Search results for "guest"
showing 10 items of 122 documents
Exploring the self-assembly of resorcinarenes : from molecular level interactions to mesoscopic structures
2012
Cilvēkresursu vadība par viesu sūdzības apmierināšanas kvalitāti viesnīcu nozarē
2020
Pētījuma mērķis ir identificēt galvenos cilvēkresursu vadības elementus, kas ietekmē viesu sūdzību apmierināšanu, un izstrādāt ieteikumus, lai labāk atrisinātu sūdzības, kas pozitīvi ietekmē viesnīcas konkurētspēju. Pirmkārt, tas sniedz teorētisku pētījumu par cilvēkresursu vadības sistēmu, parāda attiecības starp HRM un viesu sūdzībām un to, kā sūdzības var rasties uzturēšanās laikā viesnīcā. Attīstības otrā nodaļa ir Uzbekistānas tūrisma nozares analīze, valsts reformas un HRM statistika šajā jomā. Pēdējā daļa no papīra ir empīrisks pētījums, kas ir darīts Hotel Uzbekistānā, kas precizē reālus jautājumus par sūdzībām un apmierinātības kvalitāti, ietekmējot uz HRM kā sviru.
Coordination Chemistry of a Bis(Tetrazine) Tweezer: A Case of Host-Guest Behavior with Silver Salts
2021
The carbon-carbon cross-coupling of phenyl s-tetrazine (Tz) units at their ortho-phenyl positions allows the formation of constrained bis(tetrazines) with original tweezer structures. In these compounds, the face-to-face positioning of the central tetrazine cores is reinforced by π-stacking of the electron-poor nitrogen-containing heteroaromatic moieties. The resulting tetra-aromatic structure can be used as a weak coordinating ligand with cationic silver. This coordination generates a set of bis(tetrazine)-silver(I) coordination complexes tolerating a large variety of counter anions of various geometries, namely, PF6−, BF4−, SbF6−, ClO4−, NTf2−, and OTf−. These compounds were characterized…
Oligoamide Foldamers as Helical Chloride Receptors-the Influence of Electron-Withdrawing Substituents on Anion-Binding Interactions.
2019
The anion-binding properties of three closely related oligoamide foldamers were studied using NMR spectroscopy, isothermal titration calorimetry and mass spectrometry, as well as DFT calculations. The 1 H NMR spectra of the foldamers in [D6 ]acetone solution revealed partial preorganization by intramolecular hydrogen bonding, which creates a suitable cavity for anion binding. The limited size of the cavity, however, enabled efficient binding by the inner amide protons only for the chloride anion resulting in the formation of a thermodynamically stable 1:1 complex. All 1:1 chloride complexes displayed a significant favourable contribution of the entropy term. Most likely, this is due to the …
Oligoamide Foldamers as Helical Chloride Receptors : the Influence of Electron-Withdrawing Substituents on Anion-Binding Interactions
2019
The anion‐binding properties of three closely related oligoamide foldamers were studied using NMR spectroscopy, isothermal titration calorimetry and mass spectrometry, as well as DFT calculations. The 1H NMR spectra of the foldamers in [D6]acetone solution revealed partial preorganization by intramolecular hydrogen bonding, which creates a suitable cavity for anion binding. The limited size of the cavity, however, enabled efficient binding by the inner amide protons only for the chloride anion resulting in the formation of a thermodynamically stable 1:1 complex. All 1:1 chloride complexes displayed a significant favourable contribution of the entropy term. Most likely, this is due to the re…
Solution and solid-state studies on the halide binding affinity of perfluorophenyl-armed uranyl–salophen receptors enhanced by anion–π Interactions
2016
The enhancement of the binding between halide anions and a Lewis acidic uranyl-salophen receptor has been achieved by the introduction of pendant electron- deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion-p interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding.
Achieving Strong Positive Cooperativity through Activating Weak Non-Covalent Interactions
2018
Positive cooperativity achieved through activating weak non-covalent interactions is common in biological assemblies but is rarely observed in synthetic complexes. Two new molecular tubes have been synthesized and the syn isomer binds DABCO-based organic cations with high orientational selectivity. Surprisingly, the ternary complex with two hosts and one guest shows a high cooperativity factor (α=580), which is the highest reported for synthetic systems without involving ion-pairing interactions. The X-ray single-crystal structure revealed that the strong positive cooperativity likely originates from eight C-H⋅⋅⋅O hydrogen bonds between the two head-to-head-arranged syn tube molecules. Thes…
Binding properties of heptakis-(2,6-di-O-methyl)-β-cyclodextrin and mono-(3,6-anhydro)-β-cyclodextrin: a polarimetric study
2011
The binding constants for the inclusion complexes formed between heptakis-(2,6-di-O-methyl)-β-cyclodextrin (MβCD) and mono-(3,6-anhydro)-β-cyclodextrin (AβCD) with a set of suitably selected organic guests, were measured by means of polarimetry. Measurements were carried out at various pH values in order to ensure the correct protonation state for ionizable guests. Experimental data suggest that the binding properties of MβCD may be rationalized considering the less polar and more hydrophobic character of the cavity, although similar variations in conformational/dynamic behaviour occur as for native βCD. On the other hand, AβCD shows some similarities with αCD, due to the significant distor…
Binding equilibria between beta-cyclodextrin and p-nitro-aniline derivatives: the first systematic study in mixed water-methanol solvent systems.
2009
Abstract Complexation equilibria, in mixed water–methanol solvent media, between native β-cyclodextrin and a set of suitably selected p -nitro-aniline derivatives were studied by means of polarimetry. The effects exerted by the organic co-solvent on the conditional inclusion free energies Δ G cond 0 and the differential molar optical rotations Δ Θ were thoroughly analyzed under the perspective of the enthalpy–entropy compensation effect. Experimental data suggest an intimate participation (‘dynamic co-inclusion’) of solvent molecules in the formation and in the conformational dynamics of the host–guest inclusion complex.
Binding properties of mono-(6-deoxy-6-amino)-β-cyclodextrin towards p-nitroaniline derivatives: a polarimetric study
2009
Abstract Polarimetry was used in order to investigate the formation of supramolecular complexes between mono-6-amino-β-cyclodextrin and various p-nitroaniline derivatives at two different pH values. Comparison with the behaviour of native β-cyclodextrin gave us the opportunity to consider the effect exerted by the presence of charged groups, having different solvation requirements, on the binding equilibrium. Data offer some support to the hypothesis of ‘dynamic co-inclusion’ of solvent molecules within the host–guest complex.