Ag-based coordination polymer-enhanced photocatalytic degradation of ciprofloxacin and nitrophenol.

Transition-metal coordination complexes have attracted wide attention in molecular chemistry, but their applications still confront a tremendous challenge. Herein, a novel silver coordination polymer with a formula of {[Ag9(TIPA)6](NO3)9·12H2O}n (Ag-TIPA) was prepared by a solvothermal reaction of silver nitrate with triangular tris(4-imidazolylphenyl)amine (TIPA). The crystalline molecular structure was determined by single-crystal X-ray diffraction, which showed that each Ag(I) was coordinated with two nitrogen atoms of TIPA ligands. Such Ag-TIPA was used as a catalyst for the photodegradation of ciprofloxacin and 4-nitrophenol under UV-visible light irradiation. The results exhibited excellent photocatalytic performance and reusability due to high structure stability in an acidic, neutral and alkaline environment. The experimental findings and density functional theory calculations revealed that metal-ligand charge transfer in Ag-TIPA extended the absorption range of light and improved the charge transfer properties of TIPA. To further understand the photodegradation process, the intermediates were predicted and analysed through electrostatic potential, orbital weighted dual descriptor, and liquid chromatography-mass spectrometry techniques. Based on these findings, a possible degradation mechanism was proposed. This study provides new insights into the design and synthesis of Ag-based coordination polymers with novel structures, excellent catalytic activity, and good durability.

Samarium- and Ytterbium-Grafted Periodic Mesoporous Silica for Carbon Dioxide Capture and Conversion.

Immobilized coordination compounds of Lewis acidic metals are powerful catalytic components of systems for the cycloaddition of CO2 to epoxides that do not require sophisticated coordination frameworks to harness the metal center and modulate its activity. Surface organometallic chemistry (SOMC) is a valuable methodology to prepare well-defined and site-isolated surface complexes and coordination compounds on metal oxides, with ligand environments easily adjustable to a targeted catalytic reaction. In this work, the SOMC methodology is applied to prepare SmII, YbII, and SmIII alkoxide surface complexes on periodic mesoporous (organo)silica of distinct pore symmetry/size for application in the CO2 cycloaddition reaction. The surface complexes are readily accessible by the grafting of the bis(trimethylsilyl)amide precursors LnII[N(SiMe3)2]2(THF)2 (Ln = Sm, Yb) and SmIII[N(SiMe3)2]3, followed by ligand exchange with alcohols (ethanol and neopentanol). The use of periodic mesoporous supports led to hybrid materials with relatively high surface areas and pore sizes, affording good performance in CO2 capture and in the cycloaddition of CO2 to epoxides under mild conditions (60-80 °C, 1-10 bar). In terms of catalytic performance, recyclability, and low amount of added nucleophile TBAX (X = Br, I), the most active materials prepared in this work compare well to a variety of previously reported SOMC-derived surface complexes and to other heterogeneous Lewis acids displaying more elaborate ligand environments.

Advanced Photocatalytic Uranium Extraction Strategies: Progress, Challenges, and Prospects.

Nuclear energy with low carbon emission and high-energy density is considered as one of the most promising future energy sources for human beings. However, the use of nuclear energy will inevitably lead to the discharge of nuclear waste and the consumption of uranium resources. Therefore, the development of simple, efficient, and economical uranium extraction methods is of great significance for the sustainable development of nuclear energy and the restoration of the ecological environment. Photocatalytic U(VI) extraction technology as a simple, highly efficient, and low-cost strategy, received increasing attention from researchers. In this review, the development background of photocatalytic U(VI) extraction and several photocatalytic U(VI) reduction mechanisms are briefly described and the identification methods of uranium species after photocatalytic reduction are addressed. Subsequently, the modification strategies of several catalysts used for U(VI) extraction are summarized and the advantages and disadvantages of photocatalytic U(VI) extraction are compared. Additionally, the research progress of photocatalytic technology for U(VI) extraction in actual uranium-containing wastewater and seawater are evaluated. Finally, the current challenges and the developments of photocatalytic U(VI) extraction technology in the future are prospected.

Advance Progress on Luminescent Sensing of Nitroaromatics by Crystalline Lanthanide-Organic Complexes.

Water environment pollution is becoming an increasingly serious issue due to industrial pollutants with the rapid development of modern industry. Among many pollutants, the toxic and explosive nitroaromatics are used extensively in the chemical industry, resulting in environmental pollution of soil and groundwater. Therefore, the detection of nitroaromatics is of great significance to environmental monitoring, citizen life and homeland security. Lanthanide-organic complexes with controllable structural features and excellent optical performance have been rationally designed and successfully prepared and used as lanthanide-based sensors for the detection of nitroaromatics. This review will focus on crystalline luminescent lanthanide-organic sensing materials with different dimensional structures, including the 0D discrete structure, 1D and 2D coordination polymers and the 3D framework. Large numbers of studies have shown that several nitroaromatics could be detected by crystalline lanthanide-organic-complex-based sensors, for instance, nitrobenzene (NB), nitrophenol (4-NP or 2-NP), trinitrophenol (TNP) and so on. The various fluorescence detection mechanisms were summarized and sorted out in the review, which might help researchers or readers to comprehensively understand the mechanism of the fluorescence detection of nitroaromatics and provide a theoretical basis for the rational design of new crystalline lanthanide-organic complex-based sensors.

Intrinsically morphological effect of perovskite BaTiO3 boosting piezocatalytic uranium extraction efficiency and mechanism investigation.

Developing a convenient, efficient and eco-friendly approach for the recovery of U(VI) ion is a key measure to solve the environmental problems arising from the utilization of nuclear energy. Herein, the high efficiency of uranium extraction is realized by the piezo property of perovskite BaTiO3, revealing the intrinsically morphological engineering effect on the piezocatalytic performance. Especially, BaTiO3 nanowires (BTO NWs) exhibit not only an excellent piezocatalytic activity with U(VI) extraction rate of 96.8% in a UO2(NO3)2 aqueous solution compared to 71.3% of BaTiO3 nanoparticles (BTO NPs), but also a promising piezocatalyst for U extraction in a real U-mining wastewater with various pH ranges. Piezo response force microscopy and finite elemental simulation show that the piezo response of BTO NWs is much higher than BTO NPs. Additionally, some factors (pH, various ions, different powers) are explored on piezocatalytic efficiency for U(VI) extraction. The results from electron spin resonance and the charge/radical capture experiments confirm that the active species (e-, •O2-, •OH) stemmed from the piezo induction of BTO NWs and BTO NPs in the piezocatalytic U(VI) reduction process. The present work reveals the structure-performance correlation during piezocatalysis and highlights the crucial role of piezocatalysis in dealing with environmental problems.

Hydroxypropyl-ß-cyclodextrin-incorporated Pebax composite membrane for improved permselectivity in organic solvent nanofiltration.

Thanks to the characteristic hollow cavity structure and sustainable and nontoxic macrocycle molecule feature, cyclodextrins have been used as building block to fabricate organic solvent nanofiltration (OSN) membranes with enhanced permeability and selectivity. Herein, hydroxypropyl-ß-cyclodextrin (HP-ß-CD) was incorporated into a poly(ether-block-amide) (Pebax) layer on a polysulfone support, followed by crosslinking with toluene 2,4-diisocyanate to prepare a crosslinked HP-ß-CD/Pebax (CHP) membrane. By adjusting the initial HP-ß-CD concentration (x) and crosslinking reaction time (y), the microporous structure and surface morphology of CHP x-y (x = 0, 0.25, 0.5, 0.75; y = 5, 10, 15) membranes could be manipulated. The OSN performances of the CHP x-y membranes were evaluated by the removal of dyes in methanol solution. The results revealed that the optimal CHP0.5-10 membrane exhibited a high methanol permeance of 8.7 L m-2 h-1 bar-1, high dye rejection (>96%), and high running stability (at least 336 h), due to the intrinsically microporous structure and surface morphology. This work would inspire the further development of cyclodextrins and other macrocyclic molecules in the preparation of OSN membranes and provide a promising strategy to fabricate state-of-the-art membranes for the efficient separation of organic solvent reclamation and removal of organic pollutants.

Recent advanced development of metal-loaded mesoporous organosilicas as catalytic nanoreactors.

Ordered periodic mesoporous organosilicas have been widely applied in adsorption/separation/sensor technologies and the fields of biomedicine/biotechnology as well as catalysis. Crucially, surface modification with functional groups and metal complexes or nanoparticle loading has ensured high efficacy and efficiency. This review will highlight the current state of design and catalytic application of transition metal-loaded mesoporous organosilica nanoreactors. It will outline prominent synthesis approaches for the grafting of metal complexes, metal salt adsorption and in situ preparation of metal nanoparticles, and summarize the catalytic performance of the resulting mesoporous organosilica hybrid materials. Finally, the potential prospects and challenges of metal-loaded mesoporous organosilica nanoreactors are addressed.

Photocatalytic performance and mechanism insights of a S-scheme g-C3N4/Bi2MoO6 heterostructure in phenol degradation and hydrogen evolution reactions under visible light.

Photocatalysis with potentially low cost and sustainable utilization is a typically environmentally benign method for the degradation of organic pollutants, but the rational design and fabrication of photocatalysts with high catalytic performance is still an enormous challenge. The efficient segregation of photogenerated electron-hole pairs in photocatalysts is a key and essential factor to decide photocatalytic activity. Herein, a novel Step-scheme (S-scheme) heterojunction photocatalyst, a g-C3N4/Bi2MoO6 (g-CN/BMO) composite, was successfully fabricated using g-C3N4 nanosheet-wrapped Bi2MoO6 microspheres. By adjusting the amount of g-C3N4 in BMO, a series of g-CN/BMO composites was prepared while optimizing posttreatment temperature. The resulting g-CN/BMO indicated well the photocatalytic performance for the degradation of phenol and hydrogen evolution reactions, especially, 100 g of g-CN was integrated into 100 g of the pre-calcined BMO at 200 °C to produce 100% g-CN/BMO-200, showing the highest photocatalytic performance compared to single composite BMO, BMO-200, g-CN, and g-CN/BMO-200 with other mass ratios. Combining the results from the density functional theory calculations and the results of X-ray photoelectron spectroscopy, for S-scheme heterojunction-structured g-CN/BMO-200, the internal electric field-, band edge bending- and coulomb interaction-driven efficient segregation of photogenerated electrons and holes at the interface is elucidated to explain the photocatalytic mechanism, and the resulting holes on the VB of BMO and electrons on the CB of g-CN are responsible for the improvement of the photocatalytic performance. This study revealed that for the S-scheme g-CN/BMO composite the internal electric field, band edge bending and coulomb interaction at the interface between g-CN and BMO can not only promote the effective segregation of electrons and holes, but also retain stronger redox ability. Such an investigation provides a facile and simple strategy to fabricate novel S-scheme heterojunction-structured photocatalysts for solar energy conversion.

High-Capacity, Dendrite-Free, and Ultrahigh-Rate Lithium-Metal Anodes Based on Monodisperse N-Doped Hollow Carbon Nanospheres.

To unlock the great potential of lithium metal anodes for high-performance batteries, a number of critical challenges must be addressed. The uncontrolled dendrite growth and volume changes during cycling (especially, at high rates) will lead to short lifespan, low Coulombic efficiency (CE), and security risks of the batteries. Here it is reported that Li metal anodes, employing the monodisperse, lithiophilic, robust, and large-cavity N-doped hollow carbon nanospheres (NHCNSs) as the host, show remarkable performances-high areal capacity (10 mAh cm-2), high CE (up to 99.25% over 500 cycles), complete suppression of dendrite growth, dense packing of Li anode, and an extremely smooth electrode surface during repeated Li plating/stripping. In symmetric cells, a highly stable voltage hysteresis over a long cycling life >1200 h is achieved, and a low and stable voltage hysteresis can be realized even at an ultrahigh current density of 64 mA cm-2. Furthermore, the NHCNSs-based anodes, when paired with a LiFePO4 (LFP) cathode in full cells, give rise to highly improved rate capability (104 mAh g-1 at 10 C) and cycling stability (91.4% capacity retention for 200 cycles), enabling a promising candidate for the next-generation high energy/power density batteries.

Cerium Pyrazolates Grafted onto Mesoporous Silica SBA-15: Reversible CO2 Uptake and Catalytic Cycloaddition of Epoxides and Carbon Dioxide.

The activation and catalytic conversion of CO2 is a current topic relating to molecular chemistry and materials science alike. As a transdisciplinary field of research, surface organometallic chemistry (SOMC) might be applicable to perform synergistically, thus striking a new path in sustainable chemistry. Both ceric and cerous rare-earth-metal pyrazolates, which were recently shown to reversibly insert CO2 and to promote the catalytic cycloaddition of epoxides and carbon dioxide, were grafted onto large-pore mesoporous silica SBA-15500, thermally pretreated at 500 °C. The obtained hybrid materials [Ce(Me2pz)4]2@SBA-15500, Ce(Me2pz)4(thf)@SBA-15500, Ce4(Me2pz)12@SBA-15500, and [Ce(Me2pz)3(thf)]2@SBA-15500 (Me2pz = 3,5-dimethylpyrazolato) were characterized by DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy), solid-state 1H/13C NMR spectroscopy, elemental analysis, ICP/OES, and N2 physisorption. The lanthanum(III)-based material [La(Me2pz)3(thf)]2@SBA-15500 was synthesized for better assessment of the cerous materials being highly sensitive to oxidation. To mimic ceric surface species, Ce[OSi(OtBu)3]3Cl was treated with 1 equiv of K(Me2pz), generating the mixed pyrazolyl/siloxy complex KCe[OSi(OtBu)3]4(Me2pz) featuring a cerium(IV)-bonded terminal pyrazolato ligand. All hybrid materials show efficient and reversible carbon dioxide uptake of maximum 20 wt % in the solid state. When combined with tetra-n-butylammonium bromide (TBAB), the hybrid materials catalyze the cycloaddition of CO2 and epoxides, displaying good conversion of various epoxides and reusability.

Ni or FeO nanocrystal-integrated hollow (solid) N-doped carbon nanospheres: preparation, characterization and electrochemical properties.

In this paper, phase-pure monodisperse NiO nanocrystals were prepared in a temperature-dependent manner via a thermal decomposition approach, showing sphere-like shapes and snowflake-like NiO arrays. Such hydrophobic NiO nanocrystals were converted into hydrophilic nickel oxide-sodium oleate-Pluronic P123 (NiO-SO-P123) micelles in aqueous solution. Phenolic resin (PR) formed in situ was successfully deposited on the hydrophilic area of the NiO-SO-P123 micelles via a heterogeneous nucleation mechanism to form NiO-phenolic resin nanospheres (NiO-PRNSs) with uniform particle size. By adjusting the size and amount of NiO nanocrystals used, the diameter of the obtained NiO-PRNSs can be effectively controlled from 185 to 103 nm, and a narrow size distribution is seen, revealing the effects of the NiO nanocrystals on the reconstructed NiO-integrated micellar size. Meanwhile, the morphology (ring buoy, semi-bowl, sphere) depends upon the initial amount of NiO. The carbonization of NiO-PRNSs produced Ni(0)-integrated hollow N-doped carbon nanospheres (Ni(0)-HNCNSs), which involved the conversion of NiO to Ni(0) and the contraction of particle size, and the size and distribution was affected by the starting amount of NiO. However, upon using monodisperse and polyhedral FeO nanocrystals, the obtained FeO-free/-incompletely-filled/-fully-filled core-shell structured Fe-PRNSs showed relatively uniform particle size, except for when multiple FeO cores formed large FeO-PR nanospheres after starting with the same initial FeO size. The carbonized FeO-HNCNSs still preserved a pomegranate-like core-shell structure with uniform size and there was no change in the size of the FeO nanocrystals. Moreover, high-loaded Ni(0)-integrated hollow or solid N-doped carbon microspheres or flakes can be synthesized via a one-pot method, but with a broad size range, showing highly uniform Ni distribution with a Ni size as small as 8.5 nm. Note that Ni(0)- and FeO-HNCNSs were prepared for the first time according to our knowledge. Finally, low-loaded Ni- and FeO-HNCNSs with uniform morphology and size were chosen as representatives to investigate their electrochemical properties for lithium-ion batteries (LIBs), showing excellent lithium storage properties and superior reversibility. This study provides a potential strategy for controlling the sizes and morphologies of metal-integrated carbon materials to obtain adjustable electrochemical properties.

The Novel Z-Scheme Ternary-Component Ag/AgI/α-MoO3 Catalyst with Excellent Visible-Light Photocatalytic Oxidative Desulfurization Performance for Model Fuel.

The novel ternary-component Ag/AgI/α-MoO3 (AAM) photocatalyst was successfully fabricated by a facile hydrothermal method combined with a charge-induced physical adsorption and photo-reduced deposition technique. X-ray diffraction, scanning/transmission electron microscope, X-ray photoelectron, UV-vis diffuse reflectance, photoluminescence and electrochemical impedance spectroscopy were employed to characterize the composition, morphology, light-harvesting properties and charge transfer character of the as-synthesized catalysts. The ternary-component AAM heterojunctions exhibited an excellent visible-light photocatalytic oxidative desulfurization activity, in which the AAM-35 (35 represents weight percent of AgI in AAM sample) possessed the highest photocatalytic activity of the conversion of 97.5% in 2 h. On the basis of band structure analysis, radical trapping experiments and electron spin resonance (ESR) spectra results, two different catalytic mechanisms were suggested to elucidate how the photogenerated electron-hole pairs can be effectively separated for the enhancement of photocatalytic performance for dual composites AM-35 and ternary composites AAM-35 during the photocatalytic oxidative desulfurization (PODS) of thiophene. This investigation demonstrates that Z-scheme Ag/AgI/α-MoO3 will be a promising candidate material for refractory sulfur aromatic pollutant's removal in fossil fuel.

Hierarchical Mesoporous Organosilica-Silica Core-Shell Nanoparticles Capable of Controlled Fungicide Release.

A new class of hierarchically structured mesoporous silica core-shell nanoparticles (HSMSCSNs) with a periodic mesoporous organosilica (PMO) core and a mesoporous silica (MS) shell is reported. The applied one-pot, two-step strategy allows rational control over the core/shell chemical composition, topology, and pore/particle size, simply by adjusting the reaction conditions in the presence of cetyltrimethylammonium bromide (CTAB) as structure-directing agent under basic conditions. The spherical, ethylene- or methylene-bridged PMO cores feature hexagonal (p6mm) or cage-like cubic symmetry (Pm3‾ n) depending on the organosilica precursor. The hexagonal MS shell was obtained by n-hexane-induced controlled hydrolysis of TEOS followed by directional co-assembly/condensation of silicate/CTAB composites at the PMO cores. The HSMSCSNs feature a hierarchical pore structure with pore diameters of about 2.7 and 5.6 nm in the core and shell domains, respectively. The core sizes and shell thicknesses are adjustable in the ranges of 90-275 and 15-50 nm, respectively, and the surface areas (max. 1300 m2 g-1 ) and pore volumes (max. 1.83 cm3 g-1 ) are among the highest reported for core-shell nanoparticles. The adsorption and controlled release of the fungicide propiconazole by the HSMSCSNs showed a three-stage release profile.

Organozinc Precursor-Derived Crystalline ZnO Nanoparticles: Synthesis, Characterization and Their Spectroscopic Properties.

Crystalline ZnO-ROH and ZnO-OR (R = Me, Et, iPr, nBu) nanoparticles (NPs) have been successfully synthesized by the thermal decomposition of in-situ-formed organozinc complexes Zn(OR)2 deriving from the reaction of Zn[N(SiMe3)2]2 with ROH and of the freshly prepared Zn(OR)2 under an identical condition, respectively. With increasing carbon chain length of alkyl alcohol, the thermal decomposition temperature and dispersibility of in-situ-formed intermediate zinc alkoxides in oleylamine markedly influenced the particle sizes of ZnO-ROH and its shape (sphere, plate-like aggregations), while a strong diffraction peak-broadening effect is observed with decreasing particle size. For ZnO-OR NPs, different particle sizes and various morphologies (hollow sphere or cuboid-like rod, solid sphere) are also observed. As a comparison, the calcination of the fresh-prepared Zn(OR)2 generated ZnO-R NPs possessing the particle sizes of 5.4~34.1 nm. All crystalline ZnO nanoparticles are characterized using X-ray diffraction analysis, electron microscopy and solid-state ¹H and 13C nuclear magnetic resonance (NMR) spectroscopy. The size effect caused by confinement of electrons' movement and the defect centres caused by unpaired electrons on oxygen vacancies or ionized impurity heteroatoms in the crystal lattices are monitored by UV-visible spectroscopy, electron paramagnetic resonance (EPR) and photoluminescent (PL) spectroscopy, respectively. Based on the types of defects determined by EPR signals and correspondingly defect-induced probably appeared PL peak position compared to actual obtained PL spectra, we find that it is difficult to establish a direct relationship between defect types and PL peak position, revealing the complication of the formation of defect types and photoluminescence properties.

Correction: Nano-sized Al2O3 reduces acute toxic effects of thiacloprid on the non-biting midge Chironomus riparius.

[This corrects the article DOI: 10.1371/journal.pone.0176356.].

Organoindium-modified monodisperse ellipsoid-/platelet-like periodic mesoporous silicas.

In this study, an indium(iii) silylamide complex was respectively grafted onto monodisperse ellipsoid-like (E) and platelet-like (P) large-pore hexagonal periodic mesoporous silicas (PMSs) SBA-15 to afford hybrid materials In[N(SiMe3)2]3@SBA-15E and In[N(SiMe3)2]3@SBA-15P with well-defined surface species ([triple bond, length as m-dash]SiO)2In[N(SiMe3)2], [triple bond, length as m-dash]SiOIn[N(SiMe3)2]2, and [triple bond, length as m-dash]SiOSiMe3. Surface ligand exchange between silylamido and alkoxyl group led to the conversion of surface species ([triple bond, length as m-dash]SiO)2In[N(SiMe3)2] and [triple bond, length as m-dash]SiOIn[N(SiMe3)2]2 into ([triple bond, length as m-dash]SiO)2In(OR) and [triple bond, length as m-dash]SiOIn(OR)2 (R = Me, Et, iPr) with donor ligands thf or NH3, respectively, revealing that silylamido coordinated to the indium centre could be completely exchanged with alkoxyl groups (-OMe, OEt or OiPr). Solid-state 1H, 13C and 29Si nuclear magnetic resonance spectra and elemental analyses confirmed that surface species [triple bond, length as m-dash]SiOIn[N(SiMe3)2]2 are dominant in comparison with bipodal ([triple bond, length as m-dash]SiO)2In[N(SiMe3)2] and [triple bond, length as m-dash]SiOSiMe3. The diffuse reflectance infrared Fourier-transform spectroscopy of In-modified hybrid materials directly evidenced the alteration of surface species before and after grafting of In[N(SiMe3)2]3 and surface ligand exchange. In addition, the change of pore parameters (pore diameter, specific surface area and pore volume) monitored by nitrogen physisorption also indirectly corroborated the immobilization of the indium complex and the occurrence of ligand exchanges between -[N(SiMe3)2]2 and -OR (R = Me, Et, iPr) on the surface of SBA-15. Note that the calcination of In-modified hybrid materials at 540 °C led to the formation of crystalline In2O3 nanoparticles with different sizes which were respectively located in the internal pore and on the external surface of SBA-15 due to the pore confinement effect, migration effect and shape effect of the parent support, but the long-range ordered mesopore arrays were still preserved and the crystalline structures of In2O3 were verified by powder X-ray diffraction and transmission electron microscopy.

Nano-sized Al2O3 reduces acute toxic effects of thiacloprid on the non-biting midge Chironomus riparius.

This study focuses on interactions between nanoparticles and a pesticide. The aim was to investigate how nano-sized aluminum oxide (410 nm) can alter the toxic effects of thiacloprid, even if no sorption between particles and the insecticide takes place. Thus, our study investigated a rather unexplored interaction. We conducted our research with larvae of Chironomus riparius and used thiacloprid as test substance as its toxicity to C. riparius is well described. The used nano-Al2O3 particles where chosen due to their suitable properties. For testing the acute effects of the interaction, we exposed larvae to thiacloprid (0.5, 1.0, 2.0, and 5.0 µg/L) and nano-Al2O3 (300 and 1000 mg/L), either solely or in binary mixtures. While thiacloprid resulted in elevated mortality, nano-Al2O3 solely did not exert any effects. Moreover, we observed an aggregation of nano-Al2O3 within the lumen of the intestinal tract of the larvae. Further results showed a significantly reduced mortality of fourth instar larvae when they were exposed to mixtures of nanoparticles and the pesticide, compared to thiacloprid alone. With increasing nano-Al2O3 concentration, this effect became gradually stronger. Additionally, chemical analyses of internal thiacloprid concentrations implicate reduced uptake of thiacloprid in animals exposed to mixtures. However, as larvae exposed to thiacloprid concentrations > 0.5 µg/L showed severe convulsions, independent of the presence or concentration of nano-Al2O3, we assume that nano-Al2O3 leads to a delay of mortality and does not entirely prevent it. As sorption measurements on pristine or defecated nano-Al2O3 did not reveal any sorptive interaction with thiacloprid, we can exclude sorption-based reduction of thiacloprid bioavailability as a mechanism behind our results. Even though we used test substances which might not co-occur in the environment in the tested concentrations, our study gives evidence for an interaction besides adsorption, which is important to generally understand how nanoparticles might affect biota.

Monodisperse mesoporous silica nanoparticles of distinct topology.

Monodisperse and uniform high-quality MCM(Mobil Composition of Matter)-48-type CMSNs (Cubic Mesoporous Silica Nanoparticles) are readily prepared by simply optimizing the molar ratio of ethanol and surfactant in the system TEOS-CTAB-NaOH-H2O-EtOH (TEOS=tetraethyl orthosilicate, CTAB=cetyltrimethylammonium bromide, EtOH=ethanol). In the absence of ethanol only hexagonal mesoporous silica with ellipsoidal and spherical morphology are obtained. The presence of ethanol drives a mesophase transformation from hexagonal to mixed hexagonal/cubic, further to purely cubic, and finally to a mixed cubic/lamellar. This is accompanied by a morphology evolution involving a mixture of ellipses/spheres, regular rods, uniform spheres, and finally a mixture of spheres/flakes. Preserving the three-dimensional (3D) cubic MCM-48 structure, use of a small amount of ethanol is beneficial to the improvement of the monodispersity of the CMSNs. Moreover, the quality of the CMSNs can also be controlled by changing the surfactant concentration or adjusting the stirring rate. All MSNs were characterized using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and N2 physisorption, indicating highly long-range ordered pore arrays, high specific surface areas (max. 1173 m2g-1) as well as high pore volumes (max. 1.14 cm3g-1). The monodispersity of the CMSNs was verified by statistical particle size distribution from SEM (scanning electron microscopy)/TEM (transmission electron microscopy) images and DLS (dynamic light scattering). The mesophase transformation can be rationalized on the basis of an ethanol-driven change of the surfactant packing structure and charge matching at the surfactant/silicate interface. The corresponding morphology evolution can be elucidated by an ethanol-controlled hydrolysis rate of TEOS and degree of condensation of oligomeric silicate species via a nucleation and growth process.

Nanostructured catalysts via metal amide-promoted smart grafting.

The heterogenization of homogeneous catalysts is a current topic in sustainable chemistry and catalysis. Such immobilized molecular catalysts provide access to environmentally benign chemical syntheses due to the ease of product separation and concomitant waste decrease. This perspective focuses on the fabrication of nanostructured catalysts by using amorphous (non)porous silica or metal oxides and periodic mesoporous (organo)silicas PM(O)S as 1(st) and 2(nd) generation supports, respectively, as well as metal (silyl)amide complexes as tailor-made grafting precursors. The pertinent SOMC (SOMC = surface organometallic chemistry) places special emphasis on organometallic hybrid materials that display properties distinct from the respective molecular catalysts and on new catalytic avenues which originate from 2(nd) generation supports.

Functionalization of large-pore periodic mesoporous silicas: metal silylamide and isopropoxide molecular grafting and secondary surface ligand exchange.

Divalent metal silylamide complexes of zinc and cobalt and trivalent aluminium isopropoxide were successfully grafted onto large-pore hexagonal channel-like SBA-15 and cubic MCM-48-like periodic mesoporous silica (PMS) KIT-6, to afford hybrid materials Zn[N(SiMe3)2]2@SBA-15, Co[N(SiMe3)2]2(thf)@SBA-15/KIT-6 and {Al(OCHMe2)3}@SBA-15 with well-defined surface species (≡SiO)2M(thf)x, ≡SiOM[N(SiMe3)2](THF)x (x = 0, M = Zn; x = 1, M = Co), ≡SiOSiMe3 and (≡SiO)2Al(OCHMe2) and ≡SiOAl(OCHMe2)2, respectively. Surface silylamido ligand exchange with 1,4-benzenediol, 1,4-benzenedicarboxylic acid, and biphenyl-4,4'-dicarboxylic acid gave hybrid materials of type ≡SiOML(solvent)x and (≡SiO)2M(solvent)x (L = O(C6H4)OSiMe3, O2C(C6H4)CO2SiMe3, O2C(C6H4)2CO2SiMe3; M = Zn and Co) revealing in situ ligand silylation as a side reaction. Surface isopropoxide/carboxylato ligand exchange generated species (≡SiO)2AlL(DMF)x and ≡SiOAl(OCHMe2)(2-y)L(y) (L = O2C(C6H4)CO2H, y ≤ 2) devoid of any secondary functionalization (such as formation of ester groups), offering a potential approach to PMS-encapsulated metal-organic frameworks. All featured surface species were verified by (1)H, (13)C and (29)Si magic angle spinning (MAS) NMR and diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy as well as elemental analysis. Additionally, preservation of the long-range ordered mesostructures was proven by powder X-ray diffraction (PXRD), nitrogen physisorption, and transmission electron microscopy (TEM).