Orientation Of Guest Research Articles

Customer Service Behavior and Attitudes among Hotel Managers: A Look at Perceived Support Functions, Standards for Service, and Service Process Outcomes

A model of customer service behavior and outcomes was proposed and tested among managerial-supervisory personnel (N = 250) from 11 hotel properties within six large national and international hotel companies. Confirmatory factor analyses yielded a reliable approach to examine elements of customer service and outcomes in a service-based setting. Specifically, organizational support was represented by two independent dimensions of coworker support and supervisory support. A dimension of standards for service was presented and validated as a central mediating factor in the perception of service processes, along with customer (guest) orientation, job satisfaction, organizational commitment, and turnover intentions as outcome measures in a path model of customer service behavior.

Difference in Orientation of a Guest within a Cavity of b-Cyclodextrins Bearing an N-Acetylaminoacyl Group

Difference in Orientation of a Guest within a Cavity of b-Cyclodextrins Bearing an N-Acetylaminoacyl Group

Dielectric relaxation of polar aromatics in unoriented and oriented linear low-density polyethylene

The dielectric behavior of some polar aromatics dissolved in nonpolar unoriented and stretched linear low-density polyethylene was investigated within the temperature region between 150 and 350 K. The measurements were carried out in the frequency range 1 kHz to 10 MHz. The maximum temperatures and the half widths of the loss tangent peaks depend upon the shape and the polar structure of guest molecules. Stretching the samples induced a shift of the loss tangent to higher temperatures, decreased the height, and increased the width of tan δ peak. The activation energy is also influenced by the type of guest molecules and orientation of polymer matrix.

Restricted motion of guests confined in carceplexes and capsules.

Guest orientation within carceplexes and capsules was determined qualitatively from NMR data, and the molecular mobility of guests was determined via coalescence of (1)H NMR signals. Both are highly dependent on guest size and shape, as is interconversion of twistomers. Incarceration of 1,4-thioxane results in a large (1.8 kcal/mol) constraint on thioxane's conformational mobility (chair-to-chair interconversion). Similar conformational constraints (1.6 kcal/mol) were determined for 1,4-dioxane both when incarcerated in carceplex 1b and when encapsulated reversibly in capsule 3b. Encapsulation-induced conformational constraints of this magnitude are unprecedented, and are particularly striking for the noncovalently linked capsules.

Predicting Guest Orientations in Layered Double Hydroxide Intercalates

Molecular mechanics have been used to rationalize the structures of the layered double hydroxide intercalates [LiAl2(OH)6]Cl, [LiAl2(OH)6]Br, and [LiAl2(OH)6]NO3. The simulations showed that calculated lowest energy structures were in good agreement with the experimentally determined structures and were able to explain the positional disorder of the NO3- guest anions found in the structure of [LiAl2(OH)6]NO3. Furthermore, the calculations also proved to be a useful predictive tool for the interlayer spacing and consequently the guest orientation in the related intercalates [LiAl2(OH)6]2CO3, [LiAl2(OH)6]2SO4, and [LiAl2(OH)6]2C2O4, for which the structures have not been determined by conventional diffraction techniques.

Novel Prediction for the Driving Force and Guest Orientation in the Complexation of α- and β-Cyclodextrin with Benzene Derivatives

Taking the possibility of different inclusion orientations into consideration, a nonlinear free energy relationship model has been established by means of a genetic algorithm for the molecular recognition of α- and β-CD with mono- and 1,4-disubstituted benzenes. The association constants (Ka) for the inclusion complexation of α- and β-cyclodextrin with a number of benzene derivatives were evaluated by the model from the substituent molar refraction Rm, hydrophobic constant π, and Hammett constant σ, which respectively reflect the volume, hydrophobicity, and electronic property of the substituents in the guest compounds. The Ka values calculated by the model are quite close to those determined experimentally. It suggested that the van der Waals force, hydrophobic interactions, and electronic effects comprise the main driving forces for CD molecular recognition. Furthermore, van der Waals force plays a dominant role in α-CD complexation; on the other hand, van der Waals force and hydrophobic interactions play the major roles in β-CD complexation. The model is capable of quantitatively estimating the orientation of guest compounds in CD cavities. The predictions in both driving force and the orientation are in good agreement with the experimental studies.

Volumetric and compressibility studies in Clathrate forming systems

The sound velocity and density measurements of solutions of methanol and acetonitrile in n-propanol and methanol /acetonitrile + n-propanol + hydroquinone (2.5 m) were made at 25°C. The apparent molar volumes (/ gf v ) and compressibilities (/ gf k ) of methanol and acetonitrile in two solvent systems, viz., n-propanol and n-propanol + hydroquinone were evaluated using these data. The transfer volume ( Δ/gf v o ) and compressibility ( Δ/gf k o ) at infinite dilution for methanol are found to be ≅ 4.2 cm 3 mol −1 and ≅ 0.0 mm 3 mol − MPa −1 respectively for transfer from n-propanol to 2.5 m hydroquinone + n-propanol, while the similar data for acetonitrile are ≅ 0.1 cm 3 mol −1 and ≅ 40 mm 3 mol −1 MPa −1 respectively. The transfer data and variation of / gf v and / gf k parameters with concentration of CH 3 OH /CH 3 CN are interpreted in terms of clathrate formation with a stoichiometry of 1:3 in solution phase. It has also been observed that the structural interactions depend upon the size of the guest molecule as well as on the orientation of guest (CH 3 OH /CH 3 CN) molecules, exhibiting distinct concentration dependence as far as the derived properties are concerned.

Intercalation of hydrazines in lead iodide

Abstract Hydrazine and methylated hydrazines were intercalated into thin films and crystalline powders of lead iodide. Interplanar spacing increased with increasing methylation. Weight gain and X-ray data provide estimates of the guest orientation. All three guest molecules have their major axis approximately perpendicular to the layers of the host. The large optical band-edge shifts in this intercalation decreased with increasing methylation. Intercalation of 1,2-dimethylhydrazine produces the first evidence for staging in the heavy-metal iodide systems.

Glycerol/Heptane Interface: Reflection Spectroscopy of the Guest Molecule

Variable-angle reflection spectroscopy of a glycerol/heptane interface bearing 9,10-dibromoanthracene guest molecules made it possible to follow the variation of the guest optical absorption spectrum through the interface transition layer. Analysis of the surface optical functions resulted in local density profiles for 9,10-dibromoanthracene revealed the molecular field anisotropy and the preferential orientation of the guest within the interface, and demonstrated variations in 9,10-dibromoanthracene solvation shell mean composition and composition fluctuations.

Mechanism for chiral recognition of binaphthyl derivatives by cyclodextrins

The mechanism for chiral recognition of 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (BNP) and 1, 1′binaphthyl-2,2′-dicarboxylic acid (BNC) by β-cyclodextrin (β-CDx) and heptakis(2,3,6-tri-O-methyl)β-CDx (TMe-βCDx) has been investigated by ′H NMR spectroscopy, thermodynamic parameters for complexation and molecular mechanics-molecular dynamics (MM-MD) calculations. TMe-β-CDx recognizes axial chiralities of the BNP anion and undissociated BNC, (S)-BNP and (R)-BNC being the preferable guest enantiomers. The ability of β-CDx to recognize the axial chiralities is inferior to that of TMe-β-CDx. ′H NMR spectra suggest that (S)-BNP is shallowly bound to the wider side of the TMe-β-CDx cavity where a hydrophilic phosphate group is located inside the hydrophobic CDx cavity. Meanwhile, (R)-BNP seems to form the complex of TMe-β-CDx where the C2 symmetry axis of (R)-BNP is perpendicular to the C7 symmetry axis of TMe-β-CDx. The complexation of the preferable enantiomer of the guest with TMe-β-CDx is entropically favourable while that of the undesirable enantiomer of the guest is entropically unfavourable. The MM–MD calculations suggest that the orientation of the preferable guest is determined by the dipole-dipole interactions between the host and the guest. Similar orientation in the cases of the undesirable enantiomers may be prevented by steric factors. The positive entropy changes in the complexation of (S)-BNP and (R)-BNC seem to be ascribed to the extended dehydration from both the hydrophilic groups of the guest and the ethereal oxygen atoms of the wider side of the TMe-β-CDx cavity upon inclusion.

One- and two-dimensional NMR study of complexation of ursodeoxycholic acid with β-cyclodextrin

The interaction of ursodeoxycholic acid (UDCA) with β-cyclodextrin (β-CD) is investigated through one- and two-dimensional (ROESY) NMR spectroscopy. The relative orientation of host and guest is unequivocally established: the aliphatic side chain of UDCA enters the torus of β-CD on the side of the secondary hydroxy groups.

X-ray crystallographic studies and molecular calculations on 1?1 inclusion complexes of cholic acid with acetophenone and its derivatives

Molecular calculations were applied to four channel-type inclusion complexes of cholic acid (CA) with acetophenone or its derivatives (3′-, 4′-fluoroacetophenone and 2′-chloroacetophenone). According to the calculated results, both the total and van der Waals interaction energies between channel and included guests depend on the channel form determined by the guest species. Similarly, the channel form is responsible for the dipole moment of the channel. Further examination of the results suggests that dipole-dipole interaction does not play an important role in the determination of the guest orientation.

The crystal structure of the inclusion complex of cyclomaltoheptaose (?-cyclodextrin) with 3,5-dimethylbenzoic acid

The crystal of theβCD-3,5-dimethylbenzoic acid inclusion complex is triclinicP1 witha=15.707(3),b=15.694(3),c=15.999(3) A, α=101.502(5),β=101.557(5), γ=103.805(4)°,V=3624 A3, andZ=1. Two crystallographically independentβCD molecules form a dimer by means of hydrogen bonds between secondary hydroxyl groups in which disordered guest molecules in six orientations are accommodated. In two of them the guest molecules are situated at the dimer interface, their carboxyl groups interacting with the carboxyl groups of two other guest orientations that are found on either side of the monomer cavity. In the two last orientations the guest molecules enter the monomer cavities in an opposite sense with the carboxyl groups protruding from the primary side and are stabilized by cyclodextrin hydroxyl groups. A dense water network is formed in the interdimer space consisted of 18.2 water molecules distributed over 24 sites.

Artificial redox enzymes. II. A computational chemistry study1

AbstractA computational chemistry study of the artificial redox enzyme synthesized by covalently attaching flavin to cyclodextrins explains some of its properties. Calculations indicate that the flavin moiety covalently attached to cyclodextrin is not within the cavity of cyclodextrin. This result is consistent with the UV‐vis spectrum of the artificial enzyme. The calculations also indicate hydrogen bonds formed between the carbonyl groups of the catalytic functionality and the hydroxyl groups of cyclodextrin play a role in their most stable conformation. This explains the observed overall stability of these artificial enzymes compared to riboflavin. Electrostatic energies and solvation energies play a major role in the stability of the hosts and the orientation of guests included within the artificial enzymes. The rates of oxidation of various thiols catalyzed by the artificial enzyme can be explained by the relative distances between the sulfur atom of the substrates and C(4a) of the flavin moiety.

X-Ray crystallographic study of fluorine atom effect on guest orientation inside the α-cyclodextrin cavity

X-Ray crystallographic studies of α-cyclodextrin (α-CD)–2- and –4-fluorophenol complexes indicate that the fluorine atom determines the guest orientations inside the α-CD cavity in both complexes, and accordingly that the hydroxy groups of 4-FC6H4OH and 2-FC6H4OH are located inside and outside the cavity, respectively.

A Molecular Orbital Study of Cyclodextrin Inclusion Complexes, II. The Structural Analysis of α-Cyclodextrin Inclusion Complex with m-Nitrophenol in Aqueous Solution Based on the Quantum-Chemical Solvation Theory

Abstract The host–guest orientation and the position of the guest m-nitrophenol (MNP) in the α-cyclodextrin(α-CD)–MNP complex in aqueous solution have been determined by comparing the complexation-induced 13C NMR chemical shifts of MNP with those predicted by quantum chemical calculation. The results are consistent with the X-ray data of this complex.

A Molecular Orbital Study of Cyclodextrin Inclusion Complexes. I. The Calculation of the Dipole Moments of α-Cyclodextrin Aromatic Guest Complexes

Abstract The dipole moments of α-cyclodextrin(α-CD)-aromatic guest systems have been calculated by means of the CNDO/2 molecular orbital (MO) method in order to investigate the role of electrostatic interaction in the stabilization of the inclusion complexes. It is found that α-CD has a remarkably large dipole moment which amounts to 13.5 D and is directed from its secondary hydroxyl side (the wider rim) towards the primary hydroxyl side (the narrower rim). The dipole moments of the guests, benzene derivatives, run antiparallel to that of α-CD in the complexed state. The MO total energy of the α-CD-guest supermolecular complexes shows that these antiparallel-orientations are energitically more favorable than the reversed one. It is concluded that the electrostatic interaction, mainly dipole–dipole interaction, between the α-CD and the guest molecules plays an essential role in determining the guest orientation. On the basis of these results, it is deduced that during complexation the CD molecule undergoes appreciable amount of conformational change, suggesting that the “induced-fit” mechanism is operating when the guest molecule is admitted into the host cavity.

The large dipole moment of cyclomaltohexaose and its role in determining the guest orientation in inclusion complexes

The large dipole moment of cyclomaltohexaose and its role in determining the guest orientation in inclusion complexes

The host—guest orientation in the inclusion complex of hexakis(2,3,6-tri- O-methyl)cyclomaltohexaose with p-nitrophenol in aqueous solution

The host—guest orientation in the inclusion complex of hexakis(2,3,6-tri- O-methyl)cyclomaltohexaose with p-nitrophenol in aqueous solution

Specific guest orientation in guest–host association with a transition metal complex containing a permanent void

1 H N.m.r. longitudinal relaxation time measurements in aqueous solution are used to estimate distances from the protons of guest molecules to a paramagnetic copper(II) macrobicyclic complex whose ligand is known to facilitate O2 binding to both Co11 and Fe11 while in addition being sufficiently spacious to accommodate a number of organic substrates for potential autoxidation.