Studies on functional groups in organosilyl chlorides have focused on their contribution to the resulting structure and morphology of porous hollow polyorganosiloxane microspheres. The silane coupling agents employed included trifunctional (octylsilyl, methylsilyl, and phenylsilyl trichlorides) and bifunctional (dimethyldisilyl dichloride) silanes. These organosilanes participated in sol-gel reactions (hydrolysis and polycondensation) to produce hollow microspheres at the interfaces of aqueous droplets in a water-in-oil emulsion. Phenylsilyl groups contributed to forming smaller spherical hollow particles via an emulsification effect, while dimethyldisilyl groups deformed the hollow shape. Trifunctional methylsilyl groups allowed the formation of a microporous structure with a large surface area (approximately 400 m2/g), where bulky organic groups (octyl and phenyl) buried the micropores to reduce the specific surface area. These bulky groups were removed via oxidative decomposition to transform microporous polymethylsiloxane. Hence, trifunctional methylsilyl groups were key for tailoring microporous hollow spherical organosilica particles via emulsion templated syntheses.
New mixed-valence polyoxometalate (POM)-organic hybrids, i.e., [Na(SO3)2(PrPO3)4MoV4MoVI14O49]5− and [Na(SO3)2(t-BuPO3)4MoV4MoVI14O49]5−, were synthesised and studied using crystallography, solution-phase 31P NMR, and electrochemistry. These species comprise four organic phosphonates bonded to a metal oxide cage. Derivatization was achieved by considering the pKa of the organic phosphonates and sulfite anions that acted as templates for the self-assembly of molybdate with POM. All the clusters were prepared in a water-acetonitrile mixed solvent system by a one-pot procedure and showed multi-step redox cycles, revealing that [Na(SO3)2(RPO3)4MoV4MoVI14O49]5− comprised a unique set of covalently grafted POM-organic hybrids with high redox activity.
Nanographene with various molecular sizes was synthesized and incorporated into the size-controlled pores of super-microporous silica (SMPS). It was found that when the pore diameter of the SMPS matched the molecular size of the nanographene, the fluorescence quantum yield was greatly enhanced. Furthermore, co-adsorption of water molecules improved the quantum yield. This improvement is attributed to a suppression of the interaction between the nanographene and silica walls, which lowers the quantum yield. Since nanographene is insoluble in water, it becomes surrounded by water molecules, almost like in aqueous solution. Finally, highly fluorescent solid materials were obtained by incorporating nanographene into SMPS.
Cyclodextrin (CD) electrospinning is a unique technique for fabricating functional fiber materials without polymer additives. Here, we present separate fabrication of amorphous and crystalline CD nonwovens by precisely controlling solvent evaporation during electrospinning. This method would allow large-scale production of CD fibers with tuned crystallinity.
Water-soluble CuInS2 (CIS) quantum dots (QDs) were hydrothermally prepared in the presence of N-acetyl-L-cysteine (NAC) as a stabilizer, and the optimal hydrothermal synthetic conditions for NAC-capped CIS QDs were investigated. The photoluminescence (PL) quantum yield (QY) of the CIS QDs synthesized under optimal conditions was 4%, which was comparable with the highest QY reported for water-soluble CIS core QDs. The introduction of a ZnS shell produced CIS/ZnS core/shell QDs and further increased the PL QY to 30%. Furthermore, bilayer structures consisting of Au nanoparticles and CIS/ZnS QDs were fabricated using a layer-by-layer method to enhance the PL of the CIS/ZnS QDs on the basis of the localized surface plasmon resonance of Au nanoparticles.
The synergistic merger of a thiazolium N-heterocyclic carbene (NHC) catalyst and a palladium–bisphosphine catalyst enabled the allylation of aldehyde acyl anions using allylic carbonates as electrophiles. Owing to the mildness of the reaction conditions, various functional groups were tolerated in the substrates.
Metal clusters composed of several to several tens of atoms, in general, can be regarded as molecules rather than small nanoparticles. That is, a cluster bearing a different number of atoms is a “different molecule” showing different properties. Therefore, at least ultraprecision control of the size at the one-atom level is a requirement to study and fully utilize clusters. Although these substances sometimes exhibit exceptionally high catalytic activity relative to nanoparticles, highly demanding synthesis is obstructing their application. In this account, we will explain the progress of cluster supported catalyst synthesis technology in recent years and the possibility of large-scale precision synthesis.
Magnetic field induced Sagnac interference was observed for the COOH modified iron oxide magnetic nanoparticles (MNPs) dispersed in water. The effect of cationic surfactants showing agglomeration and deagglomeration of the MNPs was clearly detected by the phase shift due to the magnetic orientation of MNPs. The observed phase shifts were discussed by using Langevin parameters.
Techniques for selective deposition of conductive inks, in particular metal nano-particulate inks, by using self-assembling monolayers (SAMs) mostly involve control of wettability with highly hydrophobic compounds. In this work, we focused on electrostatic interaction of metal nano-particles and investigated the influence of functional groups on the substrate upon selective deposition of metal nanoparticles. Surface modifiers bearing four kinds of functional groups (-OH, -NH2, -SH, -COOH) protected by a photodegradable 2-nitrobenzyl ester were synthesized and used to form SAMs on an indium tin oxide-coated glass substrate. UV-irradiation through a photomask generated the respective functional group in exposed regions. High-quality patterning of aqueous Au nano-particulate ink, which is negatively charged, was successfully achieved by spin coating onto amine-bearing SAMs. These results suggest the feasibility of micro-scale patterning based on electrostatic interaction between Au nano-particles and free amino groups introduced onto the substrate by photoirradiation-induced deprotection of surface-modifying agents.
A novel selective and sensitive chemosensor, (E)-1-((((1H-benzo[d]imidazol-2-yl)methyl)imino)methyl)naphthalen-2-ol (BIN), was developed for fluorescence detection of Zn2+. The compound BIN acts as a fluorescent “turn-on” detector for Zn2+. The limit of detection (2.26 µM) for zinc ion is well below the WHO standard (76.0 µM). Probe BIN can be chemically reversible with ethylenediaminetetraacetic acid (EDTA). The binding mechanism of BIN with zinc ion was demonstrated by fluorescence, UV-visible, electrospray ionization mass spectroscopy, 1H NMR titration and calculations. Importantly, probe BIN could be applied to determine zinc ion in water samples and living zebrafish.
p-tert-Butylcalixarenediphosphonic acid (L) extracts Zr(IV) and Hf(IV) from aqueous HCl, H2SO4, and H3PO4. In the extraction from aqueous HCl of different concentrations, the percentage of extraction (E%) of Hf(IV) decreases notably with an increase in acid concentration (96% at 0.5 M HCl and 12% at 7 M HCl), whereas the E% of Zr(IV) remains at a moderate level (90% at 0.5 M HCl and ∼60% at 7 M HCl). Thus, selective extraction of Zr(IV) over Hf(IV) is achieved from high-concentration HCl solutions. The separation factor (SZr) reaches 24 when using two molar equiv of L to Zr(IV) at 7 M HCl. Mechanistic studies indicate that L extracts Zr(IV) from high-concentration HCl solutions by a solvation mechanism by forming a 1:1 complex, LZrCl4. Back extraction of Zr(IV) proceeds quantitatively by treating the organic phase with 5 M H3PO4 after the extraction of Zr(IV).
1,3-Dihydrothieno[3,4-a]- and 1,3,8,10-tetrahydrodithieno[3,4-a;3′4′-m]-HPHACs were prepared by the successive SNAr reactions of hexafluorobenzene with 1,3-dihydrothieno[3,4-c]pyrrole and 3,4-dihexylpyrrole followed by Scholl oxidation. Oxidation of 1,3-dihydrothieno-fused HPHACs with excess amounts of iodine at room temperature quantitatively gave the corresponding dication bis(triiodide)s. Further dehydrogenative oxidation of the dicationic species with iodine giving a thieno[3,4-a]HPHAC dication was achieved at a higher temperature by removing hydrogen iodide generated during the reaction. Neutral species of thieno[3,4-a]HPHAC could not be isolated.
2D nanomaterials with atomic-/molecular-level thickness are of great interest due to their unique physicochemical and functional properties derived from their planar morphologies. In vitro enzymatic synthesis of cellulose oligomers is an attractive approach for crafting 2D cellulose assemblies with tailored surface functionality. In this study, the templated synthesis of gold nanoparticles (AuNPs) was demonstrated on surface-aminated 2D cellulose assemblies prepared via enzymatic reaction. Gold precursor effectively adsorbed to the surface amino groups and was subsequently reduced for AuNP production via lateral diffusion-based nucleation and subsequent growth processes on the assemblies. The immobilized AuNPs on the assemblies showed high catalytic activities toward a model hydrogenation reaction. The cellulose-based 2D nanomaterials with molecularly designable surface functionality open a new avenue for controlled synthesis and immobilization of inorganic nanoparticles.
Incompletely condensed polyhedral oligomeric silsesquioxanes (IC-POSS) are promising building blocks for the development of organic-inorganic hybrid materials. Pd-catalyzed arylation of heptaphenyl IC-POSS has been developed to introduce various substituents on to the open moieties without using highly moisture-sensitive chlorosilane derivatives. The substituents drastically affected the thermal behavior of the corresponding IC-POSSs. The obtained IC-POSSs were well dispersed in poly(methyl methacrylate) (PMMA) matrices to tune the thermal and optical properties of their composite films.
Chemical labeling of proteins with synthetic molecular probes offers the possibility to probe the functions of proteins of interest in living cells. However, the methods for covalently labeling targeted proteins using complementary peptide tag-probe pairs are still limited, irrespective of the versatility of such pairs in biological research. Herein, we report the new CysHis tag-Ni(II) probe pair for the specific covalent labeling of proteins. A broad-range evaluation of the reactivity profiles of the probe and the CysHis peptide tag afforded a tag-probe pair with an optimized and high labeling selectivity and reactivity. In particular, the labeling specificity of this pair was notably improved compared to the previously reported one. This pair was successfully utilized for the fluorescence imaging of membrane proteins on the surfaces of living cells, demonstrating its potential utility in biological research.
Di(acenaphtho)-fused BODIPYs with four electron-withdrawing N,N-dimethylcarbamoyl groups were obtained by complexation of the corresponding dipyrrins, which were also proven to be a stable deep-red dye.
The pyrrole-containing chiral spiro π-conjugated compounds were successfully synthesized from 10,10′-spirobi[indeno[1,2-b]benzothiophene] 5,5-dioxide and 5,5,5′,5′-tetraoxide via a sequential inter/intramolecular nucleophilic aromatic substitution with arylamines. The enantiopure ones were also prepared from the enantiopure substrates. UV-vis absorption and photoluminescence spectroscopies and theoretical calculations revealed that the replacement of thiophene unit(s) of 10,10′-spirobi[indeno[1,2-b]benzothiophene] with pyrrole unit(s) has a great impact on photophysical properties. The pyrrole-containing chiral spiro π-conjugated compounds exhibited circularly polarized luminescence with a relatively large dissymmetry factor.