Search

A promising CO 2 sorbent based on the [Emim][Gly] (1-ethyl-3-methylimidazolium glycinate)/silica gel composite has been studied. CO 2 sorption experiments have shown that the optimum loading of [Emim][Gly] ionic liquid in silica gel is 40 wt.%. The 2-step process CO 2 binding mechanism in [Emim][Gly] has been proposed based on the results of sorption experiments, 2 H NMR spectroscopy and ab-initio calculations. The impact of CO 2 on the microscopic viscosity and the dynamical melting of ionic liquid has been thoroughly investigated. 2 H NMR spectroscopy has revealed that CO 2 strongly binds cation and anion in [Emim][Gly], forcing them to move in a correlated fashion., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

The metal-organic frameworks (MOFs) attract interest as potential catalysts whose catalytic properties are driven by defects. Several methods have been proposed for the defects-inducing synthesis of MOFs. However, the active species formed on the defective sites remain elusive and uncharacterized, as the spectroscopic fingerprints of these species are hidden by the regular structure signals. In this work, we have performed the synthesis of ZIF-8 MOF with defect-inducing procedures using fully deuterated 2-methylimidazolate ligands to enhance the defective sites' visibility. By combining 1 H and 31 P MAS NMR spectroscopy and X-ray absorption spectroscopy, we have found evidence for the presence of different structural hydroxyl Zn-OH groups in the ZIF-8 materials. It is demonstrated that the ZIF-8 defect sites are represented by Zn-OH hydroxyl groups with the signals at 0.3 and -0.7 ppm in the 1 H MAS NMR spectrum. These species are of basic nature and may be responsible for the catalytic activity of the ZIF-8 material., (© 2024 Wiley-VCH GmbH.)

Maxillofacial defects, arising from trauma, oncological disease or congenital abnormalities, detrimentally affect daily life. Prosthetic repair offers the aesthetic and functional reconstruction with the help of materials mimicking natural tissues. 3D polymer printing enables the design of patient-specific prostheses with high structural complexity, as well as rapid and low-cost fabrication on-demand. However, 3D printing for prosthetics is still in the early stage of development and faces various challenges for widespread use. This is because the most suitable polymers for maxillofacial restoration are soft materials that do not have the required printability, mechanical strength of the printed parts, as well as functionality. This review focuses on the challenges and opportunities of 3D printing techniques for production of polymer maxillofacial prostheses using computer-aided design and modeling software. Review discusses the widely used polymers, as well as their blends and composites, which meet the most important assessment criteria, such as the physicochemical, biological, aesthetic properties and processability in 3D printing. In addition, strategies for improving the polymer properties, such as their printability, mechanical strength, and their ability to print multimaterial and architectural structures are highlighted. The current state of the prosthetic retention system is presented with a focus on actively used polymer adhesives and the recently implemented prosthesis-supporting osseointegrated implants, with an emphasis on their creation from 3D-printed polymers. The successful prosthetics is discussed in terms of the specificity of polymer materials at the restoration site. The approaches and technological prospects are also explored through the examples of the nasal, auricle and ocular prostheses, ranging from prototypes to end-use products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Metal-organic framework (MOF) glasses have emerged as a new class of organic-inorganic hybrid glass materials. Considerable efforts have been devoted to unraveling the macroscopic dynamics of MOF glasses by studying their rheological behavior; however, their microscopic dynamics remain unclear. In this work, we studied the effect of vitrification on linker dynamics in ZIF-62 by solid-state 2 H nuclear magnetic resonance (NMR) spectroscopy. 2 H NMR relaxation analysis provided a detailed picture of the mobility of the ZIF-62 linkers, including local restricted librations and a large-amplitude twist; these details were verified by molecular dynamics. A comparison of ZIF-62 crystals and glasses revealed that vitrification does not drastically affect the fast individual flipping motions with large-amplitude twists, whereas it facilitates slow cooperative large-amplitude twist motions with a decrease in the activation barrier. These observations support the findings of previous studies, indicating that glassy ZIF-62 retains permanent porosity and that short-range disorder exists in the alignment of ligands because of distortion of the coordination angle.

Zeolites modified with metal cations are perspective catalysts for converting light alkenes to valuable chemicals. A crucial step of the transformation is an alkene interaction with zeolite to afford π-complex with metal cations. The mechanism of alkene bonding with cations is still unclear. To address this problem, propene adsorption on H + (Bro̷nsted acid site), Na + , Ca 2+ , Zn 2+ , Co 2+ , Cu 2+ , Cu + , and Ag + cationic sites in ZSM-5 zeolite has been studied by quantum chemical calculations in terms of adsorption enthalpy, ν C ═C frequency, and natural bond orbital (NBO) analysis together with natural energy decomposition analysis (NEDA). It is revealed that the conventional concept of σ- and π-bonding is only partially applicable to alkene interaction with metal cations in zeolites. The orbital interaction between an alkene molecule and a metal site is more complex. Several different bonding mechanisms have been identified depending on the nature and electron configuration of the metal cation. This finding explains the complex correlations observed for propene π-complex stability and ν C═C frequency shift or charge transfer from the alkene molecule. The results provide the basis for further understanding the interactions between alkenes and inorganic solid Bro̷nsted and Lewis acids.

Objective: The physical and mechanical properties of samples printed from different materials subjected to post-processing in a clinic were evaluated., Material and Methods: Studied hardness and modulus of elasticity before and after sterilization by autoclaving. Based on the analysis of the literature and monitoring of the dental materials market, our choice fell on the most popular materials for 3D printing of surgical templates for dental implantation, such as: material 1 (FormLabs Dental SG Resin (Formlabs, USA)) and material 2 (NextDent SG (NextDent, Netherlands)). In connection with the events of recent years, we also took into the study a domestically produced polymer - material 3 (HARZLabs Yellow Clear PRO (HARZLabs, Russia))., Results: As a result of the study, it was found that in each of the groups of materials studied, the values of the elastic modulus of sterilized samples are higher than the elastic modulus of samples that have not undergone sterilization. According to GOST 31572-2012 (ISO 1567:1999 Polymeric materials for denture bases, non-sterilized samples of group 2 are considered not to have passed the test, since all three samples of the studied group have a crack resistance index of less than 1 MN/m1.5. Crack resistance index of sterilized samples of the group of materials 2 is also close to 1. Samples of group 1 (both sterilized and non-sterilized) have the highest crack resistance. This group also has the highest flexural strength. On non-sterilized samples of material 1, there was no crack initiation along the cut and groove. The samples of other groups were mainly destroyed along the axis of the groove., Conclusion: Analyzing the obtained data and considering that all studies carried out were in accordance with dental standards, the researchers concluded that the increase in flexural strength after sterilization by autoclaving and the feasibility of using material 1 for the production of surgical templates in accordance with all manufacturer's recommendations.

Observing and quantifying the like-charge attraction in liquids and solutions is still challenging. However, we showed that elusive cation-cation hydrogen bonding may govern the structure and interaction in hydroxyl-functionalized ionic liquids. Therefore, cationic cluster formation depends on the shape, charge distribution, and functionality of the ions. We demonstrated by means of solid-state 2 H NMR spectroscopy that cationic clusters change the structure and dynamics of ionic liquids. With increasing alkyl chain length, we observed two deuteron quadrupole coupling constants for the OD groups, differing by about 30 kHz. The lower value was assigned to the cation-cation interaction, indicating that the average (c-c) hydrogen bonds are stronger than the (c-a) hydrogen bonds between the cation and the anion despite the repulsive and attractive Coulomb interaction in the first and latter cases. Ion mobility could be studied by 2 H NMR spectroscopy, although the deuterons in the hydrogen-bonded clusters underwent fast exchange. Our results also showed that simple relaxation models are not applicable anymore and that anisotropic motion must be considered.

67 Zn MAS NMR spectroscopy was used to characterize the state of Zn in Zn-modified zeolites ZSM-5. Two 67 Zn enriched zeolite samples were prepared: by solid-state exchange with metal 67 Zn (Zn 2+ /ZSM-5 sample) and by ion exchange with zinc formate solution (ZnO/H-ZSM-5 sample), both containing ca. 3.8 wt% Zn. The elemental analysis, TEM, and quantitative BAS and aluminum analyses with 1 H and 27 Al MAS NMR have shown that Zn 2+ /ZSM-5 contains zinc in the form of Zn 2+ cations, while both ZnO species and Zn 2+ cations are present in ZnO/H-ZSM-5 besides BAS. 67 Zn MAS NMR has detected the signal of Zn in a tetrahedral environment from ZnO species for both the activated and hydrated ZnO/H-ZSM-5 zeolite. The signal of Zn in an octahedral environment was detected for the hydrated Zn 2+ /ZSM-5 and ZnO/H-ZSM-5 zeolites. This signal may belong to zinc cation [HOZn] + or Zn(OH) 2 species surrounded by water molecules. Quantitative 67 Zn MAS NMR analysis has shown that only 27 and 38% of zinc loaded in the zeolite is visible for the activated and hydrated ZnO/H-ZSM-5 zeolite, and 24% of Zn is visible for the hydrated Zn 2+ /ZSM-5. Zinc in the form of ZnO species is entirely visible in both the activated and hydrated ZnO/H-ZSM-5 zeolite, while Zn 2+ cations are not detected at all for the activated sample and only 29% of Zn 2+ cations is visible for the hydrated zeolite. Detection of only a part of Zn 2+ cations in the form of [HOZn] + or Zn(OH) 2 species in octahedral environment presumes only partial hydrolysis of the bond of Zn 2+ cation with framework oxygen and further solvation of the Zn species formed at hydrolysis by the adsorbed water.

The UiO-66 (Zr) metal-organic framework (MOF) is of notable interest due to its facile synthesis, robustness under a wide range of chemical and physical conditions and its capability to separate industrially relevant hydrocarbons mixtures. However, the knowledge of the molecular mechanisms behind these process remains limited. Here, we present a combined experimental ( 2 H NMR) and computational study of the molecular mobility, transport and adsorption of C 5 alkanes isomers in a dehydroxylated UiO-66 (Zr) MOF. We show that the tetrahedral cages of the MOF are the preferred adsorption location for both n -pentane and isopentane. In a binary mixture of the isomers, isopentane interacts more strongly with the material leading it to occupy more of the tetrahedral cages than n -pentane, resulting in an isopentane/ n -pentane adsorption selectivity of α ads = 2 (at 373 K). At the same time, the microscopic diffusivity for n -pentane, D n ( E n = 18 kJ mol -1 ), is significantly lower than for isopentane, D iso ( E iso = 28 kJ mol -1 ), which results in a high separation selectivity for a n -pentane/isopentane mixture of α ≈ 13 (at 300 K). This shows that the UiO-66 MOF is indeed a promising active material for use in light hydrocarbon separation processes.

The adsorption method for atmospheric water harvesting (AWH) is considered as a promising heat-driven technology for potable water supply in arid regions. This research is focused on novel composite sorbents based on hygroscopic salts loaded in the pores of MIL-101(Cr) developed for AWH. The composites based on LiCl, LiBr, CaCl 2 , and Ca(NO 3 ) 2 were synthesized and comprehensively studied by SEM, XRD, N 2 adsorption, and thermogravimetric methods. We evidence that the CaCl 2 /MIL-101(Cr) composite demonstrates a high net water uptake of 0.52-0.59 g_(H 2 O)/g_(composite) per cycle under conditions of Saudi Arabia and the Sahara desert as the reference regions with extra-dry climate, which exceeds the appropriate values for other adsorbents. It is shown that water adsorption on the composite cannot be presented as a combination of the adsorption on the components, thus indicating a synergistic effect. A detailed characterization of water coordination, mobility, and hydrogen bonding within the confined CaCl 2 hydrates and salt solution using solid-state 2 H NMR spectroscopy has been performed. It is established that pore confinement promotes a prolonged transition to a dynamically melted state of the hydrated salt and a notable decrease of the melting temperature, which facilitates the molecular transport of water and causes the alteration of sorption properties of CaCl 2 inside MIL-101 pores. Finally, the performance of AWH employing CaCl 2 /MIL-101(Cr) was evaluated in terms of the fractions of water extracted and collected, and the specific energy consumption, demonstrating its high potential for AWH., (© 2023 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Attractive interactions between ions of like charge remain an elusive concept. Observing and quantifying this type of interaction in liquids and solutions is still a major challenge. Recently, we have shown that cation-cation interactions are present in hydroxyl-functionalized ionic liquids and that they can be controlled by the shape, charge distribution and functionality of the ions. In the present study, we demonstrate that cationic cluster formation does not only change the local structures of the ionic liquids but also influences the dynamics of the cations in a characteristic way. We show that solid-state 2 H NMR spectroscopy is well suited for the study of molecular motion, even if the hydrogen bonded species of interest are indistinguishable due to fast deuteron exchange. We also provide valuable information about the applicability of well-accepted relaxation models.

Kinetics of H/D hydrogen exchange between deuterated isobutane-d 10 and Brønsted acid sites (BAS) of three zeolite samples (H-BEA, ZnO/H-BEA, Zn 2+ /H-BEA) were monitored with 1 H MAS NMR in situ at 343-468 K. The regioselective H/D exchange in the methyl groups detected on H-BEA can be rationalized in terms of the mechanism of indirect exchange, which involves protonation of the intermediate olefin and further hydride abstraction from the other alkane molecule by the formed carbenium ion. Loading of Zn species in the zeolite results in a decrease of the rate and an increase of the activation energy of the exchange. The loaded Zn species provide the tuning effect on the reaction occurrence, changing the mechanism from the indirect one to the mechanism of the direct exchange., (© 2022 Wiley-VCH GmbH.)

This review presents an analysis of domestic and foreign literature on the issues of fixation of facial epitheses and combined maxillofacial prostheses, such as the use of craniofacial implants installed in the zygomatic bone, brow arches, orbital walls, mastoid process of the temporal bone with beam or magnetic beam fixation systems. The advantages and disadvantages of such fastening systems are described. The analysis and systematization of available data on medical adhesive compositions that can be used in maxillofacial prosthetics to hold facial epitheses has been carried out. Much attention is paid to the chemical composition of pressure-sensitive adhesives, water-based and silicone-based. Examples of such compositions are given. The physicochemical properties of medical adhesive systems that cause adhesive-cohesive interaction are described. This review presents the results of comparative studies to assess the fixing properties of various adhesives, as well as to study the formation of biofilm on the surfaces of prostheses and skin when using different adhesives.

The Aim of the Study: Was to develop and evaluate the physical and mechanical properties of a structural material for the manufacture of facial epithesis using photopolymer printing technology., Materials and Methods: The study of the physical and mechanical properties of the developed structural material consisted of measuring the Shore hardness; determination of material strength at break, conditional yield strength, relative elongation at break and modulus of elasticity; the study of the characteristics described above, after artificial aging, simulating the daily use of a prosthesis., Results: According to the test results, the samples of the studied material did not have a yield strength, they were torn at a deformation of 40-60%. The values of the conditional yield strength were 0.41±0.01 MPa, regardless of the time of the aging procedure. The values of the modulus of elasticity were 2.96±0.19 MPa and 2.88±0.14 MPa for the samples that underwent the aging procedure at 6 and 12 months, respectively., Conclusion: The results obtained were compared with the results of similar studies of structural materials used in 3D printing technology of facial prostheses, which allowed us to recommend the developed material for clinical use after evaluating its toxicological and biological characteristics.

Objective: Improving the effectiveness of treatment of patients with temporomandibular joint (TMJ) dysfunction complicated by bruxism., Material and Methods: 70 patients with signs of parafunction of the masticatory muscles were selected for the clinical study. The patients were divided into 2 groups of 35 people. Splints were made for patients from the groups using 2 different 3D printing methods. The treatment was monitored using clinical and instrumental studies, electromyography of the muscles themselves and computed tomography of the TMJ after 3, 6 and 12 months., Results: The severity of hypertonicity of the masticatory muscles decreased by the end of 3 months of treatment with the help of repositioning occlusal splints. After 6 months of treatment, the mean BEA decreased in both study groups, but to a lesser extent than in the first 3 months. After wearing a splint after 12 months, the decrease in muscle tone was insignificant., Conclusion: The clinical use of positioning splints plays a crucial role in the stabilization of occlusion and is a mandatory stage of complex treatment of patients with pathology of the occlusal-musculoskeletal complex.

The objective of the literature review was to study and analyze literature sources on the methods and means of facial prosthesis manufacture by three-dimensional printing., Materials and Methods: An analysis of information sources covering the last 15 years was carried out, in search sources as PubMed, Elsiver and eLIBRARY and on the website of the Federal Institute of Industrial Property., Results: The technology of direct production of prostheses by volumetric printing from silicone materials is the object of research for its development. Most of the materials used for the manufacture of facial prostheses using 3D printing need technical improvements, often requiring expensive equipment, which in turn does not allow the method of manufacturing face prostheses by direct method in everyday clinical practice., Conclusion: Based on the obtained data there is a need to develop a new structural material for the manufacture of facial prostheses by 3D printing using laser stereolithography and digital LED projection technologies.

We report strong isotope effects for the protic ionic liquid triethylammonium methanesulfonate [TEA][OMs] by means of deuterium solid-state NMR spectroscopy covering broad temperature ranges from 65 K to 313 K. Both isotopically labelled PILs differ in non-deuterated and fully deuterated ethyl groups of the triethyl ammonium cations. The N-D bond of both cations is used as sensitive probe for hydrogen bonding and structural ordering. The 2 H NMR line shape analysis provides the deuteron quadrupole coupling constants and the characteristics of a broad heterogeneous phase with simultaneously present static and mobile states indicating plastic crystal behavior. The temperatures where both states are equally populated differ by about 80 K for the two PILs, showing that deuteration of the ethyl groups in the trialkylammonium cations tremendously shifts the equilibrium towards the static state. In addition, it leads to a significant less cooperative transition, associated with a significantly reduced standard molar transition entropy., (© 2022 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)

13 C MAS NMR spectroscopy is a powerful technique to study the mechanisms of hydrocarbon transformations on heterogeneous catalysts. It can reliably identify the surface intermediates and the adsorbed products based on the analysis of their 13 C chemical shifts, δ ( 13 C). However, the unambiguous assignment of the detected signals is always a challenge due to the uncertainty of the nature of the surface intermediates formed and the mechanism of adsorbed species interaction with active sites. The way to solve this problem is the application of DFT calculations to predict chemical shifts for the expected intermediate hydrocarbon species. Herein, the methodology for δ ( 13 C) chemical shift calculations for adsorbed species has been proposed. It includes: (i) zeolite framework optimization with periodic DFT (pPBE); (ii) medium-sized cluster geometry optimization with hybrid GGA (PBE0), and (iii) σ ( 13 C) values calculation followed by δ ( 13 C) estimation using the linear regression method. It is inferred that the TPSS/cc-pVTZ method provides the best computational cost/accuracy ratio for the set of adsorbed hydrocarbon species that was previously detected experimentally on the surface of Zn-containing zeolites. The drawbacks of the computation method have also been revealed and discussed.

We report the complex phase behavior of the glass forming protic ionic liquid (PIL) d3-octylphosphonium bis(trifluoromethylsulfonyl)imide [C 8 H 17 PD 3 ][NTf 2 ] by means of solid-state NMR spectroscopy. Combined line shape and spin relaxation studies of the deuterons in the PD 3 group of the octylphosphonium cation allow to map and correlate the phase behavior for a broad temperature range from 71 K to 343 K. In the solid PIL at 71 K, we observed a static state, characterized by the first deuteron quadrupole coupling constant reported for PD 3 deuterons. A transition enthalpy of about 12 kJ mol -1 from the static to the mobile state with increasing temperature suggests the breaking of a weak, charge-enhanced hydrogen bond between cation and anion. The highly mobile phase above 100 K exhibits an almost disappearing activation barrier, strongly indicating quantum tunneling. Thus, we provide first evidence of tunneling driven mobility of the hydrogen bonded P-D moieties in the glassy state of PILs, already at surprisingly high temperatures up to 200 K. Above 250 K, the mobile phase turns from anisotropic to isotropic motion, and indicates strong internal rotation of the PD 3 group. The analyzed line shapes and spin relaxation times allow us to link the structural and dynamical behavior at molecular level with the phase behavior beyond the DSC traces., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

UiO-66 (Zr) is a metal-organic framework (MOF) known for its thermal and chemical stability and wide range of adsorption-based applications. This MOF exhibits high separation selectivity for butane isomers. It has been earlier inferred that the separation performance of the material depends on the hydroxylation state of the zirconia cluster. In this contribution, we apply 2 H solid-state NMR to characterize the dynamics of both the MOF organic framework itself and butane isomers in hydroxylated and dehydroxylated forms of UiO-66. It is established that the rate of π-flipping and the amplitude of the phenylene ring plane librations in the framework are higher for the dehydroxylated form. Self-diffusion coefficients of butane isomers have been estimated for both forms of UiO-66. The diffusivity is higher for n-butane in the dehydroxylated form, whereas the diffusion of isobutane is not affected by the presence of OH groups in the zirconia cluster of the MOF. Higher diffusivity of n-butane in dehydroxylated form is accounted for by the larger effective diameter of the window between the adjacent cages in this form, which arises from faster rotation and larger amplitude of framework linker libration. This rationalizes the higher efficiency of the dehydroxylated form of UiO-66(Zr) material for butane isomers separation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The reactivity theories and characterization studies for metal-containing zeolites are often focused on probing the metal sites. We present a detailed computational study of the reactivity of Zn-modified BEA zeolite towards C-H bond activation of the methane molecule as a model system that highlights the importance of representing the active site as the whole reactive ensemble integrating the extra-framework Zn EF 2+ cations, framework oxygens (O F 2- ), and the confined space of the zeolite pores. We demonstrate that for our model system the relationship between the Lewis acidity, defined by the probe molecule adsorption energy, and the activation energy for methane C-H bond cleavage performs with a determination coefficient R 2 = 0.55. This suggests that the acid properties of the localized extra-framework cations can be used only for a rough assessment of the reactivity of the cations in the metal-containing zeolites. In turn, studying the relationship between the activation energy and pyrrole adsorption energy revealed a correlation, with R 2 = 0.80. This observation was accounted for by the similarity between the local geometries of the pyrrole adsorption complexes and the transition states for methane C-H bond cleavage. The inclusion of a simple descriptor for zeolite local confinement allows transferability of the obtained property-activity relations to other zeolite topologies. Our results demonstrate that the representation of the metal cationic species as a synergistically cooperating active site ensembles allows reliable detection of the relationship between the acid properties and reactivity of the metal cation in zeolite materials.

We show that solid-state NMR spectroscopy is a suitable method for characterizing the structure, hydrogen bond dynamics and phase transition behavior in protic ionic liquids (PILs). Deuteron line shape and spin relaxation time analysis provide a description of the structural and dynamical heterogeneity in the solid state of the model PIL triethyl ammonium bis(trifluoromethanesulfonyl)amide [TEA][NTf 2 ]. Therein, we observed two deuteron quadrupole coupling constant for the ND bond of the TEA cation, indicating differently strong hydrogen bonds to the nitrogen and oxygen atoms of the NTf 2 anion, as we could confirm by DFT calculations. The transition processes in the dynamically heterogeneous phase are characterized by two standard molar enthalpies and thus different stages of melting. We provide geometry, rates and energetics of the cation in the solid and liquid states of the PIL. Comparison with PILs having stronger interacting anions shows higher enthalpy change between the solid and liquid states, lower activation barriers of tumbling motion and higher amplitude of librational motion for the TEA cation in the presence of the weakly interacting anion NTf 2 . We provide reasonable relations between microscopic and macroscopic properties, as is relevant for any kind of application.

To clarify the effects of different Zn species, zeolite topology and acidity (quantity of Brønsted acid sites, BAS) on alkane aromatization, isobutane transformation on Zn 2+ /H-ZSM-5, Zn 2+ /H-BEA, and ZnO/H-BEA zeolites has been monitored with 13 C MAS NMR. The alkane transformation has been established to occur by aromatization and hydrogenolysis pathways. Zn 2+ species is more efficient for the aromatization reaction because aromatic products are formed at lower temperatures on Zn 2+ /H-BEA and Zn 2+ /H-ZSM-5 than on ZnO/H-BEA. The larger quantity of BAS in ZnO/H-BEA seems to provide a higher degree of the hydrogenolysis pathway on this catalyst. The mechanism of the alkane aromatization is similar for the zeolites of different topology and containing different Zn species, with the main reaction steps being the following: (i) isobutane dehydrogenation to isobutene via isobutylzinc; (ii) isobutene stabilization as a π-complex on Zn sites; (iii) isobutene oligomerization via the alkene insertion into Zn-C bond of methyl-σ-allylzinc formed from the π-complex; (iv) oligomer dehydrogenation with intermediate formation of polyene carbanionic structures; (v) aromatics formation via further polyene dehydrogenation, protonation, cyclization, deprotonation steps with BAS involvement., (© 2021 Wiley-VCH GmbH.)

The Aim of the Study: Was to evaluate the clinical effectiveness of the use of a navigational surgical template in the vestibuloplasty protocol in patients with periodontal diseases., Materials and Methods: There were 48 people selected to participate in the study and randomly divided into 2 equal groups. The patients of the main group underwent vestibuloplasty procedure using a free gingival graft modeled using the developed protocol and a navigational surgical template. Patients in the control group underwent a similar operation using classical technology. The study assessed postoperative pain, the index of early wound healing, Doppler fluometry of the transplanted flap and flap morphometric measurements., Results: The results of all conducted studies confirmed the effectiveness of the developed clinical protocol., Conclusion: According to objective and subjective assessments, the use of a surgical navigation template can reduce the time and invasiveness of vestibuloplasty surgery, make it more comfortable for the patient and get a more predictable clinical result.

The Aim of the Study: Was to assess the effectiveness of the use of hydroxyapatite (HAP) and tricalcium phosphate (TCF) modified with hyaluronic acid in the treatment of patients with periimplantitis., Materials and Methods: Clinical studies were conducted in 128 patients (44% male and 56% female) aged up to 55 years, who sought dental care with the main diagnosis of periimplant mucositis and periimplantitis. To compare the features of osseointegration of dental implants under bone remodeling three groups of patients were formed: one control and 2 main ones. In the control group the wound was managed under a blood clot, in the first main group HAP and TCF and in the second main group HAP and TCF modified with hyaluronic acid were used. X-ray examination was performed in various modes. Clinical assessment of implant stability in the operated area was carried out using subjective (percussion and palpation method) and objective method of frequency resonance analysis using the Osstell ISQ device calculating the stability coefficient of the dental implant (SCDI)., Results: 12 months after the periimplant zone remodeling procedure the bone resorption rates surrounding the implant were statistically significantly the lowest in the second main group (0.682±0.006 mm, p <0.001) compared with the values in the control and first main groups (1.626±0.022 and 1.025±0.034 mm, respectively). In the former groups bone resorption continued to progress during the observation period. In patients of the second main group, the average values of the SCDI for all study periods were 68.97±1.09 units which turned out to be the highest indicator and significantly differed from the values of other observation groups ( p <0.05), which may be due to a tighter fit of the implants to the surface of the newly formed bone tissue., Conclusion: The results of the study 12 months after the periimplant zone remodeling operation procedure prove the efficacy of HAP and TCF modified with hyaluronic acid for the treatment of patients with periimplantitis.

The relationship between the adsorption of water on MIL-53 (Al) MOF, the structural phase of MIL-53 (Al), and the quadrupole coupling constant of 27 Al framework aluminium atom (QCC) of the MOF AlO 4 (OH) 2 centres (Al-sites) has been investigated by combining solid-state 27 Al MAS NMR spectroscopy with XRD analysis and DFT calculations. It is established that 27 Al QCC is primarily sensitive to water adsorption to the Al-sites and by a minor extent to the framework contraction/expansion interconversions. We thus conclude that the 27 Al MAS NMR method is sensitive enough to differentiate the effects of pore contractions and water adsorption to Al-sites basing on the changes of the QCC value.

The family of zeolitic-imidazole framework (ZIF) materials is currently considered for the challenging separation of C4 hydrocarbons. However, yet, the microscopic diffusion mechanism for these hydrocarbons in these narrow gate porous materials remains elusive by conventional methods due to its very slow nature. Experimental (solid-state 2 H nuclear magnetic resonance-NMR) and computational (molecular dynamics-MD) approaches were applied together to derive slow diffusional dynamics of n -butane and 1-butene in ZIF-8. By means of the 2 H NMR technique, we evidenced the presence of two adsorption sites for the guests localized inside the cages of ZIF-8 and in the vicinity of the gates. We characterized the molecular mobility at each site and revealed that the translational intercage diffusion is realized by a slow directional motion associated with the gate-crossing. MD simulations provide an in-depth analysis of the diffusion and fully support the proposed dynamics picture for both n -butane and 1-butene. These calculations enable the derivation of the diffusivity and barriers for the long-range diffusion of both hydrocarbons in ZIF-8 and unraveled the microscopic diffusion mechanism implying intracage and intercage motions. We show that this NMR approach combined with modeling is a valuable tool to probe the molecular mobility for slow diffusing species in ordered cagelike porous frameworks.

The desolvated (3,24)-connected metal-organic framework (MOF) material, MFM-160a, [Cu 3 (L)(H 2 O) 3 ] [H 6 L = 1,3,5-triazine-2,4,6-tris(aminophenyl-4-isophthalic acid)], exhibits excellent high-pressure uptake of CO 2 (110 wt% at 20 bar, 298 K) and highly selective separation of C 2 hydrocarbons from CH 4 at 1 bar pressure. Henry's law selectivities of 79:1 for C 2 H 2 :CH 4 and 70:1 for C 2 H 4 :CH 4 at 298 K are observed, consistent with ideal adsorption solution theory (IAST) predictions. Significantly, MFM-160a shows a selectivity of 16:1 for C 2 H 2 :CO 2 . Solid-state 2 H NMR spectroscopic studies on partially deuterated MFM-160- d 12 confirm an ultra-low barrier (∼2 kJ mol -1 ) to rotation of the phenyl group in the activated MOF and a rotation rate 5 orders of magnitude slower than usually observed for solid-state materials (1.4 × 10 6 Hz cf. 10 11 -10 13 Hz). Upon introduction of CO 2 or C 2 H 2 into desolvated MFM-160a, this rate of rotation was found to increase with increasing gas pressure, a phenomenon attributed to the weakening of an intramolecular hydrogen bond in the triazine-containing linker upon gas binding. DFT calculations of binding energies and interactions of CO 2 and C 2 H 2 around the triazine core are entirely consistent with the 2 H NMR spectroscopic observations.

The main goal of the research presented in the article was to increase the effectiveness of dental orthopedic rehabilitation of patients by developing and implementing a complex of digital planning of the initial stages of treatment, including diagnostic methods, modeling, and manufacturing of prototypes of dentures using modern computer technologies. Planning of diagnostics and treatment of a dental patient with the use of modern digital technologies was proposed to be divided into stages. A complex of digital planning of dental orthopedic treatment was formed, which is illustrated by clinical case analysis. The first stage is the planning of the rehabilitation stage, which includes the diagnosis of the patient's dental status and preparation for orthopedic treatment. The second stage is 2D virtual planning of dental rows in the smile area-includes 2D visualization in the form of mandatory use of dental digital photography protocols and 2D creation of a virtual image of a smile using digital two-dimensional planning programs. The third stage includes 3D-virtual planning (mock-up) of teeth in an aesthetically significant area-included digitalization of clinical data of patients, namely, CBCT, scanning of the dentition separately and in the bite, face scanning. The fourth stage is the computer production of prototype dentures, according to the 3D virtual functional and aesthetic layout, which includes the production of prototypes of dentures by the additive method of 3D printing. At this stage, recommendations are given for the production of prototypes of dentures by 3D printing directly-in a direct way and using a silicone key-not in a direct way, obtained from a printed model of the prototype of the patient's dentition.

The influence of the model and method choice on the DFT predicted 13 C NMR chemical shifts of zeolite surface methoxide species has been systematically analyzed. Twelve 13 C NMR chemical shift calculation protocols on full periodic and hybrid periodic-cluster DFT calculations with varied structural relaxation procedures are examined. The primary assessment of the accuracy of the computational protocols has been carried out for the Si-O(CH 3 )-Al surface methoxide species in ZSM-5 zeolite with well-defined experimental NMR parameters (chemical shift, δ( 13 C) value) as a reference. Different configurations of these surface intermediates and their location inside the ZSM-5 pores are considered explicitly. The predicted δ value deviates by up to ±0.8 ppm from the experimental value of 59 ppm due to the varied confinement of the methoxide species at different zeolite sites (model accuracy). The choice of the exchange-correlation functional (method accuracy) introduces ±1.5 ppm uncertainty in the computed chemical shifts. The accuracy of the predicted 13 C NMR chemical shifts for the computational assignment of spectral characteristics of zeolite intermediates has been further analyzed by considering the potential intermediate species formed upon methane activation by Cu/ZSM-5 zeolite. The presence of Cu species in the vicinity of surface methoxide increases the prediction uncertainty to ±2.5 ppm. The full geometry relaxation of the local environment of an active site at an appropriate level of theory is critical to ensure a good agreement between the experimental and computed NMR data. Chemical shifts (δ) calculated via full geometry relaxation of a cluster model of a relevant portion of the zeolite lattice site are in the best agreement with the experimental values. Our analysis indicates that the full geometry optimization of a cluster model at the PBE0-D3/6-311G(d,p) level of theory followed by GIAO/PBE0-D3/aug-cc-pVDZ calculations is the most suitable approach for the calculation of 13 C chemical shifts of zeolite surface intermediates.

The zeolite imidazolate framework ZIF-8 exhibits superior catalytic performance in the epoxidation of the electron-deficient C[double bond, length as m-dash]C bond in menadione using aqueous hydrogen peroxide as the oxidant. The catalysis has a truly heterogeneous nature and the framework structure remains intact. This is the first example of oxidation catalysis with ZIF-8.

We present a detailed solid-state NMR characterization of the molecular dynamics of tert-butyl alcohol (TBA) confined inside breathing metal-organic framework (MOF) MIL-53(Al). 27 Al MAS NMR has demonstrated that TBA adsorption induces the iX phase of MIL-53 material with partially shrunk channels. 2 H solid-state NMR has shown that the adsorbed alcohol exhibits anisotropic rotations of the methyl groups around two C 3 axes and librations of the molecule as a whole about the axis passing through the TBA C-O bond. These librations are realized by two distinct ways: fast molecule orientation change during the translational jump diffusion along the channel with characteristic time τ D of about 10 -9  s at 300 K; slow local librations at a single coordination site, representing framework hydroxyl groups, with τ l ≈10 -6  s at 300 K. Self-diffusion coefficient of the alcohol in the MOF has been estimated: D=3.4×10 -10  m 2  s -1 at 300 K. It has been inferred that both the framework flexibility and the interaction with framework hydroxyl groups define the dynamics of TBA confined in the channels of MIL-53 (Al)., (© 2020 Wiley-VCH GmbH.)

We measured the deuteron quadrupole coupling constants (DQCCs) for hydroxy-functionalized ionic liquids (ILs) with varying alkyl chain length over the temperature range between 60 and 200 K by means of solid-state NMR spectroscopy. For all temperatures, the 2 H spectra show two DQCCs representing different types of hydrogen bonds. Higher values, ranging from 220 to 250 kHz, indicate weaker hydrogen bonds between cation and anion (c-a), and lower values varying from 165 to 210 kHz result from stronger hydrogen bonds between the OD groups of cations (c-c), in agreement with recent observations in infrared, neutron diffraction, and NMR studies. We observed different temperature dependencies for (c-a) and (c-c) hydrogen bonding. From the static pattern of the 2 H spectra at the lowest temperatures, we derived the true DQCCs being up to 20 kHz larger than recently reported values measured at the glass transition temperature. We were able to freeze the librational motions of the hydrogen bonds in the ILs. The temperature dependence of the (c-a) and (c-c) cluster populations in the glassy state is opposite to that observed in the liquid state, partly anticipating the behavior of ILs tending to crystallize.

In this study, a successful proton conduction modulation of MOFs, from an ionic insulator to an ionic conductor, is demonstrated through their structural transformation. It is shown that the reversible structural change from amorphous to crystalline phases allows for the reversible proton conduction modulation of MOFs. Moreover, the proton conduction mechanism of the ionic conductor phase is elucidated by 2 H NMR analysis.

Highly stable superprotonic conductivity (>10 -2 S cm -1 ) has been achieved through the unprecedented solvent-free- coordinative urea insertion in MOF-74 [M 2 (dobdc), M = Ni 2+ , Mg 2+ ; dobdc = 2,5-dioxido-1,4-benzenedicarboxylate] without an acidic moiety. The urea is bound to open metal sites and alters the void volume and surface functionality, which triggers a significant change in proton conductivity and diffusion mechanism. Solid-state 2 H NMR revealed that the high conductivity was attributed to the strengthening of the hydrogen bonds between guest H 2 O induced by hydrogen bonds in the interface between H 2 O and the polarized coordinated urea.

In hydroxy-functionalized ionic liquids, two types of hydrogen bonding coexist: the conventional H-bonds between cation and anion (c-a) and those between cation and cation (c-c), although the interaction between like-charged ions is supposed to be much weaker due to the repulsive Coulomb forces. Counting the cations involved in either (c-a) or (c-c) clusters is a challenge. For that purpose, we recently performed neutron diffraction (ND) measurements and molecular dynamics (MD) simulations at and above room temperature accompanied by NMR solid-state experiments in the glassy state of the ILs. In principle, these methods are suitable for determining the populations of (c-a) and (c-c) cluster species. For different reasons we could only address single temperatures and/or small temperature intervals above 300 K. The by far largest temperature range with reasonable efforts is accessible by simple infrared (IR) spectroscopy. However, counting (c-a) or (c-c) hydrogen bonds is a difficult task due to the different transition dipole moments resulting in varying intensities and broad vibrational bands. Here we present a method for deriving the number of cations involved in (c-a) ion pairs from IR spectra in the OH stretch region. This procedure provides access to the equilibria of (c-a) and (c-c) hydrogen bonds as a function of temperature allowing derivation of the transition enthalpy.

We present a detailed 2 H NMR characterization of molecular mobility of propene and propane propagating though the microporous ZIF-8, a zeolitic imidazolate framework renowned for its outstandingly high separation selectivity for industrially relevant propene/propane mixtures. Experimental characterization of both propene and propane diffusivity in ZIF-8 has been provided. Using 2 H NMR spin relaxation analysis, the motional mechanisms for propene and propane guests trapped within the ZIF-8 framework have been elucidated. Kinetic parameters for each type of motion were derived. The characteristic times for microscopic translational diffusion and activation barriers (E C3H8 = 38 kJ mol -1 , E C3H6 = 13.5 kJ mol -1 ) for propane and propene diffusivities have been estimated. A notable difference in the observed activation barriers emphasizes that the ZIF-8 window crossing is associated with the "gate-opening" and represents an extremely shape selective process. Finally, we show that the 2 H NMR technique is capable of providing reliable information on microscopic diffusivity in the ZIF-8 MOF even for molecules with slow diffusivity (<10 -14 m 2 s -1 ).

Cu-modified zeolites have enormous potential as the catalysts facilitating the conversion of methane to methanol. It becomes important to investigate the active sites and the reaction mechanisms involved. In this paper, several spectroscopic methods such as UV-vis diffuse reflectance spectroscopy (UV-vis DRS), pulse electron paramagnetic resonance (EPR), diffuse reflectance Fourier transform infrared spectroscopy, and solid-state ( 13 C MAS) NMR have been employed to characterize the state of the Cu sites and the intermediates formed during the catalyst activation and methane-to-methanol transformation on Cu/H-ZSM-5 zeolite with low (0.10 wt %) Cu content. UV-vis DRS and EPR data imply the presence of two types of Cu 2+ cations bound to the zeolite framework Si-O - -Al sites (Z). One of them is a species of the type Z[Cu(II)O] or Z[Cu(II)(OH)] with extra-framework O - or OH - ligands. The other one refers to Z 2 Cu(II) species without extra-framework O-containing ligands. CW EPR studies reveal that the Z 2 Cu(II) species are the major part of the Cu(II) sites present in the zeolite. 1 H HYSCORE and DRIFTS data are supportive of the formation of a molecular complex of methane and Z 2 Cu(II) species, with a strongly polarized C-H bond and a 3.3 Å separation between the hydrogen atom of methane and Cu. 13 C MAS NMR provides evidence for the formation of both the surface methoxy intermediate and physisorbed methanol. It is suggested that experimentally identified Z[Cu(II)O] or Z[Cu(II)(OH)] are those sites that provide a homolytic cleavage of the methane C-H bond to yield surface bound methoxy species and/or methanol molecule, the possibility that has been recently justified with density functional theory ( Kulkarni et al. Catal. Sci. Technol. 2018 , 8 , 114 ). The comparison of the amount of the surface methoxy intermediates formed and the number of different Cu(II) sites present in the zeolite allowed us to conclude the involvement of Z 2 Cu(II) sites in methane C-H bond activation. The mechanism of methane activation on Z 2 Cu(II) sites has been proposed. It includes two steps: (1) the formation of the molecular complex of methane with Z 2 Cu(II); (2) heterolytic dissociation of the polarized C-H bond affording surface copper(II) hydride and methoxy species, both bound to zeolite framework Si-O - -Al sites.

Aim: To evaluate the effectiveness of the innovative concept of dental medical technologies in patients with resected (amputated) roots of teeth with and without periodontal diseases., Material and Methods: Of the 516 examined patients with periapical destructive foci of infection of various genesis, 4 clinical groups of 24 people were randomly formed: (1) with a diagnosis of apical periodontitis of incisors, canines or premolars with individual milled transdental implants made of zirconium dioxide; (2) patients with a similar diagnosis and concomitant periodontitis of moderate severity with the same implants; (3) patients with periapical destructive process of molars without periodontitis with the same implants. Control group (4) included patients with similar diagnoses with resection of the root apex without implantation. Patients of the study groups were operated in accordance with the developed clinical protocols, including the manufacture and installation of individual transdental implants with fixation in the postoperative period, developed within the framework of tooth-preserving technologies of immobilizing structures., Results: The reinforcement of teeth with resected roots with transdental implants together with immobilization of these teeth in the postoperative period restores the biomechanical characteristics of the tooth 2.7 times more effectively. However, there is a slight change in the mobility of the operated teeth in an earlier period (after 3 months), which is associated with the resorption of the bone-replacing agent used to fill the intraoperative defect and with the defective formation of bone tissue. The values of peritelomeric 6 months after the operation differ from the control by 1.4 units only.

We present deuteron quadrupole coupling constants (DQCC) for hydroxyl-functionalized ionic liquids (ILs) in the crystalline or glassy states characterizing two types of hydrogen bonding: The regular Coulomb-enhanced hydrogen bonds between cation and anion (c-a), and the unusual hydrogen bonds between cation and cation (c-c), which are present despite repulsive Coulomb forces. We measure these sensitive probes of hydrogen bonding by means of solid-state NMR spectroscopy. The DQCCs of (c-a) ion pairs and (c-c) H-bonds are compared to those of salt bridges in supramolecular complexes and those present in molecular liquids. At low temperatures, the (c-c) species successfully compete with the (c-a) ion pairs and dominate the cluster populations. Equilibrium constants obtained from molecular-dynamics (MD) simulations show van't Hoff behavior with small transition enthalpies between the differently H-bonded species. We show that cationic-cluster formation prevents these ILs from crystallizing. With cooling, the (c-c) hydrogen bonds persist, resulting in supercooling and glass formation., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

We show that deuteron quadrupole coupling constants (DQCCs), and reorientational correlation times of molecular bonds N-D that are involved in hydrogen bonding, can be determined from NMR T1 relaxation time experiments simultaneously. For this purpose, we used trialkylammonium-based protic ionic liquids (PILs) as model compounds. They exhibit high viscosities and wide liquid ranges that allow measurements far beyond the extreme narrowing region (ω0τc ≪ 1). The T1 minima already occur at temperatures significantly above room temperature. We obtain reasonable DQCCs for the liquid phase if anisotropic motion is considered. The DQCCs are very small due to attractive Coulomb interaction between the cation and anion, which is further enhanced by hydrogen bonding. The DQCCs strongly depend on the interaction strength of the anion but are independent of the alkyl chain length of the trialkyl ammonium cations pointing to the exclusive cation-anion interaction along the hydrogen bond.

Coordinatively unsaturated metal sites (CUS) play an important role in catalysis by metal-organic frameworks (MOF). Being an intrinsic part of the framework the CUS take the role of acidic sites active in industrially relevant processes such as condensation or oxidation reactions. The key step of such reactions represents the coordination of the reagents to CUS. In MOFs the mechanism of the reagent interaction with CUS is poorly understood. Herein, we characterize the interaction of a widely used acidity probe pyridine with CUS of MIL-100(Al) MOF by means of the 2 H solid-state NMR spectroscopy. 2 H NMR reveals that pyridine species, which are interacting with CUS and the ones which are coordinated to the Al-OH site, exhibit different motional behavior. 2 H NMR line shape as well as T 1 , T 2 relaxation analyses for [D 5 ]pyridine adsorbed in MIL-100(Al) allowed us to perform a detailed characterization of pyridine dynamics in both states including the kinetics of the exchange process between these adsorption states., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We investigated the effect of amorphization on the mobility of the 2-methylimidazolate linkers in ZIF-8. Solid-state 2 H NMR studies revealed that amorphization significantly affects the mobility of the linkers, including the rotational angle and speed. Furthermore, a new intermediate librational mode appeared in amorphous ZIF-8.

We present investigation of the effect of electron-donor guests on framework mobility in the metal-organic framework (MOF) MIL-101(Cr) monitored by solid state 2 H NMR spectroscopy. In a guest-free material, the mobile phenylene fragments of the terephthalate (TP) linkers populate two fractions with notably different kinetic parameters for torsional motion. Two fractions of rotational motion are indicative of non-equivalence of TP linker binding to the Cr 3 O trimer, the primary building unit of the MIL-101 framework. It is established that the interaction of the guest molecules with coordinatively unsaturated metal sites (CUS) of the MOF dramatically decreases torsional barriers for the linker motions, enhancing the rotation rate. This result is opposite to a more conventional slowing down effect on the linker rotation of the guests not selectively interacting with the adsorption sites inside the framework of the MOFs. The effect of coordination on both the torsional barrier and the rotation rate depends notably on the particular guest interacting with the CUS. The found effects of the guest on the rotational motion represent a basis for developing the strategy for ruling and controlling the linker rotation in MOFs with CUS. It is shown that if water occupies CUS, another guest (tert-butanol, cyclohexanone) fails to competitively coordinate to the site., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Modulation of pore environment is an effective strategy to optimize guest binding in porous materials. We report the post-synthetic modification of the charge distribution in a charged metal-organic framework, MFM-305-CH 3 , [Al(OH)(L)]Cl, [(H 2 L)Cl = 3,5-dicarboxy-1-methylpyridinium chloride] and its effect on guest binding. MFM-305-CH 3 shows a distribution of cationic (methylpyridinium) and anionic (chloride) centers and can be modified to release free pyridyl N-centres by thermal demethylation of the 1-methylpyridinium moiety to give the neutral isostructural MFM-305. This leads simultaneously to enhanced adsorption capacities and selectivities (two parameters that often change in opposite directions) for CO 2 and SO 2 in MFM-305. The host-guest binding has been comprehensively investigated by in situ synchrotron X-ray and neutron powder diffraction, inelastic neutron scattering, synchrotron infrared and 2 H NMR spectroscopy and theoretical modelling to reveal the binding domains of CO 2 and SO 2 in these materials. CO 2 and SO 2 binding in MFM-305-CH 3 is shown to occur via hydrogen bonding to the methyl and aromatic-CH groups, with a long range interaction to chloride for CO 2 . In MFM-305 the hydroxyl, pyridyl and aromatic C-H groups bind CO 2 and SO 2 more effectively via hydrogen bonds and dipole interactions. Post-synthetic modification via dealkylation of the as-synthesised metal-organic framework is a powerful route to the synthesis of materials incorporating active polar groups that cannot be prepared directly.

The heterogeneity in dynamics has important consequences for understanding the viscosity, diffusion, ionic mobility, and the rates of chemical reactions in technology relevant systems such as polymers, metallic glasses, aqueous solutions, and inorganic materials. Herein, we study the spatial and dynamic heterogeneities in ionic liquids by means of solid state NMR spectroscopy. In the 2 H spectra of the protic ionic liquid [TEA][OTf] we observe anisotropic and isotropic signals at the same time. The spectra measured below the melting temperature at 306 K could be simulated by a superposition of the solid and liquid line shapes, which provided the transition enthalpies between the rigid and mobile fractions. Consequently, we measured the spin-lattice relaxation times T 1 for the anisotropic and the isotropic signals for the temperature range between 203 and 436 K. Both dispersion curves could be fitted to models including rotational correlation times, activation barriers and rate constants. This approach allowed determining the rotational correlation times for the N-D molecular vector of the [TEA] + cation in differently mobile environments. The mobility is only slightly different, as indicated by small differences in activation energies for these processes. The NMR correlation times for the highly mobile phase are linearly related to measured viscosities, which supports the applicability of the Stokes-Einstein-Debye relation.

Transdental implantation is an effective way to restore the lost biomechanical properties of a resected or amputated tooth. The choice of structural materials for the implant is the most important stage of treatment, in relation to the adhesion of aggressive microbiota to them. To characterize the adhesion of microorganisms of periodontopathogenic and cariogenic groups in vitro to experimental samples of zirconium dioxide and titanium alloys using cultural and electronic microscopic methods of adhesion evaluation as the first stage of biofilm formation. Samples for the experiment were prepared in the form of a tablet of standard form, on which the test strains were applied in an amount of 106CFU/ml. After shaking the unattached cells with ultrasound, they were seeded into dense nutrient medium to determine their number. In total, 14 strains of perodontopathogenic and cariogenic groups (including 3 reference strains) were used in the experiment. Scanning electron microscopy was used to visualize the adhesion of microorganisms. The results of the adhesion test to titanium nickelide and zirconium dioxide showed a significant reduction in adhesion for all microorganism species. In all variants (with all strains) the adhesion values to titanium nickelide and zirconium dioxide were statistically significantly lower than when using samples from a traditional titanium alloy. In scanning electron microscopy, single cells of test strains of perodontopathogenic microorganisms were determined on zirconium dioxide samples, while a considerable number of cells and the initial phase of biofilm formation were observed on the compared structural materials. Zirconium dioxide can be considered as an optimal choice material for the manufacture of transdental implants, which, in terms of its technological characteristics and low adhesion characteristics of microbes, is superior to the traditionally used titanium alloys., Competing Interests: The authors declare no conflict of interest.

We present the first deuteron quadrupole coupling constants (DQCCs) for selected protic ionic liquids (PILs) measured by solid-state NMR spectroscopy. The experimental data are supported by dispersion-corrected density functional theory (DFT-D3) calculations and molecular dynamics (MD) simulations. The DQCCs of the N-D bond in the triethylammonium cations are the lowest reported for deuterons in PILs, indicating strong hydrogen bonds between ions. The NMR coupling parameters are compared to those in amides, peptides, and proteins. The DQCCs show characteristic behavior with increasing interaction strength of the counterion and variation of the H-bond motifs. We report the similar presence of the quadrupolar splitting pattern and the narrow liquid line in the NMR spectra over large temperature ranges, indicating the heterogeneous nature of PILs., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Gas transport through metal-organic framework membranes (MOFs) was switched in situ by applying an external electric field (E-field). The switching of gas permeation upon E-field polarization could be explained by the structural transformation of the zeolitic imidazolate framework ZIF-8 into polymorphs with more rigid lattices. Permeation measurements under a direct-current E-field poling of 500 volts per millimeter showed reversibly controlled switching of the ZIF-8 into polar polymorphs, which was confirmed by x-ray diffraction and ab initio calculations. The stiffening of the lattice causes a reduction in gas transport through the membrane and sharpens the molecular sieving capability. Dielectric spectroscopy, polarization, and deuterium nuclear magnetic resonance studies revealed low-frequency resonances of ZIF-8 that we attribute to lattice flexibility and linker movement. Upon E-field polarization, we observed a defibrillation of the different lattice motions., (Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Natural gas (methane, CH 4 ) is widely considered as a promising energy carrier for mobile applications. Maximizing the storage capacity is the primary goal for the design of future storage media. Here we report the CH 4 storage properties in a family of isostructural (3,24)-connected porous materials, MFM-112a, MFM-115a, and MFM-132a, with different linker backbone functionalization. Both MFM-112a and MFM-115a show excellent CH 4 uptakes of 236 and 256 cm 3 (STP) cm -3 (v/v) at 80 bar and room temperature, respectively. Significantly, MFM-115a displays an exceptionally high deliverable CH 4 capacity of 208 v/v between 5 and 80 bar at room temperature, making it among the best performing metal-organic frameworks for CH 4 storage. We also synthesized the partially deuterated versions of the above materials and applied solid-state 2 H NMR spectroscopy to show that these three frameworks contain molecular rotors that exhibit motion in fast, medium, and slow regimes, respectively. In situ neutron powder diffraction studies on the binding sites for CD 4 within MFM-132a and MFM-115a reveal that the primary binding site is located within the small pocket enclosed by the [(Cu 2 ) 3 (isophthalate) 3 ] window and three anthracene/phenyl panels. The open Cu(II) sites are the secondary/tertiary adsorption sites in these structures. Thus, we obtained direct experimental evidence showing that a tight cavity can generate a stronger binding affinity to gas molecules than open metal sites. Solid-state 2 H NMR spectroscopy and neutron diffraction studies reveal that it is the combination of optimal molecular dynamics, pore geometry and size, and favorable binding sites that leads to the exceptional and different methane uptakes in these materials.