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Chen S, Wang J, Li X, Lv H, Wang Q, Dong E, Yang X, Liu R, Liu B. Hydrogen-bonded structures and low temperature transitions of the confined water in subnano channels. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 302:122912. [PMID: 37348273 DOI: 10.1016/j.saa.2023.122912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 05/23/2023] [Indexed: 06/24/2023]
Abstract
The interfacial and confined water have long been attractive objects due to their crucial roles in biological, geological processes, etc. In this paper, we investigate the hydrogen-bonded structures of water and their low temperature transitions in the subnano channels of AlPO4-11 for the first time on the basis of infrared spectroscopy. The number of the adsorbed water molecules is estimated to be 8.45 per channel in one unit cell by thermogravimetric analysis. It is found that the confined water molecules are involved in saturated and unsaturated coordination with different hydrogen bond strengths at ambient temperature. The former refers to ice-like four-coordinated water and the latter includes liquid-like structures, Al-coordinated and relatively free water molecules. Unique coordination between water molecules and framework Al sites is responsible for the ice-like structures in the channels above the ice melting point. The appearance of liquid-like structures is closely related to the strong channel confinement, which does not allow the formation of extensive tetrahedral hydrogen-bonded configuration. As temperature decreases, a structural transformation of confined water happens in the channels of AlPO4-11. Isolated small water oligomers and two new components with stronger hydrogen bonds, such as low-density amorphous ice-like structures and a kind of low-density liquid-like structures are preferred. Our results provide important insights into the structural organizations and thermal-dynamic behaviors of confined water in extreme narrow channels.
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Affiliation(s)
- Shuanglong Chen
- College of Physical Science and Technology, Bohai University, Jinzhou, Liaoning 121013, China
| | - Jianwen Wang
- College of Physical Science and Technology, Bohai University, Jinzhou, Liaoning 121013, China
| | - Xin Li
- College of Physical Science and Technology, Bohai University, Jinzhou, Liaoning 121013, China.
| | - Hang Lv
- College of Physical Science and Technology, Bohai University, Jinzhou, Liaoning 121013, China
| | - Qiushi Wang
- College of Physical Science and Technology, Bohai University, Jinzhou, Liaoning 121013, China
| | - Enlai Dong
- College of Chemistry and Materials Engineering, Bohai University, Jinzhou, Liaoning 121013, China
| | - Xibao Yang
- Laboratory Management Center, Bohai University, Jinzhou, Liaoning 121013, China
| | - Ran Liu
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, Jilin 130012, China
| | - Bingbing Liu
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun, Jilin 130012, China.
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Fischer M. Revisiting the Structure of Calcined and Hydrated AlPO-11 with DFT-Based Molecular Dynamics Simulations*. Chemphyschem 2021; 22:2063-2077. [PMID: 34314095 PMCID: PMC8596996 DOI: 10.1002/cphc.202100486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/26/2021] [Indexed: 11/07/2022]
Abstract
Published crystal structures of the AEL‐type aluminophosphate AlPO‐11 in its calcined form (space group Ima2
) show some peculiar features, such as unusually short Al−O and P−O bonds and near‐linear Al−O−P angles. Although experimental evidence for the presence of dynamic disorder was presented, the nature of the associated distortions remained unresolved. In this study, ab initio molecular dynamics (AIMD) calculations in the framework of density functional theory (DFT) were employed to study the dynamic behaviour of this zeotype. At 100 K, static local distortions that break the Ima2
symmetry are present in the time‐averaged structures computed from the AIMD trajectories. At 300 and 500 K, the time‐averaged structures approach Ima2
symmetry. Although shortened Al−O and P−O bonds and near‐linear Al−O−P angles were found in the average structures, an analysis of radial and angular distribution functions confirmed their absence in the instantaneous structures. This deviation is due to a precession‐like motion of some oxygen atoms around the Al−P connection line, which moves their time‐averaged positions closer to this line. In hydrated AlPO‐11, some of the water molecules are coordinated to framework Al atoms, leading to an octahedral coordination of 1/5 of the Al sites. DFT optimisations and AIMD simulations on partially hydrated models delivered evidence for a preferential adsorption at the Al1 site. No dynamic disorder was observed for the hydrated form.
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Affiliation(s)
- Michael Fischer
- Faculty of Geosciences, University of Bremen, Klagenfurter Straße 2-4, 28359, Bremen, Germany.,MAPEX Center for Materials and Processes, University of Bremen, 28359, Bremen, Germany
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Fischer M. Proton Acidity and Proton Mobility in ECR-40, a Silicoaluminophosphate that Violates Löwenstein's Rule. Chemistry 2019; 25:13579-13590. [PMID: 31441561 PMCID: PMC6856796 DOI: 10.1002/chem.201902945] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/21/2019] [Indexed: 11/11/2022]
Abstract
The silicoaluminophosphate zeotype ECR-40 contains linkages of AlO4 tetrahedra via a common oxygen atom, thereby violating the famous "Löwenstein's rule". In this work, a combination of static density functional theory (DFT) calculations and DFT-based ab-initio molecular dynamics (AIMD) simulations were employed to study the acidity and mobility of protons associated with such unusual linkages. It was found that the Al-O-Al linkages are preferentially protonated, as deprotonation causes a local accumulation of negative charge. The protons at these linkages possess a somewhat lower Brønsted acidity than those at Si-O-Al links. AIMD simulations for fully hydrated ECR-40 predicted a partial deprotonation of the Al-O-Al linkages, whereas Si-O-Al linkages were fully deprotonated. Frequently, a coordination of water molecules to framework Al atoms was observed in the vicinity of the Al-O-Al links. Hence, these linkages appear prone to break upon dehydration, potentially explaining why Löwenstein's rule is mostly obeyed in materials formed in aqueous media.
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Affiliation(s)
- Michael Fischer
- Crystallography GroupDepartment of GeosciencesUniversity of BremenKlagenfurter Straße 2–428359BremenGermany
- MAPEX Center for Materials and ProcessesUniversity of Bremen28359BremenGermany
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Giussani L, Tabacchi G, Coluccia S, Fois E. Confining a Protein-Containing Water Nanodroplet inside Silica Nanochannels. Int J Mol Sci 2019; 20:E2965. [PMID: 31216631 PMCID: PMC6627703 DOI: 10.3390/ijms20122965] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 02/01/2023] Open
Abstract
Incorporation of biological systems in water nanodroplets has recently emerged as a new frontier to investigate structural changes of biomolecules, with perspective applications in ultra-fast drug delivery. We report on the molecular dynamics of the digestive protein Pepsin subjected to a double confinement. The double confinement stemmed from embedding the protein inside a water nanodroplet, which in turn was caged in a nanochannel mimicking the mesoporous silica SBA-15. The nano-bio-droplet, whose size fits with the pore diameter, behaved differently depending on the protonation state of the pore surface silanols. Neutral channel sections allowed for the droplet to flow, while deprotonated sections acted as anchoring piers for the droplet. Inside the droplet, the protein, not directly bonded to the surface, showed a behavior similar to that reported for bulk water solutions, indicating that double confinement should not alter its catalytic activity. Our results suggest that nanobiodroplets, recently fabricated in volatile environments, can be encapsulated and stored in mesoporous silicas.
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Affiliation(s)
- Lara Giussani
- Dipartimento di Scienza e Alta Tecnologia and INSTM udr Como, Insubria University, Via Valleggio 9, I-22100 Como, Italy.
| | - Gloria Tabacchi
- Dipartimento di Scienza e Alta Tecnologia and INSTM udr Como, Insubria University, Via Valleggio 9, I-22100 Como, Italy.
| | - Salvatore Coluccia
- Dipartimento di Chimica, Turin University, Via P. Giuria 7, I-10125 Turin, Italy.
| | - Ettore Fois
- Dipartimento di Scienza e Alta Tecnologia and INSTM udr Como, Insubria University, Via Valleggio 9, I-22100 Como, Italy.
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