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Surface pressure versus molecular area (π-A) curves were measured on pure water as a subphase for a series of N,N′-diperfluoroalkanoyl-1,2(R,R)-diaminocyclohexanes. A molecule is denoted as RR-CFn,...

Solid-state vibrational circular dichroism (SD-VCD) spectra were measured on the ion-exchange adducts of sodium montmorillonite and [Cu(RR- or SS-oxa)]2+ as prepared in the presence of a substrate ...

The supramolecular chirality of the hindwing of Anomala albopilosa (male) was investigated using a microscopic vibrational circular dichroism (VCD) system, denoted as MultiD-VCD. The source of intense infrared (IR) light for the system was a quantum cascade laser. Two-dimensional maps of IR and VCD spectra were taken by scanning the surface area (ca. 2 mm × 2 mm) of the insect hindwing tissue. The spectra ranged from 1500 to 1700 cm-1, and the maps have a spatial resolution of 100 μm. The distribution of proteins, including their supramolecular structures, was analyzed from the location-dependent spectral shape of the VCD bands assigned to amides I and II. The results revealed that the hindwing consists of segregated domains of proteins with different secondary structures: an α-helix (in one part of the membrane), a hybrid of α-helix and β-sheet (in another part of the membrane), and a coil (in a vein).

Vibrational circular dichroism (VCD) spectra were recorded for the intercalation compounds of sodium montmorillonite co-adsorbing two kinds of metal complexes, Δ- (or Λ-)[Ru(phen)3]2+ and Λ- (or Δ-...

Cu(II) complexes containing RR- or SS-2,2′-isopropylidene-bis(4-phenyl-2-oxazoline) (denoted as [Cu(RR- or SS-oxa)]2+) are known to catalyse many asymmetric organic reactions. Herein, the source of enantioselectivity was investigated by vibrational circular dichroism (VCD) spectroscopy. An achiral β-diketonato ligand (denoted as LH), such as 1-phenyl-1,3-butanedione and dibenzoylmethane, was added to form [Cu(RR- or SS-oxa)L]+. Clear VCD peaks were obtained from a CDCl3 solution of [Cu(RR- or SS-oxa)]2+ or [Cu(RR- or SS-oxa)L]+ at 1000–1800 cm−1. It is to be noted that when LH was coordinated, a new VCD peak appeared at ∼1380 cm−1, which was assigned to the C–O asymmetric stretching vibration of L−. Theoretical simulation helped rationalise the results in terms of the transformation of coordinated L− into a twisted chiral form. The extent of steric control within the coordination sphere was demonstrated, revealing the first step for enantioselectivity during catalysis.

Proteins that specifically bind to metals have been used for research on development of new organic-inorganic hybrid materials. Several peptides and proteins that bind to metals have been reported; this property can be attributed to their structures. In this paper, we assessed the binding of a sequence of the protein called LARFH to a metal surface. We performed simulation with several models of LARFH protein with different loop sequences binding to the metal surface. It was found that the angle between the LARFH protein and the metal surface varied for different loop sequences. We also performed simulations of the detachment process of LARFH. It was concluded that the stronger binding to metal is established by two gold-binding loops of the LARFH sequences.

A mixture of chiral low-molecular weight gelators, (1R,2R)- or (1S,2S)-N,N'-diperfluoroheptanoyl-1,2-diaminocyclohexane (denoted as RR- or SS-CF7, respectively) and (1R,2R)- or (1S,2S)-N,N'-diheptanoyl-1,2-diaminocyclohexane (denoted as RR- or SS-CH7, respectively), was used as a two-component gelator in acetonitrile solvent. The process of gelation was investigated by time-step vibrational circular dichroism (VCD) spectroscopy. The method enabled us to study the dynamical behavior of CF7 and CH7 molecules independent of their characteristic vibrational bands. We focused on the effects of the chirality relation between the two gelators. In the case of the enantiomeric mixtures (RR-CF7/RR-CH7 or SS-CF7/SS-CH7), the two components exhibited different time-courses in their VCD spectra. As for CF7, the couplet peak intensities assigned to C[double bond, length as m-dash]O stretching increased with time, while those for CH7 remained low. In the case of the racemic mixture (RR-CF7/SS-CH7 or SS-CF7/RR-CH7), the intensities of the peaks assigned to the C[double bond, length as m-dash]O stretching vibration for both CF7 and CH7 molecules maintained a constant level with time. The VCD results were compared with the SEM images of the freeze-dried gel samples taken at various time intervals. Furthermore, the mechanisms for the gelation of two-component systems are discussed.

Further improvement of the thermostability of inherently thermostable proteins is an attractive challenge because more thermostable proteins are industrially more useful and serve as better scaffolds for protein engineering. To establish guidelines that can be applied for the rational design of hyperthermostable proteins, we compared the amino acid sequences of two ancestral nucleoside diphosphate kinases, Arc1 and Bac1, reconstructed in our previous study. Although Bac1 is a thermostable protein whose unfolding temperature is around 100°C, Arc1 is much more thermostable with an unfolding temperature of 114°C. However, only 12 out of 139 amino acids are different between the two sequences. In this study, one or a combination of amino acid(s) in Bac1 was/were substituted by a residue(s) found in Arc1 at the same position(s). The best mutant, which contained three amino acid substitutions (S108D, G116A and L120P substitutions), showed an unfolding temperature more than 10°C higher than that of Bac1. Furthermore, a combination of the other nine amino acid substitutions also led to improved thermostability of Bac1, although the effects of individual substitutions were small. Therefore, not only the sum of the contributions of individual amino acids, but also the synergistic effects of multiple amino acids are deeply involved in the stability of a hyperthermostable protein. Such insights will be helpful for future rational design of hyperthermostable proteins.

The monolayer behavior of a chiral gelator with perfluoroalkyl chains, (1R,2R)- or (1S,2S)- N,N’-diperfluoroheptanoyl 1,2-diaminocyclohexane (denoted as RR- or SS-CF7, respectively), was investigated by means of the Langmuir-Blodgett method. The AFM image of an enantiomeric film deposited onto a hydrophilic glass plate exhibited an array of rod-like aggregates with 0.05-0.8 μm in diameter, suggesting that they were a two-dimensional analogue of fibrils in a gel.

The solid-state vibrational circular dichroism spectra were measured for isoleucine and its related compounds. These amino acids are characterized by the presence of two chiral centers (the asymmetric carbon in an alkyl chain and the one at the α-position). The couplet peaks were observed for the stretching vibrations of –COOH and the bending vibration of –NH2. The signs of the peaks due to –COOH were determined uniquely by the RS-chirality of the α-carbon, while those due to –NH2 were dependent on the combination of the chirality of the α-carbon and the carbon in an alkyl chain. The results implied that the asymmetric vibrational behavior of an –NH2 group was affected by the interplay between two chiral centers.

Vibrational circular dichroism (VCD) spectroscopy was applied to gelation by a chiral low-molecular mass weight gelator, N,N'-diperfluoroalkanoyl-1,2-trans-diaminocyclohexane. Attention was focused on the winding effects of (-CF2 )n chains on the gelating ability. For this purpose, a series of gelators were synthesized with perfluoroalkyl chains of different length (n = 6-8). When gelation was studied using acetonitrile as a solvent, the fibrils took different morphologies, depending on the chain length: twisted saddle-like ribbon or helical ribbon from fibril (n = 6) and a helical ribbon from platelet (n = 8). The signs of VCD peaks assigned to the couplet of C=O stretching and to the C-F stretching were also dependent on n, indicating that a gelator molecule changed conformation on elongating perfluoroalkyl chains. A model is proposed for the aggregation modes in fibrils. Chirality 28:361-364, 2016. © 2016 Wiley Periodicals, Inc.

Through various in situ analyses, we have revealed the structural changes that occur during the reversible melting-solidification process of layered alkylsiloxanes (CnLSiloxanes) with carbon numbers (n) of 18 and 16. In situ high-resolution solid-state (13)C nuclear magnetic resonance (NMR) analysis at controlled temperatures indicates drastic conformational changes of the long alkyl chains during the melting-solidification process. A (13)C NMR signal at 33 ppm, which shows the highest intensity at room temperature (RT), is assigned to an inner methylene group with an all-trans conformation. As the temperature increases, the 33-ppm signal intensity decreases while the signal intensity at 30.5 ppm simultaneously increases. The 30.5 ppm signal is assigned to an inner methylene group with a trans-gauche conformation. Subsequently, upon cooling, the signal at 33 ppm recovers, even after CnLSiloxanes have melted. In situ X-ray diffraction measurements at controlled temperatures reveal that the ordered arrangement of the long alkyl chains becomes disordered with elevating temperatures and reordered upon cooling to RT. In situ high-resolution solid-state (29)Si NMR analysis shows that the melting-solidification process progresses without any structural change in siloxane sheets of the CnLSiloxanes. Thus, the in situ analyses show that disordering of the long alkyl chains causes the CnLSiloxanes to melt. Because the majority of long alkyl chains are packed again in the ordered arrangement with the all-trans conformation upon cooling, the CnLSiloxanes are reversibly solidified and the CnLSiloxane structure is recovered.

Vibrational circular dichroism (VCD) spectroscopy was applied to study intermolecular interactions on the surface of a clay mineral. A montmorillonite clay loaded with two kinds of chiral molecules was prepared. Firstly a cationic ruthenium(ii) complex, Δ- or Λ-[Ru(phen)3]2+ (phen = 1,10-phenanthroline), was ion-exchanged into sodium montmorillonite (denoted as [Ru(phen)3]2+/mont). Thereafter a neutral metal(iii) complex, Δ- or Λ-[M(acac)3] (acac = acetylacetonato; M = Co and Cr), was adsorbed spontaneously, when the complex was added to an aqueous dispersion of [Ru(phen)3]2+/mont (denoted as [M(acac)3]/[Ru(phen)3]2+/mont). VCD measurements were performed on a KBr disk containing ca. 1 wt% of solid [M(acac)3]/[Ru(phen)3]2+/mont. Both of the chiral components gave clear VCD peaks in the wavelength region of 1200-1800 cm-1. Attention was focussed on the spectral differences between the following two samples: the one containing a pair of co-adsorbed chelates with the same chirality (i.e. Λ-[M(acac)3]/Λ-[Ru(phen)3]2+/mont or Δ-[M(acac)3]/Δ-[Ru(phen)3]2+/mont) and the other containing a pair of co-adsorbed chelates with the opposite chirality (i.e. Δ-[M(acac)3]/Λ-[Ru(phen)3]2+/mont or Λ-[M(acac)3]/Δ-[Ru(phen)3]2+/mont). Notably a new peak shoulder appeared and the relative peak intensity of the couplet peaks varied, depending on the chirality relation between the co-existing complexes. With the help of theoretical calculations, these results were rationalized in terms of the stereoselective intermolecular interactions.

The present article reports the application of vibrational circular dichroism (VCD) and temperature-dependent electronic circular dichroism (ECD) methods to reveal the dynamical aspects of a star-burst tetranuclear metal complex with a labile central core in a solution. One-handed chiral inert tecton, ∆- or &Lambda, [Ru(III)(acac)2(taetH)] (acacH = acetylacetone, taetH2 = tetraacetylethane), was prepared by reacting [Ru(acac)3] with taetH2 in solid at 120 &deg, C. The ∆&Lambda, pair of pure enantiomers was obtained chromatographically. On adding Al(ClO4)3 to its enantiopure solution, three units of one-handed tecton were assembled spontaneously around an aluminum(III) ion to form a star-burst tetranuclear complex, [{∆- or &Lambda, Ru(acac)2(taet)}3Al(III)]. The VCD spectrum recorded on the CDCl3 solution of the complex showed that the central chirality around an Al(III) ion took dominantly the absolute configuration antipodal to those of peripheral Ru(III) units at the temperature lower than &minus, 10 &deg, C. The complex underwent interconversion between the ∆- and &Lambda, configurations around a central Al(III) core (or epimerization) in solution. The activation energy barrier was determined from the time courses of ECD spectra in CHCl3 and CH3OH.

This review examines the modification of clay mineral surfaces with/by chiral metal complex ions. It was motivated by the observation that the adsorption of a chiral cation, [Ru(phen)3]2 +(phen = 1,10-phenanthroline), by sodium montmorillonite (Na+-Mt) remarkably depended on its stereochemical properties. It was postulated that a clay mineral surface covered with the enantiomer of the complex provided a vacant space capable of discriminating molecular chirality. The postulates led to the use of an ion-exchange adduct of a smectite and enantiomeric [Ru(phen)3]2 + as packing material in liquid column chromatography for optical resolution. The application was further extended to asymmetric syntheses. The enantioselective sensing by iridium complexes adsorbed on a colloidal particle of synthetic saponite (Sap) was summarised. Chirality recognition on a montmorillonite by means of the solid state vibrational circular dichroism was described.

The attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low-molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoroalkyl chains. The effects of the helical conformation of the perfluoroalkyl chains on the formation of chiral architectures are reported. It is described how the conformation of a chiral gelator was determined by comparing the experimental and theoretical VCD spectra together with a model proposed for the molecular aggregation in fibrils. The results demonstrate the potential utility of the chiroptical method in analyzing organized chiral aggregates. Chirality 27:659–666, 2015. © 2015 Wiley Periodicals, Inc.

Dinuclear square planar palladium(ii) complexes, [{Pd(ii)La}2(baet)] (La(-) = β-diketonato and baet(2-) = 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato), were prepared and used as chiral dopants to induce chiral nematic phases. The following β-diketones were used as LaH: pentane-2,4-dione (acacH), dibenzoylmethane (dbmH), di-4-nonyloxybenzoylmethane (C9-dbmH) and 3-[4'-(4''-(octyloxy)phenylazo)phenyl]-2,4-dione (C8-azoacacH). When the enantiomers were doped in a nematic liquid crystal, they induced a chiral nematic phase with a helical twisting power (HTP) of 5-50 μm(-1). In particular, the sample doped with [{Pd(ii)(C8-azoacac)}2(baet)] exhibited a reversible change of the circular dichroism spectrum under alternate irradiation at 350 nm and 460 nm. It implied that the HTP changed reversibly in response to the cis-trans isomerization of the coordinated C8-azoacac ligand.

Vibrational circular dichroism (VCD) spectroscopy was applied to study chirality recognition in the interlayer space of a clay mineral. Clay intercalation compounds including two kinds of chiral molecules were prepared. Firstly a cationic metal complex, Δ- or Λ-[Ru(phen)3]2+ (phen = 1,10-phenanthroline), was ion-exchanged into sodium montmorillonite. Thereafter a neutral organic molecule, R- or S-1,1′-bi-2-naphthol (denoted as R- or S-BINOL), was co-adsorbed. The solid state VCD spectra were recorded on the hybrid compounds thus prepared. The intensity of VCD peaks in the region of 1300–1400 cm−1, which were assigned to the bending vibrations of OH groups in BINOL, was remarkably dependent on the chirality relation between the two intercalated species. This implied that BINOL took a different conformation in response to the chirality of co-existing [Ru(phen)3]2+.

Gel formation by low molecular mass gelators was investigated. The gelator was trans(RR)- or trans(SS)-N,N′-n-bromoalkanoyl-1,2-diaminocyclohexane (denoted as RR-CnBr or SS-CnBr, respectively; n = the number of carbon atoms in an alkanoyl group). When n was varied from 5 to 12, the gelators formed transparent or opaque or turbid gels in benzene except for n = 8. Focusing on the end effects, the gelation behavior of CnBr was compared with that of non-brominated counterparts (denoted as RR- or SS-Cn). From the vibrational circular dichroism (VCD) spectra of enantiomeric gelator/benzene-d6 gels, the signs of the coupled peaks around 1640 cm−1, which were assigned to the symmetric and asymmetric CO stretching vibrations from the higher to lower wavenumber, respectively, were opposite between SS-CnBr and SS-Cn (or between RR-CnBr and RR-Cn). On the other hand, the signs of the coupled peaks around 1550 cm−1 assigned to the NH stretching vibrations remained unaffected. The observed reversal of the signs in the CO couplet was rationalized in terms of the different modes of stacking in fibrils. In the case of Cn, for example, the molecules were stacked through anti-parallel double intermolecular hydrogen bonds using two pairs of >NH and >CO groups, while, in the case of CnBr, a single intermolecular hydrogen bond was formed with the remaining pair of >NH and >CO groups forming an intramolecular hydrogen bond. Single crystal X-ray analyses were performed for SS-C6Br and SS-C8Br. The results demonstrated that the length of the bromoalkanoyl chains drastically affected the packing modes in crystalline states.

Rational design of protein surface is important for creating higher order protein structures, but it is still challenging. In this study, we designed in silico the several binding interfaces on protein surfaces that allow a de novo protein–protein interaction to be formed. We used a computer simulation technique to find appropriate amino acid arrangements for the binding interface. The protein–protein interaction can be made by forming an intermolecular four-helix bundle structure, which is often found in naturally occurring protein subunit interfaces. As a model protein, we used a helical protein, YciF. Molecular dynamics simulation showed that a new protein–protein interaction is formed depending on the number of hydrophobic and charged amino acid residues present in the binding surfaces. However, too many hydrophobic amino acid residues present in the interface negatively affected on the binding. Finally, we found an appropriate arrangement of hydrophobic and charged amino acid residues that induces a ...

Mononuclear and dinuclear ruthenium(III) complexes with bis-β-diketonato ligands (denoted by [Ru(acac)(2)(L-LH)] and [Ru(acac)(2)(L-L)Ru(acac)(2)], respectively) were synthesized, where acac, L-LH(-) and L-L(2-) denote acetylacetonato, monoprotonated and unprotonated bis-β-diketonato ligands, respectively. The following three ligands were used as the bis-β-diketonato ligand (L-L(2-)): 1,2-diacetyl-1,2-dibenzoylethanato (denoted by dabe(2-)), 1,2-diacetyl-1,2-bis(3-methylbutanoyl)ethanato (baet(2-)) and 1,2-diacetyl-1,2-dipropanoylethanato (dpe(2-)). For the mononuclear and the meso-type dinuclear complexes, a pair of diastereomeric species were identified as Δ- (or Λ-) [Ru(acac)(2)(R- or S-L-LH)] and [Δ-Ru(acac)(2)(R- or S-L-L)Λ-Ru(acac)(2)], respectively. The possibility of thermal inversion in coordinated L-LH(-) (mononuclear) or L-L(2-) (dinuclear) was pursued by monitoring the changes in the electronic circular dichroism or the (1)H NMR spectra. No inversion occurred for the dinuclear complexes, when their chloroform solutions were kept at 50 °C for ca. 100 h. In contrast, some of the mononuclear complexes underwent the inversion of axial chirality to give an equilibrium mixture under the same conditions. The reaction followed the first-order rate law and the overall first-order rate constants (k) of [Ru(acac)(2)(L-LH)] were determined to be k = 0.13, 0.0048 and less than 0.001 h(-1) for L-LH(-) = dabeH(-), baetH(-) and dpeH(-), respectively. The results suggest that the main factor determining the barrier height of the internal rotation is not the steric but the electronic properties of the carbon-carbon bond connecting the two β-diketonato moieties.

The present article reviews the results on the application of vibrational circular dichroism (VCD) spectroscopy to the study of stereochemical properties of chiral metal complexes in solution. The chiral characters reflecting on the vibrational properties of metal complexes are revealed by measurements of a series of β-diketonato complexes with the help of theoretical calculation. Attention is paid to the effects of electronic properties of a central metal ion on vibrational energy levels or low-lying electronic states. The investigation is further extended to the oligomers of β-diketonato complex units. The induction of chiral structures is confirmed by the VCD spectra when chiral inert moieties are connected with labile metal ions. These results have demonstrated how VCD spectroscopy is efficient in revealing the static and dynamic properties of mononuclear and multinuclear chiral metal complexes, which are difficult to clarify by means of other spectroscopes.

A series of bimetallic coordination polymers with the elemental composition of [Cd(II)L2][Au(CN)2]2, (L = 3-methylpyridine, 4-ethylpyridine, 3,5-lutidine and 3-fluoropyridine) were synthesized and their crystal structures were determined. In all of the investigated compounds, there existed a pair of Au-Au atoms whose interatomic distance was shorter than the sum of van der Waals radii (0.36 nm) as an indication of the aurophilic interaction. The compounds were emissive under the irradiation at 370 nm. The emission spectra recorded in the temperature range of 183-363 K were characterized by the vibronic structures with a peak spacing (Δν) of ca. 2000 cm(-1). The value of Δν was close to the stretching vibration of the coordinated C[triple bond, length as m-dash]N (2150-2170 cm(-1)). It was postulated that C[triple bond, length as m-dash]N groups participated in the emission processes through their vibronic coupling. In the case of L = 4-ethylpyridine, the lifetime of emission was measured in the same temperature range, leading to the conclusion that the activation energy of the non-radiative processes (ΔEa) was estimated to be 20 kJ mol(-1).

Internal symmetry is a common feature of the tertiary structures of proteins and protein domains. Probably, because the genes of homo-oligomeric proteins duplicated and fused, their evolutionary descendants are proteins with internal symmetry. To identify any advantages that cause monomeric proteins with internal symmetry to be selected evolutionarily, we characterized some of the physical properties of a recombinant protein with a sequence consisting of two tandemly fused copies of the Escherichia coli Lac repressor C-terminal alpha-helix. This polypeptide exists in solution mainly as dimer that likely maintains a four-helix bundle motif. Thermal unfolding experiments demonstrate that the protein is considerably more stable at elevated temperatures than is a homotetramer consisting of four non-covalently associated copies of a 21-residue polypeptide similar in sequence to that of the Lac repressor C-terminal alpha-helix. A tandem duplication of our helix-loop-helix polypeptide yields an even more thermally stable protein. Our results exemplify the concept that fusion of non-covalently assembled polypeptide chains leads to enhanced protein stability. Herein, we discuss how our work relates to the evolutionary selective-advantages realized when symmetrical homo-oligomers evolve into monomers. Moreover, our thermally stable single-chain four-helix bundle protein may provide a robust scaffold for development of new biomaterials.

The Delta- and Lambda-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a dopant, it has been found that tris(beta-diketonato)metal(III) complexes exhibit an extremely high value of helical twisting power. The mechanism of induction of the chiral nematic phase is postulated on the basis of a surface chirality model. The strategy for designing an efficient dopant is described, together with the results using a number of examples of Co(III), Cr(III) and Ru(III) complexes with C(2) symmetry. The development of photo-responsive dopants to achieve the photo-induced structural change of liquid crystal by use of photo-isomerization of chiral metal complexes is also described.

We did a molecular dynamics simulation of a system consisting of a peptide and a protein in explicit solvent to study biomolecular approach process. In the initial structure of simulation, the minimum inter-biomolecular distance was 30 A. During the simulation, the biomolecules approached and contacted to each other. In spite of diffusive motions of water molecules, the orientations of water molecules tended to order in the inter-biomolecular zone showing coherent spatial patterns (solvent site-dipole field) of the ordering. The degree of ordering was synchronized well with the inter-biomolecular distance. This result strongly suggests that the biomolecules distant to each other can interact via the solvent site-dipole field. The effective range for the coherent ordering (i.e., the interaction range via the solvent site-dipole field) was larger than 20 A. A bridge-like structure of the solvent orientational ordering connected the two biomolecules. Biological and physicochemical significance of the ordering is discussed.

For de novo design of protein-protein interactions (PPIs), information on the shape and chemical complementarity of their interfaces is generally required. Recent advances in computational PPI design have allowed for de novo design of protein complexes, and several successful examples have been reported. In addition, a simple and easy-to-use approach has also been reported that arranges leucines on a solvent-accessible region of an α-helix and places charged residues around the leucine patch to induce interactions between the two helical peptides. For this study, we adopted this approach to de novo design a new PPI between the helical bundle proteins sulerythrin and LARFH. A non-polar patch was created on an α-helix of LARFH around which arginine residues were introduced to retain its solubility. The strongest interaction found was for the LARFH variant cysLARFH-IV-3L3R and the sulerythrin mutant 6L6D (KD=0.16 μM). This artificial protein complex is maintained by hydrophobic and ionic interactions formed by the inter-molecular helical bundle structure. Therefore, by the simple and easy-to-use approach to create de novo interfaces on the α-helices, we successfully generated an artificial PPI. We also created a second LARFH variant with the non-polar patch surrounded by positively charged residues at each end. Upon mixing this LARFH variant with 6L6D, mesh-like fibrous nanostructures were observed by atomic force microscopy. Our method may, therefore, also be applicable to the de novo design of protein nanostructures.

Stacking structures in pyrophyllite, Al 2 Si 4 O 10 (OH) 2 , were investigated mainly by using high-resolution transmission electron microscopy (HRTEM). The specimens examined were large lath-shaped crystals (Berosovska, Urals, Russia) and massive aggregates of fine platy crystals (Nohwa, southwest Korea). Both specimens showed powder X-ray diffraction (XRD) patterns similar to those reported previously as the 2 M polytype. The common stacking sequence in the two specimens is not monoclinic with two-layer periodicity as previously reported, but a uniform orientation of the 2:1 layers and near complete disorder of two alternative directions of interlayer displacement, i.e., lateral displacement between the two tetrahedral sheets across an interlayer region. The directions of interlayer displacement are about ±2π/3 from that of the intralayer shift (lateral displacement between the two tetrahedral sheets within a 2:1 layer). Simulation of powder XRD patterns by this stacking model closely approximates the experimental pattern. Elongation of the lath-shaped Berosovska crystals corresponds to the direction of the intralayer shift, as seen in illite-1 M . 2:1 layers with different orientations, and interlayer displacement almost parallel to the intralayer shift, were occasionally observed as stacking faults. Such disorder occurs more frequently in the massive Nohwa specimen than in the Berosovska specimen. Sub-micrometer domains of the 2 M stacking sequence with regular alternation of the two directions of interlayer displacement were found in the Nohwa specimen.

The src SH3 domain has been known to be a two-state folder near room temperature. However, in a previous study with an all-atom model simulation near room temperature, the transition state of this protein was not successfully detected on a free-energy profile using two axes: the radius of gyration (R(g)) and native contact reproduction ratio (Q value). In this study, we focused on an atom packing effect to characterize the transition state and tried another analysis to detect it. To explore the atom packing effect more efficiently, we introduced a charge-neutralized all-atom model, where all of the atoms in the protein and water molecules were treated explicitly, but their partial atomic charges were set to zero. Ten molecular dynamics simulations were performed starting from the native structure at 300 K, where the simulation length of each run was 90 ns, and the protein unfolded in all runs. The integrated trajectories (10 x 90 = 900 ns) were analyzed by a principal component analysis (PCA) and showed a clear free-energy barrier between folded- and unfolded-state conformational clusters in a conformational space generated by PCA. There were segments that largely deformed when the conformation passed through the free-energy barrier. These segments correlated well with the structural core regions characterized by large phi-values, and the atom-packing changes correlated with the conformational deformations. Interestingly, using the same simulation data, no significant barrier was found in a free-energy profile using the R(g) and Q values for the coordinate axes. These results suggest that the atom packing effect may be one of the most important determinants of the transition state.

A high-power chiral dopant system involving 6-coordinate metal complexes was designed on the basis of a shape model. Accordingly, a series of mixed 1,3-diketonate complexes of Ru(III), [Ru(acac)2(L-n)], in which acac = acetylacetonate and L-n = dibenzoylmethanate substituted with n octyloxy groups (abbreviated as Ru-n hereafter), was prepared and optically resolved. Their performance as chiral dopants was evaluated in terms of helical twisting power (HTP) in a room-temperature nematic liquid crystal, N-(4-methoxybenzylidene)-4-n-butylaniline (MBBA), by measuring the helical pitch lengths and CD spectra for the induced chiral nematic phases. The Δ- and Λ-enantiomers induced macroscopic left-handed (M) and right-handed (P) helices, respectively, and the (absolute) values for HTP have proven to be remarkably large, e.g. βM = 1.8 × 102 μm-1 in the case of Λ-Ru-2. The induced CD spectra for the dilute MBBA* materials (the asterisk denotes in this paper that MBBA has been doped with a chiral substance) were fit...

Morphology of kaolinite crystals with high-crystallinity (Keokuk, Iowa) has been investigated by electron back-scattered diffraction (EBSD) and high-resolution scanning electron microscopy (SEM). EBSD patterns from the specimen generally correspond to those expected from ordered kaolinite. Elongated hexagonal crystals always show the a -axis parallel to the elongated direction. The side-facets of these crystals are in parallel to the c -axis, which is inclined by about 15° from the normal to the basal plane. The Miller indices of the side-facets are exactly ±(110), ±(110), and ±(010). A facet indexed as ±(130) is developed in some crystals. These morphological characteristics must be reflected in the ordered stacking sequences (the position of the octahedral vacancy site and the direction of the interlayer shift) of the Keokuk kaolinite. Inversely, the crystallinity of individual kaolinite grains may be evaluated from their morphology in a SEM. The feasibility to discriminate the enantiomers in kaolinite using EBSD is also described.

Coadsorption studies of chiral tris(1,10-phenanthroline)ruthenium(II) ([Ru(phen)3]2+) and N-methylated cinchona alkaloid cation (MQN+) were conducted on a smectite clay by ion exchange reactions. Photoinduced energy transfer between these cations was confirmed by the photoluminescence spectra, indicating that the cations were co-intercalated in the interlayer space of a smectite. When a ternary ion-exchanged adduct of [Ru(phen)3]2+/MQN+/smectite was employed as a packing material for liquid chromatography, the column proved to resolve a racemic mixture of 1,1‘-binaphthol more effectively than the column packed with a binary adduct of [Ru(phen)3]2+/smectite. The results reflected the enhancement of the chiral discrimination ability through the cooperative interactions among two kinds of preadsorbed chiral cations.

The polytype structures of the three 1:1 dioctahedral phyllosilicates found in nature, kaolinite, dickite, and nacrite, have been investigated, using first-principle calculations within density functional theory. The crystal structures were calculated by being optimized with relaxation of all atomic positions. The calculated structural parameters, including the orientation of the OH groups, for the three polytypes are in good agreement with experimental data. In particular, for kaolinite and dickite, the three-inner surface OH groups were predicted to be oriented nearly perpendicular to the (001) plane. In contrast, one of the inner surface OH groups of nacrite was predicted to be nearly parallel with respect to the (001) plane. Based on a comparison of formation energies, the chiral polymorphs of kaolinite (B- or C-site vacancy) have similar formation energies as dickite and nacrite, while achiral kaolinite with A-site vacancy is only slightly less stable than the other polytypes.

The following six types of Ru(II) complexes were synthesized with an aim to develop a monolayer with chiral discrimination: 1 [Ru(bpy)2(4-C11bpy)](ClO4)2 (bpy = 2,2‘-bipyridine, 4-C11bpy= 4-methyl-4‘-undecyl-2,2‘-bipyridine); 2 [Ru(bpy)2(4,4‘-dC11bpy)](ClO4)2 (4,4‘-dC11bpy = 4,4‘-diundecyl-2,2‘ -bipyridine); 3 [Ru(bpy)2(5-C11bpy)](ClO4)2 (5-C11bpy= 5-methyl-5‘-undecyl-2,2‘-bipyridine); 4 [Ru(bpy)2(5,5‘-dC11bpy)](ClO4)2 (5,5‘-dC11bpy = 5,5‘-diundecyl-2,2‘-bipyridine); 5 [Ru(bpy)2(4-C18bpy)](ClO4)2 (4-C18bpy= 4-methyl-4‘-octadecyl-2,2‘-bipyridine); 6 [Ru(bpy)2(4,4‘-dC18bpy)](ClO4)2 (4,4‘-dC11bpy = 4,4‘-dioctadecyl-2,2‘-bipyridine). These complexes possess one or two alkyl chains at 4,4‘- or 5,5‘-positions of the 2,2‘-bipyridine ligand. A traditional amphiphile is a linear molecule with a polar head attached by one or two alkyl chains, whereas the present complexes cover both traditional (1, 2, 5, and 6) and nontraditional amphiphilic molecules (3 and 4). The monolayer behavior of these Ru(II) complexes on ...

β(14) Galactosyltransferase expressed as a fusion protein with maltose binding protein (MBP-GalT) was displayed specifically on a Langmuir–Blodgett (LB) membrane prepared by photopolymerization of maltotriose-carrying glycolipid (1) with 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (2). The catalytic activity of MBP-GalT on the LB film was directly monitored by the surface plasmon resonance (SPR) method using a GlcNAc-carrying water-soluble polymer (3) as an acceptor substrate. Highly sensitive sigmoidal-type signals were obtained upon the addition of the acceptor substrate in the presence of the donor substrate, UDP-galactose (UDP-Gal), while the binding of 3 was not detected in the absence of UDP-Gal. The intensities of the signals were dependent on the amount of immobilized MBP-GalT on the LB film, which was estimated from the images obtained by atomic force microscope (AFM).

Two-dimensional adlayer of a helically shaped aromatic compound, hexathia[11]heterohelicene ([11]TH), which consists of fused five benzene rings and six thiophene rings, was prepared on Au(1 1 1), Au(1 1 0) and polycrystalline gold under UHV condition. LEED and STM were used for characterization of alignment, ordering and chirality of [11]TH on these Au substrates. A [11]TH monolayer on Au(1 1 1) showed the presence of an adlayer lattice with six-fold symmetry, while [11]TH on Au(1 1 0) did align along 〈1 1 0〉 direction, and [11]TH adsorbed on a step bunching area formed chiral sensitive arrays, being one-dimensionally aligned chains. These observations are discussed in terms of stereoselective interaction among [11]TH’s, which is strongly affected by the surface structure of a substrate.

Different spectroscopic and photoelectrochemical behaviors were observed when racemic and enantiomeric [Ru(bpy)3]2+ complexes were intercalated in the interlayer of K4Nb6O17, even for the same intercalation amount. The results are interpreted in terms of the stronger interaction between racemic [Ru(bpy)3]2+ molecules in the interlayer spaces of K4Nb6O17. The faster emission decay and lower photocurrent of the racemic [Ru(bpy)3]2+−K4Nb6O17 compound compared to the enantiomeric ones suggest that stronger concentration quenching exists between the racemic [Ru(bpy)3]2+ ions in the interlayer of K4Nb6O17. Combining the spectroscopic and photoelectrochemical results, the racemic [Ru(bpy)3]2+ ions are considered to intercalate more densely than the enantiomeric [Ru(bpy)3]2+ ions in the interlayer of K4Nb6O17, even for the same intercalation amount. Two cationic dyes were also directly intercalated into K4Nb6O17. The spectroscopic and photoelectrochemical behaviors of the dye−K4Nb6O17 compounds were investigated.

A novel amphiphilic Ru(II) bipyridine complex, (N(C 2 H 5 ) 4 ) 2 [Ru(CN) 4 (dc18bpy)] (dc18bpy=4,4′-dioctadecyl-2,2′-bipyridine), has been synthesized. The reversible π– A curves were measured after spreading a chloroform solution of the compound onto either pure water or an aqueous 10 mM solution of Fe(ClO 4 ) 3 . The molecular-occupied area changed from 0.6 nm 2 molecule −1 on pure water to 1.0 nm 2 molecule −1 on an aqueous Fe(ClO 4 ) 3 solution. The results suggested that Fe(III) ions were incorporated into a monolayer of [Ru(CN) 4 (dc18bpy)] 2+ . The floating monolayer on an aqueous Fe(ClO 4 ) 3 solution was transferred as a Y-type Langmuir-Blodgett (LB) film (denoted by Ru–Fe–LB film) onto a solid substrate by the vertical dipping method. The Ru–Fe–LB film contained Fe and Ru at the ratio of [Fe]/[Ru]=1.60±0.05 as determined by the X-ray fluorescence analyses. The intensity of the broad band approximately 600 nm, which was assigned to the intermetallic charge–transfer from Ru(II) to Fe(III), increased linearly with the layer number up to 30 layers. According to the atomic force microscope observation of a monolayer Ru–Fe–LB film deposited on mica, the film had a uniform thickness of approximately 2 nm. These observations support a view that the Ru–Fe–LB film should be regarded as a two-dimensional Prussian Blue type film or it consisted of a two-dimensional network of Ru(II)–CN–Fe(III).

Monolayers of helically shaped aromatic compound, hexathia[1 1]heterohelicene ([1 1]TH), which consists of five benzene rings and six thiophene rings were prepared on gold(1 1 1) and gold(1 1 0) surface under UHV condition. LEED and STM were used for the structural study focused on the molecular chirality. [1 1]TH monolayer on gold(1 1 1) substrate showed the same structure as on (1 1 1) analogue of polycrystalline surface. [1 1]TH evaporated on gold(1 1 0) showed loosely packed molecular chains. The results were compared with the results on gold polycrystalline surface and the bulk structural analysis.

We have attempted to develop a novel Langmuir-Blodgett (LB) film with a non-centrosymmetric molecular alignment by hybridizing a clay and an organic molecule, a D-π-A zwitter ionic molecule based on amine and TCNQ derivatives. Hybridization is made by forming a monolayer of the organic molecule onto a subphase of an aqueous dispersion of a clay. Second Harmonic Generation (SHG) measurements have revealed that the hybridized LB film possesses noncentrosymmetry in spite of the fact that the used organic molecule has neither a positive charge nor a long alkyl chain. Observations with a Brewster Angle Microscope (BAM) have revealed a clear difference in film properties when pure water as opposed to and a clay suspension is used as a subphase. These facts suggest that the clay plays an important role in the organization of zwitter ionic molecules in the film.

Cs+ ions intercalated in a South African vermiculite were so firmly bound that they were hardly dissociated on treating with an aqueous solution of 1 M KNO3 or NH4NO3. When a vermiculite having adsorbed the saturated amount of Cs+ ions (0.61 mol g−1) was stirred in an aqueous solution containing 0.4 M of Mg(NO3)2 and 20 mM of tetra kis(4-fluorophenyl)borate sodium salt (denoted as Na+L−), the intercalated Cs+ ions were fully replaced with Mg2+ ions within 2 h. The results were rationalized in terms of the ion-exchange reaction between Cs+ and Mg2+ ions: $$ 2 {\text{Cs}}^{ + } /{\text{clay}} + {\text{Mg}}^{ 2+ } \,\,\, \rightleftarrows \,\,\,\, 2 {\text{Cs}}^{ + } + {\text{ Mg}}^{ 2+ } /{\text{clay}} $$ , in which the reverse reaction (or re-binding) of Cs+ ions was prohibited by the formation of an insoluble salt, Cs+L−.

protein to study the effect of mutation to the binding sites of protein. We replace original amino acids on the surface by negatively or positively charged amino acids. We also study the effect of solvent to the binding of proteins. Our computational study may be useful for future experimental study of protein bindings. Making nano-fibers with proteins (1-3) is an interesting and challenging field. We have tried to construct nano-fibers while retaining native structure. We started with proteins which form 4-helix bundle structure (4) by two proteins, each having two helices. In our previous studies (5-6) of molecular dynamics simulation of all-atom model, we have found that IPMDH (3-isopropylmalate dehydrogenase) (7-9) is a good candidate for a building unit of constructing nano-fibers because of the high stability of the mutated IPMDH. In this study, we have performed molecular dynamics simulation of coarse-grained model of IPMDH proteins. We have introduced several mutations on the surface of IPMDH and found that the mutated IPMDHs are likely to make larger clusters than the wild-type IPMDH. 2. Simulation Model and Method We used coarse grained model of IPMDH with MARTINI force field (10), where one interaction point represents on average four heavy atoms. There are four kinds of interaction points in MARTINI force field: polar, nonpolar, apolar and charged. Using coarse grained model, we can perform simulation of long-time behavior of large scale system. To check the model, we calculated radial distribution function for both all-atom model and coarse grained model, and obtained similar results.

To characterize the thermal stability of 3-isopropylmalate dehydrogenase (IPMDH) from an extreme thermophile, Thermus thermophilus, urea-induced unfolding of the enzyme and of its mesophilic counterpart from Escherichia coli was investigated at various temperatures. The unfolding curves were analyzed with a three-state model for E.coli IPMDH and with a two-state model for T.thermophilus IPMDH, to obtain the free energy change DeltaG degrees of each unfolding process. Other thermodynamic parameters, enthalpy change DeltaH, entropy change DeltaS and heat capacity change DeltaC(p), were derived from the temperature dependence of DeltaG degrees. The main feature of the thermophilic enzyme was its lower dependence of DeltaG degrees on temperature resulting from a low DeltaC(p). The thermophilic IPMDH had a significantly lower DeltaC(p), 1.73 kcal/mol.K, than that of E.coli IPMDH (20.7 kcal/mol.K). The low DeltaC(p) of T.thermophilus IPMDH could not be predicted from its change in solvent-accessible surface area DeltaASA. The results suggested that there is a large structural difference between the unfolded state of T.thermophilus and that of E.coli IPMDH. Another responsible factor for the higher thermal stability of T.thermophilus IPMDH was the increase in the most stable temperature T(s). The DeltaG degrees maximum of T.thermophilus IPMDH was much smaller than that of E.coli IPMDH. The present results clearly demonstrated that a higher melting temperature T(m) is not necessarily accompanied by a higher DeltaG degrees maximum.

Thin hybrid films of an amphiphilic anionic Ru(II) complex (K2[Ru(CN)4L]: L=4,4′-di-n-dodecylaminoyl-2,2′-bipyridyl) with Mg–Al–Cl or Ni–Al–Cl layered double hydroxides (LDHs) were prepared by the Langmuir–Blodgett (LB) method. A chloroform solution of K2[Ru(CN)4L] was spread onto an aqueous dispersion of the LDH. Hybridization proceeded through the adsorption of the positively charged LDH particles by the floating film of [Ru(CN)4L]2− at the air–water interface. The hybridized films were deposited onto mica by the vertical dipping method. Atomic force microscope (AFM) observation of the film surface confirmed that 15–50 nm thick LDH particles were combined with the string-like aggregates of the Ru(II) complex. Cyclic voltammograms of indium tin oxide (ITO) electrodes modified with the single layer of the hybrid films were recorded. No peak was observed in the potential range of 0–1200 mV (vs. SCE) for electrodes modified with [Ru(CN)4L]2−/Mg–Al–Cl LDH films. For electrodes modified with [Ru(CN)4L]2−/Ni–Al–Cl LDH films, oxidation–reduction peaks due to Ni(II)/Ni(III) couple in the LDH were observed, along with a peak attributed to the reduction of chemically oxidized [Ru(CN)4L]−. This implies that the electrochemically produced Ni(III) sites in the LDH layers acted as mediator in oxidizing [Ru(CN)4L]2−. In this way, a cascade of electron flow from [Ru(CN)4L]2− to the electrode by way of Ni–Al–Cl LDH has been established.

Chirality effects have been observed in the intercalation, spectroscopic and photoelectrochemical behavior when enantiomeric and racemic [Ru(phen)3]2+ complexes were intercalated in the interlayer spaces of K4Nb6O17. The results were interpreted in terms of a [Nb6O17]4−-chelate and chelate–chelate interactions. The faster luminescence decay and higher photocurrent of the enantiomeric [Ru(phen)3]2+–K4Nb6O17 compounds than the racemic ones suggest that the emission of adsorbed [Ru(phen)3]2+ ions was not only quenched by adsorbed complexes (or concentration quenching) but also by the semiconductive host lattices.

Molecular dynamics (MD) simulations have been performed to study the flexibility of smectite clay minerals. We aim at the quantitative understanding of the mechanical behavior of a single clay layer in a completely exfoliated state. The repeating unit of a clay layer is taken to be ao = 0.52 nm and bo = 0.902 nm with formula of 2Na1/3 Al2[Si11/3Al1/3]O10(OH)2 which corresponds to that of beidellite. When the size of the basic cell (A = 9.3 nm, B = 2.6 nm, and C = 5 nm) (denoted by A-type cell) is reduced by 3−40% in the A-direction, the stationary structure of a clay layer is obtained as a curved sheet with a 2:1 smectite-type layer structure. In such a curved state, the layer experiences a stress of 0.5−0.7 GPa. The layer structure of a clay fractures when the size of the same basic cell is reduced by more than 40%. The bending constant is estimated for a curved layer by plotting the inverse of the average radius against stress. The similar calculations are performed by reducing the size of the basic cel...

Energy transfer from tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchlorate (denoted by Ru(II)) to tris(4,7-diphenyl-1,10-phenanthroline)osmium(II) perchlorate (denoted by Os(II)) has been studied in cast and Langmuir−Blodgett (LB) films. The work is focused on the packing effects of chiral metal complexes on energy-transfer rates. Three kinds of films were prepared: a cast film of a 100:1 mixture of Λ-Ru(II) and Λ-Os(II) (or Δ-Os(II)) (sample 1), a Y-type LB film of a 100:1 mixture of Λ-Ru(II) and Λ-Os(II) (or Δ-Os(II)) (sample 2), and an alternative Y-type LB film of Λ-Ru(II) and Λ-Os(II) (or Δ-Os(II)) monolayers (sample 3). In all of these samples, stearic acid (SA) is added at a molecular ratio of [SA]/[Ru(II)] = 3 to stabilize a monolayer state. From the analyses of the decay curves of excited Os(II) (denoted by Os(II)*), the apparent unimolecular energy-transfer rate constant from excited Ru(II) (denoted by Ru(II)*) to Os(II), k2, is determined. As a result, k2 is found to be larger for Λ-...

Imaging of molecule–molecule recognition of chirality on a solid surface was attempted using scanning tunneling spectrocopy (STM) under ultra-high vacuum (UHV) conditions. The target molecule in this work, thiaheterohelicene ([11]TH), is a fused product which consists of five benzene rings and six thiophene rings. It has a helical chirality which can be compared to a spring washer. A racemic mixture of [11]TH was vaporized to prepare an adsorbed layer onto an Au(111)/mica substrate under UHV conditions. Images were obtained with molecular resolution on wide terrace areas and faceted narrow steps. The images obtained in the terrace areas show that the right handed and the left handed isomers were randomly adsorbed on the surface with little interaction. On the other hand, the images obtained in the steps showed that molecules of the same chirality formed a tightly packed row. The high resolution STM image obtained for [11]TH enabled us to distinguish not only the domain structures but also the domain compositions caused by the structural difference of the substrate.

The electrochemical STM method has been applied to a hydrotalcite clay-modified electrode with the aim of obtaining evidence for the formation of a surface layer of the [Fe(CN) 6 ] 3−/4− couple. As a result, ordered surface layers of [Fe(CN) 6 ] 3−/4− ions on a hydrotalcite-modified electrode have been observed with an in-situ electrochemical STM instrument: the initial lattice of [Fe(CN) 6 ] 3− with a =1.40±0.04 nm, b =1.85±0.04 nm and α =63±3° changed to an expanded lattice of [Fe(CN) 6 ] 4− with a =1.94±0.04 nm, b =1.90±0.04 nm and α =60±3° due to the electrochemical reduction.

Atomic force microscopy (AFM) and scanningtunnel microscopy (STM) observations have been performed on the surfaces of a hydrotalcite (HT) crystal ([Mg 6 Al 2 (OH) 16 ](CO 3 ) 1/2 .Cl.2H 2 O) and HT crystals ion-exchanged with [Fe(CN) 6 ] 3- and [Fe(CN) 6 ] 4- (denoted by HT-[Fe(CN) 6 ] 3- and HT-[Fe(CN) 6 ] 4- , respectively). The AFM image of a HT crystal surface in contact with an aqueous solution of 0.1 M Na 2 SO 4 shows two-dimensional periodicity with the unit lattice of a = 0.31 ± 0.02 nm, b = 0.31 ± 0.02 nm, and α = 58 ± 3°. This corresponds to the lattice made by the external hydroxyl groups on a basal plane. No ion-exchanged anion was observed by the AFM method, indicating that an external anion is so weakly bound to a surface that it is removed under the scanning operation of an AFM tip. The STM image of the same crystal under air shows a two-dimensional lattice with a = 0.75 ± 0.04 nm, b = 1.10 ± 0.03 nm, and α = 70 ± 3°. One bright spot in the image exists at every 1.1 [Mg 6 Al 2 (OH) 16 ] 2+ unit, leading to the conclusion that the spot represents a chloride ion adsorbed on a surface. The STM image of the same crystal at less negative bias voltage exhibits a different two-dimensional lattice with a = 0.62 ± 0.03 nm, b = 0.62 ± 0.03 nm, and α = 65 ± 3°. This is ascribed to the lattice made by the aluminum atoms at the octahedral sites inside a layer. The STM images of HT-[Fe(CN) 6 ] 3- and HT-[Fe(CN) 6 ] 4- crystals in contact with an aqueous solution of 0.1 M Na 2 SO 4 show the two-dimensional lattices of a = 1.43 ± 0.06 nm, b = 1.86 ± 0.06 nm, and α = 90 ± 4° and a = 2.20 ± 0.06 nm, b = 2.20 ± 0.06 nm, and α = 75 ± 3°, respectively. These are ascribed to the molecular layers of [Fe(CN) 6 ] 3- and [Fe(CN) 6 ] 4- on a surface, respectively. The causes for the ordered molecular adsorption are discussed.