Application of organic selenides and tellurides in organic synthesis

This paper describes the progress on the synthesis of organic selenides and tellurides and their application in organic synthesis.Low valent selenium and telluronium compounds having high reducing selectivity can be used to form carbon-hydrogen bonds as special reducing reagents.Telluronium ylides can react with aldehydes and ketones by Wittig-type condensation to produce (E)-configuration alkenes stereoselectively.α-Phenylselanyl arsonium ylides were prepared by transyl-idation reaction of arsonium ylides with phenylselanyl halides which can undergo Wittig-type reactions with carbonyl compounds to give (Z)-α-selanyl-α,β-unsaturated compounds with high stereoselectiv-ity.Zirconium,tin,boron,halogen,metal or hetero-atom were introduced in organoselenium and telluronium compounds as new difunctional group reagents.Under transition metal catalysis,the corresponding cross coupling reactions provide new methods of formation of carbon-carbon double bonds,which were used in the stereoselective synthesis of     

Perylene-diimide derived organic photovoltaic materials

In organic solar cells(OSCs), the material design on photovoltaic layers and interlayers has significantly contributed to the rapid progress of the device performance. Perylene-diimides(PDIs), owing to their distinct advantages of high electron affinity, high electron mobility and facial chemical modification, are being widely studied in OSCs, especially designed as photovoltaic acceptors and cathode interlayers. In this review, recent progress on those PDI derived photovoltaic materials is systematically summarized. Due to the different working mechanism in devices, the design strategies on modification of the parent PDI units towards their application as acceptors and cathode interlayers are explained. After disclosing the fundamental structure-property relationships, we disclose some common features in the design of those tailor-made PDI-based photovoltaic materials, and we also highlight the challenges and opportunities in improving their device performance in the future.     

Metal organic framework–organic polymer monolith stationary phases for capillary electrochromatography and nano-liquid chromatography

In this study, metal organic framework (MOF)–organic polymer monoliths prepared via a 5-min microwave-assisted polymerization of ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) with the addition of various weight percentages (30–60%) of porous MOF (MIL-101(Cr)) were developed as stationary phases for capillary electrochromatography (CEC) and nano-liquid chromatography (nano-LC). Powder X-ray diffraction (PXRD) patterns and nitrogen adsorption/desorption isotherms of these MOF–organic polymer monoliths showed the presence of the inherent characteristic peaks and the nano-sized pores of MIL-101(Cr), which confirmed an unaltered crystalline MIL-101(Cr) skeleton after synthesis; while energy dispersive spectrometer (EDS) and micro-FT-IR spectra suggested homogenous distribution of MIL-101(Cr) in the MIL-101(Cr)–poly(BMA–EDMA) monoliths. This hybrid MOF–polymer column demonstrated high permeability, with almost 800-fold increase compared to MOF packed column, and efficient separation of various analytes (xylene, chlorotoluene, cymene, aromatic acids, polycyclic aromatic hydrocarbons and trypsin digested BSA peptides) either in CEC or nano-LC. This work demonstrated high potentials for MOF–organic polymer monolith as stationary phase in miniaturized chromatography for the first time.     

Investigation of inorganic–organic hybrid materials containing polyoxometalate cluster anions and organic dye cations

Two new ionic-pair salts containing an organic dye cation, i.e. New Fuchsin or Pararosaniline cation, with Keggin-type POMs, [SiW₁₂O₄₀]^4? and [BW₁₂O₄₀]^6?, have been isolated under hydrothermal conditions. [(C₂₂H₂₄N₃)₄][SiW₁₂O₄₀] (1) and [(C₁₉H₁₈N₃)₆][BW₁₂O₄₀] (2) have been characterized by elemental analyses, FT-IR and single crystal X-ray crystallography. Both of these complexes have strong absorption in the visible-light range due to the involvement of the organic dye and both show weak fluorescence emission.     

Stimuli-responsive organic phosphorescence through energy transfer

Organic room-temperature phosphorescence(RTP)has attracted much academic and engineering interest in the fields of bioimaging,light-emitting devices,and anti-counterfeiting.It is documented that the triplet excitons for generating RTP in molecular systems are highly sensitive to external quenchers(such as oxygen and water).     

Hybrid UV-cured organic–inorganic IPNs

Hybrid organic–inorganic UV-cured coatings based on interpenetrating polymer networks (IPN) were prepared starting by an equimolar methacrylate-epoxy UV-curable mixture (bisphenol-A-diglycidyl dimethacrylate/bisphenol-A-diglycidyl ether, abbreviated as BisGMA/BADGE), in the presence of tetrafunctional silane monomer tetrakis(methacryloyloxy-ethoxy)silane (TetMESi) as inorganic precursor. The photocuring kinetics of the BisGMA/BADGE IPN monomer mixture were strongly affected by the order of the cure of the individual components. Addition of TetMESi resulted in higher degrees of reaction. DMTA of the BisGMA/BADGE IPN suggest a two phase structure. The rubbery modulus of the hydrolysed BisGMA/BADGE/TetMESi systems increased as the level of TetMESi was raised in the formulation due primarily to the significant reinforcing effect of the nano-silica particles. TGA of the BisGMA/BADGE IPN showed three degradation stages with no residual char but the hydrolysed BisGMA/BADGE/TetMESi systems formed a carbonaceous silica char which increased in mass as the level of TetMESi was raised. The two phase morphology of the BisGMA/BADGE IPN was confirmed by FE-SEM analysis. For IPNs prepared with TetMESi, SiO₂ particles are evident in the FE-SEM image and have diameters in the nanometric size range.     

Microwave-assisted Kornblum oxidation of organic halides

Microwave-assisted Kornblum oxidation is proved to be an effective way to obtain aldehyde and ketones from their corresponding chlorides. Under microwave irradiation, not only the reaction time was greatly decreased, due to avoiding the by-product, the yield was increased. It is noteworthy that the scope of the method was broadly expanded.     

A stable organic triradical with truncated π-conjugation as a model for single-component organic molecule-based ferrimagnetics

As a novel molecular design for genuinely organic molecule-based ferrimagnets, we have proposed a strategy of ‘single-component ferrimagnetics.’ When a π-biradical with an S=1 ground state and a π-monoradical with S=1/2 are united by σ-bonds, the π-conjugation between the biradical and the monoradical moieties should be truncated in the resultant triradical. This gives magnetic degrees of freedom for both S=1 and S=1/2 in the single molecule, serving as a building block for organic molecular ferrimagnets. We have designed and synthesized a triradical, 2,2,6,6-tetramethyl-pipelidine-1-N-oxyl-4-carboxylic acid 2,4-bis(1-oxyl-3-oxido-4,4,5,5-tetramethyl-2-imidazolin-2-yl)-phenyl ester (2) as a model compound for single-component ferrimagnetics. Solution-phase ESR spectra from 2 are explained by a perturbation treatment assuming that the exchange interaction within the biradical moiety is much larger than those between the biradical and the monoradical moieties, which is suitable for single-component ferrimagnetics. From susceptibility measurements for a cyclohexane-substituted biradical, cyclohexane carboxylic acid 2,4-bis(1-oxyl-3-oxido-4,4,5,5-tetramethyl-2-imidazolin-2-yl) phenyl ester (4) as a biradical analogue of 2, it is shown that the intramolecular ferromagnetic interaction has been found to be unaffected by the chemical modification for anchoring the monoradical moiety.     

Progress on the optoelectronic functional organic crystals

Organic crystals constructed by pi-conjugated molecules have been paid great attention to in the field of organic optoelectronic materials. The superiorities of these organic crystal materials, such as high thermal stability, highly ordered structure, and high carrier mobility over the amorphous thin film ma-terials, make them attractive candidates for optoelectronic devices. Single crystal with definite struc-ture provides a model to investigate the basic interactions between the molecules (supramolecular interaction), and the relationship between molecular stacking modes and optoelectronic performance (luminescence and carrier mobility). Through modulating molecular arrangement in organic crystal, the luminescence efficiency of organic crystal has exceeded 80% and carrier mobility has been up to the level of 10 cm2·V?1·s?1. Amplified stimulated emission phenomena have been observed in many crys-tals. In this paper, we will emphatically introduce the progress in optoelectronic functional organic crystals and some correlative principle.     

Synthesis of metal−organic complex arrays

The Merrifield solid-phase peptide synthesis technique has been adapted to the synthesis of homo- and heterometallic metal?organic complex arrays (MOCAs). A terpyridine-appended and Fmoc-protected L-tyrosine derivative was metalated with Pt(II), Rh(III), or Ru(II) ions in solution and sequentially coupled at the surface of functionalized polymeric resin to give a metal complex triad (Rh?Pt?Ru), tetrad (Ru?Rh?Pt?Pt), pentad (Rh?Pt?Ru?Pt?Rh), and hexad (Rh?Pt?Ru?Pt?Rh?Pt) with specific metal sequence arrangements. These were cleaved from the resin, and their character was confirmed by mass spectrometry.     

Self-assembling metal–organic coordinated fractal crystals

<正>Fractals are essentially characterized by their self-similarity at different scales and non-integer Hausdorff dimensions[1],while crystals always show certain symmetries and discrete diffraction diagrams[2].Thus,a fractal crystal by definition must be identical at all scales with a compatible symmetry with crystals.Although fractals,e.g.snowflakes,trees,coastlines and blood-vascular systems,     

Self-assembly of functionalized inorganic–organic hybrids

Recent advances on the synthesis and self-assembly of hybrid inorganic–organic materials have been reviewed in terms of the synthetic strategies and emerging techniques, including in-situ self-assembly, template-induced self-assembly, evaporation-induced self-assembly, and layer-by-layer assembly for assembling functional hybrids. The perspectives and outlook on this research topic are given.     

First-principles measurements of charge mobility in organic semiconductors: Valence hole–vibration coupling in organic ultrathin films

Although a great deal of research has been conducted on the electrical properties of organic devices, numerous crucial problems still remain. Of these, the study of charge mobility in organic semiconductor systems has been one of the most important subjects that has remained a puzzle for many years. It is essential to quantitatively understand conduction charge-molecular vibration coupling as well as the intermolecular interaction to discuss mobility. This article describes recent successes with direct measurements of valence hole–vibration coupling in ultrathin films of organic semiconductors with ultraviolet photoelectron spectroscopy (UPS), which can be used to experimentally study charge mobility based on energy and momentum conservation rules. The method may thus be categorized as a first-principles study of charge mobility. The detection of hole–vibration coupling of the highest occupied molecular orbital (HOMO) state in a thin film by UPS is essential to comprehending hole-hopping transport and polaron-related transport in organic semiconductors. We also need to experimentally determine energy-band dispersion or energy-level splitting in a molecular multilayer to obtain information on intermolecular interactions. Since the information on these is concealed behind the finite bandwidth of the HOMO in UPS spectra, we need to obtain high-resolution UPS measurements on organic thin films. Only careful measurements can attain the high-resolution spectra and provide these key parameters in hole-transport dynamics. A key method in achieving such high-resolution UPS measurements is also described.     

Elastic organic–inorganic hybrid aerogels and xerogels

Novel aerogels and xerogels with methylsilsesquioxane (MSQ, CH₃SiO_1.5) networks have been prepared by a modified sol–gel process using surfactant and urea as a phase-separation inhibitor and as an accelerator for the condensation reaction, respectively. Optimized aerogels dried under a supercritical condition not only showed the similar properties as conventional pure silica aerogels such as high transparency and porosity etc, but also demonstrated outstanding mechanical strength against compression; the aerogel drastically shrank upon loading and then recovered when unloaded, which is called a “spring-back” behavior. On ambient pressure drying, the wet gel also exhibited the similar response against compression stress originated from the capillary pressure, and thus xerogels with the comparative structure and properties to those of corresponding aerogels have also been obtained. This unusual mechanical behavior is attributed to the trifunctional flexible networks of MSQ, low silanol concentration which prevents the irreversible shrinkage, and high concentration of a hydrophobic methyl group directly attached to every silicon atom which helps re-expansion after the temporal shrinkage.     

Responsive microstructures on organic–inorganic hybrid films

Micro-periodic structures exhibiting shape memory have been fabricated on organic–inorganic hybrid films. The microscale structures are obtained by forming wrinkles via buckling of the stiff surface layer. The surface-modified layers are obtained by surface photopolymerization or by oxidation of the hybrid films. The microscale structures are spontaneously formed by the shrinkage of the underlayer via gelation. The surface microstructures on titania- or silica-based films with hydrophilic swellable polymers exhibit a humidity response, i.e., a shape memory effect. This is observed when the surface microstructure disappears and is subsequently recovered with cyclic variation of the surrounding humidity. Micro-rolls are also fabricated by the selective swelling of surface-modified layers.     

Recent advances in graphene oxide catalyzed organic transformations

Graphene oxide(GO), as a metal-free and readily available carbocatalyst, has been extensively applied in catalytic organic transformations. This minireview aims to give an overview of the progress on the application of native GO as a catalyst for various organic transformations in the past decade(mainly from 2011 to 2020).     

Nmr analysis of α-methyl branched organic acids

A methode for analyzing α-methyl branched organic acids has been developed using NMR spectroscopy. The composition is determined in terms of α,α-dimethyl, α-methyl-α-alkyl and α-methyl strnetures. Peak assignmunts were made on the basis of model compound studies. This technique has been successfully used in analyzing Koch acid synthesis mixtures.     

Recent Progress toward white organic light emitting diodes

An efficient and stable white organic light emitting diode (WOLED) is highly desirable in potential applications such as lighting, background light source, and full color display. A series of highly fluorescent dyes based on a dipyrazolopyridine skeleton, 1,7-diphenyl-1,7-dihydrodipyrazolo[3,4-b,4',3'-e]pyridine, were synthesized and evaluated as emitting as well as charge-transporting material in the fabrication of electroluminescent devices. Several of the blue derivatives are found to be …     

Sedimentation analysis of organic–inorganic hybrid colloids

Hybrid organic–inorganic latex particles are synthesized to combine the beneficial properties of the constituents which thus lead to synergistic improvement in the properties. The properties of hybrid particles are dependent on the successful hybridization process, thus controlling or tuning of such processes by effective characterization is immensely important. Analytical ultracentrifugation provides these characterization possibilities owing to its high statistical capability and ability to characterize multiple parameters. The use of different detection methodologies can help in generating valuable information on the overall size and density distributions of the particles. Apart from that, it is also possible to quantify the presence of any free polymer and inorganic particles in the hybrid latex which would affect the properties of hybrid latexes. By following the densities of the pure and hybrid particles, it is also possible to quantify the amounts of the constituent phases in the hybrid particles. The density gradients generated in preparative ultracentrifugation also provide additional possibilities for the characterization of the hybrid particles which have densities higher than the measurable range in the analytical ultracentrifuge. Evolution of hybrid particles can also be studied as a function of time. It also provides advantage of separation of the various fractions for further characterization.     

Bacterial cellulose–silica organic–inorganic hybrids

Bacterial cellulose (BC) hydrated membranes present nanometric reticulated structure that can be used as a template in the preparation of new organic–inorganic hybrids. BC–silica hybrids were prepared from BC membranes and tetraethoxysilane, (TEOS) at neutral pH conditions at room temperature. Macroscopically homogeneous membranes were obtained containing up to 66 wt.% of silica spheres, 20–30 nm diameter. Scanning electron micrographs clearly show the silica spheres attached to cellulose microfibrils. By removing the cellulose, the silica spheres can be easily recovered. The new hybrids are stable up to 300 °C and display a broad emission band under UV excitation assigned to oxygen-related defects at the silica particles surface. Emission color can be tuned by changing the excitation wavelength.