Yasuaki Kikuchi

Energy density analysis of cluster size dependence of surface-molecule interactions (II): Formate adsorption onto a Cu(111) surface

Adsorption of formate (HCOO) onto a Cu(111) surface has been treated theoretically using 18 kinds of Cun (6 ≤ n ≤ 56) clusters. The energy density analysis (EDA) proposed by Nakai has been adopted to examine surface–molecule interactions for different cluster sizes. EDA results for the largest model cluster Cu56 have shown that the adsorption‐induced energy density variation in Cu atoms decays with distance from the adsorption site. Analysis of this decay, which can be carried out using the EDA technique, is important because it enables verification of the reliability of the model cluster used. In the case of formate adsorption onto the Cu(111) surface, it is found that at least a four‐layer model cluster is necessary to treat the surface–molecule interaction with chemical accuracy.

Predominant hosting lead(II) in ternary mixtures of heavy metal ions by a novel of diethylaminomethyl-calix[4]resorcinarene

Heavy metal ions from single and ternary systems of Pb(II), Cu(II), and Ni(II) adsorbed by calix[4]resorcinarenes in water–chloroform extraction were studied. Comparison was made of calix[4]resorcinarenes, 2,8,14,20-tetraundecyl calix[4]resorcinarene-4,6,10,12,16,18,22,24-octol, and diethylaminomethyl-calix[4]resorcinarene, 5,11,17,23-tetra(diethylaminomethyl)-2,8,14,20- tetraundecylcalix[4]resorcinarene-4,6,10,12,16,18,22,24-octol, for predominant extraction of their ions from the ternary mixture of aqueous solution at different pH in a water layer. The hosting of Pb(II) by the diethylaminomethyl-calix[4]resorcinarene occurred efficiently at pH 6–7. The hosting of Pb(II), Cu(II), and Ni(II) ions for the ternary aqueous mixture was applied to the Langmuir isotherm. Adsorption was studied using nuclear magnetic resonance spectroscopy in a water–deuterium chloroform extraction system. Results showed that as the heavy metal ions were included into the host cavity, the observation of shifted peaks of water molecules from downfield to higher field was visible in the nuclear magnetic resonance spectra, meaning that water molecules were included with heavy metal ion into the host cavity. The spectra also showed that the diethylamino group expressed formation of the coordination complex between the diethylaminomethyl-calix[4]resorcinarene and Pb(II) for the purpose of predominant hosting of Pb(II).

Interaction of achiral host and guest in a chiral solvent as studied by circular dichroism spectroscopy. Complexation of esters and ethers with calix[4]resorcarene in limonene

Abstract When dissolved in limonene as a chiral hydrocarbon solvent, calix[4]resorcarene exhibits induced circular dichroism (CD). The CD intensities become weaker in the presence of increasing amounts of an ester or ether as a guest. This is due to the formation of an achiral host-guest complex, which competes with the chiral host-solvent interaction. Analysis of the CD data allowed characterization of the host-guest complexes in terms of binding constants and stoichiometries. The major driving force of the complexation is host-guest hydrogen-bonding. Dimethyl dicarboxylates and diac-etoxyalkanes form expectedly more stable complexes than the corresponding monoesters; diesters are capable of multiple host-guest hydogen-bonding. The affinities of monoesters are remarkably dependent on the chain-lengths of the alkyl moieties; this provides further evidence for the importance of guest-host CH-π or van der Waals interactions. Diesters having an appropriate chain-length exhibit a 2:1 (host to guest) stoichiom...

Molecular imprinting membrane having calix[4]resorcarenes moieties for selective separation of α-tocopherol

A novel type of molecular imprinted membrane was prepared from the complexation solution of α-tocopherol (α-Toc) template and calix[4]resorcarenes host with PSf as scaffold polymer by phase inversion technique. The adsorption properties were tunable by slight modification of the calix[4]resorcarenes unit, whereby the recognition of the α-tocopherol towards its analogues by permselective experiments was achieved.

Bond energy analysis revisited and designed toward a rigorous methodology

The present study theoretically revisits and numerically assesses two-body energy decomposition schemes including a newly proposed one. The new decomposition scheme is designed to make the equilibrium bond distance equivalent with the minimum point of bond energies. Although the other decomposition schemes generally predict the wrong order of the C-C bond strengths of C(2)H(2), C(2)H(4), and C(2)H(6), the new decomposition scheme is capable of reproducing the C-C bond strengths. Numerical assessment on a training set of molecules demonstrates that the present scheme exhibits a stronger correlation with bond dissociation energies than the other decomposition schemes do, which suggests that the new decomposition scheme is a reliable and powerful analysis methodology.

Ionic Imprinting Polymers Using Diallylaminomethyl-Calix[4] Resorcinarene Host for the Recognition of Pb (II) Ions

A novel ion-imprinted microspheres of copolymerized diallylaminomethyl-calix [4] resorcinarene and divinylbenzene were prepared through precipitation polymerization. These microspheres were used for the adsorption experiments of Pb (II) ions mixture solution containing Pb (II), Ni (II) and Cu (II). The selective complexion towards Pb (II) ions was examined. The adsorption was conducted in batches by investigating the effects of pH and initial concentration of a heavy metal solution. The adsorption of Pb (II) metal ions on the adsorbents had the optimum pH rating in region of 6. For single ion system, the imprinted polymer showed that the adsorption capacity of Pb (II) metal ions was 64 mg/g, while for Cu (II and Ni (II) were 24 mg/g and 8 mg/g, respectively. Competitive extraction experiments in the presence of Cu (II) and Ni (II) ions were also carried out and high selectivity of the imprinted polymer adsorbents towards Pb (II) over Cu (II) and Ni (II) was found. In ternary mixture of heavy metal ions, the imprinted polymer showed effective adsorption to Pb (II) obeying Langmuir isotherm. The outstanding adsorption abilities for Pb (II) metal ion have exhibited good prospects for disposal application of polluted water and environmental protection.