We revealed the effects of the substituents in ligands on properties of Phebox-aluminum complexes. The substituents at the 4-position of Phebox ligands effectively influenced the Lewis acidity via the conjugation between the vacant orbital on the Al atom and π* orbital of the benzene ring, which is supported by DFT calculation. The catalytic activity was also tuned, and a series of substituted Phebox-Al(ClO4)2 effectively catalyzed hydroboration of benzaldehyde. In addition, an unexpected photocatalytic activity of Phebox-Al complexes was found and applied to the hydrodebromination of a 4-bromo benzoic ester.
Linear polysiloxanes were synthesized by using organometallic carboxylic acid catalysts containing tin, zinc, or iron. By optimizing the amount of catalyst and the reaction temperature, polysiloxanes could be synthesized from dialkoxysilanes linked with vinyl monomers by the thiol–ene reaction. Furthermore, cross-linked polysiloxanes could be formed through interactions between the catalyst and the carboxylic acid in the monomer side chain.
Upconverted circularly polarized luminescence (UC-CPL) is coined by combining two individual concepts of photon upconversion (UC) and circularly polarized luminescence (CPL). It has exhibited great performance and potential applications in various fields, arousing enormous attention from scientists. The emergence, amplification and modulation of UC-CPL can be adjusted through regulation of the UC process and assembled state of emitters. Benefitting from the abundant upconverted photoluminescence mechanisms, we can flexibly build UC-CPL systems with distinct properties. In addition, based on different photophysical processes, the circular polarization of some UC-CPL can be promoted. Furthermore, the practical application of UC-CPL has been confirmed in enantioselective photopolymerization. Thus, in this review, we will briefly highlight the recent development and advances of UC-CPL. We envisage providing a guide for the development of those remarkable chiroptical materials.
Upconverted circularly polarized luminescence (UC-CPL), with great application prospects, is coined by combining two individual concepts of photon upconversion (UC) and circularly polarized luminescence (CPL). Benefitting from the abundant UC mechanisms, we can flexibly build UC-CPL systems. Moreover, CPL can be improved in some UC photophysical processes. Here, we briefly highlight review the recent development and advances of UC-CPL.
Catalytic enantioselective defluorinative functionalization of easily accessible allylic fluorines is well recognized as one of the most attractive strategies for creating allylic stereogenic centers with high enantioselectivity. This highlight review precisely aims to summarize the recent developments of this area mainly from the following six aspects: enantioselective defluoroarylation, enantioselective defluoroalkylation, enantioselective defluoroborylation, enantioselective defluorosilylation, enantioselective defluorohydrolation, and desymmetrization of difluoromethylene groups. Primarily, these reactions occur through two pathways, including β-fluorine elimination and C–F oxidative addition. Despite this, the mechanisms and limitations of these strategies have been a focus, and it is hoped that this review will provide a comprehensive overview to evaluate the prospects of this rapidly emerging field.
Catalytic asymmetric defluorinative functionalization of easily accessible allylic fluorines has been well recognized as one of the most attractive strategies for creating allylic stereogenic centers. This highlight review precisely aims to summarize the recent developments of this area. We hope this review can provide a comprehensive overview to evaluate the prospects of this rapidly emerging field.
The characteristics of loss on ignition (LOI) at 200–500 °C of three types of authentic organic biomolecules (monosaccharides: MSs, fatty acids: FAs, and amino acids: AAs) are evaluated and compared to those of reference organic natural samples. FAs and branched-chain AAs degraded almost completely by 300 °C, whereas MSs and unbranched AAs degraded at a slower rate. The exponential regression coefficients matched closely between the references and the authentic compounds, and lipid content was correlated with rate of LOI.
A suitable microenvironment provided by artificial granule scaffold plays a critical regulatory role in bone repairing progression. Till now, it is still a challenge to prepare large hydroxyapatite granules (millimetre level) which provide beneficial physical and chemical stimulation for bone reconstruction. Herein, we developed a facile synthetic strategy for synthesizing hydroxyapatite granules by a repaid gelling method. Also, the satisfying drug-releasing behavior of these granules further proves their potential prospect for bone tissue engineering as bone filler.
Ceria (CeO2) is a promising metal-oxide support that is used in three-way catalysis (TWC). The activity of ceria-supported TWC depends on the location and concentration of oxygen vacancies. Oxygen diffusion can occur once the oxygen vacancy is created, and it leads to enhanced catalytic activity. In this study, the density-functional tight-binding method was used to estimate the free-energy barriers of oxygen diffusion in bulk CeO2 and on a (111)-CeO2 surface. The reconstructed free-energy surfaces from metadynamics sampling show that the diffusion in the bulk CeO2 is faster than that on the (111)-CeO2 surface, with activation barriers of 7.4 and 31.6 kcal/mol, respectively.
Spherical palladium nanoparticles between graphite layers were prepared by the intercalation of palladium chloride followed by its reduction between graphite layers. The palladium particles intercalated between graphite layers were more active for cinnamaldehyde hydrogenation to hydrocinnamaldehyde and hydrocinnamyl alcohol in n-heptane solvent than those supported on graphite surface.
Liquid-liquid interfacial reactions between FeSO4 (aq.) and benzenehexathiol (BHT) in chloroform at room temperature and at 45 °C give bis(dithiolato)iron nanosheets 1-RT and 1-H, respectively. Nanosheets were characterized by IR, UV-Vis, SEM-EDS, TEM, XPS and PXRD. 1-H is remarkably more crystalline than 1-RT and its chemical structure resembles not the porous nickel-BHT nanosheet ([Ni3(C6S6)2]n, “Type 1”) but the non-porous copper-BHT nanosheet ([Cu3(C6S6)]n, “Type 2”), evidenced by PXRD data. Electrical conductivity of 1-H is 0.68 S cm−1 with Ea = 270 meV.
Aplyronine A, an antitumor marine macrolide, has a novel mode of action, inducing the protein-protein interaction between two major cytoskeletons, actin and tubulin. This review discusses recent progress in the design of artificial analogs including hybridization and structure-activity relationship studies of aplyronine A.
Aplyronine A, an antitumor marine macrolide, has a novel mode of action, inducing the protein-protein interaction between two major cytoskeletons, actin and tubulin. This review discusses recent progress in the design of artificial analogs including hybridization and structureactivity relationship studies of aplyronine A.
The rhodium(III)-catalyzed annulative coupling of 9-benzoylcarbazoles with internal alkynes proceeds efficiently through ortho C–H and C–N bond cleavages. This reaction provides direct access to variously substituted indanone derivatives. The carbazolyl leaving group can be readily recovered and reused for preparing the starting materials.
The ruthenium(II)-catalyzed ortho-C–H arylation of 2-aroyl-imidazoles with aryl bromides and chloride is reported. An imidazole ring functions both as a masked ester and a directing group for C–H activation. A variety of functional groups are tolerated under the reaction conditions. The arylated final products could be easily converted into the corresponding esters and amide.
Polydopamine (PDA), formed by self-polymerizing dopamine, is coated over a lactate oxidase (LOx)- and 1,2-naphthoquinone-modified MgO-template carbon electrode to improve electrode stability. After one week, the activity of the resultant electrode without a polydopamine film decreases to ∼60%, whereas that with a PDA coating can be maintained at ∼80%. This method is widely useful for improving the stability of biosensors and biofuel cells.
We report the synthesis of molybdenum–ruthenium–carbon alloy nanoparticles with molybdenum-rich composition by an annealing treatment following a thermal decomposition. We first found its superconductivity with a transition temperature at around 5 K through the observation of zero resistivity and Meisner effect.
We found a positive correlation between C=C selective hydrogenation activity of cinnamaldehyde (CAL) and the fraction of the Pd step site on Pd nanoparticles. Owing to a high fraction of step sites, Pd/θ-Al2O3 catalysts with Pd particle size of 5–10 nm were highly active for the C=C selective hydrogenation of CAL.
We have determined the crystal structure of thermoglobin (AaTgb) from a hyperthermophilic bacterium Aquifex aeolicus. Tyrosine and glutamine at the B10 and E7 position, respectively, are conserved in AaTgb as are the case of single domain hemoglobins (sdHbs). While the binding affinity of O2 or CO is affected by the replacement of Tyr29 in the distal heme pocket, wild type and Y29F variant of AaTgb show a similar binding affinity of imidazole.
The effects of depositing Pd alloy nanoparticles (NPs) on an amine-functionalized Fe-metal organic framework (MOF; MIL-88B-NH2) were investigated, with the aim of developing a photo-switchable bifunctional catalyst for hydrogen storage/delivery mediated by CO2/formic acid (FA). The highly dispersed PdAg NPs promoted photocatalytic FA synthesis from CO2 under visible light and inhibited electron-hole recombination by efficiently trapping excited electrons. The release of H2 via the dehydrogenation of FA upon heating was efficiently catalyzed by the electron-rich Pd species generated by alloying with Ag. These Pd species acted as crucial active centers associated with amine-functionalized moieties in the linker groups of the Fe-MOF.
We present a new synthetic approach for Cu–Pd–B nanoscale alloys. Crystalline face-centered cubic Cu–Pd–B alloy nanoparticles were successfully obtained via an amorphous structure phase caused by external heavy B doping. Elemental mapping with simultaneous energy-dispersive X-ray spectroscopy and energy loss spectroscopy in a scanning transmission electron microscope revealed a solid-solution structure composed of the three elements.
Organic-inorganic hybrid molecular architectures utilizing self-assembled monolayers (SAMs) of organic chromophores (e.g., acene derivatives) are systematically discussed to examine the photophysical properties together with covalently-linked dimeric and oligomeric forms. Multi-exciton generation (i.e., singlet fission) and light energy conversion processes that occur in a reaction site composed of chemically modified organic chromophores on the surface of inorganic nanomaterials such as gold nanocluster, gold nanorod and quantum dot are described.
Organic-inorganic hybrid molecular architectures utilizing self-assembled monolayers (SAMs) of organic chromophores (e.g., acene derivatives) are systematically discussed to examine the photophysical properties together with covalently linked dimeric and oligomeric forms. Multi-exciton generation (i.e., singlet fission) and light energy conversion processes that occur in a reaction site composed of chemically modified organic chromophores on the surface of inorganic nanomaterials such as gold nanocluster, gold nanorod and quantum dots are described.
In recent years, inverse material design using machine learning techniques has attracted attention for material development. Almost all studies have used crystal structures of materials, although material engineers rarely store the crystal information and they only save chemical compositions and target properties for high-throughput materials discovery. Thus, we propose a method to generate chemical compositions for desired target properties by using conditional generative adversarial networks (CondGAN) and a post-processing method to balance the oxidation numbers. Numerical experimental results demonstrate that our CondGAN generates chemical compositions holding the desired properties.
Functions and performance metrics are much sought after by materials researchers and editors; not to be sidelined, however, are fundamental design works directed at general methodological breakthrough and wide-scope applicability. For a close union of form and function is often crucial in catalysing paradigm shift. We use two forms of contrast to illustrate: the hard/soft design in carboxyl-thiol molecules, and the starburst/backfolded alkyne motifs. The former affords thiol-decked Zr4+-carboxyl frameworks, the latter, domino cyclization for crosslinked nanographene components. The versatile reactivity of the thiol and alkyne functions (e.g., for metal uptake), deployed in symmetrical dendritic forms, serves to bridge the worlds of coordination and covalent solids.
Not just pretty structures: symmetrical sulfur functions enhance framework stability, facilitate metal uptake, and impart versatile properties for applications in solar cells, electrocatalysis, and photocatalytic hydrogen production. We also outline a strategy toward ordered 3D graphene materials by way of domino alkyne cyclization on a pre-assembled crystalline coordination framework.
A single stranded DNA (ssDNA) labeled with fluorescein isothiocyanate (FITC) was grafted on hexaniobate nanosheets as confirmed by infrared spectra, X-ray diffraction, and confocal laser scanning microscopy; this is the first case that a ssDNA was grafted on nanosheets. The grafted ssDNA retained the capability of hybridization with complementary ssDNA to form double stranded DNA so that the fluorescence of FITC was effectively quenched by hybridization with the target ssDNA having a quencher moiety.
A chitosan-derived nitrogen-doped carbon (NDC) with a well-designed pore structure is prepared by a novel activation process using ZnO and water vapor. The gas diffusion electrode comprising the obtained NDC for oxygen reduction exhibits higher performance than Pt/carbon black electrode in the current density range of 1–500 mA/cm2.
Here we report enhanced CO2 molecular recognition ability by incorporating insertion reaction into a metal porphyrin complex in a metal-organic framework (MOF). PCN-222(Cu)-INA was synthesized by the reaction of PCN-222(Cu) [Zr6O8(H2O)8(Cu-TCPP)2], where Cu-TCPP = Cu(II) tetrakis(4-carboxyphenyl)porphyrin, and isonicotinic acid (INA). PCN-222(Cu)-INA exhibited a 1.5 times larger CO2 adsorption amount than PCN-222(Cu) at 298 K and 1 bar. The mechanism involving insertion reaction of CO2 into Cu–N bonds enhanced the adsorption, which was revealed by in situ IR spectroscopy and theoretical calculations.
Changes in surface and bulk structures of rutile titania particles induced by braying up to 10 d and post calcination in air at 773 K were analyzed by reversed double-beam photoacoustic spectroscopy. The observed energy-resolved distribution of electron traps indicated that the surface was amorphized by braying to give rutile-core amorphous-shell structure and the amorphous layer was partly recrystallized by post-calcination leaving grain boundaries in the surface layers, both of which may cause the observed markedly decreased photocatalytic activities.
Mechanochromic luminescence (MCL) refers to a reversible color change of the solid-state emission induced by mechanical stimulus such as grinding, shearing, and compressing. A growing number of MCL materials has recently been reported owing to the wealth of their potential applications in advanced optoelectronic technologies. This review highlights recent progress on the development of organic crystalline compounds that exhibit various MCL behaviors, which include self-recovery of the original color, bathochromically and hypsochromically shifted emission from the same luminophore, two-step emission-color switching, and multi-stimuli-responsive emission. In addition, the creation of polymorphic and pseudopolymorphic crystals and the construction of two-component systems as promising strategies to control and improve MCL properties of organic crystals are discussed.
Mechanochromic luminescence (MCL) refers to a reversible color change of the solid-state emission induced by mechanical stimulus. This review highlights recent progress on the development of organic crystalline compounds that exhibit various MCL behaviors. The creation of polymorphic and pseudopolymorphic crystals and the construction of two-component systems as promising strategies to control and improve MCL properties of organic crystals are also discussed.
The energy conversion efficiency of a micromotor system was quantified. The output of the micromotor system is the mechanical energy of the revolving and spinning motions of the spherical micromotor, which were calculated based on the viscous drag and torque. The input power was calculated using the applied voltage and electric current. Quantification of energy conversion efficiency of the micromotors provides guidelines for the development of the micromotor system and is expected to play a key role in micromotor studies.
Top-down methods produce nanographenes with many carboxy groups on their edges. These functional groups can be utilized for developing multichromophoric systems. As proof of concept, pyrene is installed on the edges by Pd-catalyzed cross-coupling reactions. The lack of monomer emissions from the functionalized nanographenes indicates that the neighboring chromophores are sufficiently distant to form the excimer. The pyrene-installed nanographene emits bluish-white-light. Its lipophilic nature allows fabricating a nanographene-dispersed polymethyl methacrylate film emitting visible light.
Diazocarbonyl compounds are versatile precursors of carbenes leading to various structures by using several metal catalysts, especially copper and rhodium salts. In this study, eight different diazocarbonyls having N-O moiety were used. The N-O tethered structures were preferred because they may allow some useful transformations of the final products into valuable compounds via N-O cleavage. In the presence of a double bond on the –OR function of the starting diazo compound, CuCl/AgSbF6 catalyst yielded only cyclopropyl fused oxazinane/oxazepane derivatives over cyclopropanation while Rh2(OAc)4 catalyst was giving mainly isooxazolidinones via C-H insertion.
The redox reaction pathway of silver nanocluster formation in the polyol method is investigated by density functional theory calculation. It is suggested that the formation of Ag2(0) cluster with silver acetate dimer and glycol is more likely to occur via the Ag–carbon bond intermediate rather than via concerted double proton transfer or Ag-alkoxide intermediate. The aldehyde produced from glycol acts as a stronger reducing agent in the reaction. This mechanism provides important insights for controlling the reaction of the polyol process.
An energy crisis is presently encountered with a promising opportunity for the rise of hydrogen technology, while feasible production of hydrogen calls for sophisticated structural design of water-splitting photocatalysts in terms of light harvesting and photogenerated exciton separation. Tuning to these can be anticipated from reticular synthesis of a newly emerging porous crystalline materials, covalent organic frameworks (COFs). In this review, we highlight synthetic strategies to modulate the photocatalytic water splitting performance. Future investigations regarding mechanistic aspects of the photocatalytic process of COFs are also outlined.
Feasible production of hydrogen calls for sophisticated structural design of water-splitting photocatalysts in terms of light harvesting and photogenerated exciton separation. In this review, we highlight strategies to optimize exciton migration and separation in covalent organic framework photocatalysts for water splitting.
Strong basic oxide–supported Ru catalysts are easily prepared and handled, and they have been used as effective catalysts for ammonia synthesis under mild reaction conditions since the 1970s. Recent research has revealed that precise control of the boundary states between the basic oxide (i.e., rare-earth oxide, alkali earth oxide), oxygen defect sites, and Ru nanoparticles can be used to enhance ammonia synthesis under mild reaction conditions and inhibit hydrogen poisoning, which is a typical drawback of strong basic oxide–supported Ru catalysts.
Strong basic oxide-supported Ru catalysts are easily prepared and handled, and have been used as effective catalysts for ammonia synthesis since the 1970s. Recent research has revealed that precise control of the boundary states between the basic oxide, oxygen defect sites, and Ru nanoparticles can be used to enhance ammonia synthesis under mild reaction conditions and inhibit hydrogen poisoning.
Coordination compounds have been increasingly studied as a new class of promising candidates for the matrix of ionic conducting materials because of their designability and high crystallinity. The ionic conduction of light alkali metal ions (Li+ and Na+) has been developed in polymeric coordination systems, which are commonly used under nonaqueous conditions. Recent studies have shown that discrete coordination compounds, as well as hydrated polymeric coordination compounds, can function as excellent ionic conductors even for heavier K+.
Coordination compounds have become a promising candidate for the matrix of ion-conducting materials because of their designability and high crystallinity. The ionic conduction of light alkali metal ions (Li+ and Na+) has been a focus in polymeric coordination systems under nonaqueous conditions. However, a recent study has shown that a discrete coordination system or hydrated polymeric system can exhibit a high ionic conductivity even for heavier K+.
Here, we report a novel structured material, titania inverse-opal photonic crystal with or without a single gold nanoparticle in each void, to provide a photoabsorption design strategy as enhanced photoreaction rates, only when wavelengths of photoirradiation, photoabsorption (by gold nanoparticles or titania), and photonic-bandgap edge are trebly matched.
Metal organic framework materials (MOFs) have a drawback that limits their wider application: poor electrical conductivity. In this paper, some research advances in improving the conductivity of MOFs in recent years are reviewed. They are divided into two categories: intrinsic improvement of conductivity and extrinsic improvement of conductivity. The application of MOFs with improved electrical conductivity in the construction of biosensors is shown. Finally, research trends of improving the conductivity of MOFs and their applications in biosensors are summarized, and promising directions such as the comprehensive application of multiple strategies and the space-oriented assembly of MOFs are proposed.
This article focuses on the strategy to overcome the poor conductivity of MOFs in the construction of biosensors. So take the most common strategy of doping guest molecules as an example to show how to improve conductivity. Use guest molecules as internal bridges to connect the parts that are difficult to form charge transfer in MOFs.
To open up the possibility of synthesizing useful substances from CO2, we have developed new catalysts that hydrogenate CO2 to methanol with high yield at 300 °C and higher. In this study, methanol synthesis via CO2 hydrogenation at 250–350 °C and 10 bar was investigated using Zr-based metal oxide catalysts, MZrOx (M = Al, Mn, Cu, Zn, Ga, and In). The different metals (M) determined the suitable reaction temperature wherein the maximum yield of methanol was obtained. CuZrOx was a suitable catalyst for low-temperature methanol synthesis because the yield decreased with increasing reaction temperature from 250 °C to 350 °C. In contrast, ZnZrOx, GaZrOx, and InZrOx were suitable for methanol synthesis at 300 °C and higher. In particular, ZnZrOx afforded the highest yield of methanol (60 mLSTP h−1 g−1 at 300 °C) among the prepared MZrOx catalysts.
Even without external photon pumping, cavity vacuum fields can be strongly coupled with molecular transitions (electronic excitation and molecular vibration), resulting in the formation of polaritonic states. The energy states of molecular systems are altered under strong coupling, revealing intriguing phenomena, such as improvements in energy/exciton transfer and modulation of chemical reactions. In this review, we highlight recent advances in cavity strong coupling, including exciton strong coupling and vibrational strong coupling, from a chemistry-based viewpoint.
Cavity vacuum fields are strongly coupled with molecular transitions, resulting in the formation of polaritonic states. The energy states of molecular systems are altered under strong coupling, revealing intriguing phenomena, such as improvements in energy/exciton transfer and modulation of chemical reactions. In this review, we highlight recent advances in cavity strong coupling, including exciton strong coupling and vibrational strong coupling.
Boron-doped diamond powder (BDDP) and boron-doped nanodiamond (BDND) were developed with the aim of expanding the area of application of conductive diamond electrodes. BDDP and BDND are conductive diamond powders obtained by depositing a boron-doped diamond (BDD) layer on the surface of diamond powder (DP) and nanodiamond (ND) substrates, respectively, by using the chemical vapor deposition method. As the particle size of BDDP depends on that of the DP substrate, it can be arbitrarily selected in the range of at least submicrometer to several micrometers. BDDP can be used for an electrode material of screen-printed diamond electrode, which is a disposable and sensitive electrode for electrochemical detection even from biological fluids. BDDP can also be applied to a durable cathode catalyst support of a polymer electrolyte fuel cell. BDND is a conductive diamond particle with a large specific surface area of 650 m2/g or more, and is expected to be used as an electrode material for aqueous electric double-layer capacitors with a large cell voltage leading to high energy and high-power densities. BDDP and BDND are highly versatile functional electrode materials that can be made into inks and pastes, and can be combined easily with other compounds. Therefore, they should be useful for greatly expanding the application fields of diamond electrodes.
Boron-doped diamond powder (BDDP) and boron-doped nanodiamond (BDND) were developed with the aim of expanding the area of application of conductive diamond electrodes including screen-printed diamond electrodes for sensitive electroanalysis, durable PEFC cathode catalyst support, and high energy and high power density aqueous EDLC.
The synthesis, structure, magnetic properties and magnetic structure of two molecular chiral magnets and one inorganic chiral magnet are presented. In magnetic crystals belonging to the Sohncke group, which includes the chiral group, the chiral non-collinear spin structure is achieved through Dzyaloshinsky-Moriya interactions in addition to the usual exchange spin interactions and dipole-dipole spin interactions. Experimentally, a chiral helical magnetic (CHM) structure is observed as the ground state in most of this category of uniaxial chiral magnets as a non-collinear spin structure. CHM structure transforms into a chiral spin soliton (CS) magnetic structure in a magnetic field. The (CS) magnetic structure forms a chiral spin soliton lattice (CSL) magnetic structure when the nearest neighbor magnetic interaction is ferromagnetic. Since the CHM and CSL magnetic structures are topologically protected, they are not affected by defects and are therefore extremely stable. A series of studies have revealed that the chiral magnetic structure is perfectly coupled to the non-symmetric crystal structure. It was also found that the CHM and CSL magnetic structures are macroscopic spin-phase coherent states.
Non-collinear spin structures are realized in non-centrosymmetric magnets due to Dzyaloshinsky-Moriya interactions. A series of studies have revealed that the chiral magnetic structure is coupled to the non-symmetric crystal structure. It was also found that the CHM and CSL magnetic structures are macroscopic spin-phase coherent states.
Recent developments for ammonia (NH3) combustion catalysts are covered in this highlight review. NH3 has been proposed as a renewable and carbon-free energy source. However, use of NH3 fuel poses the problems of high ignition temperature and nitrogen oxide (N2O/NOx) production. In order to overcome these issues, a novel catalytic combustion system was probed, and high performance catalysts were developed. This review introduces their research with including related studies.
Recent developments in NH3 combustion catalysts are covered in this highlight review. NH3 has been proposed as a renewable and carbon-free energy source. However, use of NH3 fuel poses the problems of high ignition temperature and nitrogen oxide (N2O/NOx) production. In order to overcome these issues, a novel catalytic combustion system was probed, and high performance catalysts were developed. This review introduces their research with including related studies.
Pd-catalyzed reaction of olefins is sometimes accompanied by isomerization of the Pd center along the aliphatic chain (chain walking). The chain walking reaction enables synthesis of polyolefins with regulated structure, via C-C bond formation between vinyl or vinylene groups with the carbon atom at a remote position of the olefin monomers. The chain walking reaction also allows synthesis of poly(arylene alkenylene)s by three-component polycondensation of diiodoarenes, non-conjugated dienes and nucleophiles. Polycondensation of diols, diacids, and diamines with long alkylene chain, obtained by chain-walking alkoxycarbonylation, affords long-chain polyesters and polyamides.
Chain walking reaction enables synthesis of polyolefins with regulated structure, via C-C bond formation between vinyl or vinylene group with the carbon atom at a remote position of the olefin monomers. The chain walking reaction also allows synthesis of poly(arylene alkenylene)s, and syntheses of diols, diacids, and diamines with long alkylene chain, usable for polycondensation.
Of the various synthetic biodegradable polymers, polylactide, poly(butylene succinate), and poly(hydroxyalkanoate) have been widely studied and developed. This review focuses on studies of the chain end modification of these polymers. The selected research was categorized into initiators, chain end modification, including chain extending, and the degradation reaction. We cover the recent literature on this topic, and discuss the developing trends and challenges of biodegradable polymers.
Of the various synthetic biodegradable polymers, polylactide (PLA), poly(butylene succinate) (PBS), and poly(hydroxyalkanoate) (PHA) have been widely studied and developed. This review focuses on studies of the chain end modification of these polymers. The selected papers were categorized into initiators, chain end modification, including chain extending, and the degradation reaction, from the viewpoint of the modification approaches.
Transition-metal complexes featuring triple bonds to heavier Group 14 elements (Si, Ge, Sn, and Pb), which have long been synthetic challenges in organometallic chemistry, have been synthesized in the last few decades. In this highlight, synthetic methods for numerous kinds of complexes and their structural properties are overviewed. Application leading to new multiple bonded systems with M≡Ge–Ge≡M, M≡Si–M, and M=Si=M linkages, and to relevant metallotetrylenes are also highlighted.
Transition-metal complexes featuring triple bonds to heavier Group 14 elements (Si, Ge, Sn, and Pb), which have long been synthetic challenges in organometallic chemistry, have been synthesized in the last few decades. In this highlight, synthetic methods for all these complexes and their structural properties are overviewed. Application leading to new multiple bonded systems with M≡Ge-Ge≡M, M≡Si-M, and M=Si=M linkages, and to relevant metallotetrylenes are also highlighted.
We previously showed that the hybridization of water-insoluble 12-hydroxystearic acid (HSA) with water-soluble long-chain amidoamine derivatives yields hydrogels composed of self-assembled helical nanofibers. In this work, we investigated the effect of introducing an amide group into the alkyl chain of amidoamine derivatives on the helical structure of the nanofibers. We also demonstrated that improving the solubility of HSA by changing the gelation solvent is a very effective method for preparing homogeneous nanofibers composed of two compounds.
This highlight review describes the recent development of an electrophile-triggered 1,2-metallate rearrangement of organoboronic ester ate-complex, which proceeds through 1,2-difunctionalization of carbon–carbon σ- and π-bonds, using strain energy as a driving force. Coupling reactions of small ring carbocyclic boronic esters, such as cyclopropyl-, bicyclo[1.1.0]butyl-, and cyclopropenyl-boronic ester, are summarized along with the proposed reaction mechanisms and representative examples.
This highlight review describes the recent development of an electrophile-triggered 1,2-metallate rearrangement of organoboronic ester ate-complex, which proceeds through 1,2-difunctionalization of carboncarbon σ- and π-bonds, using strain energy as a driving force. Coupling reactions of small ring carbocyclic boronic esters, such as cyclopropyl-, bicyclo[1.1.0]butyl-, and cyclopropenyl-boronic ester, are summarized along with the proposed reaction mechanisms and representative examples.
A tetracene dimer, 5,5′-bitetracene (55BT), has successfully been synthesized for the first time and its structure was confirmed by X-ray single crystal analysis. The electrochemical and optical properties of 55BT were investigated and compared to those of tetracene. Although the photoluminescence quantum yield of 55BT was slightly higher than that of tetracene, the results of the transient absorption spectroscopy suggested triplet formation by singlet fission in solution.
Circularly polarized luminescence (CPL) of unsubstituted helicenes is weak due to their low fluorescence quantum yield (Φf) and small dissymmetry factor (gCPL). In this study, we designed and synthesized a donor-acceptor type helicene, 5,10-dicyano-2,13-bis(3,4,5-tris(n-octyloxy)phenyl)helicene. This helicene showed high fluorescence quantum yield (Φf = 0.63) and good |gCPL| (4.2 × 10−3) due to symmetry-allowed transition and its helical structure. Moreover, the helicene showed solvatofluorochromism while maintaining gCPL.
We developed iridium-catalyzed 2-position-selective C–H borylation of indole derivatives by modifying the structure of a bipyridine-type ligand. The yields ranged from good to excellent, even on a gram scale, and were dramatically improved by the addition of a urea derivative catalyst. The introduced boryl group was converted to chloro, bromo, and phenyl groups without isolation of the borylated intermediate. Preliminary results indicated the importance of hydrogen bonding between the substrate and the urea additive.
Mechanochromic luminescence (MCL) compounds exhibit change of their photoluminescent color in response to mechanical stimuli. The initial molecular alignment of a liquid-crystalline MCL compound was controlled by using an alignment layer. The rubbing method and rubbing direction were successfully determined. Influence of mechanical force on photoluminescent behavior was evaluated.
The design, synthesis, and optical characterization of refractive-index-contrast (RIC) triazine-based poly(phenylene sulfide)s (PPSs) are investigated. Indeed, novel PPSs with two pendant groups, either tert-butyl (tBu) ester or carboxylic acid groups, at each monomer repeating unit (PPS-2E or PPS-2CA, respectively) were successfully synthesized. PPS-2CA showed high refractive index (n) values of 1.6964 (633 nm) and 1.6714 (940 nm) as well as high δn (increase in the n value by the deprotection of PPS-2E) values of +0.062 (633 nm) and +0.058 (940 nm).