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We conducted a study on the trajectory-dependent threshold effects of proton stopping power in LiF nanosheets using time-dependent density functional theory non-adiabatically coupled to the molecular dynamics. This study covered protons with initial velocities in the range of 0.1–1.0 a.u., offering a vast amount of detailed information on the electronic structure during the stopping process with superior spatial and temporal resolution. Our results show that the impact parameters of incident protons play a crucial role in determining the threshold behavior of proton stopping power in LiF nanosheets. Most importantly, we found that close collisions do not exhibit a discernible threshold. In addition, the research results also revealed the time dependence of the number of electrons occupying the atomic orbitals of F and Li as protons pass through the nanosheets. [ABSTRACT FROM AUTHOR]

Dynamic infrared radiation regulation has been widely explored for smart windows because of its vital importance for comfortable and energy-efficient buildings. However, it remains a great challenge to synchronously achieve high visible transmittance and pronounced infrared tunability. Here, we propose a dynamic infrared tunable metamaterial composed of indium tin oxide (ITO) gratings, an air insulator, and an ITO reflector. The ITO grating-based infrared radiation regulator exhibits a high emissivity tunability of 0.73 at 8–13 μm while maintaining a high visible transmittance of 0.65 and 0.72 before and after actuation, respectively. By adjusting the geometric parameters, the tunable bandwidth can be further extended to 3–30 μm and the ultra-broadband tunability reaches 0.62. The excellent infrared tunable performance arises from the insulator thickness-dependent effect of Fabry–Pérot and propagating surface plasmon resonance coupling and decoupling, which lead to perfect and low absorption, respectively. This work provides potential for the advancement of smart window technology and makes a significant contribution to sustainable buildings. [ABSTRACT FROM AUTHOR]

The uniaxial zero thermal expansion (ZTE) in distorted Prussian blue analogue (PBA) RbCuCo(CN)6 is reproduced by employing first-principles calculations, which agrees well with the experimental data. Also, the zero linear compressibility (ZLC) behavior in RbCuCo(CN)6 can be found. The special Jahn–Teller distortion introduced by Cu2+ in RbCuCo(CN)6 is noticed by investigating the change of the local structure with temperature and hydrostatic pressure. The lattice thermal conductivity (LTC) and phonon group velocity of RbCuCo(CN)6 are studied, where the LTC and phonon group velocity are significantly anisotropic. Especially, RbCuCo(CN)6 exhibits a quite low LTC, and its c-axis shows a characteristic of glasslike LTC at low temperatures. Our work facilitates a deep understanding of the coexistence mechanisms of uniaxial ZTE and ZLC properties in RbCuCo(CN)6. [ABSTRACT FROM AUTHOR]

A series of seaweed-like heterogeneous Co3(PO4)2/Ni3(PO4)2/MOF-74-x electrocatalysts were synthesized via a hydrothermal method. The optimal composite exhibits excellent catalytic performance toward methanol/ethanol oxidation reactions (MOR/EOR) with peak current densities reaching 27.5 and 32.6 mA cm−2, respectively. This work heralds the advent of more efficient heterogeneous electrocatalysts for DAFCs and other energy conversion systems. [ABSTRACT FROM AUTHOR]

The stopping power of energetic He ions traversing an Al film is studied by combining the time-dependent density-functional theory method with molecular dynamics simulations. We investigated the dependence of the semicore electron excitation of the Al film on the projectile's trajectory and its charge state. Our results show that for the off-channeling trajectories the semicore electrons contribute significantly to the stopping power of the Al film as the He+ ion velocity exceeds 1.0 a.u, and in contrast, it is negligible for the channeling trajectories. Most importantly, we found two unexpected effects of semicore electrons on the stopping power in helium-irradiated aluminum nanosheets, i.e., (1) the semicore electrons can contribute to the energy loss for both high and low energy projectiles under the off-channeling trajectory; (2) as the projectile velocity increases from 0.4 a.u. to 2.0 a.u. although semicore electron excitation (including transition in the target, ionization away from the target and transfer to the projectile ion) of the target atom is gradually inhibited, the influence of semicore electrons on valence electron excitation is gradually enhanced. Our finding allows us to gain new insights into the stopping of ions in metals. [ABSTRACT FROM AUTHOR]

Breaking through the traditional 1,7,3,5-aryl substituted aza-BODIPY structure, asymmetric aza-BODIPYs, tBu-azaBDPs , containing non-aryl group at 3-site were prepared for the first time. tBu-azaBDP exhibited a severely twisted configuration. tBu-azaBDPs had a near-infrared fluorescence emission and high molar extinction coefficients. Although the barrier-free rotation of the distal –tBu group in tBu-azaBDP resulted in low fluorescence quantum yield, the photothermal conversion efficiency was markedly enhanced. tBu-azaBDP nanoparticles with laser irradiation were revealed to induce cell apoptosis in photothermal therapy. We consider that development of aza-BODIPYs with the barrier-free rotation of the –tBu group at 3-site provides a strong platform for design of phototherapy agents for cancer treatment in photothermal therapy by apoptosis. [ABSTRACT FROM AUTHOR]

Bioinspired asymmetric two-dimensional (2D) nanochannels with ionic diode behavior are highly desirable, as they can be constructed and modified easily. However, the knowledge about the rectification mechanism of the nanochannels is still very limited. In this paper, the ionic current rectification (ICR) of the 2D trapezoidal-shaped nanochannels was studied both numerically and experimentally. A multi-physics model, considering the electric field, the ion concentration field, and the flow field, was built for simulating the ion transportation inside the nanochannels. With a limited channel height, the 2D nanochannels are counter-ion selective; therefore, under an external electric field, the accumulation of co-ions takes place at one end of the nanochannels. By introducing shape asymmetry to the nanochannels, the ICR was achieved due to the asymmetric ion concentration polarization at two ends of the nanochannels under opposite electric fields. The structure of the nanochannels, the surface charge density of the nanochannel walls, and the ionic strength of the working fluids affect the ICR of the ionic diodes by changing the ion concentration polarization at two ends of the nanochannels. In the experiment, the current–voltage curves of the nanochannel arrays fabricated by assembling graphene oxide nanosheets were measured, which are in accordance with the numerical results. This paper provides a comprehensive understanding of the mechanism of the 2D trapezoidal-shaped ionic diodes, which may act as a guideline for the design and optimization of ionic diodes. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) spectroscopy is a rapid and non-destructive optical detection method that has been applied in various applications. Recently, three-dimensional (3D) substrate-based silicon nanostructures have been widely used as SERS substrates due to their high detection sensitivity, repeatability, and reusability. This paper uses a simple and low-cost electroless etching deposition process to generate silver nanoparticle-decorated porous silicon (Ag-PS) substrates. We propose a contact deposition process to generate localized Ag-PS (LocAg-PS) for SERS analysis. Due to the hydrophilic LocAg-PS pad on the hydrophobic PS background, the sample droplets self-aligned to the predefined LocAg-PS pads and condensed into a higher local concentration for high sensitivity SERS detection without extensive search for the hot spot. The effects of critical fabrication parameters and SERS analysis on the LocAg-PS surface were evaluated. [ABSTRACT FROM AUTHOR]

In view of Hg2+ ion sensing by luminescence, a series of new, phenanthroline-decorated 3D lanthanide metal organic frameworks (Ln-MOFs) valorising an original combination of four different lanthanides and two organic ligands, i.e. thiobis(4-methylene-benzoic acid) (H2tmba) and 1,10-phenanthroline (phen), have been successfully synthesized, namely {[Ln4(tmba)6(phen)4]·m(H2O)(phen)}n [Ln = Ce, m = 3 (1); Pr, m = 1 (2); Eu, m = 3 (3); and Tb, m = 3 (4)]. Compounds 1–4 were characterised by single-crystal X-ray diffraction, elemental and thermogravimetric analyses, and powder X-ray diffraction. The luminescence properties of complexes 3 and 4 were thoroughly investigated. It is herein proved that compound 3 sensitively and selectively acts as an excellent luminescent probe for the detection of Hg2+ ions in waters, with a detection limit of 1.00 μM. As additional assets, 3 displays superb stability over a wide pH range (3–12) of the aqueous media, as well as convenient recycling after completion of the detection experiments. The rationale for the observed luminescence quenching effect of mercury might be a strong interaction arising between Hg2+ ions and the carboxylate oxygen atoms of the tmba2− ligand. The results open new perspectives for applications in environmental remediation. [ABSTRACT FROM AUTHOR]

Rapid construction of molecules bearing all-substituted quaternary stereocenters represents a highly significant but challenging task in organic synthesis. Herein, we report a novel palladium-catalyzed cascade between alkene-tethered aryl iodides and carbon monoxide, which has resulted in a practical and powerful method for the synthesis of complex polycyclic molecules containing aryl-substituted quaternary stereocenters. Mechanistic studies suggested that the reaction proceeded via a Heck-type carbonylative cyclization, followed by a ketene-involved Friedel–Crafts acylation. [ABSTRACT FROM AUTHOR]

Designing novel multifunctional rare-earth metal–organic frameworks (MOFs) has attracted intensive attention. In particular, employing such materials for sensing or catalytic reactions is still very challenging. Here, a new 3D porous Eu(III)-MOF, [Eu(cppa)(OH)]·xS (denoted as CTGU-19, S = solvent molecule, CTGU = China Three Gorges University), was synthesized by using 5-(4-carboxyphenyl)picolinic acid (H2cppa) as an organic ligand, and it shows a 3D (3,12)-connected topological net with the point symbol (420·628·818)(43)4, constructed from cubane-shaped tetranuclear europium building units. Interestingly, CTGU-19 can be used as a highly sensitive luminescent sensor to identify ornidazole (ODZ) and nitrofurantoin (NFT) at different excitation wavelengths. This result represents the first example of a lanthanide-metal–organic-framework (Eu-MOF) that can be employed as a discriminating fluorescent probe to recognize ODZ and NFT at different excitation wavelengths. Furthermore, after loading CTGU-19 with Ag and/or Au nanoparticles, the composites exhibit efficient catalytic performance for reducing 2-/3-/4-nitrophenols (2-/3-/4-NP), in which the unit mass reduction rate constants of Ag0.8Au0.2@CTGU-19 for 2-NP, 3-NP, and 4-NP reach 68.8, 53.80, and 52.34 s−1 g−1, respectively. [ABSTRACT FROM AUTHOR]

Pd nanoparticles were immobilized on a highly porous, hydrothermally stable Eu-MOF via solution impregnation and H2 reduction to yield a novel Pd@Eu-MOF nanocatalyst. This composite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopy (XPS). Unprecedentedly, the Pd@Eu-MOF nanocatalyst could be applied with excellent results in two strikingly different, mechanistically distinct, reactions i.e., Suzuki–Miyaura cross-coupling and cycloaddition of CO2 to a range of epoxides. Under the best reaction conditions, 98–99% yields have been attained in both catalytic processes. Moreover, in either case the heterogeneous catalyst was easily recovered and efficiently reused for more than four cycles, indicating its high stability and reproducibility. PXRD, TEM and XPS measurements on the recycled catalyst confirmed that it maintained its original structure and morphology; no Pd NP agglomeration was observed. [ABSTRACT FROM AUTHOR]

The lithium dendrites issue presents a major challenge limiting the commercialization of Li metal anodes for high-energy-density batteries. Herein, an AgPF6–LiNO3 hybrid electrolyte additive was introduced into a carbonate electrolyte, which was found to induce the formation of a homogeneous dense layer of Ag–Li alloy seeds with small sizes on the Li metal surface. The formation mechanism of such fine Ag–Li alloy seeds on the Li metal substrate was evaluated, which revealed an interesting synergistic effect between AgPF6 and LiNO3. The occurrence of such a dense layer of Ag–Li alloy seeds was found to play a significant positive role in homogeneous nucleation and growth of Li dendrites, and LiNO3 could inhibit the growth of Li and act as a grain refiner during a repetitive plating/stripping process, thus enabling profoundly improved structural stability and excellent long-term cycle performance for the Li anode during the cycling process. With the co-presence of AgPF6–LiNO3 in the electrolyte, the relevant symmetric cells could work steadily for 3000 h with slight polarization at a density of 0.5 mA cm−2; and the Li–graphite battery can exhibit good cycle performances and deliver a specific energy density of 374 W h kg−1 at a power density of 747 W kg−1. [ABSTRACT FROM AUTHOR]

Regulation of the activity and stability of enzymes is important for their biological and biomedical applications. In this regard, considerable attention has been paid to the regulation of enzyme activity by controlling steric effects in protein–thermoresponsive polymer conjugates via temperature change. However, it is difficult to accomplish on/off regulation of activity via steric effects alone. In this work, pH- and temperature-dually-responsive gold nanoparticles (AuNPs) conjugated to poly(N-isopropylacrylamide) (pNIPAM) and poly(methacrylic acid) (pMAA), designated AuNP–pNIPAM–pMAA, are proposed in this work for the regulation of enzyme activity with high precision. Using these particles adsorbed with inorganic pyrophosphatase (PPase) as a model enzyme (AuNP–PPase–pNIPAM–pMAA), it was shown that, by changes in pH and temperature leading to changes in “steric covering” of the protein active site via interpolymer hydrogen bonding, the activity of PPase could be closely regulated. At 25 °C and pH 5.0, the steric covering of pNIPAM and the interpolymer hydrogen bonding between pNIPAM and pMAA gave a cage-like “locking in” structure in the protein active site as the “hidden” state, with a very low specific activity of only 12 U mg−1, around 2% of its normal activity. At 45 °C and pH 8.0, the cage structure did not form due to the lack of coverage by the collapsed pNIPAM chains and the inability of the dissociated carboxyl groups in pMAA to form hydrogen bonds, leaving the protein active center fully exposed as the “available” state, and resulting in a high specific activity of 498 U mg−1. Thus the activity of the enzyme in the conjugate is almost totally suppressed at 25 °C/pH 5.0 and completely recovered at 45 °C/pH 8.0. The controllable range of activity is thus very wide, i.e., from 2 to 100%. The AuNP–PPase–pNIPAM–pMAA conjugate also has strong resistance to trypsin digestion. In addition, it was shown that after cycling three times between the “hidden” and “available” states, the conjugate retained more than 85% of its initial activity, showing that this system can be cycled and used multiple times without significant loss of activity. It is concluded that this dual-responsive gold nanoparticle–protein–polymer conjugate has great potential in applications requiring close control of protein activity under complex environmental conditions. [ABSTRACT FROM AUTHOR]

A novel metal–organic hybrid photochromic compound [Zn (CV) (L2)]·2H2O (1) (CV = N,N′-4,4′-bipyridiniodipropionate, H2L2 = isophthalic acid) has been synthesized solvothermally. Compound 1 features a two-dimensional (2D) framework structure, exhibiting photochromic properties under sunlight and UV irradiation with an obvious color change from colorless to dark blue. Meanwhile, the luminescence properties of 1 were investigated, and the results suggested that 1 has good properties of detecting dichromate ions. Furthermore, compound 1 shows different color changes when exposed to different alkyl-amines, and 1 can also be deposited into paper to use as portable test strips. This work can be applied to practical applications as a multifunctional detector against light and chemicals. [ABSTRACT FROM AUTHOR]

The emergence of carbon dots (CDs) has opened up an exciting new field in the science and technology of carbon nanomaterials and has attracted increasing interest in recent years. Due to their diverse physicochemical properties and favourable attributes, such as quantum confinement effects and abundant surface defects, CDs and their derived hybrids have shown exciting and indispensable prospects in the energy conversion and storage fields. Considering the latest developments, in this review, we comprehensively summarize the classification and structure of CDs. Three strategies for structural engineering of CDs are presented and analyzed, in terms of the tuning of size and crystallinity, and the methodologies for surface modification and heteroatom doping, with a focus on the relationship among the synthesis methods, structure and properties of the concerned CDs. More importantly, the recent advances in energy-oriented applications of CDs, including photo- and electro-catalysis, light-emitting diodes, photovoltaic cells, lithium/sodium ion batteries and supercapacitors, will be systematically highlighted. Finally, we discuss and outline the remaining major challenges and opportunities for CDs in the future. [ABSTRACT FROM AUTHOR]

Eight homochiral lanthanide coordination polymers, namely [Ln2L3(H2O)2]n·4nH2O [Ln = Sm (1); Eu (2); Gd (3); Tb (4); Dy (5); Ho (6); Er (7); Yb (8)], based on an achiral rigid ligand, 5-[(pyridin-4-ylmethyl)amino]-isophthalic acid (H2L), have been hydrothermally prepared and characterized by single X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and circular dichroism spectroscopy. Compounds 1–8 featured three-dimensional frameworks with triple-stranded helical chains, exhibiting a topological structure with the Schläfli symbol {45·6·104}{45·6}. Solid-state circular dichroism (CD) spectroscopy revealed the occurrence of spontaneous chiral symmetry breaking during crystallization and that the origin of chirality might be the helicity. Furthermore, luminescence and second harmonic generation (SHG) activity have been studied. Compound 5 showed SHG activity. Compounds 1, 2 and 4 displayed characteristic luminescence stemming from the trivalent lanthanides. [ABSTRACT FROM AUTHOR]

We report straightforward access to two new anionic porous organic polymers (Si-POPs) based on hexacoordinate [SiO6]2– species and polyimine aromatic linkers which exhibit outstanding capabilities for removal of cationic dyes from contaminated industrial water. These multifunctional materials are stable under air and in water; they were synthesized via solvothermal chemistry exploiting Schiff base formation between tri(protocatechuic aldehyde)-silicate and 4,4′-diaminobiphenyl acid (for Si-POP-1) or 4,4′-diamino-2,2′-stilbenedisulfonic acid (for Si-POP-2). Charge neutrality of the Si-POPs was achieved by [Et3NH]+ cations. The structures were determined by spectroscopic techniques (FT-IR and solid 13C-NMR spectroscopy), while SEM and TEM revealed a micrometer-scale solid sphere morphology for Si-POP-1 and hollow nanometer-sized tubes for Si-POP-2. BET specific surface area determination gave 376 and 234 m2 g−1 for Si-POP-1 and Si-POP-2, respectively. The unprecedented adsorption abilities of these materials for standard cationic dyes such as methylene blue (MB), malachite green (MG), and Basic Blue 7 (BB7) were revealed by studying the effects of system variables such as pH, contact time, temperature and mixed-dye solutions. At 25 °C, the maximum adsorption capacity of Si-POP-1 reached 300.3 mg g−1 for MB and 378.5 mg g−1 for MG, while the performance of Si-POP-2 at the same temperature was substantially higher (3516 mg g−1 for MB and 662 mg g−1 for MG). Furthermore, at 35 °C, the maximum adsorption of MB on Si-POP-2 reached 4098 mg g−1, surpassing the performance of previous adsorbents. It was found that both Si-POP-1 and Si-POP-2 exhibit charge and size-selective adsorption. Thermodynamics studies indicated that the adsorptions were spontaneous and endothermic. A minimal loss of adsorptive capacity of Si-POP-2 (less than 4%) was observed after four cycles, demonstrating an effective reuse of the regenerated POP in discarding MB from effluents. Importantly, this green protocol also allows recovery of the dye retained in the POP. These assets recommend these new hexacoordinate silicate-based adsorbents as viable materials for wastewater remediation by removal of organic dye pollutants affecting nature and public health. [ABSTRACT FROM AUTHOR]

A case study of two new covalently bonded polyoxomolybdate–viologen hybrids revealed that “reversible” photochromic properties can be achieved without the need for proton transfer, and the weak electron-withdrawing ability of the coordinated ligand favors photoreduction of Mo(vi) to Mo(v). [ABSTRACT FROM AUTHOR]

Compact and dense zeolite membranes were prepared on the inner surface of 170 mm long ceramic tubes by maintaining the pressure difference between the two sides of the support during the hydrothermal synthesis process. The effects of the pressure difference on the formation of NaA zeolite membrane were investigated in detail by X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM). The characterization results showed that the pressure difference created by controlling temperature or vacuum not only continuously drove fresh synthesis solution to the inner surface of the support, but also increased the binding force of the zeolite membrane to the support. However, a very large pressure difference led to a large amount of Si/Al active ingredients entering the channels of the support and blocking the pores, resulting in decrease in the permeability of the membrane. Gas permeation performance demonstrated that the pressure difference produced by controlling either the temperature or vacuum resulted in membranes with the highest permselectivities of H2 over other gases at the pressure difference of ca. 0.05 MPa between the two sides of the support. At 25 °C and 0.1 MPa, the permselectivity of H2 over N2 through the zeolite membrane synthesized by the pressure-driven method was as high as 5.21, and it was much higher than the corresponding Knudsen diffusion coefficient. [ABSTRACT FROM AUTHOR]

Two novel cadmium-based isomeric coordination polymers constructed from naphthalenediimide chromophoric components and aromatic dicarboxylic acids, [Cd(DPMNI)(m-BDC)]n (1) and [Cd(DPMNI)(p-BDC)]n (2) (DPMNI = N,N′-bis(4-pyridylmethyl)-1,4,5,8-naphthalenediimide, m-BDC2− = isophthalate, p-BDC2− = terephthalate) have been synthesized by solvothermal reactions and characterized systematically. Single-crystal X-ray diffraction analyses results indicate that compounds 1–2 possess the same basic building block, but show different 2D resultant constructions. The formation of non-covalent intermolecular interactions (CH–π, π–π, lone pair–π interactions) can not only generate 3D supramolecular structures, but also improve structural thermostabilities up to approximately 405 °C and 330 °C, according to their thermogravimetric analyses (TGA) results. Importantly, due to the stereocontrolled self-assembly of the isomeric coordination polymers, two kinds of lone pair–π interactions with varying strengths have been produced leading to different photochromic behaviors in 1–2. It is worth mentioning that the immediate photochromism of 1 is rare in NDI-based photochromic materials. Moreover, their photoluminescence properties have also been investigated to enrich the research on crystal photophysical properties. [ABSTRACT FROM AUTHOR]

Three novel square grid metal–organic frameworks (MOFs) based on cadmium have been synthesized successfully by analogous solvothermal reactions where N,N′-di(4-pyridylacylamino)-1,4,5,8-naphthalenediimide (IsoNDI) as the predesigned ligand was reacted with three kinds of aromatic dicarboxylic acids as the secondary building linkers. The geometries of these secondary building linkers have an influence on the formation of photochromism-leading intermolecular interactions in the obtained crystal structures. Owing to the existence of an NH group in the adopted NDI-type ligand, N–H…O hydrogen bonds are observed between the IsoNDI ligands and neighbouring dicarboxyl groups in all the compounds. However, face-to-face π–π stacking interactions are only found in compound 1 and not in 2 and 3, for the naphthalene ring possessing a larger π-plane in 1 is more likely to form interactions with the π-conjugated planar IsoNDI ligand. Meanwhile, lone pair–π interactions appear in compounds 2 and 3 but not in 1 because their close packing patterns have a tendency to generate such interactions between adjacent IsoNDI ligands. Moreover, all three compounds exhibit interesting reversible photochromic behaviors in the presence of photoinduced electron transfers through the above intermolecular interactions. Besides, photo-controlled luminescence properties have also been investigated showing a competitive relationship with photochromic behaviors. [ABSTRACT FROM AUTHOR]

An array of heterobimetallic Pd/Ln MOFs (1–4) with Sm, Eu, Tb, Dy as preferred metal nodes and 1,1′-di(p-carboxybenzyl)-2,2′-diimidazole (H2L) as a fairly suitable bifunctional organic linker have been synthesized, fully characterized and tested as catalysts in cross-coupling reactions. These robust MOFs, ensuring a uniform distribution of Pd, showed excellent stability in air and high catalytic activity in Suzuki–Miyaura reactions conducted in neat water, neat ethanol as well as water–ethanol mixture. Depending on the solvent, complex 1 could be effectively recycled 4–8 times without significant loss of catalytic activity. Importantly, this complex was found to be pH responsive in a reversible way, enabling convenient recovery from acidic aqueous solutions, indicating good recyclability as well as environment-friendly separation of the metal residues after the reaction. [ABSTRACT FROM AUTHOR]

Carbon-based hybrid nanostructures, especially carbon hybrid dots with metal oxides, are important to both fundamental studies and technological applications. In this work, carbon–TiO2 hybrid dots in two different structural configurations were prepared and investigated comparatively for their optical properties and photoinduced redox characteristics, and the results suggested major differences. In the configuration of small carbon nanoparticles each coated/doped with only a small amount of TiO2, the TiO2 played the role of enhancing the surface passivation effect in conjunction with organic surface functionalization agents for the hybrid dots to exhibit a much improved performance over that of their corresponding neat carbon dots. In the other configuration, however, the hybrid dots of TiO2 nanocrystals each composited with nanoscale carbon domains were apparently similar to dye-sensitized TiO2 nanoparticle systems, with the carbon domains providing the dye function for the harvesting of visible photons. While combining nanoscale carbon and TiO2 for various applications has been a popular topic in the recent literature, the results reported here provide new insights into the different structural configurations or arrangements between the carbon and TiO2 and their associated effects on the optical and photoinduced redox properties of the hybrid nanostructures. Significant implications of the results on an understanding of the mechanistic relationships between the hybrid nano-structures/configurations and optical/redox properties are highlighted, and opportunities in the further exploration of carbon–metal oxide hybrid dots and their applications are discussed. [ABSTRACT FROM AUTHOR]

Considering the reliable characteristics and the suitable silica alumina content of kaolin, a new way of synthesizing a ZSM-5/NaA hybrid zeolite membrane on 170 mm length ceramic tubes by employing kaolin as a modification layer using a hydrothermal synthesis process was presented for the first time in this work. Kaolin was filtrated on the surface of the support (not only the ceramic tube, but also the NaA membrane layer) as a modification layer not only promoting the interface interlinkage among the support, NaA membrane and ZSM-5 membrane layer, but also promoting the growth of zeolite membranes. The SEM and XRD results showed that compact and homogeneous NaA and ZSM-5 zeolite layers were both formed with the thicknesses being 7.06 μm and 6.14 μm, respectively, after modification with kaolin. The permeation separation experiments demonstrated that the performance of the ZSM-5/NaA hybrid membrane was better than that of the monolayer zeolite membrane with permselectivities of H2 over CO2, N2, CO and CH4 of 5.40, 4.65, 4.70 and 3.93, respectively, which were higher than the corresponding Knudsen diffusion coefficients. Above all, modifying the support with kaolin and then synthesizing the ZSM-5/NaA hybrid membrane could strengthen the performance of the zeolite membrane effectively, which provided a new approach for the synthesis of high performance zeolite membranes in the field of membrane separation. [ABSTRACT FROM AUTHOR]

Nineteen lanthanide–benzenedicarboxylate complexes were obtained under similar hydrothermal conditions: [Ln(IP-Py)(HIP-Py)(H2O)2]n (Ln = Pr (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6)), [Ln4(IP)6(H2O)4(DMF)·DMF·mH2O]n (Ln = Sm, m = 1 (7), Eu, m = 1.5 (8), Gd, m = 1.5 (9), Tb, m = 1.5 (10), Dy, m = 1 (11), Ho, m = 1.5 (12)), [Ln2(IP-Py)2(IP)(H2O)4·H2O]n (Ln = Sm (13), Eu (14), Tb (15), Dy (16)) and [Ln2(IP-Py)2(TP)(H2O)4·H2O]n (Ln = Sm (17), Eu (18), Gd (19)), where: H2IP-Py = 5-(4-pyridyl)-isophthalic acid), H2IP = isophthalic acid, H2TP = terephthalic acid. Complexes 1–6 exhibit a two-dimensional layered structure based on H2IP-Py. For 7–12, the Ln3+ ions are linked into one-dimensional chains with two triple-stranded helices of opposite handedness and further constructed into a two-dimensional layer by coordination of the IP2− ligands. For complexes 13–16 and 17–19, a similar two-dimensional layer was formed by coordination of Ln3+ and IP-Py2−, and three-dimensional pillar-layered frameworks were formed due to the layers bridged by the auxiliary IP2− or TP2− ligand, respectively. Most complexes show the characteristic narrow-banded lanthanide 4fN–4fN emission in combination with luminescence from the ligands, with the relative contribution depending on the energy transfer from the ligands to the lanthanides. The ligands play an important role in the sensitization of the lanthanide emission. The onset of the main excitation band for the Eu3+ complexes is found at the lowest energy for 14, enabling excitation by near-UV LEDs. The complexes containing the technologically relevant ions for (back) lighting applications, Tb3+ (green) and Eu3+ (red), are evaluated in detail in terms of luminescence lifetime and thermal stability. The emission intensity of selected Eu3+ and Tb3+ compounds is stable up to room temperature. [ABSTRACT FROM AUTHOR]

Host–guest carbon dots (G@CDots) represent a new platform in the rapidly advancing and expanding research field of carbon “quantum” dots or carbon dots, enabling the development of novel carbon hybrid nanostructures of unique and/or advantageous properties and capabilities beyond those of conventional carbon dots. In this study, the red/near-IR emissive dye nile blue (NB) was selected as the guest, and NB@CDots were prepared in a microwave-assisted one-pot thermal carbonization synthesis with oligomeric polyethylene glycols (PEGs) as the precursor and also surface passivation species in the resulting host–guest dots. The NB@CDots exhibited unique and/or favorable characteristics, including especially the bright red/near-IR fluorescence emissions, with the observed fluorescence quantum yield due to the guest nile blue species more than an order of magnitude higher than that of free nile blue molecules, all in aqueous solutions. The higher fluorescence intensities were coupled with a longer fluorescence lifetime, and also accompanied by excellent photochemical stability, making the NB@CDots high-performance fluorescence probes for bioimaging-sensing and related applications. Indeed, their potential in this regard was explored and demonstrated in the fluorescence imaging of live stem cells. The NB@CDots were also evaluated in cytotoxicity assays, and the results suggested their being nontoxic. Excellent opportunities in further development of the host–guest carbon dots platform for high-performance yet nontoxic fluorescence probes are discussed. [ABSTRACT FROM AUTHOR]

This work introduces the new trimetallic complex CoPd2(HBPDC)2Cl4·(H2O)4(H2BPDC = 2,2′-bipyridine-4,4′-dicarboxylic acid) as a highly efficient and more cost-effective catalyst for a Suzuki–Miyaura reaction proceeding in water, without additives and under aerobic conditions. Catalytic studies revealed a synergistic Co–Pd cooperativity, fostered by ligation through H2BPDC, and accounting for the superior performance of the heterobimetallic complex vs. its Co-free counterpart. [ABSTRACT FROM AUTHOR]

Carbon dots are small carbon nanoparticles with various surface passivation schemes, in which more effective has been the deliberate chemical functionalization of the nanoparticles for brighter fluorescence emissions, even though the synthesis method is more tedious and subject to some limitations in the selection of functionalization molecules. Another more popular synthesis method has been the carbonization of organic species, with the method being more efficient and versatile, but less controllable regarding synthesis and achieving the desired dot structure and performance. In this work, a hybrid approach combining the advantageous characteristics of the two synthesis methods was applied to the preparation of carbon dots using polyethyleneimine (PEI) for surface passivation, where pre-processed and selected small carbon nanoparticles were functionalized with PEI by microwave-induced thermal reactions. Their optical absorption and fluorescence emission properties were evaluated, and the results suggested that the carbon dots thus prepared shared the same photoexcited state characteristics with those from the deliberate chemical functionalization, including comparable fluorescence colors and other properties. A further demonstration of the similarity in photoexcited state properties was based on the same visible light-activated bactericidal functions of the PEI-carbon dots as those found in carbon dots from the deliberate chemical functionalization method. The advantages and potential limitations of the hybrid approach for more controllable yet versatile and efficient syntheses of carbon dots are highlighted and discussed. [ABSTRACT FROM AUTHOR]

Flower shaped WO3 architectures weaved up of ultrathin nanorods with oriented {001} facets were successfully prepared via a facile ethanol/water solvothermal strategy, at a low temperature of 100 °C for 4 h. Characterizations of phase, morphology, microstructure, optical absorption, BET surface area, photoluminescence, photoelectrochemical properties and photocatalytic behavior were systematically explored. The volume ratio of ethanol and water was confirmed to be a key parameter in regulating the morphology and microstructure of WO3 by tuning the dielectric properties of the mixed solvent. The {001} faceted WO3 structures exhibit improved photocatalytic activity for the degradation of methyl orange with the reaction rate constant k enhanced by 2.1 fold, compared to the hydrothermal counterpart assembled by thick, individual WO3 nanorods. The active {001} facets with faster charge migration and enhanced surface area with more adsorption sites account for the excellent photocatalytic behavior. In addition, the active species in the photocatalytic reaction were investigated in detail, using terephthalic acid capture, ESR and radical scavengers. Combining the band edge positions of WO3 and the redox potentials of the active species, a possible migration mechanism of photogenerated e−/h+ pairs on the surface of WO3 is proposed. This work provides some new insights into the rational design and synthesis of facet-dependent 3D semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

Carbon dots of small carbon nanoparticles surface-functionalized with 2,2′-(ethylenedioxy)bis(ethylamine) (EDA) were synthesized, and the as-synthesized sample was separated on an aqueous gel column to obtain fractions of the EDA–carbon dots with different fluorescence quantum yields. As already discussed in the literature, the variations in fluorescence performance among the fractions were attributed to the different levels and/or effectiveness of the surface functionalization–passivation in the carbon dots. These fractions, as well as carbon nanoparticles without any deliberate surface functionalization, were dispersed into poly(vinyl alcohol) (PVA) for composite films. In the PVA film matrix, the carbon dots and nanoparticles exhibited much enhanced fluorescence emissions in comparison with their corresponding aqueous solutions. The increased fluorescence quantum yields in the films were determined quantitatively by using a specifically designed and constructed film sample holder in the emission spectrometer. The observed fluorescence decays of the EDA–carbon dots in the films and in the solution were essentially the same, suggesting that the significant enhancement in fluorescence quantum yields from the solution to films is static in nature. Mechanistic implications of the results, including a rationalization in terms of the compression effect on the surface passivation layer (similar to a soft corona) in carbon dots when embedded in the more restrictive film environment resulting in more favorable radiative recombinations of the carbon particle surface-trapped electrons and holes, and also potential technological applications of the brightly fluorescent composite films are highlighted and discussed. [ABSTRACT FROM AUTHOR]