bluuebunny/crossref_metadata_2025_split huggingface dataset:
ESR Studies on Irreversible Reactions of Poly(methyl methacrylate) Radicals and on Structures of Stable Polymer Radicals in the Frozen State
Authors: Sugiyama Yoshio 
Published: February 2006

Abstract
Irreversible reactions of poly(methyl methacrylate) radicals generated from the polymerization of methyl methacrylate (MMA) and structures of the produced stable polymer radicals in the frozen state have been investigated by Electron Spin Resonance (ESR). The stable polymer radicals were produced through disproportionation and addition reactions of poly(MMA) radicals. The structure of stable polymer radicals was also determined by the simulation of the ESR spectrum.
Extractive Separation of Selenium and Tellurium Using 2,3,5-Triphenyltetrazolium Chloride
Authors: Ramesh A , Subramanian M S 
Published: February 2006

Abstract
A simple and selective solvent-extraction method has been devised for the separation of SeIV and TeIV, not only from each other, but also from the other accompanying elements. 2,3,5-Triphenyltetrazolium chloride has been used as an extractant for the quantitative extraction of TeIV and SeIV from bromide and thiocyanate medium, respectively. The formed ion-pair complex of TeIV and SeIV can be quantitatively extracted into a dichloromethane and 1 : 1 cyclohexanol–toluene solvent mixture, respectively. The optimum conditions have been evaluated based on a critical study of the acid concentration, extractant concentration, period of equilibration, effect of dilution and effect of the solvent. Water was used for the stripping of tellurium, while a fresh solution of sodium hypobromite was used for selenium. This separation procedure in conjunction with the developed methods was applied to an analysis of the selenium and tellurium content of copper concentrate, incineration ash and In–Sb alloy samples.
Aggregation Effects on Electrochemical and Spectroelectrochemical Properties of [2,3,9,10,16,17,23,24-Octa(3,3-dimethyl-1-butynyl)phthalocyaninato]cobalt(II) Complex
Authors: Isago Hiroaki , Leznoff Clifford C , Ryan Matthew F , Metcalfe Robert A , Davids Rifka , Lever A B P 
Published: February 2006

Abstract
The title complex, [Co(odmbpc)], which is a single isomer and is highly soluble in common organic solvents, has been prepared and investigated electrochemically and spectroelectrochemically in dichloromethane solutions. The cyclic voltammograms of this complex at a concentration of ca. 6 × 10−5 mol dm−3 exhibited two reversible reduction waves at E1/2 = −0.67 V (vs. ferrocenium+/ ferrocene) and −1.74 V, which were attributed to cobalt-centered and triple-bond-centered (in a peripheral substituent) reductions, respectively, and three quasi-reversible oxidation waves at 0.26, 0.46, and 0.74 V, the former two and the latter one of which were attributed to phthalocyanine-chromophore-centered and cobalt-centered oxidations, respectively. Some of these assignments were supported by the electronic absorption spectra of the electro-generated species. The first reduction wave was not observed at 6 × 10−4 mol dm−3 until the applied potential was swept to the second reduction wave. Nevertheless, under the same conditions, the controlled-potential electrolyses in an optically transparent thin-layer electrode at potentials around the first reduction wave gave rise to drastic spectral changes without any preliminary electrolysis at potentials around the second reduction wave. Such strange phenomena are discussed in terms of molecular aggregation of the complexes in solutions. The peripheral alkynyl group has been found to be slightly electron-donating.
Preparation and Properties of S-Bridged CoIIIAgI3CoIII Pentanuclear Complexes Having a Triple Helical Chirality. Crystal Structure of [Ag3{Co(aet)3}2](BF4)3 (aet = 2-Aminoethanethiolate)
Authors: Konno Takumi , Tokuda Keiji , Suzuki Tomoya , Okamoto Ken-ichi 
Published: February 2006

Abstract
Novel S-bridged CoIIIAgI3CoIII pentanuclear complexes, [Ag3{Co(aet)3}2]3+ (1) and [Ag3{Co(l-cys-N,S)3}2]3− (2), were prepared by reacting fac(S)-[Co(aet)3] (aet = 2-aminoethanethiolate) or ΔLll-fac(S)-[Co(l-cys-N,S)3]3− (l-cys = l-cysteinate) with Ag+ in a ratio of 2 : 3. The crystal structure of 1(BF4)3 was determined by X-ray crystallography. 1(BF4)3·H2O, chemical formula C12H38B3N6OF12S6Co2Ag3, crystallizes in the orthorhombic space group Pnma with a = 16.397(2), b = 13.239(2), c = 15.803(4) Å, V = 3430.5(9) Å3, Z = 4, and R = 0.066. In 1 the two thiolato S atoms from two octahedral fac(S)-[Co(aet)3] units coordinate to each of three Ag atoms, such that the three S–Ag–S linkages form a triple helical structure. 1 gave only racemic isomer, ΔΔ and ΛΛ, which were optically resolved by cation-exchange column chromatography, while the ΔLllΔLll isomer was selectively formed for 2 with a retention of the absolute configuration of the starting ΔLll-fac(S)-[Co(l-cys-N,S)3]3−. 1 was converted to the S-bridged tricobalt(III) complex [Co{Co(aet)3}2]3+ by a reaction with I− in the presence of Co2+, accompanied by an intermolecular exchange and racemization of the Δ/Λ-fac(S)-[Co(aet)3] units. The electronic absorption and CD spectral properties of 1 and 2 are also reported.
Chromatographic Resolution of a Diastereomeric Mixture of Tris(trans-1,2-diaminocyclohexane)cobalt(III) by Bis(μ-tartrato)diantimonate(III) Anion and Association Modes Found in Their Diastereomeric Salts
Authors: Mizuta Tsutomu , Sasaki Ken-ichi , Yamane Hiromi , Miyoshi Katsuhiko , Yoneda Hayami 
Published: February 2006

Abstract
The chromatographic resolution of a diastereomeric mixture of Λ-ob3-, Δ-ob3-, Λ-lel3-, and Δ-lel3-[Co(chxn)3]3+ (chxn = trans-1,2-diaminocyclohexane) was carried out on an ion-exchange column using bis(μ-tartrato)diantimonate(III), [Sb2(d-tart)2]2− as a resolving reagent. The resulting elution order of Λ-ob3 &gt; Λ-lel3 &gt; Δ-lel3 &gt; Δ-ob3 was interpreted on the basis of an association model in which lone-pairs on three oxygen atoms of [Sb2(d-tart)2]2− form triple hydrogen bonds with three N–H groups directed along the C3-axis of [Co(chxn)3]3+. Since the three N–H groups of the Λ-ob3 isomer have a right-handed helicity, they form the strongest linear hydrogen bonds with the three lone-pairs of [Sb2(d-tart)2]2−, which are also spirally oriented in the same sense, whereas those of the two lel3 isomers having practically no such helicity form weaker hydrogen bonds, and those of the Δ-ob3 isomer having the opposite helicity have the hydrogen bonds much damaged. To obtain structural evidence for the above association model, crystal structures of diastereomeric salts, Λ-ob3-[Co(chxn)3]X[Sb2(d-tart)2]·nH2O, X− = Cl− (1) and ClO4− (2) have been determined by single-crystal analyses. The crystal data are as follows: 1 is orthorhombic, with a space group P212121, Z = 4, a = 10.823(2), b = 17.901(7), c = 21.477(6) Å, V = 4161(2) Å3, and R = 0.057; 2 is monoclinic with a space group P21, Z = 4, a = 13.338(2), b = 17.119(3), c = 18.060(3) Å, β = 98.31(1)°, V = 4080(1) Å3, and R = 0.049. In both crystals, [Sb2(d-tart)2]2− approaches Λ-ob3-[Co(chxn)3]3+ along the C3-axis of the complex to form multiple hydrogen bonds, as expected, and one of the contact modes found in 2 is close to our proposed association model.
Characteristic Behavior of an Electron-Transfer Reaction across a Tributyl Phosphate Droplet/Water Interface: Micrometer Droplet-Size Effect
Authors: Chikama Katsumi , Nakatani Kiyoharu , Kitamura Noboru 
Published: February 2006

Abstract
An electron-transfer (ET) reaction between decamethylferrocene in a single tributyl phosphate (TBP) droplet and hexacyanoferrate(III) in the surrounding water phase was investigated by laser trapping, microspectroscopic, and electrochemical techniques. The interfacial ET rate constant (kobs) was inversely proportional to the droplet radius (r) at &gt; 5 μm, but deviated from a linear relationship between kobs and r−1 at r &lt; 5 μm. The characteristic droplet-size effect was independent of the Galvani potential between the TBP and water phases. The results are discussed in terms of the physical properties of the micrometer-sized TBP droplet/water interface.
Molecular Structure of Hg-Bridged Tetramethyl[2]ferrocenophane Salt ([{C5H4(CH3)2}2Fe–Hg–Fe{C5H4(CH3)2}2]2+ (BF4−)2) and Related Salts
Authors: Watanabe Masanobu , Nagasawa Akira , Sato Masaru , Motoyama Izumi , Takayama Toshio 
Published: February 2006

Abstract
The crystal form of the salt [{C5H4(CH3)2}2Fe–Hg–Fe{C5H4(CH3)2}2Hg(BF4)2, 1], prepared by a reaction of tetramethyl[2]ferrocenophane and Hg(CN)2 in ethanol containing HBF4, is triclinic, space group , a = 9.315(3), b = 12.823(4), c = 14.108(5) Å, α = 106.055(2), β = 100.253(2), γ = 94.460(2)°, Z = 2 and the final R = 0.059 and Rw = 0.072. Two ferrocene moieties are coordinated to the Hg atom from the opposite side, and the previously proposed Fe–Hg–Fe bridged structure has been verified. The structural feature of the cation is found in the conformation of the ferrocene moiety around the Fe–Hg–Fe bond. In order to reduce the steric hindrance between the Hg and ferrocene moieties, each moiety rotates largely with respect to the other (the torsion angle of the Cpcnt–Fe(1)···Fe(2)–Cpcnt is 75(1)° and Cpcnt is defined as the centroid of the Cp-ring). The mean Fe–Hg distance is 2.598(8) Å and the Fe–Hg–Fe bond angle is 176.4(1)°. The two C5H4 rings are greatly tilted, the mean tilting angle between them being 33.72°. Analogous Hg(II) salts of ruthenocene (2) and osmocene (3) were prepared by a similar method. Crystal 2 is monoclinic, space group P21/a, a = 9.633(1), b = 18.864(3), c = 13.388(1) Å, β = 94.161(9)°, Z = 4 and the final R = 0.058 and Rw = 0.072. The mean Ru–Hg distance is 2.661(2) Å and the Ru–Hg–Ru bond angle is 174.4(1)°; the mean tilting angle between the C5H4-planes is 27.39°. The structure of the cation is very similar to that of 1 (the torsion angle of the Cpcnt–Ru(1)···Ru(2)–Cpcnt is 70(1)°).
The crystal form of 3 is triclinic, space group , a = 9.823(1), b = 11.194(1), c = 12.241(1) Å, α = 113.822(8), β = 95.828(8), γ = 90.104(8)°, Z = 2 and the final R = 0.030 and Rw = 0.032. The mean Os–Hg distance is 2.69(2) Å and the Os–Hg–Os angle is 170.1(3)°. The most interesting structural difference of 3 compared with 1, 2 is found to be the conformation of the osmocene moieties around the Os–Hg–Os bond. The two moieties are coordinated to Hg in parallel, and the torsion angle of Cpcnt–Os(1)···Os(2)–Cpcnt is negligible (2(1)°) so as to reduce the steric hindrance between the cations and the PF6− anions.
High Activities of Hydrogen Peroxide Decomposition Catalyzed by Dinuclear Schiff Base Mn(III)–Cu(II) Complexes Accompanying Metal Substitution in N,N-Dimethylformamide and the Crystal Structure of a Substituted Schiff Base Cu(II) Complex
Authors: Uehara Minori , Urade Mika , Ueda Atsuko , Sakagami Narumi , Abe Yuriko 
Published: February 2006

Abstract
The effects of divalent metal ions (M2+ = Mn2+, Co2+, Ni2+, Cu2+, and Zn2+ ions) on the catalase-like activities of mononuclear Schiff base Mn(III) complexes, such as [Mn(salen)Cl] (H2salen: N,N′ -ethylenebis(salicylideneamine)), [Mn(saltn)Cl] (H2saltn: N,N′-propane-1,3-diylbis(salicylideneamine)), [Mn(saltnOH)Cl] (H2saltnOH: N,N′-(2-hydroxypropane-1,3-diyl)bis(salicylideneamine)), and [Mn(saltnOCOPh)Cl] (H2saltnOCOPh: N,N′-(2-benzoyloxypropane-1,3-diyl)bis(salicylideneamine)), in N,N-dimethylformamide (DMF) have been reported. Except for the Cu2+ ion, H2O2 decomposition was depressed in the presence of M2+ = Mn2+, Co2+, Ni2+, and Zn2+ ions because [Mn(salen)]+reacted with M2+ to give dinuclear Mn(III)–M(II) and trinuclear Mn(III)2–M(II) complexes inactive toward H2O2 in DMF. For the Cu2+ ion, the dinuclear complexes with the salen and saltnOCOPh ligands showed high activities, although the trinuclear complexes were inactive toward H2O2. The ESR spectra suggested that the intramolecular electron transfer from Cu(II) to Mn(III) on the dinuclear Mn(III)–Cu(II) complex partly occurs to produce a dinuclear Mn(II)–Cu(III) complex active toward H2O2. During H2O2 decomposition including the radical reaction path, [Cu(salR)] (R = en, tnOCOPh) and Mn2+ were produced accompanying metal substitution by Cu2+ on the dinuclear complex. To clarify the substituted product, the preparation and an X-ray crystal structure analysis of [Cu(saltnOCOPh)] were carried out. Three independent [Cu(saltnOCOPh)] complexes (CuA, CuB, and CuC) were present along with an intermolecular π–π stacking interaction between benzene rings on the salicylidenediamine moiety and benzene ring on the benzoyloxy group in the crystal. The geometries around the coppers in both CuA and CuC are more distorted toward tetrahedral from square plane than that in CuB. No stacking interaction between benzene rings on [Cu(saltnOCOPh)] occurs in DMF solution.
Studies on the Retrogradation and Structural Properties of Waxy Corn Starch
Authors: Ogawa Kazuo , Yamazaki Isao , Yoshimura Toshiaki , Ono Shin , Rengakuji Seichi , Nakamura Yuuko , Shimasaki Choichiro 
Published: February 2006

Abstract
The protective effect of guanidine hydrochloride (Gu-HCl) on the retrogradation of waxy corn starch (WCS) gel was studied using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and solid-state 1H nuclear magnetic resonance (NMR). The areas of the endothermic peaks on DSC curves attributed to re-gelatinization of WCS gels became small and shifted to lower temperature with increasing Gu-HCl contents; finally, the endothermic peak for WCS gel containing 40% Gu-HCl disappeared, indicating that the WCS gel remained in the gelatinized state.
The solid-state 1H NMR and FT-IR spectra for retrograded WCS gels showed significant changes compared with those for gelatinized WCS gels. In the process of retrogradation, these spectral changes should imply the formation of intra- and intermolecular hydrogen bonds of WCS and the increase of free water molecules. However, the 1H NMR and FT-IR spectra for a WCS gel containing 40% Gu-HCl did not show such changes along with the progress of retrogradation. From these results, we found that the retrogradation of starch can be protected by the addition of hydrogen bond-breaking materials, such as Gu-HCl.
Thermally Irreversible Photochromic Systems. Reversible Photocyclization of 2-(1-Benzothiophen-3-yl)-3-(2 or 3-thienyl)maleimide Derivatives
Authors: Uchida Kingo , Kido Yuichi , Yamaguchi Tadatsugu , Irie Masahiro 
Published: February 2006

Abstract
Non-symmetric diarylethenes that have a 1-benzothiophene ring on one end and a 2-thienyl or 3-thienyl group on the other end of the double bond of maleimide were synthesized in order to study the effects of the substitution position of the thiophene ring on the absorption bands and the reactivities. The open-and closed-ring forms of N-cyanomethyl-2-(2,4-dimethyl-5-phenyl-3-thienyl)-3-(2-methoxy-1-benzothiophen-3-yl)maleimide showed absorption bands at 420 and 563 nm in hexane, respectively. When 3-thienyl was changed to 2-thienyl, the absorption bands of N-cyanomethyl-2-(3,4-dimethyl-5-phenyl-2-thienyl)-3-(2-methoxy-1-benzothiophen-3-yl)maleimide shifted to 448 nm (the open-ring form) and 487 nm (the closed-ring form), respectively. The cyclization and ring-opening quantum yields were also dependent on the substitution position. The cyclization yield decreased from 0.30 to 0.03 by changing the position from 3- to 2-thienyl, while the ring-opening yield increased from 0.03 to 0.13. No absorption spectral change by photoirradiation was observed for N-cyanomethyl-2,3-bis(3,4-dimethyl-5-phenyl-2-thienyl)maleimide, which has two 2-thienyl groups.
The Role of Water-Solvation in the Optical Resolution of Dl-Leucine with (S)-(−)-1-Phenylethanesulfonic Acid. Characterization and X-Ray Crystal Structures of Their Diastereomeric Salts
Authors: Yoshioka Ryuzo , Okamura Kimio , Yamada Shin-ichi , Aoe Ken-ichi , Da-te Tadamasa 
Published: February 2006

Abstract
In the optical resolution by diasteromeric salt formation of Dl-leucine with (S)-(−)-1-phenylethanesulfonic acid (PES), the less-soluble l-Leu·(−)-PES salt preferentially crystallized from acetonitrile–methanol and, in contrast, the same resolution from acetonitrile–water afforded the monohydrated d-salt [d-Leu·(−)-PES·H2O]. The role of the water of crystallization formed during this resolution system has been explored through a comparison of the crystalline characteristics of d-, monohydrated d-, and l-Leu·(−)-PES by thermoanalysis (DSC) and spectroscopy. The DSC indicated that d-Leu·(−)-PES had a polymorphic form with the water of crystallization; that is, d-Leu·(−)-PES·H2O was thoroughly dehydrated at 60—90 °C and simultaneously converted into the d-Leu·(−)-PES form. However, l-Leu·(−)-PES does not have the water of crystallization even in 75% relative humidity. Detailed comparisons among the X-ray crystal structures of three salts have revealed that in all of the salts the conformations of the PES anion and the Leu cation, respectively, were approximately the same, and their crystal structures comprised specific interaction modes having characteristic hydrogen-bond networks. In particular, in d-Leu·(−)-PES·H2O the PES and Leu ions are cross-linked to each other through water molecules. These observations suggested that the water of crystallization, together with the formation of a stable crystal-packing mode by cross-linking the PES and Leu ions, presumably plays an important role in the selective crystallization in the resolution.
Molecular Design of Highly Selective and Sensitive “Sugar Tweezers” from Boronic Acid-Appended μ-Oxo-bis[porphinatoiron(III)]s
Authors: Takeuchi Masayuki , Imada Tomoyuki , Shinkai Seiji 
Published: February 2006

Abstract
5,10,15,20-Tetrakis[3- and 4-(dihydroxyboryl)phenyl]porphinatoiron(III)s (1a and 1b, respectively) were synthesized and the saccharide-binding ability of their μ-oxo dimers was investigated. The saccharide-binding process with boronic acids can be conveniently monitored by CD spectroscopy. The μ-oxo dimer of 1b with 4-(hydroxyboryl) groups can bind glucose and galactose among monosaccharides with extremely high selectivity and sensitivity (association constants 104—105 dm3 mol−1), whereas that of 1a with 3-(hydroxyboryl) groups shows only a weak affinity with these monosaccharides. A similar trend was also observed for disaccharides. The origin of the CD activity in 2b can be ascribed to the formation of 1 : 1 μ-oxo dimer/saccharide complexes, in which two porphyrin rings are chirally bridged by one saccharide molecule. The CD sign is well-correlated with the absolute configuration of these saccharides. Thus, the present paper demonstrates that the μ-oxo dimer of 1b, which is formed in a self-assembled manner in aqueous alkaline solution, acts as an excellent pair of artificial “sugar tweezers”.
Synthesis and Physical Properties of Pyrido[1′,2′ : 1,2]imidazo[4,5-b]quinoxalines
Authors: Tomoda Haruhiko , Saito Shojiro , Araki Koji , Shiraishi Shinsaku 
Published: February 2006

Abstract
A series of 2-, 3-, or 4-substituted pyrido[1′,2′ : 1,2]imidazo[4,5-b]quinoxalines (PIQs) were synthesized in moderate-to-good yields by the reactions of 2-amino-3-chloroquinoxalines (ACQs) with substituted pyridines, and the structures were established. The reactions of ACQs with 3-phenoxycarbonyl and 3-benzoylpyridines gave the corresponding 2-substituted PIQs, while those with 3-methyl, 3-ethyl, 3-benzyl, 3-phenyl, 3-ethoxycarbonyl, and 3-acetylpyridines gave the corresponding 4-substituted PIQs. PIQ derivatives having substituents at the 2,4,8, and/or 9-positions were also studied. The spectroscopic and electrochemical properties of a series of PIQs derivatives were studied. PIQ showed a strong green fluorescence at 481.5 and 505 nm (Φ = 0.40) in ethanol. The introduction of substituents at the 3 position of PIQ altered the color of the fluorescence from blue to green without deteriorating the high quantum yield of PIQ. All of the derivatives showed strong (blue to orange) fluorescence in both solution and the solid state.
Hydrogen-Transfer Polymerization of Vinyl Monomers Derived from p-Tolylsulfonyl Isocyanate and Acrylamide Derivatives
Authors: Iwamura Takeru , Tomita Ikuyoshi , Suzuki Masato , Endo Takeshi 
Published: February 2006

Abstract
The hydrogen-transfer polymerization of N-acryloyl-N′-p-tolylsulfonylurea (1) prepared by the reaction of p-tolylsulfonyl isocyanate with acrylamide, was carried out at 80 °C for 24 h in N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile (MeCN), and toluene containing N-phenyl-2-naphthylamine (1 mol%) as a radical inhibitor using t-BuOK or 1,3-diazabicyclo[5.4.0]undec-7-ene (DBU) (3 mol%) as an initiator. Polymers obtained by t-BuOK in polar solvents were composed of the hydrogen-transfer polymerization unit selectively, while those afforded by t-BuOK in less polar solvents or by DBU were composed of both the hydrogen-transfer and the vinyl polymerization units. Although N-acryloyl-N-methyl-N′-p-tolylsulfonylurea (2) prepared by the reaction of p-tolylsulfonyl isocyanate with N-methylacrylamide, gave low molecular-weight compounds (6—8) via the generation of the sulfonyl isocyanate, N-acryloyl-N′-methyl-N′-p-tolylsulfonylurea (3) underwent the selective hydrogen-transfer polymerization.
Hydrocarbon Anions with High Stability. Part 2. Structure and Stability of Cyclopentadienide Ions with Condensed Aromatic Rings
Authors: Kinoshita Tomomi , Fujita Masaya , Kaneko Hideyuki , Takeuchi Ken’ichi , Yoshizawa Kazunari , Yamabe Tokio 
Published: February 2006

Abstract
The ionization-potential and oxidation-potential values have been examined as stability parameters in the gas and solution phase, respectively, for cyclopentadienide ions with from one to four condensed aromatic rings. They indicate that, without solvation effects, the condensed aromatic rings intrinsically stabilize the cyclopentadienide ion in solution as well as in the gas phase, and that an apparent destabilization effect by the aromatic rings in solution is most probably ascribed to a decrease in the stabilizing solvation effects due to charge delocalization on the carbanions. Theoretical investigations from governing orbital interactions using the frontier orbital theory demonstrate that the essential stability of the cyclopentadienide ions is dependent on the structure, itself.
N- and C-Terminal Effect of Amphiphilic α-Helical Peptides on the Interaction with Model- and Bio-Membranes
Authors: Kitamura Akiko , Kiyota Taira , Lee Sannamu , Sugihara Gohsuke 
Published: February 2006

Abstract
We previously designed and synthesized five N- and C-termini-free amphiphilic α-helical model peptides (Hel series) with a systematically varied hydrophobic–hydrophilic balance (HHB) that showed hemolytic activity, but no antimicrobial activity. However, an N-acetylated and C-amidated model peptide, peptide 3 [S. E. Blondelle and R. A. Houghten, Biochemistry, 31, 12688 (1992)], similar to a Hel series peptide, Hel 9-9, whose hydrophobic and hydrophilic amino acid residues and areas are equal in the α-helical structure, have exhibited both hemolytic and antimicrobial activities. Thus, to investigate the N- and C-terminal effect of the Hel series peptides on their antimicrobial activity, we designed and synthesized three peptides (Cap-Hel series), both termini-blocked by N-acetyl and C-amide groups. Their interaction mode with membranes was examined through reverse-phase high-performance liquid chromatography and circular dichroism spectroscopy as well as measurements of the hemolytic activity, antimicrobial activity, and membrane-clearing ability. No essential difference was found in either the terminal-free or -protected peptides, indicating that acetylation of the N-terminal and amidation of C-terminal did not affect their intrinsic antimicrobial activity in spite of a considerable change in the binding properties to lipids and hemolytic activities.