• The Journal of the Acoustical Society of Korea
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• 제31권2호
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• pp.100-106
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• 2012

The aim of this work was to reveal the effect of butanoic acid in its dissociated form and undissociated form as a guest molecule on the kinetic parameters in an inclusion reaction with ${\beta}$-cyclodextrin (${\beta}$-CD). Ultrasonic absorption measurements in the frequency range from 0.2 to 45 MHz were carried out for ${\beta}$-CD solutions with butanoic acid at $25^{\circ}C$ by ultrasonic relaxation method. The rate and the equilibrium constants were obtained from the guest concentration dependence of the relaxation frequency, and the standard volume change of the complexation reaction were obtained from the maximum absorption per wavelength. A single relaxational absorption was observed, and the cause of the relaxation was attributed to a perturbation of the chemical equilibrium associated with a complexation reaction between ${\beta}$-CD and butanoic acid. These results were compared with those in solutions containing both ${\beta}$-CD and different guest molecules. It was found that the hydrophobicity of guest molecules played an important role in the formation of the inclusion complex and also that the charge on the carboxylic group had a considerable effect on the kinetic characteristics of the complexation reaction.

• Applied Chemistry for Engineering
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• 제29권5호
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• pp.519-523
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• 2018

Cyclodextrins are a class of oligosaccharides having an extremely low toxicity, so that they have been used for the formation of host-guest complexes and removal of toxic gases or molecules. In this study, the subtle phenomenon associated with the formation of host-guest complexes between cyclodextrin and toxic molecules (methyl paraben) was experimentally investigated. First, the formation of cyclodextrin-methyl paraben complexes was monitored by UV/Vis spectroscopy as a function of the cyclodextrin concentration. Secondly, the electrochemical measurement was performed with the surface engineered Au electrode having cyclodextrin molecules on the Au substrate. The sensing signal derived from the addition of methyl paraben solution into the Au surface was measured delicately. This study can be informative for future applications such as sensors.

• Bulletin of the Korean Chemical Society
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• 제17권10호
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• pp.919-924
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• 1996

Crystal structure of two inclusion compounds Cd(pn)Ni(CN)4·0.25G (G=toluene and p-xylene, pn=1,2-diaminopropane) have been determined from single-crystal X-ray diffraction data; toluene clathrate: monoclinic P21/n, a=13.838(6), b=26.893(5), c= 7.543(5) Å, γ=90.92(3)°, Z=4, R=0.0616; p-xylene clathrate: monoclinic P21/n, a=13.895(2), b=26.900(3), c=7.613(1) Å, γ=91.06(1)°, Z=4, R=0.0486. The host structures determined for toluene- and pxylene-guest clathrates are substantially identical to the U-type structures observed for the straight chain aliphatic-guest clathrates. However, the alternating arrangement of occupied channels with the guest molecules and vacant channels appears in the host structure. The non-centrosymmetric toluene molecules are distributed about the inversion center to give an image like p-xylene molecule. The guests, toluene and p-xylene, prefer the U-type channel, favoring the interaction between the π-electrons of the aromatic ring and the pn-amino groups to hold the aromatic ring vertical to the cyanometallate meshes.

• Bulletin of the Korean Chemical Society
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• 제22권11호
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• pp.1248-1254
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• 2001

The conformations and energies of p-tert-butylcalix[4]crown-6-ether (1) and its alkyl ammonium complexes have been calculated by ab initio HF/6-31G quantum mechanics method. The cone conformation was found to be most stable for free host 1. We hav e determined the binding site of these host-guest complexes focusing on the crown-6-ether or p-tert-butylcalix[4]arene pocket of the cone conformation of host molecule 1. The primary binding site of host 1 for the recognition of alkyl ammonium guests was confirmed to be the central part of the crown moiety of cone conformation. The complexation energy calculations revealed that the ammonium cation without alkyl group showed the highest complexation efficiency when combined with host 1, that is in satisfactory agreement with the experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.615-617
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• 2005

[ $^{13}C$ ] NMR spectra were obtained for pure $CH_4$ hydrate in order to identify hydrate structure and cage occupancy of guest molecule. The NMR technique can provide both qualitative and quantitative hydrate characteristics. The moles of methane captured into pure $CH_4$ hydrate per mole of water were found to be similar to the full occupancy value. The overall results drawn from this study can be usefully applied to storage and transportation of natural gas.

• Korean Journal of Crystallography
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• 제10권1호
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• pp.28-32
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• 1999

The title compound consisting of a calix[4]arene molecule with four phenyl rings arranged alternately in anti-orientation fashion, two propyloxy groups attached on the upper rim of calix[4]arene, and polyther chain with two phyenyl rings attached on the lower rim of calix[4]arene offers a big cavity inside a molecule with might a potential for forming host-guest complexes.

• Korean Journal of Crystallography
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• 제10권2호
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• pp.114-118
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• 1999

The title compound consisting of a calix[4]arene molecule with four phenyl rings arranged alter-nately in anti-orientation fashion, two propyloxy groups, and four para-tert-butyl group, attached on the upper rim of calix[4]arene, and polyether chain with two phenyl rings attached on the lower rim of calix[4]arene offers a big cavity inside the molecule that might possess a potential for form-ing host-guest complexes.

• Korean Journal of Crystallography
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• 제10권2호
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• pp.130-135
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• 1999

The title compound consisting of a calix[4]arene molecule with four phenyl rings bridged by four methylene groups and arranged alternately in anti-orientation fashion, two 25,27-bis(1-pro-pyloxy) groups attached on the two lower rims of calix[4]arene, and crown-6 chain attached on the other set of lower rims of calix[4]arene offers a big cavity inside a molecule which might possess a potential for forming host-guest complexes. The molecular packing is accomplished by van der Waals forces.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.232-243
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• 2010

Gas hydrates are crystalline solids composed of water and gas molecules. Water molecules are linked through hydrogen bonding and create cavities(host lattice) that can capture a large variety of guest molecules under appropriate conditions, generally high pressure and low temperature. Recently, many researchers try to apply gas hydrates to industrial processes to capture greenhouse gases due to the facts that the process is eco-friendly and target gas molecules can be preferentially captured. In this paper, we introduced recent studies on $CO_2$ and $CO_2-N_2$ mixture hydrates to evaluate the feasibility of industrial application of gas hydrate technology to $CO_2$ capture process. Specifically, we put emphasis on the technical feasibility of $CO_2$ separation in steel industry using gas hydrate formation principles.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1549-1552
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• 2006

We report a new series of blue dopants composed of both electron donating and electron accepting moieties in one molecule, based on nalidixic acid. The EL device derived from the dopant exhibits pure blue light emission (0.15, 0.14) The current efficiency is estimated to be 3.88 cd/A at 100 $cd/m^2$, which shows remarkable enhancement, compared to that of the host itself (2.5 cd/A at 100 $cd/m^2$) under the same conditions. These results demonstrate that the incorporation of a proper guest into the host in a guest-host doped system improves not only the purity of the fluorescent blue emission but also elevates its quantum efficiency, thus improving the OLED performance.