bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glycosylation of 4,7,8,9-Tetra-O-acetyl-2-deoxy-2β,3β-epoxy-N-acetylneuraminic Acid Methyl Ester
Authors: Okamoto Kaoru , Kondo Tadao , Goto Toshio 
Published: July 2006

Abstract
Reaction of the 2β,3β-epoxyneuraminic acid derivative prepared from 2,3-dehydroneuraminic acid derivative with primary or secondary alcohol gave the corresponding glycoside(s) or ortho ester.
Optical Resolution by Preferential Crystallization of 1,1,3,3-Tetramethylbutylammonium Salt of N-Formyl-Dl-α-phenylglycine
Authors: Shiraiwa Tadashi , Miyazaki Hideya , Imai Tomoki , Sunami Michio , Kurokawa Hidemoto 
Published: July 2006

Abstract
Infrared spectrum, solubility, and ternary phase diagram of solubility indicated that 1,1,3,3-tetramethylbutylammonium salt (Dl-TMB salt) of N-formyl-Dl-α-phenylglycine is a conglomerate. In order to resolve Dl-TMB salt efficiently, crystallization of d- and l-TMB salts was examined by free energy of critical nucleation in supersaturated solutions. Successive preferential crystallization of Dl-TMB salt was experimented at 10 °C for racemic solution in ethanol with the degree of supersaturation of 130%, and d- and l-α-phenylglycine with 100% optical purity were obtained from pure d- and l-TMB salts.
A Highly Stereoselective Synthesis of (E)-Enol Lactones by the Wittig Reaction of Cyclic Anhydrides with (α-Alkoxycarbonylethylidene)triphenylphosphorane
Authors: Tsuboi Sadao , Fukumoto Hirohumi , Wada Hiroshi , Takeda Akira , Fukuyama Keiichi 
Published: July 2006

Abstract
Reactions of glutaric anhydride and methyl- or phenyl-substituted ones with (α-alkoxycarbonylethylidene)triphenylphosphorane (2a, ethoxy; 2b, t-butoxy) gave the corresponding 6-alkoxycarbonyl-5-hepten-5-olides (3) and 6-alkoxycarbonyl-4-hepten-5-olides in good yields. The reaction proceeded highly stereoselectively to give (E)-3. The stereochemistry of 3 was determined by an X-ray crystallographic analysis. The reaction of adipic anhydride with 2a afforded 7-ethoxycarbonyl-5-octen-6-olide, 7-ethoxycarbonyl-5,6-octadienoic acid, and (4E, 6E)-7-ethoxycarbonyl-4,6-octadienoic acid. A treatment of nonanedioic anhydride with 2a gave 10-ethoxycarbonyl-8,9-undecadienoic acid, (7E,9E)-10-ethoxycarbonyl-7,9-undecadienoic acid, and diethyl 2-methyl-2,4-undecadienedioate in low yields.
Syntheses of 2′,3′-Dideoxykanamycin A, 2′,3′-Dideoxyamikacin and Related Substances
Authors: Kobayashi Yoshihiko , Tsuchiya Tsutomu , Umezawa Sumio , Yoneta Toshio , Fukatsu Shunzo , Umezawa Hamao 
Published: July 2006

Abstract
2′,3′-Dideoxykanamycin A has been prepared via two ways. 2″-O-Acetyl-4″,6″-O-benzylidene-6′-N,4′-O-carbonyl-1,3,3″-tri-N-tosylkanamycin A was converted to a 2′,3′-unsaturated compound by a modified Tipson and Cohen method. Hydrogenation followed by deblocking gave 2′,3′-dideoxykanamycin A (12). Another route for 12 was through 2′,3′-anhydro-4′,2″,4″,6″-tetra-O-benzoyl-2′-epi-1,3,6′,3″-tetrakis(N-ethoxycarbonyl)kanamycin A (16). Epoxide-ring opening of 16 with hydrogen iodide gave the 3′,2′-iodohydrin, which, after 2′-O-mesylation, led to the 2′,3′-unsaturated compound (19). Deblocking and hydrogenation of 19 gave 12. 2′,3′-Dideoxykanamycin A thus synthesized was led to 2′,3′-dideoxyamikacin and other related compounds by amino protection of 12 other than the 1-amino group by zinc acetate–ethyl trifluoroacetate method followed by 1-N-acyl or 1-urethane formation with appropriate reagents. Their antibacterial activities were described.
Synthesis of Imido-Substituted 3,8-Diphenyl-1,2-diazacycloocta-2,4,6,8-tetraenes and Their Thermolysis
Authors: Yogi Seiichi , Hokama Kozo , Takayoshi Sadamori , Tsuge Otohiko 
Published: July 2006

Abstract
Nucleophilic substitution of 4,7-dichloro-3,8-diphenyl-1,2-diazocine with succinimide, phthalimide, N-methyl-p-toluenesulfonamide, and o-benzosulfimide, in the presence of silver oxide, gave the corresponding 4-mono(imido)- and 4,7-di(imido)-1,2-diazocines. 4-Acetoxy-7-phthalimido- and 4-phenylthio-7-phthalimido-1,2-diazocine were also prepared. Thermolysis of the mono(imido)-1,2-diazocines in xylene under reflux afforded the corresponding di(imido)-1,2-diazocine and/or five pyridine derivatives, whose relative yields depended upon the nature of imido substitutents in the diazocines. However, 4,7-di(imido)-1,2-diazocines did not decompose in xylene under reflux. Thermolysis of 4,7-bis(phthalimido)-1,2-diazocine at 300–310 °C gave 3,6-bis(phthalimido)-2-phenylpyridine with the extrusion of benzonitrile. In the thermolysis of the acetoxy(230–240 °C) or phenylthio-substituted 1,2-diazocine (240–260 °C), 6-acetoxy- and 6-benzoyl-3-phthalimido-2-phenylpyridine, or 6(and 3)-phenylthio-3(and 6)-phthalimido-2-phenylpyridines were isolated together with benzonitrile, respectively. The feature of thermolysis was also discussed.
In Situ Generation and Synthetic Application of 2-Phenylbenzimidazoline to the Selective Reduction of Carbon–Carbon Double Bonds of Electron-Deficient Olefins
Authors: Chikashita Hidenori , Nishida Shuichi , Miyazaki Makoto , Morita Yasuhiro , Itoh Kazuyoshi 
Published: July 2006

Abstract
2-Phenylbenzimidazoline (PBI) as a mild, selective, and convenient reducing agent was efficiently generated in situ from o-phenylenediamine and benzaldehyde in alcohols. A generally applicable method for the selective reduction of carbon–carbon double bonds of a variety of electron-deficient olefins with an alcoholic solution of PBI is described. The reduction of α,β-unsaturated ketones to the corresponding saturated ketones could also be accomplished (but, less effectively) with PBI with the aid of a Lewis-acid catalyst. 1-Methyl-2-(o-nitrophenyl)benzimidazoline prepared and isolated by the reaction of o-nitrobenzaldehyde with N-methyl-o-phenylenediamine reduced benzylidenemalononitrile to give benzylmalononitrile and 1-methyl-2-(o-nitrophenyl)benzimidazole in high yields. This shows the validity of PBI to be the actual reducing species in the present reduction system. From a mechanistic study, the present reductions could be interpreted in terms of a mechanism involving a synchronous transport of a pair of hydrogens or a sequential transfer of a hydride and a proton from PBI to the olefins.
On a Solid-State ECD, WO3/Solid Electrolyte/Metal
Authors: Kuwabara Katsumi , Ichikawa Shoichi , Sugiyama Kohzo 
Published: July 2006

Abstract
Electrochromic display (ECD) was investigated using WO3 as the electrochromic material and metals as the counter electrode. WO3 was vacuum-evaporated on a glass substrate coated with indium tin oxide. A film of solid electrolyte, Sn(HPO4)2·H2O, was prepared by means of the spray method on the thin film of WO3. ECDs with metal electrodes were examined from the points of view of the change in optical density, the current-wave forms, and the response speeds in coloring and bleaching processes. ECD cells with noble metals indicated comparatively high optical density changes on coloration at a constant-voltage operation. The cell with Ag showed a high coloration speed compared with the cells containing graphite and other metals.
Synthesis of Sulfoxide-Modified Cellulose Derivatives Designed for the Permselective Membrane of Sulfur Dioxide
Authors: Imai Kiyokazu , Tezuka Yasuyuki , Shiomi Tomoo , Takada Matsunori 
Published: July 2006

Abstract
The Michael type addition reaction of cellulose with a series of vinyl sulfoxides, namely methyl vinyl sulfoxide, ethyl vinyl sulfoxide, t-butyl vinyl sulfoxide, and phenyl vinyl sulfoxide, was performed with NaOH as a catalyst to produce 2-(alkyl- or arylsulfinyl)ethyl cellulose derivatives. The high permselectivity of sulfur dioxide against nitrogen and oxygen was achieved through these sulfoxide modified cellulose membranes.
Self Regulation in the Cooperative Binding of Small Molecules to Linear Polymers
Authors: Sano Takayuki , Nakatsuka Thoru , Tsuruta Hirotsugu , Harada Shoji 
Published: July 2006

Abstract
As for the cooperative binding of small molecules to the linear polymers, including not only synthetic polymers but also biopolymers, an interesting relationship, the so called “self regulation effect” between the isolated binding constant (intrinsic binding constant) and the cooperative binding constant, (binding constant of growth process) can be observed amongst the large amount of data so far reported. The biological significances as well as the possible origin for this “self regulation mechanism” will be discussed.
Potentiometric Study of Heteropolyanion Formation from Telluric Acid and Molybdate Anion in 1M Na(Cl)
Authors: Yagasaki Atsushi , Sasaki Yukiyoshi 
Published: July 2006

Abstract
The equilibria in the H+–MoO42−–Te(OH)6 system in aqueous solutions were studied potentiometrically at 25.0 °C. The data were expained by (6,6,1), (7,6,1), and (8,6,1) with formation constants logβ6,6,1=50.40±0.02,logβ7,6,1=53.68±0.07andlogβ8,6,1=55.47±0.07.
Synthesis of (1-Halo-1-alkenyl)trimethylsilanes via gem-Trimethylsilylation of Vinyl Halides
Authors: Shimizu Nobujiro , Shibata Fumihiro , Tsuno Yuho 
Published: July 2006

Abstract
Various vinyl halides including enol silyl ethers of α-halo ketones and esters give the corresponding (1-halo-1-alkenyl)trimethylsilanes in fair to good yields on treatment with lithium diisopropylamide at Dry Ice temperature in the presence of chlorotrimethylsilane.
Electrochemical Studies of Poly(mercaptohydroquinone) and Poly(mercapto-p-benzoquinone) Films Prepared by Electropolymerization. I. Preparation of pH Microsensor and Its Fundamental Characteristics
Authors: Arai Gorou , Koike Takashi , Yasumori Iwao 
Published: July 2006

Abstract
Carbon fibers were electrochemically modified with poly(mercaptohydroquinones). These modified carbon fiber electrodes showed excellent Nernstian response to pH from ca. 2 to 10 and could respond within 2s in the pH range from 3 to 8. These electrodes could work well one month after kept stored in a weak acidic buffer solution and could be easily restored by electroreduction even after their functions had been lowered by successive pH measurements.
Reactions of α,β-Unsaturated Carboxylates, Malonates and Phenylacetates with Manganese(III) Acetate in the Presence of Chloride Ions
Authors: Yonemura Hiroshi , Nishino Hiroshi , Kurosawa Kazu 
Published: July 2006

Abstract
The reaction of alkyl (E)-3-phenylpropenoates with manganese(III) acetate in the presence of Cl− ions gave alkyl (Z)-2-chloro-3-phenylpropenoates and alkyl 2,3-dichloro-3-phenylpropanoates. Ethyl (E)-2,3-diphenylpropenoate yielded ethyl 2,3-dichloro-2,3-diphenylpropanoate. Alkyl 3,3-diphenylpropenoates gave mainly alkyl 2-chloro-3,3-diphenyl-propenoates. Ethyl 1-cyclohexenecarboxylate gave ethyl 1,2-dichlorocyclohexanecarboxylate. Dimethyl malonate yielded dimethyl dichloromalonate and tetramethyl 1,2-dichloro-1,1,2,2-ethanetetracarboxylate. Substituted malonates resulted in α-chloro derivatives. Methyl phenylacetates gave α-acetoxy derivatives.
Reaction of Dimethyl 1-Hydroxyalkylphosphonates with Some Chlorides
Authors: Yamashita Mitsuji , Morizane Takashi , Fujita Keiji , Nakatani Kaname , Inokawa Saburo 
Published: July 2006

Abstract
The reactions of dimethyl 1-hydroxycycloalkylphosphonates having a five- to seven-membered ring with sulfuryl chloride and phosphorus pentachloride afforded olefinic and/or dichloro derivatives of phosphonates. The mechanism of the formation of new dichloro derivatives and the reactions of dimethyl 1-methylethylphosphonate with sulfuryl chloride and phosphorus pentachloride were also investigated.
Deacylation Effect in the Hydrolysis of p-Nitrophenyl Esters by Bifunctional Comicelles Containing Imidazolyl and Hydroxyl Groups
Authors: Ihara Yasuji , Nango Mamoru , Koga Joichi 
Published: July 2006

Abstract
The rate constants for hydrolysis of p-nitrophenyl acetate, hexanoate, and dodecanoate catalyzed by bifunctional catalysts containing the imidazolyl and hydroxyl groups have been determined in the presence of hexadecyltrimethylammonium bromide micelles at 25 °C. The kinetic analysis suggests a nucleophilic mechanism which involves acylation followed by deacylation at the imidazolyl group. Although no appreciable differences in cooperative catalytic efficiencies are observed between the bifunctional groups in the acylation step, it is found that the deacylation rates are accelerated by the hydroxyl group of the catalyst in the presence of micelles.
Optical Resolution of (±)-Phenylsuccinic Acid by Using (−)-Proline as Resolving Agent
Authors: Shiraiwa Tadashi , Sado Yujin , Fujii Shigeru , Nakamura Mitsuhiro , Kurokawa Hidemoto 
Published: July 2006

Abstract
A solution of equimolar mixture of (±)-phenylsuccinic acid ((±)-PSA) and (−)-proline ((−)-Pro) in ethanol or its suspension in 2-propanol selectively gave a salt composed of 1-molar amount of PSA and 2-molar amount of (−)-Pro. The salt purified gave (+)-PSA with an optical purity of about 100%. A salt composed of equimolar amounts of PSA and (−)-Pro was obtained from the ethanolic mother liquor, and gave (−)-PSA with an optical purity of 98%.
A Michael Addition-Induced Favorskii Rearrangement
Authors: Tsuboi Sadao , Nagae Hiroyuki , Yamato Hirofumi , Takeda Akira 
Published: July 2006

Abstract
Reaction of 6-chloro-2-vinylidenecyclohexanone with sodium methoxide gave methyl 2-vinylidene-1-cyclopentanecarboxylate and methyl trans-2-(1-methoxyalkyl)-1-cyclopentanecarboxylate along with 6-methoxy-2-vinylidenecyclohexanone via a Michael addition-induced Favorskii rearrangement.
Effects of Surfactants and Surface Treatment on Aqueous Dispersion of Silicon Carbide
Authors: Meguro Kenjiro , Ushida Takahisa , Hiraoka Tetsuya , Esumi Kunio 
Published: July 2006

Abstract
The effects of the addition of surfactants and of the surface treatment upon the aqueous dispersion of silicon carbide were examined. In the case of β-SiC, the addition of nonionic surfactants having relatively longer lengths of hydrocarbon and oxyethylene chain to the β-SiC treated with a silane coupling agent enhanced the dispersion stability. On the other hand, the lack of a difference for the dispersion stability was observed between a silane coupling treated α-SiC and an untreated one by the addition of surfactants. These differences in the surface property of two kinds of SiC were confirmed by measuring the zeta potential and the heat of immersion in water.
Band Shape of Photoelectron Spectrum and Potential Energy Curve for Alkylamine
Authors: Takahashi Masao , Watanabe Iwao , Ikeda Shigero 
Published: July 2006

Abstract
Accurate measurements of UPS and ab initio potential energy calculations have been carried out for ammonia and several alkylamines to interpret the band shape of the UPS. Theoretical photoelectron band shape was obtained by a simple Franck–Condon approach. The calculation predicted very well the alkyl substitution effects on the ionization potentials and on the band widths of the first bands in UPS for the alkylamines. The following conclusions were obtained by comparing these theoretical photoelectron bands with experimental ones. The threshold ionization potential observed in the UPS is not always thermodynamically adiabatic ionization energy, but it can be subject to hot bands. Adiabatic ionization potential IPa of ammonia is concluded to be 10.08 eV. And the values of IPa for a series of alkylamines are evaluated by taking account of molecular vibrational frequency for the neutral state.
Use of Monoclonal Antibodies in the Study of the Conformation and Conformational Alterations in Proteins
Authors: Katchalski-Katzir Ephraim , Kenett Dan 
Published: July 2006

Abstract
The conformational flexibility of many of the native proteins facilitates their attainment of new reversible three-dimensional structures under well-specified conditions. Such structures appear to be of great importance in biological processes involving biologically active proteins, such as enzymes, receptors or protein hormones. Recently it was shown that the above conformational alterations can be followed not only by physicochemical methods but also immunochemically by the use of monoclonal antibodies (mAbs). mAbs are specific proteins, each capable of recognizing a corresponding well-characterized region (epitope) on the surface of a protein antigen. They are thus useful as tools in the study of the structure and properties of protein surfaces. Of particular interest is the fact that it is possible to prepare mAbs with predetermined specificities towards the different epitopes of a given protein. Such mAbs can thus be used to detect conformational alterations occurring at the different segments of a protein antigen. In the present review article we describe our own work and that of others on the use of mAbs as probes to detect the conformation and conformational alterations occurring in proteins exposed to different conditions, such as heat, adsorption onto solid surfaces, interaction with ligands and protein–protein interaction. The use of mAbs in the detection of protein folding intermediates is also described.
Design of Novel Mesomorphic Compounds: N,N′,N″-Trialkyl-1,3,5-benzenetricarboxamides
Authors: Matsunaga Yoshio , Miyajima Nobuhiko , Nakayasu Yuichi , Sakai Satoshi , Yonenaga Michihiro 
Published: July 2006

Abstract
N,N′-Dialkyl-1,4-benzenedicarboxamides melt with anomalously small enthalpy changes. The 1,3-analogs behave similarly but at lower temperatures. These observations provide a clue to design novel mesomorphic compounds; N,N′,N″-trialkyl-1,3,5-benzenetricarboxamides. The compounds carrying pentyl to octadecyl groups melt at temperatures between 49 and 119 °C depending upon the alkyl chain length. The clearing points are located above 200 °C. The unoriented liquid crystals show X-ray diffraction patterns consisting of two major peaks. The inner sharp peak gives a spacing, which increases as the series is ascended, from 1.40 to 2.26 nm. The outer one is sharp in the pentyl and hexyl derivatives but diffuse in the higher homologous members. The second moments of the broad-line proton NMR spectra measured above the melting points are as small as a few hundredths G2 and firmly establish the liquid-like characteristics of the alkyl chains.
A Twin-TCNQ-Type Acceptor. Synthesis of 11,11,12,12,13,13,14,14-Octacyano-1,4:5,8-anthradiquinotetramethane and Structures of the Tetraethylammonium Salts of Its Mono- and Dianion
Authors: Mitsuhashi Tsutomu , Goto Midori , Honda Kazumasa , Maruyama Yusei , Inabe Tamotsu , Sugawara Tadashi , Watanabe Tokuko 
Published: July 2006

Abstract
The title compound (OCNAQ) was synthesized. Treatment of 1,2,3,4,5,6,7,8-octahydroanthracene with N-bromosuccinimide (NBS) under irradiation using a 100-W light bulb in refluxing CCl4 followed by dicyanomethylation with excess of NaCH(CN)2 in Me2SO gave an isomeric mixture of 1,4,5,8-tetrakis(dicyanomethyl) derivatives. The mixture was subjected by repetition of the successive bromination-dehydrobromination procedure giving OCNAQ in 20% overall yield. The cyclic voltammogram of OCNAQ exhibits four redox waves (E1⁄21 0.26, E1⁄22 0.05, E1⁄23 −0.44, and E1⁄24 −0.53 V vs. SCE in MeCN), indicating that OCNAQ is a stronger acceptor than tetracyanoquinodimethane (TCNQ, E1⁄21 0.17 V vs. SCE). Both 1:1 and 2:1 salts, (Et4N)(OCNAQ) and (Et4N)2(OCNAQ), were obtained from reactions of Et4NI with potassium and lithium salts of OCNAQ, respectively. The X-ray crystal analyses of these salts indicate that the TCNQ moieties are boat-shaped bent to opposite directions. With the 1:1 salt, which behaves as a semiconductor (4×10−4Ω−1 cm−1 at room temperature, Ea 0.22 eV), the OCNAQ molecules are arrayed in the segregated stacking mode, while the 2:1 salt (10−4Ω−1 cm−1) has no columnar structure of the OCNAQ molecules.
Convenient Synthesis of N-Protected Amino Acid Amides
Authors: Nozaki Sukekatsu , Muramatsu Ichiro 
Published: July 2006

Abstract
Boc- or Z-amino acids were conveniently amidated at room temperature by a one-pot procedure employing ammonium hydrogencarbonate and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline in yields of 81–96%. The benzyl ester-type protector for the side chains of aspartic acid and glutamic acid was not affected by the procedure.
A Convenient Synthesis of Spironorcamphors
Authors: Hori Kimihiko , Takaishi Naotake , Inamoto Yoshiaki 
Published: July 2006

Abstract
The effects of the base, molar ratio of the reagent, solvent and reaction temperature on the cycloalkylation of norcamphor with 1,4-dibromobutane were explored, and optimum conditions for the preparation of spiro[bicyclo[2.2.1]heptane-2,1′-cyclopentan]-3-one have been established. 3-exo-(4-Bromobutyl)norcamphor was isolated and characterized as a reaction intermediate. A series of spironorcamphors with various ring sizes were obtained in good yields using a 1:1.5:2.5 ratio of norcamphor/α,ω-dibromoalkanes /NaNH2 in Et2O.
13C NMR Spectra and Anomerization of cis- and trans-5-Arylamino-3-isopropyl-1,2,4-trioxanes
Authors: Yamamoto Hiroshi , Hirayama Masatoshi , Akutagawa Masamoto , Nishio Takehiko , Kashima Choji , Omote Yoshimori 
Published: July 2006

Abstract
The cis and trans isomers of 3-isopropyl-6,6-dimethyl-5-arylamino-1,2,4-trioxanes have been clearly identified and the anomerization of arylaminotrioxanes has been detected by the 13C NMR spectra in chloroform-d.
Halogenation Using Quaternary Ammonium Polyhalides. XI. Bromination of Acetanilides by Use of Tetraalkylammonium Polyhalides
Authors: Kajigaeshi Shoji , Kakinami Takaaki , Yamasaki Hiromichi , Fujisaki Shizuo , Okamoto Tsuyoshi 
Published: July 2006

Abstract
The reaction of acetanilides with tetraalkylammonium polyhalides, such as tetrabutylammonium tribromide, benzyltrimethylammonium tribromide, and benzyltrimethylammonium chlorobromate(1–), in dichloromethane-methanol at room temperature gave bromosubstituted acetanilides in good yields, respectively.
Hydrostannation and Hydrogermylation of Allenes
Authors: Ichinose Yoshifumi , Oshima Koichiro , Utimoto Kiitiro 
Published: July 2006

Abstract
Treatment of allenes with Ph3SnH or Ph3GeH in the presence of Pd(PPh3)4 catalyst provides the corresponding allylic stannanes or allylic germanes in good yields. Et3B induced radical addition of Ph3SnH or Ph3GeH to allenes are also described.
A Conductance Study of 1 : 1 Complexes of 1,2-Bis[2-(2-methoxyethoxy)ethoxy]benzene (Noncyclic Polyether) with Alkali Metal Ions in Nonaqueous Solvents
Authors: Takeda Yasuyuki , Sakamoto Shinichi , Ohashi Naohiko , Fukada Naoaki 
Published: July 2006

Abstract
Conductivities of alkali metal salts in the presence of 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (AC·B18C6), which is a linear counterpart of benzo-18-crown-6 (B18C6), were measured at 25 °C in acetonitrile, propylene carbonate, and methanol. Formation constants and limiting ionic molar conductivities of the 1 : 1 AC·B18C6–alkali metal ion complexes were determined. Selectivity of AC·B18C6 for alkali metal ions is lower than that of B18C6. The selectivity order of AC·B18C6 for K+, Rb+, and Cs+ is consistent entirely with that of B18C6 (K+&gt;Rb+&gt;Cs+), but the selectivity order of AC·B18C6 for Na+ differs from that of B18C6. The AC·B18C6–alkali metal ion complex is less stable than the corresponding B18C6 complex. The AC·B18C6 complex may be entropy-destabilized due to the two flexible arms. The AC·B18C6–alkali metal ion complex is more mobile than the corresponding B18C6 complex; the mobility of the AC·B18C6 complex is less sensitive to a variety of the alkali metal ions in the complexes than that of the B18C6 complex. This indicates that the alkali metal ion in the AC·B18C6 complex is coordinated with the two arms and the surface charge of the alkali metal ion in the AC·B18C6 complex is more effectively shielded than that in the B18C6 complex.