies of the tetramer structure in different environments (including hydrophobic CCl 4 and hydrophobic ion tags) all fall in the range of 3360–3440 cm –1 . , Therefore, the peaks observed at ∼3397 cm –1 in the ssp spectrum and at ∼3381 cm –1 in the ppp spectrum most likely arise from cyclic water tetramer. Such assignment can be further confirmed by the spectral profiles given by previous theoretical calculations which show that only the calculated spectrum for the cyclic water tetramer structure looks like the ppp spectrum in Figure a.…”
Hydrophobic-like water monolayers have been predicted at the metal and some polar surfaces by theoretical simulations. However, direct experimental evidence for the presence of this water layer at surfaces, particularly at biomolecule and polymer surfaces, is yet to be validated at room temperature.Here we observe experimentally that an ordered molecular water layer is present at the hydrophobic fluorinated polymer such as polytetrafluoroethylene (PTFE) surface by using sum frequency generation vibrational spectroscopy. The macroscopic hydrophobicity of PTFE surface is actually hydrophilic at the molecular level. The macroscopically hydrophobic character of PTFE is indeed resulting from the hydrophobicity of the ordered twodimension (2D) water layer, in which cyclic water tetramer structure is found. The water layer at humidity of ≤40% has a vibrational relaxation time of 550 ± 60 fs. The vibrational relaxation time in the frequency range of 3200−3400 cm −1 shows remarkable difference from the interfacial water at the air/H 2 O interface and the lipid/H 2 O interface. No discernible frequency dependence of the vibrational relaxation time is observed, indicating the homogeneous dynamics of OH groups in the water layer. These insights into the water layer at the macroscopically hydrophobic surface may contribute to a better understanding of the hydrophobic interaction and interfacial water dynamics.
“…Hydrogen-bonding interactions involving water molecules are the main driving forces that influence the structures and properties of host systems and water aggregates. , The investigations of hydrogen-bonded water clusters (H 2 O) n have attracted a great deal of interest because they provide clues not only to unraveling the properties of bulk water in a molecular level but also to understanding the interactions of water aggregates and their surroundings. Theoretical studies have predicted the relative stability of various water clusters with varying size and geometry and some of them have been identified in crystal hosts. − Among these clusters, cyclic tetramer is a common form, and there are a number of examples of the crystallographic observation of the tetramers in crystals . As compared with tetramer, water decamer requires larger space and specific environments in host matrix.…”
mentioning
confidence: 99%
“…The tetramer adopts the uudd configuration,3b with four free hydrogen atoms in an up−up−down−down (uudd) fashion. Although the uudd configuration is energetically less stable compared to the energy minimum up−down−up−down (udud) configuration,3b it has been observed in the crystalline solids of metal complexes. 5b,g The decamers and tetramers are linked through O5w−H···O6w hydrogen bonds to produce an extended chain passing through the channel. 2 1D water chain built of the tetramers and decamers, showing the uudd configuration of the tetramer and the butterfly configuration of the decamer.…”
The reaction of Cu(BF4)2 with pyridine-2,6-dicarboxylic acid (H2pydc) and trans-1,2-bis(4-pyridyl)ethylene (bpe) under
hydrothermal conditions afforded a porous mixed-valence CuICuII coordination polymer. Coexistence of tetrameric and decameric water
clusters within the channels of the complex leads to a novel water chain. The metal−organic framework provides both hydrophilic and
hydrophobic environments for stabilizing the clusters and retains its integrity upon dehydration and rehydration.
A novel zinc‐based metal–organic framework (Zn‐MOF), designated as [Zn3(L)(bpyp)2(HCOO)3·2DMF·H2O] (1), was synthesized using 2,5‐bis(pyrid‐4‐yl)pyridine (bpyp), 1,3,5‐benzenetricarboxylic acid (H3L), and Zn(CH3COO)2·2H2O in a DMF solution. Single‐crystal X‐ray diffraction analysis revealed that MOF 1 crystallizes in the monoclinic system with a C2/c space group, featuring a (3,5)‐connected binodal network. The structural integrity and characteristics of MOF 1 were confirmed by Fourier transform infrared (FT‐IR), thermal gravimetric analysis (TGA), powder X‐ray diffraction (PXRD), and Brunauer–Emmett–Teller (BET) analyses, showing type IV isotherms indicative of microporous structures. The photocatalytic efficiency of MOF 1 was evaluated for the degradation of various antibiotics under UV light, with nitrofurantoin (NFT) demonstrating the highest degradation rate of 83.9% at an optimal concentration of 40 ppm and catalyst loading of 5 mg. The degradation process followed a pseudo‐first‐order kinetic model with a rate constant of 0.02492 min−1. Radical trapping experiments identified superoxide radicals (O2˙−) and holes (h+) as the predominant reactive species, while hydroxyl radicals (˙OH) played a negligible role. Reusability tests over four cycles confirmed the stability and durability of MOF 1, with consistent photocatalytic performance and unchanged structural morphology as evidenced by PXRD and SEM analyses. The proposed mechanism involves photoinduced electron–hole pair generation, with subsequent formation of reactive oxygen species (ROS) facilitating NFT degradation. This study highlights MOF 1 as a promising photocatalyst for environmental remediation, specifically for the efficient degradation of pharmaceutical contaminants in aquatic systems, providing insights into its structural properties, photocatalytic activity, and underlying degradation mechanisms.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
