Transition metal catalysis plays a leading role in C(sp2)–C(sp2) bond formation through substitution reactions. On the other hand, a similar type of substitution reaction has recently been achieved without the aid of transition-metal catalysts. In this review, recent transition-metal-free coupling reactions of aryl halides with arenes, alkenes, or aryl Grignard reagents are summarized in view of SRN1 reaction.
We here describe a rapid and convenient sample preparation in a single tube for detecting single nucleotide variation based on oligonucleotide ligation assay (OLA) using a biotinylated primer and a set of four different fluorophore-labeled primers. Only one of the fluorophore-labeled primers that was fully complementary to a DNA template was ligated with the biotin-primer by DNA ligase. We isolated the ligated fragments that carried a biotin at the 3′-end by capture with streptavidin-coated magnetic beads. The distinct fluorescence signature of each ligation product coded the single nucleotide differences.
Monoacylation and trifluoromethanesulfonylation of phenolic diols were achieved by the aid of HF–pyridine, whereas diacylation occurred with pyridine alone. Furthermore, HF–pyridine was found to promote the direct conversion of t-butyldimethylsilyl ethers to the corresponding acetates.
A two-step procedure of two-dimensional polymer constructed from benzo[b]trithiophene (BTT) was proposed by electrochemical polymerization and thermal conversion. Electropolymerized BTT oligomer on an electrode was thermally converted to conjugated polymer. Obtained conductive material is found to retain BTT structure by Raman spectra and to extend π conjugation by absorption spectra.
This investigation demonstrated that bicarbonate ions were selectively formed over carbamate in a CO2 absorption process using piperidine and piperazine derivatives based on 13C NMR. Piperidines with methyl or hydroxymethyl substituent at 2 position (PiP-Me and PiP-MeOH) and 2,5-dimethylpiperazine (DM-PiZ) generated the bicarbonate ions as main adducts in reaction with CO2. The absorptions of CO2 by those aqueous amines (PiP-Me and DM-PiZ) were faster than those of MEA (2-aminoethanol).
A bis(hydrosulfido)platinum(II) complex with a bidentate chelate N-heterocyclic carbene ligand was oxidized by O2 to give a linear tetrasulfide complex in the presence of excess hydrogen sulfide and a thiosulfato-bridged dinuclear complex without hydrogen sulfide.
We found that none of twenty natural amino acids quenches the fluorescence of anionic PTP, but phenylalanine, tryptophan, and tyrosine do quench obviously the fluorescence of cationic PFP. The overlaps between the Q-band absorption spectrum of myoglobin, cytochrome c, and horseradish peroxidase and the fluorescence emission spectrum of PTP indicate that the fluorescence quenching of PTP by hemeproteins is via fluorescence resonance energy transfer, not via photoinduced electron transfer.
Oxidative alkenylation of N,N-disubstituted benzamides with alkenes accompanied by regioselective C–H bond cleavage proceeds efficiently in the presence of a Ru/Ag catalyst system together with a copper oxidant. The procedure is also applicable to phenylazoles.
A single-component layered molecular conductor, [Au(ptdt)2] (ptdt: propylenedithiotetrathiafulvalenedithiolate) was prepared. Unlike the single-component molecular metal, [Au(tmdt)2] (tmdt: trimethylenetetrathiafulvalenedithiolate) exhibiting three-dimensional compact molecular packing and antiferromagnetic transition at 110 K, the compressed pellet of the microcrystals of [Au(ptdt)2] exhibited fairly high conductivity and small temperature-independent paramagnetic susceptibility.
Highly diastereoselective reductive coupling reaction was achieved between an aldehyde and a norbornene to afford an alcohol compound using a nickel/phosphine catalyst system in the presence of a reducing agent. The combination of a PCy3 ligand and triethylborane as the reducing agent proved effective for the reaction. A wide range of aldehydes were found to participate in the reaction with high diastereoselectivities.
The structure of nanometer-order sulfuric acid solution in carbon micropores is investigated by large- and small-angle X-ray scattering experiments. The electron radial distribution function of the nanosolution is different from that of bulk solution. The intermolecular structure of nanosolution does not change with fractional filling. These results and the dependency of density fluctuations of the system with fractional filling showed that the nanometer-order sulfuric acid solutions in carbon micropores form a small molecular assembly with a hydration structure at low fractional filling.
LiMnPO4 nanocrystallite-embedded porous carbons were successfully synthesized within a few minutes by a microwave-heating process. The nanocomposites showed higher charge–discharge capacity and better rate capability than bulk-LiMnPO4 particles synthesized in a similar manner without porous carbons.
A novel cytotoxic macrolide biselyngbyolide A (1) was isolated from the marine cyanobacterium Lyngbya sp., collected on Tokunoshima Island, Japan. This macrolide was revealed to be structurally related to biselyngbyaside (2). The gross structure of 1 was elucidated based on the extensive application of 2D NMR techniques. The stereostructure was deduced based on analyses of the NOESY spectrum and CD data. Biselyngbyolide A (1) exhibited strong apoptosis-inducing activity against HeLa S3 cells and HL60 cells.
An expanded porphyrin analogue embedded with binaphthol units provides unidirectional overall helical conformation with hexaanionic N4O4 coordination environment that is suited to support a linear array of three metals.
Nanodisks with uniform height and tunable diameter on the nanometer scale were constructed without any lithographic processes. The disks consisting of an amphiphilic triimide module were formed at the air–water interface in the presence of cyclen as an aqueous shackle and transferred onto substrates by the surface-touching (Langmuir–Schaefer) technique. The 3 nm height of the disks was maintained, whereas the diameter was tunable from 45 to 74 nm by varying surface pressures.
Echinoid-like TiO2 particles were prepared via modified sol–gel process using PVA as a surface-directing agent in acetic acid solution. The surface of echinoid-like TiO2 particle is significantly rough, and the size of the particles is 800–1100 nm. The specific surface area and average pore size of echinoid-like TiO2 particles are 82.81 m2 g−1 and 11.79 nm, respectively. The photocatalytic activity of echinoid-like TiO2 particles was very high compared with P25 due to larger surface area.
A naphthalenediimide derivative 3a carrying TEMPO radical and azobenzene substituent was found to show photoresponsive magnetic as well as FET properties upon illumination. The alteration of its mobility has also been demonstrated by applying magnetic field and hence the FET characteristics of 3a have been proven to be photo- as well as magneto-responsive.
A time-resolved resonance Raman analysis shows that the vinyl stretching band (1629 cm−1) of the O2-binding heme of cytochrome c oxidase shifts to 1627 cm−1 instantaneously upon photolysis of CO and remains for at least 5 ms before reaching the static band (1626 cm−1). Within the same time scale, an intermediate vinyl bending mode of another heme appears at 435 cm−1. These results suggest that both hemes cooperatively control O2 binding by forming an intermediate conformation for effective proton pumping.
Molecular gel-forming glutamide lipid-grafted porous silica particles (Sil-SiDg) are designed and prepared as the stationary phase in high-performance liquid chromatography (HPLC) for molecular shape recognition. It was proven that the glutamide lipids formed a highly oriented structure on the silica surface and showed thermally reversible phase transition like self-assembled molecular gels even on the silica surface. Unprecedented excellent results were achieved in the separation of tocopherols (Vitamin E) using Sil-SiDg as the stationary phase in HPLC analysis.
Ultrathin films of P3HT and P3HT/PCBM prepared on glass and ITO glass substrates by spin-coating were studied by means of highly sensitive absorption spectroscopy. For pristine P3HT films, we discuss the morphology and electronic structure at the interface between the substrate and the P3HT layer. For P3HT/PCBM films, we found that phase separation could be controlled by changing the concentration of the solutions used to prepare the films.
We found that graphite surfaces can be etched by electrochemical reduction in sulfuric acid. Terraces with straight edges crossing with 60°-multiple angles were found on surfaces by AFM observation. It suggests that crystallographic edges can be formed at room temperature in a controlled manner. Layer-by-layer etching of graphene sheets was possible by tuning the etching condition.
Deconjugative esterification of optically active 2-(4-phenylcyclohexylidene)acetic acid (1) and 2-(4-tert-butylcyclohexylidene)acetic acid (4) with an axis of chirality afforded the corresponding β,γ-unsaturated esters 2 and 6, each with a center of chirality. Additionally, a plausible reaction mechanism for the intramolecular chirality transfer is described.
We have successfully observed the ESR signals of radical cations in the thin films of N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine (NPB), typical hole-transport material, for the first time to our best knowledge. In order to characterize the radical cation state, ESR spectra obtained upon chemical doping with iodine are analyzed combined with density functional theory (DFT) calculation. The ESR line width is inversely correlated with doping concentration.
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 which the NCN-pincer Pd complex moieties assemble in a highly oriented manner.
Stable dispersion of chemically reduced graphene oxide (RGO) is prepared by simple noncovalent interaction with hydroxypropyl cellulose (HPC). Prepared RGO/HPC assembly shows temperature-dependent optical modulation below or above lower critical solution temperature (LCST). Different anchoring modes of HPC chains on RGO plates might contribute to the change of LCST for RGO/HPC assembly at different HPC-to-graphene mass ratio.