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Herein, a conjugated oligomer is reported possessing a unique U‐shaped molecular geometry, which significantly affects the intramolecular charge transfer and modulates the fluorescence properties. Upon excitation, it displays blue/red dual emission, which is very sensitive to the polarity and viscosity of solvents. After being incorporated into Pluronic F127 micelles, a dramatic fluorescence enhancement is found in its red emission (up to 27‐fold) along with a stable blue emission at elevated temperature. Accordingly, the emissive micelles are successfully explored as a reliable ratiometric nanothermometer both in solution and in cellular environment. Moreover, compared to nanoparticle counterpart prepared by classical nanoprecipitation, the conjugated oligomer/F127 micelles exhibit a remarkable improvement in photo‐triggered reactive oxygen species (ROS) generation efficiency and photodynamic killing behavior on cancer cells. The current study will help researchers to further understand the structure–property relationship of π‐conjugated fluorophores and design various nanomaterials with promising potential for simultaneous diagnostic and treatment on cancers. [ABSTRACT FROM AUTHOR]

Viscosity is a key parameter of mitochondria that related to several diseases. To design a probe acting as both the mitochondria-targeted viscosity sensor and photosensitizer is meaningful for diagnosis and therapies. Herein, we report a ratiometric viscosity sensor with dual-emission mediated by excitation energy transfer (EET) effect, which can detect the mitochondrial viscosity and serve as an efficient photosensitizer to eradicate cancer cells. The probe comprises of a blue-emitting imidazole moiety as the energy donor and a green-emitting boron dipyrromethene (BODIPY) core as the energy acceptor, respectively. Via viscosity-modulated EET effect, the dual-emissive probe can sensitively detect the medium viscosity in a ratiometric model. Directed by imidazole as the targeting factor, the probe can specifically accumulate in mitochondria and ratiometrically determine the intracellular viscosity increase induced by Nystatin treatment. Furthermore, it also exhibits light-triggered reactive oxygen species (ROS) generation including singlet oxygen and superoxide radical, which can efficiently kill the cancer cells under white light illumination. Thus, this work provides a versatile and promising candidate for disease diagnosis and phototherapy. [Display omitted] • Excitation energy transfer (EET) conjugated molecule shows viscosity-mediated dual-emission fluorescence property. • The fluorophore can specially target mitochondria and ratiometrically reveal the viscosity change. • Viscosity sensor exhibits light-triggered ROS generation for efficient photokilling on dysfunctional cells. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) are of great potential in antibacterial field, but their unsatisfactory stability as a result of high surface free energy limits their practical applications. One efficient solution is loading the ultrasmall AuNCs onto a substrate or matrix. In this work, graphitic carbon nitride (CN) nanoparticles were firstly functionalized with imidazole groups via a photocatalytic reaction. Then, AuNCs were in-situ synthesized on surface of CN by using imidazole moieties as the reducing and stabilizing ligands via formation of Au-N bonds. Transmission electron microscopy (TEM) analysis of the obtained CN-AuNC nanocomposites verified the uniform distribution of AuNCs with a mean size of 1.8 nm on CN surface. Since the coordination strength of Au-N bond is weaker than that of Au-S bond, ligand exchange can occur for the imidazole-protected AuNCs due to ligand exchange in the presence of thiol compounds. Accordingly, the obtained CN-AuNC nanocomposites exhibited thiol depletion ability. The AuNCs slowly released from the CN surface can enter Escherichia coli (E. coli) due to their ultrasmall size, consume bio-thiols reducing species and increase the oxidative stress, which effectively killed the bacteria and inhibited subsequent biofilm formation. This paper provides a promising bactericidal nanocomposite with intrinsic properties for sterilization. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Copolymers, poly(acrylonitrile-co-monobutylitaconate-co-n-butylacrylate) (copolyacrylonitrile, co-PANs) with different content of monobutyl itaconate (MBI) were synthesized by free radical polymerization and then electrospun into aligned nanofibers. After thermal treatments of stabilization, carbonization, and graphitization, the resulting aligned co-PAN nanofibers were converted to aligned electrospun carbon nanofiber bundles (ECNFB) with diameters of approximately 200nm. FT-IR technique was applied to investigate the stabilization process of co-PAN nanofibers, while XRD, TEM and tensile tester were used to characterize the microstructures and mechanical properties of the ECNFB. The measured results revealed that MBI was a fairly useful comonomer for preparing high performance PAN-based CNFs by improving the stabilization of co-PAN nanofibers and by promoting the formation of ordered graphite crystals in the ECNFB. When the content of MBI unit in co-PAN was 5wt%, the aligned ECNFB exhibited a tensile strength of up to 1.8GPa and a Young׳s modulus of up to 97.0GPa, which is 86% and 67% higher than those of the ECNFB previously reported in our group respectively. [Copyright &y& Elsevier]

Highlights: [•] Heat-resistant electrospun PBO nanofibers were prepared from precursor OH-PAA. [•] The obtained PBO nanofibers are thermally stable up to 643°C. [•] The obtained PBO nanofibers have excellent mechanical properties. [•] PBO nanofibers have retention of tensile strength and modulus over 80% at 350°C. [•] Such heat-resistant PBO nanofibers could be used in high temperature fields. [ABSTRACT FROM AUTHOR]

Organic room-temperature phosphorescence (RTP) shows high potential in optical fields, and self-assembly method via various non-covalent interactions is one facile and efficient way to enhance RTP performance. Herein, we investigated the RTP behaviors of three imidazole-based polymer films containing imidazole, methyl imidazolium, and benzyl imidazolium moieties, respectively. Their RTP behaviors and chemical structures were compared and discussed to explore the underlying structure-properties relationships. Owing to plenty of hydrogen bonds of polyacrylamide matrix to lock phosphors, imidazolium-based films gave an obvious green RTP due to cations and iodine anions-enhanced intersystem crossing. The blue RTP signals of imidazole-containing film was aroused by coordination with Zn2+ ions due to crosslinking and heavy atom effects. Moreover, the RTP performance of benzyl imidazolium-based film was remarkably improved by host-guest complexation with cucurbit[7]uril, showing a long lifetime up to 230.6 ms. By utilizing the difference in their RTP lifetimes, information encryption application was successfully achieved as a proof of concept. [Display omitted] [ABSTRACT FROM AUTHOR]

The reductive coupling of disulfides and diselenides with alkyl halides was achieved in THF at 65 °C in the presence of 3 mol% of a silica-supported phosphine rhodium complex and triethylamine using hydrogen as a reducing agent, affording a variety of unsymmetrical sulfides and selenides in high yields. The heterogeneous rhodium catalyst can be recovered by a simple filtration and reused several times without significant loss of activity. Reaction with an acyl halide was also observed. [ABSTRACT FROM AUTHOR]

An MCM-41-immobilised bidentate nitrogen platinum complex (MCM-41-2N-Pt) was very conveniently synthesised from commercially available and cheap 3-(2-aminoethylamino)propyltrimethoxysilane by immobilisation on the mesoporous silica nanoparticles, MCM-41, followed by reaction with potassium chloroplatinite. It was found that the MCM-41-2N-Pt complex is a highly efficient catalyst for the hydrosilylation of olefins with triethoxysilane and can be easily recovered and reused several times without significant loss of activity. [ABSTRACT FROM AUTHOR]

The design of efficient catalysts for the selective oxidation of sp3 C–H bond with air at low temperature is of great importance to the scientific and industrial community. In this work, we design a CeO2–δ modified CuFe2O4 catalyst by a post‐modification method for the selective oxidation of fluorene under an air atmosphere and N‐hydroxyphthalimide (NHPI) at 60 °C. HRTEM results indicate that CeO2–δ nanoclusters sized around 5 nm are successfully modified on the surface of CuFe2O4. XPS and H2‐TPR results show that CeO2–δ modification would favor oxygen transfer at lower temperature due to the synergetic effect between CuFe2O4 and CeO2–δ with rich Ce3+/Ce4+ couples. The results demonstrate that CuFe2O4@CeO2–δ‐0.05 with 4.20 wt.‐% Ce present the best catalytic performance with 94 % conversion of fluorene and excellent reusability at least five times. It is anticipated that the modification of CeO2–δ nanoclusters on the surface leads to increased oxygen activation and transfer to CuFe2O4, which favors the activation of NHPI to phthalimide‐N‐oxyl (PINO) radicals and exhibits an improved catalytic performance. Our results provide some guidance on the design of efficient catalysts by the surface modification strategy. CeO2–δ modification with 4.20 wt.‐% Ce on the surface of CuFe2O4 nanoparticles favors oxygen transfer at lower temperature and leads to better catalytic activity than that of pure CuFe2O4 for the aerobic selective oxidation of fluorene due to the synergetic effect between CuFe2O4 and CeO2–δ with Ce3+/Ce4+. [ABSTRACT FROM AUTHOR]

The catalyst can be reused at least five times. [ABSTRACT FROM AUTHOR]

An MCM-41-immobilized bidentate nitrogen platinum complex is shown to be an efficient catalyst for the hydrosilylation of olefins with triethoxysilane. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4), as a metal-free semiconductor, has been widely investigated in energy and photoelectric fields. In recent years, its excellent capacity as visible light-driven initiator for photopolymerization has also aroused increasing interests. In this work, g-C 3 N 4 was explored to act as the sole photoinitiator in a two-step polymerization to prepare functional hybrid hydrogel. Firstly, poly(N-isopropylacrylamide) (PNIPAM) hydrogel was facilely obtained by free radical polymerization in the presence of g-C 3 N 4 colloid and visible light. After adsorbing aniline monomer, the oxidative polymerization took place to get polyaniline (PAN) polymer in the network of g-C 3 N 4 /PNIPAM hydrogel, and the original g-C 3 N 4 acted as the oxidative agents in the presence of oxygen. The obtained interpenetrating double network, g-C 3 N 4 /PNIPAM/PAN hydrogel, displayed an excellent photothermal effect irradiated by near-infrared (NIR) laser and good electrical conductivity. This work presents a green method to prepare functional hybrid hydrogel avoiding usage of excessive traditional molecular initiator in radical polymerization. [Display omitted] [ABSTRACT FROM AUTHOR]

This work reports a facile method for in situ growth of graphitic carbon nitride (CN) on surface of multiwalled carbon nanotubes (CNTs), which was performed via the self-assembly of molecular precursors of CN on CNTs and subsequent calcination step. The self-assembly was directed by the hydrogen bonds formed between amino groups of Melamine and carboxyl units of CNTs. After polycondensation reaction, CN nanostructures grew homogeneously on surface of CNTs possibly linked by covalent bonds. The incorporation of CN improved the interfacial properties of CNTs by increasing the functional groups and wettability, which could promote the dispersion of CNTs in polymer matrix and enhance the heat conductive capacity. Accordingly, the obtained thermal conductive silicon grease involving CNTs/CN nanocomposites showed an enhancement in thermal conductivity at a loading amount of CN (~ 8%). Meanwhile, the insulation resistance of the nanocomposites increased significantly with the dose amount of CN due to its semi-conductivity. Therefore, the obtained CNTs/CN nanocomposites were suitable for interfacial thermal management that require high thermal conductivity and electrically insulative properties. [Display omitted] • Graphitic carbon nitride (CN) was in situ synthesized on surface of multiwalled carbon nanotubes (CNTs). • The thermal conductivity and electrical insulation of CNTs were enhanced by CN. • The nanocomposites are applicable for interfacial thermal management. [ABSTRACT FROM AUTHOR]

Pure organic room-temperature phosphorescence (RTP) materials built upon noncovalent interactions have attracted much attention because of their high efficiency, long lifetime, and stimulus-responsive behavior. However, there are limited reports of noncovalent RTP materials because of the lack of specific design principles and clear mechanisms. Here, we report on a noncovalent material prepared via facile grinding that can emit fluorescence and RTP emission differing from their components' photoluminescent behavior. Exciplex can be formed during the preparation process to act as the minimum emission unit. We found that H-bonds in the RTP system provide restriction to nonradiative transition but also enhance energy transformation and energy level degeneracy in the system. Moreover, water-stimulated photoluminescent ink is produced from the materials to achieve double-encryption application with good resolution. [ABSTRACT FROM AUTHOR]

Abstract: A series of high molecular weight PI precursors, poly(p-phenylene biphenyltetracarboxamide acid), were synthesized from 3,4,3′,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) by using intense mechanical stirring at −15 to 0°C for 48–72h. The as-synthesized PI precursor solution was used to make BPDA/PDA polyimide thin films and electrospun nanofibers. IR, Ostward Viscometer, CMT-8102 Electromechanical Universal Testing Machine and scanning electron microscope (SEM) were used for the characterizations of the as-synthesized PI precursor, PI films and nanofiber sheets. The high molecular weight BPDA/PDA PI thin films and electrospun nanofiber sheets possess excellent mechanical properties of up to 900MPa tensile strength with up to 18.0GPa E-modulus and up to 210MPa tensile strength with up to 2.5GPa E-modulus, respectively. [Copyright &y& Elsevier]

Development of mechanically flexible carbon nanofibers is highly desired for the applications in modern flexible electronics and energy storage devices. This work reports the manufacture and characterization of highly flexible carbon nanofibers (CNFs) and graphitic carbon nanofibers (GCNFs) from a non-processable heteroaromatic rigid-rod polymer, polybisbenzimidazobenzophenanthroline-dione (BBB). The flexible CNFs/GCNFs were prepared by a newly developed method of electrospun nanofiber template solid-state polymerization, followed by carbonization/graphitization. In specific, BBB nanofibers were prepared first by the nanofiber template solid-state polymerization method using polyimide as template by electrospinning and heat treatment (500 °C). Subsequently, CNFs/GCNFs were obtained through carbonization under different temperatures of 1200-2700 °C. SEM, HRTEM, Raman spectroscopy, and XRD were used to characterize the morphologies and microstructures. Intriguingly, the BBB-derived CNFs/GCNFs presented extremely good mechanical flexibility that resisting to readily bending, folding, and kneading. Hence, this newly developed extremely flexible BBB-derived CNFs/GCNFs with such good performance could have great potential applications such as using as electrode materials for flexible electrochemical devices. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbene (NHC) is regarded as a versatile ligand to stabilize gold nanoclusters (AuNCs) via forming strong Au-C bonds. However, reports on NHC-protected AuNCs are rare, especially in aqueous systems. Herein, we present a facile one-step approach to fabricate hydrophilic AuNCs in an aqueous medium using a NHC-based ligand as both a reducing agent and stabilizer. The coordination mechanism involves formation of covalent Au-C bond, as evidenced by nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. Taking advantages of their ultrasmall size and positively charged surface, these AuNCs can readily penetrate the cell wall and accumulate in bacteria, leading to an obvious increase in intracellular reactive oxygen species. Accordingly, these AuNCs have wide-spectrum antibacterial activity toward Staphylococcus aureus (gram-positive bacterium), Escherichia coli (gram-negative bacterium), and Candida albicans (fungi). [Display omitted] • N-Heterocyclic carbene-protected gold nanoclusters (AuNCs) are facilely synthesized in aqueous solution. • The stability of AuNCs is enhanced by formation of covalent Au-C bond and auxiliary binding from imidazole ring. • The AuNCs can promote generation of intracellular reactive oxygen species to give wide-spectrum antibacterial activity. [ABSTRACT FROM AUTHOR]

Surface ligand plays a crucial role in regulating the physicochemical properties and functionalities of gold nanoclusters (AuNCs). Compared to the widely studied thiolate-stabilized AuNCs, the reports on imidazole-based ligands to protect AuNCs are still rare. Herein, we report the facile preparation of imidazole-stabilized AuNCs using 1-vinylimidazole as both a reducing and capping agent. The coordination pattern of imidazole ring to Au core was proved by formation of Au-N bond, which can protect the AuNCs with moderate stability against different pH and temperature. Owing to the weaker binding strength of Au-N bond than Au-S bond, the obtained AuNCs possessed thiol depletion capacity due to ligand exchange in the presence of thiol compounds. By consuming the cellular bio-thiols that act as the reducing species in redox balance, the imidazole-protected AuNCs can cause the accumulation of oxidizing species and the elevation of the oxidative stress. Accordingly, the obtained AuNCs exhibited intrinsic antibacterial activity toward Staphylococcus aureus , which could be a promising bactericidal nanomaterial for sterilization. [Display omitted] • Imidazole-stabilized AuNCs were facilely synthesized using 1-vinylimidazole as a reducing and capping agent. • Owing to formation of Au-N bond, they showed good stability and thiol depletion capacity. • They exhibited intrinsic antibacterial activity toward Staphylococcus aureus by consuming cellular bio-thiols. [ABSTRACT FROM AUTHOR]

Abstract: Protective agents based on tetraethoxysilane (TEOS) have been widely used for the protection of stone heritages. However, TEOS-based protective agents suffer from practical drawbacks, such as crack formation of the gel during the drying phase due to the developed capillary force, which is typical for TEOS-based protective agents. In this paper, we have prepared new TEOS-based protective agent containing flexible hydroxyl-terminated polydimethylsiloxane (PDMS-OH) and colloidal silica particles (167nm) using n-octylamine as a catalyst in order to reduce capillary force development and increase hydrophobicity, and have characterized them for the application of stone protective agent. The extent of surface hydrophobization depends on concentration of colloidal silica particles and reaches a maximum value of 123° at 0.2% (w/v) of colloidal silica particles for the case of treated with the modified composition. The presence of n-octylamine is a key factor which promotes the increase of the gel pore size. The protective performances were also evaluated by its ability to resist acid corrosion. The results reveal that the protective effects are satisfying. [Copyright &y& Elsevier]

• Cu-doped CeO 2 nanocrystals have been prepared by a hydrothermal method. • The catalyst shows high activity conversion for imine synthesis from amines. • The catalyst exhibits excellent cycling stability for at least four cycles. • Dispersed copper species and abundant oxygen vacancies contributed to the high activity. The study and development of CeO 2 nanocrystals containing transition-metal species are of crucial importance for understanding the effect of transition-metal species on their catalytic activity. In this work, CeO 2 nanocrystals containing only 0.61 wt% Cu have been demonstrated as an effective catalyst for imine synthesis from amines at 110 °C using NHPI as radical initiator and air as oxidant. Especially, Cu-doped CeO 2 nanocrystals after thermal treatment at 300 °C for 2 h show high conversion (97.8%) and high selectivity (98.6%) for the synthesis of N-benzylidene benzylamine from benzylamine, as well as acceptable yield for the synthesis of several other kinds of imines from amines. The Cu-doped CeO 2 nanocrystals also exhibited excellent cycling stability for at least four cycles with only a slightly decreased yield. It has been demonstrated that the high catalytic activity of Cu-doped CeO 2 can be ascribed to the highly dispersed Cu species and abundant oxygen vacancies on their surfaces which activated the NHPI and O 2 and promoted the adsorption/conversion of amine. [ABSTRACT FROM AUTHOR]