We combine experiments and simulations to study the adsorption of water in several UiO-66 frameworks (ideal defect-containing structures). propose a new set charges for that accurately provides water-structure interaction at molecular level. The is suitable predicting ideal structure, providing first time, good agreement between experimental calculated isotherms. proposed procedure tuning point framework achieve with universal can easily be extended other MOFs. explore structural...

Abstract Structural defects in metal–organic frameworks can be exploited to tune material properties. In the case of UiO-66 material, they may change its nature from hydrophobic hydrophilic and therefore affect mechanism adsorption polar non-polar molecules. this work, we focused on understanding during molecules with different dipole moments, using standard volumetric measurements, IR spectroscopy, DFT + D calculations, Monte Carlo calculations. Average occupation profiles showed that...

Proton-conducting solids operating in both anhydrous and humid conditions are of paramount importance for the development fuel cells. We demonstrate that incorporating formamidinium or methylammonium ions CPO-27/MOF-74 metal–organic frameworks renders them highly conductive under two conditions. Highest proton conductivities reach 8 × 10–4 S/cm conditions, exceed 10–3 already at low relative humidity (30–50% RH) temperatures (25–60 °C), 10–2 60 °C 70% RH. The dense pore filling with protic...

The location of Cu cations in CuZSM-5, properties cationic sites and their interaction with guest molecules have been studied by quantum chemical (DFT) modeling IR spectroscopy based on the frequency shift antisymmetric T–O–T vibration oxygen rings. has found sensitive both to framework adsorbed molecules. It measured estimated theoretically from parameters characterising distorsion Cu+ Cu2+, MgZSM-5 NaZSM-5 used as ''reference samples''. was that ordering cation perturbing effect was:...

The rapidly rising level of carbon dioxide in the atmosphere resulting from human activity is one greatest environmental problems facing our civilization today. Most technologies are not yet sufficiently developed to move existing infrastructure cleaner alternatives. Therefore, techniques for capturing emission sources may play a key role at moment. structure UiO-66 material only meets requirement high stability contact with water vapor but through pre-adsorbed pores, selectivity adsorption...

Rational design of organic building blocks provides opportunities to control and tune various physicochemical properties metal–organic frameworks (MOFs), including gas handling, proton conduction, structural flexibility, the latter which is responsible for new adsorption phenomena often superior compared rigid porous materials. In this work, we report synthesis, crystal structures, adsorption, conduction a flexible two-dimensional cadmium-based MOF (JUK-13-SO3H-SO2) containing sulfonated...

It is well-known that Cu+ cations in zeolites, especially ZSM-5 activate NO molecule resulting its decomposition. Quantum chemical calculations evidenced it due to π-backdonation. The aim of our studies was answer the question whether zeolites also able other π-electron systems according same mechanism, i.e. by π-backdonation d electrons copper π* antibonding orbitals. We studied adsorption alkenes (ethene, propene, cis-but-2-ene, trans-but-2-ene), acetylene, benzene, and acetone with sites...

This paper concerns the activation of ethene and ethyne molecules on two cationic sites (Cu(I) Ag(I)) in ZSM-5 zeolite. QM/MM calculations were carried out to obtain geometric structure vibrational frequencies. A novel analysis tool, NOCV (natural orbitals for chemical valence) supported by an ETS energy decomposition scheme, was applied characterize charge flow between adsorbed site The ETS-NOCV method allows separating independent components differential electron density into donation...

Three essential factors have been identified (i–iii) for the interaction between H₂ and Ag⁺, Cu⁺, Mg²⁺, Cd²⁺, Zn²⁺ sites in zeolites: (i) donation from σ_H2 to cation, (ii) π-backdonation cation antibonding orbital of molecule, (iii) oxygen framework which is crucial dissociation on sites.

In this work, density functional theory (DFT) and Monte Carlo calculations were combined with standard volumetric adsorption as well quasi-equilibrated temperature-programmed desorption measurements to study water in UiO-66 derivatives containing −NH2, −NO2, −Br substituents. Based on DFT modeling, both the position geometry of substituents determined one model was selected for each structure. By using simulations force field developed our previous work metal–organic frameworks, we...

Adsorption and activation of ethene, ethyne, formaldehyde by copper silver sites in ZSM-5 are reinspected quantitative assessment the donation backdonation processes between three molecules either models comprising bare cations (M+) or embedded zeolite framework (M(I)). ETS-NOCV analysis (decoupling deformation density upon substrate bonding into independent components) reveals two predominant channels for electron transfer adsorbed molecule a cation cationic site, namely π*-backdonation...

The low temperature adsorption of CO has been investigated on NaX (Si/Al a. r. = 1.3), NaY 2.4), NaMOR 6.5) and NaFER 25) zeolites by FT-IR spectroscopy. For comparison also Na-silica–alumina. Bands assigned to C-bonded O-bonded Na+ ions have observed discussed. A correlation between the position band siting coordination state for species. Some effect cavity envisaged Low frequency bands corresponding quite stable species found carbon monoxide bonded two cations. This suggests that may probe...

Electronic factors essential for NO activation by Cu(I) sites in zeolites are investigated within spin-resolved analysis of electron transfer channels (natural orbitals chemical valence). NOCV is performed three DFT-optimized models Cu(I)–NO site ZSM-5: [CuNO]+, (T1)CuNO, and (M7)CuNO. as a non-innocent, open-shell ligand reveals significant differences between independent deformation density components α β spins. Four distinct identified: (i) unpaired donation from π‖* antibonding orbital...

Electronic factors responsible for the notable decline of NO activation by Cu(II) with respect to Cu(I) sites in zeolites are investigated within spin-resolved analysis electron transfer channels between copper center and substrate. The results natural orbitals chemical valence (NOCV) charge a minimal model zeolite ZSM-5 ({T1Cu} + NO) compared those Cu(I)–NO referenced an interaction bare Cu cations. bonding NO, which is open-shell non-innocent ligand, gives rise noticeable nondynamical...

We report here a concise resume reporting the way of constructing model an active site composed transition metal cation exchanged in zeolites. The main goal was to devise CuZSM-5 capable describing geometrical and electronic properties sites adsorption complexes with small molecules. models were built up starting from simple ring structures encountered ZSM-5 framework fused rings’ selected as representative α position for hosting cation. Geometrical basal model, extended cluster Cu+ or Cu2+...