Search

The first enantioselective carbometalation reaction of azabicycloalkenes has been achieved by iron catalysis to in situ form optically active organozinc intermediates, which are amenable to further synthetic elaborations. The observed chiral induction, along with the DFT and XAS analyses, reveals the direct coordination of the chiral phosphine ligand to the iron centre during the carbon–carbon and carbon–metal bond forming step. This new class of iron-catalysed asymmetric reaction will contribute to the synthesis and production of bioactive molecules.

Laying-down gold nanorods (GNRs) of a monolayer immobilized on a solid substrate was realized with a hybrid method, a combination of three elemental technologies: surface modification, electrophoresis, and solvent evaporation. The self-assembly of CTAB-protected GNRs in the solution was induced by 0.05 mM of EDTA. The assembled GNRs were deposited in a laying-down form on the solid surface during the hybrid method. The final coverage was over 71% on the substrate with an area larger than 0.6 cm2. The spacing between the sides of the GNRs was fixed to be 4.6 ± 0.9 nm by the thermal annealing-promoted crystalline packing of the bilayer of CTAB salt-bridged with EDTA. The obtained laying-down GNRs of a monolayer on the gold substrate show a small shift of the transverse LSPR around 550-570 nm (with a width of around 100 nm) and a large red shift of the longitudinal LSPR to be 900-1050 nm (with a width of 500 nm), because of the strong electromagnetic coupling between the GNRs and gold substrate. Therefore it can be used in a wide range of wavelengths for surface enhanced Raman spectroscopy (SERS) applications. The film has a high enhancement factor with 105 for R6G.

The first iron-catalyzed cross-coupling reaction of alkyl halides with alkylaluminum reagents (alkyl–alkyl Negishi coupling) is developed using an iron/bisphosphine catalyst system. The reaction shows high functional group tolerance: various primary alkyl halides possessing a non-protected indole, carboxyl, or hydroxy group are coupled with primary alkylaluminum reagents in good yields. Potassium fluoride plays a key role to promote the reaction by generating an aluminate species, which facilitates the transmetalation between the organoaluminum and the iron catalyst.

The first iron-catalysed cross coupling of propargyl electrophiles with lithium alkenylborates has been developed. Various propargyl electrophiles can be cross-coupled with lithium (E)- or (Z)-alkenylborates in a stereospecific manner to afford the corresponding 1,4-enynes in good to excellent yields. The reaction features high SN2-type regioselectivity and functional group compatibility.

We have developed novel surface plasmon resonance (SPR) sensor chips whose surfaces bear newly synthesized functional self-assembled monolayer (SAM) anchoring lignin through covalent chemical bonds. The SPR sensor chips are remarkably robust and suitable for repetitive and accurate measurement of noncovalent lignin–peptide interactions, which is of significant interest in the chemical or biochemical conversion of renewable woody biomass to valuable chemical feedstocks. The lignin-anchored SAMs were prepared for the first time by click chemistry based on an azide–alkyne Huisgen cycloaddition: mixed SAMs are fabricated on gold thin film using a mixture of alkynyl and methyl thioalkyloligo(ethylene oxide) disulfides and then reacted with azidated milled wood lignins to furnish the functional SAMs anchoring lignins covalently. The resulting SAMs were characterized using infrared reflection–absorption, Raman, and X-ray photoelectron spectroscopies to confirm covalent immobilization of the lignins to the SAMs via triazole linkages and also to reveal that the SAM formation induces a helical conformation of the ethylene oxide chains. Further, SPR measurements of the noncovalent lignin–peptide interactions using lignin-binding peptides have demonstrated high reproducibility and durability of the prepared lignin-anchored sensor chips.

We have developed a novel diastereoselective iron-catalyzed cross-coupling reaction of various glycosyl halides with aryl metal reagents for the efficient synthesis of aryl C-glycosides, which are of significant pharmaceutical interest due to their biological activities and resistance toward metabolic degradation. A variety of aryl, heteroaryl, and vinyl metal reagents can be cross-coupled with glycosyl halides in high yields in the presence of a well-defined iron complex, composed of iron(II) chloride and a bulky bisphosphine ligand, TMS-SciOPP. The chemoselective nature of the reaction allows the use of synthetically versatile acetyl-protected glycosyl donors and the incorporation of various functional groups on the aryl moieties, producing a diverse array of aryl C-glycosides, including Canagliflozin, an inhibitor of sodium-glucose cotransporter 2 (SGLT2), and a prevailing diabetes drug. The cross-coupling reaction proceeds via generation and stereoselective trapping of glycosyl radical intermediates, representing a rare example of highly stereoselective carbon-carbon bond formation based on iron catalysis. Radical probe experiments using 3,4,6-tri-O-acetyl-2-O-allyl-α-d-glucopyranosyl bromide (8) and 6-bromo-1-hexene (10) confirm the generation and intermediacy of the corresponding glycosyl radicals. Density functional theory (DFT) calculations reveal that the observed anomeric diastereoselectivity is attributable to the relative stability of the conformers of glycosyl radical intermediates. The present cross-coupling reaction demonstrates the potential of iron-catalyzed stereo- and chemoselective carbon-carbon bond formation in the synthesis of bioactive compounds of certain structural complexity.

A series of norvaline (Nva) peptides possessing ONO-pincer ruthenium complexes, Boc-{l-[Ru(pydc)(t-Bu-terpy)]Nva}n-OMe (n = 2–6), were synthesized successfully by solution-phase peptide synthesis. Efficient coupling of equimolar amounts of N-free Ru-bound norvaline peptides, H-{l-[Ru(pydc)(t-Bu-terpy)]Nva}n-OMe, and C-free Ru-bound norvaline, Boc-l-[Ru(pydc)(t-Bu-terpy)]Nva-OH, was achieved by using the 2-chloro-4,6-dimethoxy-1,3,5-triazine-based method. Structural analysis by means of CD and NMR spectroscopy revealed the formation of stable helical conformations in peptides more than three residues.

Chapter 4 introduces programmable metal array fabrication based on metalated amino acids and peptides, where various transition-metal complexes are covalently conjugated to the α-side chains of amino acids and peptides. It starts by explaining what metalated amino acids and peptides are including a brief history, classification, and their application. It then presents syntheses of a series of Pd- and Pt-complex bound glutamines and Pd- and Ru- complex bound norvalines and their sonication-induced self-assembly properties into a supramolecular gel along with the formation of well-regulated metal arrays. By the end of this chapter, applications of the supramolecular aggregates of metalated amino acids toward a cyclization reaction of alkynes, a cross-coupling reaction, and oxidations of alcohols and methoxybenzenes in aqueous conditions are explained. A detailed discussion of the mechanism of sonication-induced self-assembly and precise structural study of the supramolecular aggregates are included to show the effectiveness of metalated amino acids- and peptide-based metal array fabrication to design advanced smart materials based on bioorganometallic compounds.

Two (ONO pincer)ruthenium‐complex‐bound norvalines, Boc−[Ru(pydc)(terpy)]Nva−OMe (1; Boc=tert‐butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc−[Ru(pydc)(tBu‐terpy)]Nva−OMe (5), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single‐crystal X‐ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high‐temperature conditions enabled us to perform selective transformations of the N‐Boc and C−OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru‐bound norvaline, n‐C11H23CO−l‐[Ru(pydc)(terpy)]Nva−NH‐n‐C11H23 (l‐4) was found to have excellent self‐assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru‐bound norvaline l‐1 exhibited a higher catalytic activity for the oxidation of alcohols by H2O2 than parent complex [Ru(pydc)(terpy)] (11 a).

The self-assembled monolayer (SAM)-modified metallic nanoparticles (MNPs) often exhibit improved chemoselectivity in various catalytic reactions by controlling the reactants&rsquo, orientations adsorbed in the SAM, however, there have been a few examples showing that the reaction rate, i.e., catalytic activity, is enhanced by the SAM-modification of MNP catalysts. The critical parameters that affect the catalytic activity, such as the supports, nanoparticle size, and molecular structures of the SAM components, remain uninvestigated in these sporadic literature precedents. Here, we report the mechanistic investigation on the effects of those parameters on the catalytic activity of alkanethiolate SAM-functionalized gold nanoparticles (AuNPs) toward silane alcoholysis reactions. The evaluation of the catalytic reaction over two-dimensionally arrayed dodecanethiolate SAM-functionalized AuNPs with different supports revealed the electronic interactions between AuNPs and the supports contributing to the rate enhancement. Additionally, an unprecedented size effect appeared&mdash, the AuNP with a 20 nm radius showed higher catalytic activity than those at 10 and 40 nm. Infrared reflection&ndash, absorption spectroscopy revealed that the conformational change of alkyl chains of the SAM affects the entrapment of reactants and products inside the SAM, and therefore brings about the acceleration effect. These findings provide a guideline for further applying the SAM-functionalization technique to stereoselective organic transformations with designer MNP catalysts.

High-yielding cross-coupling reactions of various combinations of aryl chlorides and alkyl Grignard reagents have been developed by using an iron(III) fluoride/1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene (SIPr) catalyst composite. The iron(III) fluoride/SIPr-catalyzed aryl–alkyl coupling demonstrates unprecedented scope for both aryl chlorides and alkyl Grignard reagents, thus enabling the first efficient coupling of electron-rich (deactivated) aryl chlorides with alkyl Grignard­ reagents without β-hydrogens. The present reaction is also effective for diverse alkyl Grignard reagents such as (trimethylsilyl)methyl, primary, and secondary alkyl Grignard reagents.

In the molecule of (2,7-dimethoxynaphthalen-1-yl)(3-fluorophenyl)methanone, C19H15FO3, (I), the dihedral angle between the plane of the naphthalene ring system and that of the benzene ring is 85.90 (5)°. The molecules exhibit axial chirality, with either anR- or anS-stereogenic axis. In the crystal structure, each enantiomer is stacked into a columnar structure and the columns are arranged alternately to form a stripe structure. A pair of (methoxy)C—H...F hydrogen bonds and π–π interactions between the benzene rings of the aroyl groups link anR- and anS-isomer to form a dimeric pair. These dimeric pairs are piled up in a columnar fashion through (benzene)C—H...O=C and (benzene)C—H...OCH3hydrogen bonds. The analogous 1-benzoylated compound, namely (2,7-dimethoxynaphthalen-1-yl)(phenyl)methanone [Katoet al.(2010).Acta Cryst.E66, o2659], (II), affords three independent molecules having slightly different dihedral angles between the benzene and naphthalene rings. The three independent molecules form separate columns and the three types of column are connected to each otherviatwo C—H...OCH3hydrogen bonds and one C—H...O=C hydrogen bond. Two of the three columns are formed by the same enantiomeric isomer, whereas the remaining column consists of the counterpart isomer. In the case of the fluorinated 1-benzoylated naphthalene analogue, namely (2,7-dimethoxynaphthalen-1-yl)(4-fluorophenyl)methanone [Watanabeet al.(2011).Acta Cryst.E67, o1466], (III), the molecular packing is similar to that of (I),i.e.it consists of stripes ofR- andS-enantiomeric columns. A pair of C—H...F hydrogen bonds betweenR- andS-isomers, and C—H...O=C hydrogen bonds betweenR(orS)-isomers, are also observed. Consequently, the stripe structure is apparently induced by the formation ofR...Sdimeric pairs stacked in a columnar fashion. The pair of C—H...F hydrogen bonds effectively stabilizes the dimeric pair ofR- andS-enantiomers. In addition, the co-existence of C—H...F and C—H...O=C hydrogen bonds makes possible the formation of a structure with just one independent molecule.

Solution-phase synchrotron X-ray absorption spectroscopy (XAS) is a powerful tool for structural and mechanistic investigations of paramagnetic organoiron intermediates in solution-phase reactions. For paramagnetic organotransition metal intermediates, difficulties are often encountered with conventional NMR- and EPR-based analyses. By using solution-phase XAS, we succeeded in identifying the organoiron species formed in the reaction of iron bisphosphine with mesitylmagnesium bromide, MesMgBr, and 1-bromodecane in a [FeX2(SciOPP)]-catalyzed Kumada–Tamao–Corriu (KTC)-type cross-coupling reaction. X-ray absorption near-edge structure (XANES) spectra showed that the resulting aryliron species possessed a divalent oxidation state. Extended X-ray absorption fine structure (EXAFS) demonstrated that the solution-phase molecular geometries of these species are in satisfactory agreement with the crystallographic geometries of [FeIIBrMes(SciOPP)] and [FeIIMes2(SciOPP)]. By combining GC-quantitative analysis and solution-phase XAS, the cross-coupling reactivities of these aryliron species were successfully investigated in the reaction with 1-bromodecane under stoichiometric and catalytic conditions., 放射光施設SPring-8で鉄触媒の作用を直接観察. 京都大学プレスリリース. 2015-03-16.

A series of two-dimensional (2D) arrays of Au-core/Ag-shell nanoparticles with fixed sub-3 nm gap distance was obtained on 1 cm2 substrates. All 2D arrays resulted in homogeneous and dense monolayers of nanoparticles thanks to our original hybrid deposition method based on self-assembly. Midnanosized gold nanoparticles were used as the core and Ag-shell with different thicknesses were grown to tune the LSPR to around 633 nm. The resulting SERS substrates enhanced Raman signal by up to about 107 with remarkable spatial uniformity. Our SERS substrate is highly promising as a practical SERS-based sensor substrate.

The title compound, C24H16O4, crystallized with two independent molecules in the asymmetric unit. Both carbonyl groups in these molecules form intramolecular O—H...O=C hydrogen bonds with neighbouring hydroxy groups, affording six-membered cyclic structures. In the crystal, dimeric aggregates arise from two intermolecular O—H...O=C hydrogen bonds between both independent molecules, forming head-to-tail square-shaped cyclic ...O...H...O...H... hydrogen bonds. These dimeric aggregates are connected into layers in thebcplane by intermolecular (naphthalene)C—H...O=C interactions. On the other hand, the analogous compound bearing methoxy groups at the 2- and 7-positions of the naphthalene ring, namely 1,8-dibenzoyl-2,7-dimethoxynaphthalene [Nakaemaet al.(2008).Acta Cryst.E64, o807], forms a three-dimensional molecular networkviaC—H...O=C and π–π interactions between the benzoyl groups. These results show that the intramolecular O—H...O=C hydrogen bonds in the title compound control the orientations of the benzoyl groups and thus promote the formation of the cyclic intermolecular O—H...O=C interactions involving the same donor and acceptor groups in pairs of molecules.

A PCP pincer palladium-complex-bound norvaline, Boc- l -[Pd]Nva-OMe, was synthesized and fully characterized by NMR, FT-ICR-MS, and X-ray crystallography. Selective N- and C-terminus transformations of Boc- l -[Pd]Nva-OMe were performed by conventional deprotection–condensation procedures to afford lipophilic palladium-bound norvaline derivatives without metal detachment. The N-/C-bisfunctionalized palladium-bound norvaline showed self-assembly properties, as evidenced by supramolecular gel formation. The catalytic activity of the supramolecular gel was assessed in the 1,4-conjugate addition of phenylboronic acid.

The NCN-pincer Pd-complex-bound norvalines Boc-D/L-[PdCl(dpb)]Nva-OMe (1) were synthesized in multigram quantities. The molecular structure and absolute configuration of 1 were unequivocally determined by single-crystal X-ray structure analysis. The robustness of 1 under acidic/basic conditions provides a wide range of N-/C-terminus convertibility based on the related synthetic transformations. Installation of a variety of functional groups into the N-/C-terminus of 1 was readily carried out through N-Boc- or C-methyl ester deprotection and subsequent condensations with carboxylic acids, R(1)COOH, or amines, R(2)NH2 , to give the corresponding N-/C-functionalized norvalines R(1)-D/L-[PdCl(dpb)]Nva-R(2) 2-9. The dipeptide bearing two Pd units 10 was successfully synthesized through the condensation of C-free 1 with N-free 1. The robustness of these Pd-bound norvalines was adequately demonstrated by the preservation of the optical purity and Pd unit during the synthetic transformations. The lipophilic Pd-bound norvalines L-2, Boc-L-[PdCl(dpb)]Nva-NH-n-C11H23, and L-4, n-C4H9CO-L-[PdCl(dpb)]Nva-NH-n-C11H23, self-assembled in aromatic solvents to afford supramolecular gels. The assembled structures in a thermodynamically stable single crystal of L-2 and kinetically stable supramolecular aggregates of L-2 were precisely elucidated by cryo-TEM, WAX, SAXS, UV/Vis, IR analyses, and single-crystal X-ray crystallography. An antiparallel β-sheet-type aggregate consisting of an infinite one-dimensional hydrogen-bonding network of amide groups and π-stacking of PdCl(dpb) moieties was observed in the supramolecular gel fiber of L-2, even though discrete dimers are assembled through hydrogen bonding in the thermodynamically stable single crystal of L-2. The disparate DSC profiles of the single crystal and xerogel of L-2 indicate different thermodynamics of the molecular assembly process.

The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-L-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity.

The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-L-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity.

Novel Pt-complex-bound oligo(glutamic acid)s were synthesized by two different routes: postmetalation of peptides and stepwise conjugation of metalated amino acids. Sonication-induced supramolecula...

offering a practical alternative to conventional nickel- and palladium-catalyzed aryl-alkyl couplings

In this research, we report the development, characterization and application of various plasmonic substrates (with localized surface plasmon resonance wavelength tunable by gold nanoparticle size) for two-photon absorption (TPA)-induced photodimerization of an anthracene derivative, anthracene carboxylic acid, in both surface and solution phase under incoherent visible light irradiation. Despite the efficient photoreaction property of anthracene derivatives and the huge number of publications about them, there has never been a report of a multiphoton photoreaction involving an anthracene derivative with the exception of a reverse photoconversion of anthracene photodimer to monomer with three-photon absorption. We examined the progress of the TPA-induced photoreaction by means of surface-enhanced Raman scattering, taking advantage of the ability of our plasmonic substrate to enhance and localize both incident light for photoreaction and Raman scattering signal for analysis of photoreaction products. The TPA-induced photoreaction in the case of anthracene carboxylic acid coated 2D array of gold nanoparticles gave different results according to the properties of the plasmonic substrate, such as the size of the gold nanoparticle and also its resultant optical properties. In particular, a stringent requirement to achieve TPA-induced photodimerization was found to be the matching between irradiation wavelength, localized surface plasmon resonance of the 2D array, and twice the wavelength of the molecular excitation of the target material (in this case, anthracene carboxylic acid). These results will be useful for the future development of efficient plasmonic substrates for TPA-induced photoreactions with various materials.

The dimerization reactions of 2-bromo-3,5,6-trimethyl-1,4-benzoquinone have been examined. 2,2′-Dimeric benzoquinone was prepared via a Stille-type homocoupling, whereas an oxepin was formed by the...

An NCN-pincer Pd-complex-bound norvaline-based supramolecular gel showed efficient catalytic activities for the intramolecular addition–cyclization of alkynoic acid and phenol derivatives in water ...

Novel NCN-pincer Pd-complex-bound norvaline derivatives were synthesized. The N- and C-termini-alkylated Pd–norvalines spontaneously assemble into fibrous aggregates to form supramolecular gels, in...

The title molecule, C44H30O8, lies about a crystallographic inversion centre located at the centre of the central benzene ring. The benzene rings in the benzoyl and the terephthalate units make dihedral angles of 67.05 (7)° and 57.57 (7)°, respectively, with the naphthalene ring system. There is an intramolecular C—H...O interaction between the ketonic carbonyl O atom and an H atom on the naphthalene ring system. In the crystal, C—H...O interaction of the benzene ring in the benzoyl group and weak C=O...π interaction [O...centroid = 3.375 (2) Å] of the naphthalene ring with the O atom in the ketonic carbonyl group are observed. These interactions form layers parallel to the bc plane.

Boron-modified pyrrole-based anion receptors (catechol–boron and diphenylboron dipyrrolyldiketone derivatives) formed planar receptor–anion complexes, leading to charge-by-charge assemblies with planar cations, as in the corresponding difluoroboron derivative.

Surface enhanced Raman scattering (SERS) is recognized as an extremely powerful technique for highly sensitive and spatially resolved detection. This technique takes advantage of the strong near-field light induced by metallic nanostructures to enhance the weak Raman signal of the analyte up to 14 orders of magnitude. Up to now, research on SERS substrates focused on two different approaches, the first relies on top-down techniques, such as lithography, and allows good control of optical properties of the device but has huge limits concerning the scalability of the substrate, which is usually limited a sub millimeters in size; the second relies on bottom-up techniques and usually cannot guarantee high enhancement factor (due to low density of metallic nanostructures) and good reproducibility and is limited to small-size (diameter < 20 nm) nanoparticles. In order to overcome the main issues of the common SERS substrates, we developed a SERS substrate which shows both good control of optical properties and good reproducibility.

The need for environmentally sustainable sources of energy has driven new momentum to the research for materials that may allow efficient solar water splitting. Titania is a well studied material for water splitting since the discovery by Honda and Fujishima [1] but its large bandgap limits its use for solar applications. In the past various approaches have been tried up to now to increase the photocatalytic activity of titania, but all present major disadvantages. As an idea, recently metallic nanoparticles came to be recognized as good candidate to improve the visible light activity of titania, due to their interesting chemical and optical properties. In this work, we focused on the latter to take advantage of the intense near-field light that is originated near metallic nanoparticles when their localized surface plasmon resonances (LSPRs) are excited by incident light. This intense near-field light is deemed to induce two-photon absorption (TPA) in the titania nanocrystals deposited on the top of the gold nanoparticles (AuNPs) provided that the LSPR of the array corresponds to twice the wavelength of the titania bandgap.

A xerogel derived from the supramolecular gel of NHC-pincer Pd-complex-bound norvaline shows high catalytic activity for the intramolecular addition-cyclization of alkynoic acid and phenol derivatives in water furnishing ene-lactones in good to excellent yields.

An unprecedented substrate-selective catalytic enhancement effect of an alkanethiol-self-assembled monolayer (SAM) on Au nanoparticles (AuNPs) is reported. In the supported 2D-array of AuNPs, the alkanethiol-SAM acts as a protein-like soft reaction space in which the substrate molecules are encapsulated through non-covalent intermolecular hydrophobic interactions, and thus catalytic reactions are accelerated at AuNP surfaces.

A new type of Pt-complex-bound amino acid was synthesized by condensation of a cyclometalated Pt complex with the side-chain residue of N- and C-alkylated glutamic acid. Self-assembly of the Pt-bound lipophilic amino acid afforded a supramolecular gel in organic solvents, which comprised fibrous lamellar aggregates that supported a highly oriented Pt array.

A novel DNA base-pairing beta-hairpin peptide involving intramolecular hydrogen bonds for induction of beta-hairpin secondary structure and intermolecular complementary hydrogen bonds between thymine and diaminopyridine for molecular recognition has been synthesized.

The title compound, [Pt(C(15)H(18)NO(2)S)Cl], was obtained by the cyclo-metallation reaction of cis-bis-(benzonitrile)dichlorido-platinum(II) with N-benzyl-idene-l-methio-nine allyl ester in refluxing toluene. The Pt(II) atom has a square-planar geometry and is tetra-coordinated by the Cl atom and the C, N and S atoms from the benzyl-idene methio-nine ester ligand. In the crystal structure, the S atoms show opposite chiral configurations with respect to the α-carbon of the methio-nine, reducing steric repulsion between the methyl and allyl ester groups.

Densely arraying gold nanoparticles (AuNPs) immobilized on substrates is still a challenge. For the arraying, surface modification of AuNPs with alkanethiols is a key technology. However, if the particle size is larger than 20 nm, short-chain alkanethiols have very weak interparticle interaction such that self-assembly is not realized, whereas long-chain alkanethiols have very strong interaction such that self-aggregation is induced in solution. One solution is their combination. Eventually, a mixture gave a dense array of 55 nm AuNPs on an ITO substrate with a coverage of approximately 80%. Our approach provides high-performance plasmonic optics with a resonance wavelength of more than 700 nm.

Two-dimensional arrays of gold nanoparticles (AuNPs) as localized surface plasmon-resonant (LSPR) optics on a transparent conductive layer of indium–tin-oxide (ITO) were successfully fabricated. The typical surface coverage of the 10 nm sized AuNPs is over 87% for on ITO film roughness of ±0.2 nm. The LSPR wavelength is tunable in the range of 622–905 nm. By adjusting the LSPR wavelength to 905 nm at peak, two-photon photochromic reaction of diarylethene derivative in solution phase was demonstrated with irradiation by an incoherent near-infrared light in the range of 0.017–0.033 W/cm2 instead of a laser, thanks to the AuNP two-dimensional array.

In the mol­ecule of the title compound, C28H22F2O4, the benzoyl groups are aligned almost anti­parallel and the fluorobenzene rings form a dihedral angle of 14.12 (7)°. The dihedral angles between the 2,7-dieth­oxy­naphthalene ring system and the benzene rings are 70.00 (4) and 67.28 (4)°. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯F hydrogen bonds, forming layers parallel to the ab plane. The layers are further connected by π–π inter­actions [centroid–centroid distances of 3.6115 (10) Å] into a three-dimensional structure.

Pd- and Pt-bound bis-metalated peptides were synthesised by the condensation of Pd- or Pt-aldimine-complex-bound glutamic acids to afford the four possible metal isomers of bis-Pd and bis-Pt-homometalated dipeptides and PdPt- and PtPd-heterometalated dipeptides without metal disproportionation. Ultrasound-induced self-assembly of these bis-metalated peptides proceeded effectively to afford supramolecular gels that displayed well-ordered metal arrays. The formation of parallel β-sheet type aggregates through interpeptide amide-amide hydrogen bonding was confirmed by IR, scanning electron microscopy (SEM), and synchrotron X-ray diffraction analyses (WAXS and SAXS). The mechanism of the ultrasound-induced self-assembly of the metalated dipeptides was elucidated via kinetic and association experiments by (1)H NMR, in which ultrasound-triggered dissociation of intramolecular hydrogen bonds between the chloride ligands of the Pd- and Pt-complexes and amides initially occurred. This was followed by the formation of intermolecular amide-amide hydrogen bonds, which afforded the corresponding oligomeric peptide self-assembly as the nucleus for supramolecular aggregation. The observed first-order relationship of the gelation rate versus the sonication frequency suggested that the microcavitation generated under sonication conditions acted as a crucial trigger and provided a reaction field for efficient self-assembly.