Configurationally Nonselective Aquation of a Mononuclear Ru(II) Chloro Complex to Aquo Complex Isomers with Distinctive Aspects in Photoisomerization, Redox, and Catalytic Water Oxidation.

distal-[Ru(EtOtpy)(pynp)Cl]+ (d-EtO1Cl) (EtOtpy = 4'-ethoxy-2,2':6',2″-terpyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine), and distal/proximal-[Ru(EtOtpy)(pynp)OH2]2+ (d/p-EtO1H2O) complexes were newly synthesized to investigate the synergistic influence of the geometric configuration coupled with substituent introduction of an ethoxy (EtO) group on the physicochemical properties and reactions of the Ru(II) complexes. Configurationally nonselective aquation of d-EtO1Cl was uniquely observed to form d/p-EtO1H2O isomers in water, in contrast to configurationally selective aquation of distal-[Ru(tpy)(pynp)Cl]+ (d-1Cl, tpy = 2,2':6',2″-terpyridine) without the EtO group [Yamazaki, H. . J. Am. Chem. Soc. 2011, 133, 8846-8849].The kinetic profiles of the aquation reactions of d-EtO1Cl were well analyzed using a sequential reversible reaction model assuming the reversible interconversion between d/p-EtO1H2O isomers via d-EtO1Cl. The observed equilibrium constant (Kiso) of isomerization between p/d-EtO1H2O was calculated from the kinetic analysis as Kiso = 0.45, which is consistent with the final concentration ratio (1:0.43) of p/d-EtO1H2O generated in the aquation reaction of d-EtO1Cl. The irreversible photoisomerization from d-EtO1H2O to p-EtO1H2O was observed in water with an internal quantum yield (Φ) of 0.44% at 520 nm. Electrochemical measurements showed that d-EtO1H2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1.3-9.7, whereas p-EtO1H2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of 1.8-11.5. Any redox potential of d/p-EtO1H2O isomers was decreased by the electro-donating EtO substitution, compared with distal/proximal-[Ru(tpy)(pynp)OH2]2+ (d/p-1H2O). The turnover frequency (kO2 = 1.7 × 10-2 s-1) of d-EtO1H2O for water oxidation catalysis is higher than that (3.5 × 10-4 s-1) of p-EtO1H2O by a factor of 48.6. The kO2 value (1.7 × 10-2 s-1) for d-EtO1H2O is 4.5-fold higher than those of d-1H2O (3.8 × 10-3 s-1). The higher kO2 value of d-EtO1H2O compared with d-1H2O could be explained by the fast oxidation rate from RuIV═O to RuV═O involved in the rate-determining step due to the electron-donating EtO group.

Temperature-Controlled Transformation of WO3 Nanowires into Active Facets-Exposed Hexagonal Prisms toward Efficient Visible-Light-Driven Water Oxidation.

A unique transformation of WO3 nanowires (NW-WO3) into hexagonal prisms (HP-WO3) was demonstrated by tuning the temperature of the (N2H4)WO3 precursor suspension prepared from tungstic acid and hydrazine as a structure-directing agent. The precursor preparation at 20 °C followed by calcination at 550 °C produced NW-WO3 nanocrystals (ca. <100 nm width, 3-5 µm length) with anisotropic growth of monoclinic WO3 crystals to (002) and (200) planes and a polycrystalline character with randomly oriented crystallites in the lateral face of nanowires. The precursor preparation at 45 °C followed by calcination at 550 °C produced HP-WO3 nanocrystals (ca. 500-1000 nm diameter) with preferentially exposed (002) and (020) facets on the top-flat and side-rectangle surfaces, respectively, of hexagonal prismatic WO3 nanocrystals with a single-crystalline character. The HP-WO3 electrode exhibited the superior photoelectrochemical (PEC) performance for visible-light-driven water oxidation to that for the NW-WO3 electrode; the incident photon-to-current conversion efficiency (IPCE) of 47% at 420 nm and 1.23 V vs RHE for HP-WO3 was 3.1-fold higher than 15% for the NW-WO3 electrode. PEC impedance data revealed that the bulk electron transport through the NW-WO3 layer with the unidirectional nanowire structure is more efficient than that through the HP-WO3 layer with the hexagonal prismatic structure. However, the water oxidation reaction at the surface for the HP-WO3 electrode is more efficient than the NW-WO3 electrode, contributing significantly to the superior PEC water oxidation performance observed for the HP-WO3 electrode. The efficient water oxidation reaction at the surface for the HP-WO3 electrode was explained by the high surface fraction of the active (002) facet with fewer grain boundaries and defects on the surface of HP-WO3 to suppress the electron-hole recombination at the surface.

N-Rich, Polyphenolic Porous Organic Polymer and Its In Vitro Anticancer Activity on Colorectal Cancer.

N-rich organic materials bearing polyphenolic moieties in their building networks and nanoscale porosities are very demanding in the context of designing efficient biomaterials or drug carriers for the cancer treatment. Here, we report the synthesis of a new triazine-based secondary-amine- and imine-linked polyphenolic porous organic polymer material TrzTFPPOP and explored its potential for in vitro anticancer activity on the human colorectal carcinoma (HCT 116) cell line. This functionalized (-OH, -NH-, -C=N-) organic material displayed an exceptionally high BET surface area of 2140 m2 g-1 along with hierarchical porosity (micropores and mesopores), and it induced apoptotic changes leading to high efficiency in colon cancer cell destruction via p53-regulated DNA damage pathway. The IC30, IC50, and IC70 values obtained from the MTT assay are 1.24, 3.25, and 5.25 µg/mL, respectively.

Distinctive Aspects in Aquation, Proton-Coupled Redox, and Photoisomerization Reactions between Geometric Isomers of Mononuclear Ruthenium Complexes with a Large-π-Conjugated Tetradentate Ligand.

Geometric isomers of mononuclear ruthenium(II) complexes, distal-/proximal-[Ru(tpy)(dpda)Cl]+ (d-/p-RuCl, tpy = 2,2':6',2″-terpyridine, dpda = 2,7-bis(2-pyridyl)-1,8-diazaanthracene), were newly synthesized to comprehensively investigate the geometric and electronic structures and distinctive aspects in various reactions between isomers. The ultraviolet (UV)-visible absorption spectra of d-/p-RuCl isomers show intense bands for metal-to-ligand charge transfer (MLCT) at close wavelengths of 576 and 573 nm, respectively. However, time-dependent density functional theory (TD-DFT) calculations suggest that the MLCT transition of d-RuCl involves mainly single transitions to the π* orbital of the dpda ligand in contrast to mixing of the π* orbitals of the dpda and tpy ligands for p-RuCl. The aquation reaction (1.5 × 10-3 s-1) of p-RuCl to yield proximal-[Ru(tpy)(dpda)(OH2)]2+ (p-RuH2O) is faster than that (5.3 × 10-6 s-1) of d-RuCl in D2O/CD3OD (4:1 v/v) by three orders of magnitude, which resulted from the longer Ru-Cl bond by 0.017 Å and the distorted angle (100.2(3)°) of Cl-Ru-N (a nitrogen of dpda, being on a tpy plane) due to the steric repulsion between Cl and dpda for p-RuCl. Electrochemical measurements showed that d-RuH2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1-9, whereas p-RuH2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of pH 1-10. The irreversible photoisomerization from d-RuH2O to p-RuH2O was observed in aqueous solution with an internal quantum yield (Φ) of 5.4 × 10-3% at 520 nm, which is lower compared with Φ = 1.1-2.1% of mononuclear Ru(II) aquo complexes with similar bidentate ligands instead of dpda by three orders of magnitude. This is possibly ascribed to the faster nonradiative decay rate from the excited 3MLCT state to the ground state for d-RuH2O due to the lower π* level of dpda ligands according to the energy-gap law: the rate decreases exponentially with the increasing energy gap.

Synergistic Effects of Earth-Abundant Metal-Metal Oxide Enable Reductive Amination of Carbonyls at 50 °C.

Reductive amination of carbonyls to primary amines is of importance to the synthesis of fine chemicals; however, this reaction with heterogeneous catalysts containing earth-abundant metals under mild conditions remains scarce. Here, we show that the nickel catalyst with mixed oxidation states enables such synthesis of primary amines under low temperature (50 °C) and H2 pressure (0.9 MPa). The catalyst shows activity in both water and toluene. The high activity likely results from the formation of small (ca. 4.6 nm) partially oxidized nickel nanoparticles (NPs) homogeneously anchored onto the silica and their synergistic effect. Detailed characterizations indicate stabilization of NPs through strong metal support interaction via electron donation from the metal to support. We identify that the support endowed with an amphoteric nature shows better performance. This strategy of making small metal-metal oxide NPs will open an avenue toward the rational development of efficient catalysts that would allow for other organic transformations under mild reaction conditions.

Electronic Effect in a Ruthenium Catalyst Designed in Nanoporous N-Functionalized Carbon for Efficient Hydrogenation of Heteroarenes.

Active metal catalysts are the key in chemical industry for sustainable production of multitude of chemical resources. Here, we report a new ruthenium (Ru) composite with a synergistically controlled nanostructure and electronic properties as a highly efficient hydrogenation catalyst which comprises stable small Ru nanoparticles (mean particle size, ca. 0.9 nm) in situ generated into a nanoporous N-functionalized carbon with high surface area (ca. 650 m2 g-1) and has strong electron-donating power of Ru sites of nanoparticles. The scalable and highly reusable catalyst, prepared from a self-assembled Ru complex, performs actively with low per metal usage under mild conditions (60-80 °C and 0.5-1.0 MPa H2) for selective hydrogenation of various quinolines and pyridines. The role of electron-donating properties of the new Ru nanohybrid for highly efficient catalysis was characterized by both experiments and computational studies. Density functional theory calculations reveal that weak adsorption energies of quinoline at the electron-rich Ru surface prevents poisoning caused by its strong coordination and provides excellent reusability of the catalyst, while low activation barriers for the hydrogenation steps of the N-heterocyclic ring correlate with high catalytic activity. Our catalyst exhibits 5-24-fold higher turnover frequency up to ca. 167 h-1 among the efficient noble metal catalysts reported for selective hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline.

Folic acid-conjugated magnetic mesoporous silica nanoparticles loaded with quercetin: a theranostic approach for cancer management.

The development of drug carriers based on nanomaterials that can selectively carry chemotherapeutic agents to cancer cells has become a major focus in biomedical research. A novel pH-sensitive multifunctional envelope-type mesoporous silica nanoparticle (SBA-15) was fabricated for targeted drug delivery to human colorectal carcinoma cells (HCT-116). SBA-15 was functionalized with folic acid (FA), and the material was loaded with the water-insoluble flavonoid, quercetin (QN). Additionally, acid-labile magnetite Fe3O4 nanoparticles were embedded over the FA-functionalized QN-loaded monodisperse SBA-15 to prepare the highly orchestrated material FA-FE-SBA15QN. The in vitro and in vivo anti-carcinogenic efficacy of FA-FE-SBA15QN was carried out to explore the pH-sensitive QN release with putative mechanistic aspects. FA-FE-SBA15QN caused a marked tumor suppression, and triggered mitochondrial-dependent apoptosis through a redox-regulated cellular signaling system. Furthermore, FA-IO-SBA-15-QN initiated the c-Jun N-terminal Kinase (JNK)-guided H2AX phosphorylation, which relayed the downstream apoptotic signal to the phosphorylate tumor suppressor protein, p53. On the other hand, the selective inhibition of heat shock protein-27 (HSP-27) by FA-FE-SBA15QN augmented the apoptotic fate through JNK/H2AX/p53 axis. The in vitro and in vivo magnetic resonance imaging (MRI) studies have indicated the theranostic perspective of the composite. Thus, the result suggested that the newly synthesized FA-FE-SBA15QN could be used as a promising chemo theranostic material for the management of carcinoma.

Ag nanoparticle-decorated, ordered mesoporous silica as an efficient electrocatalyst for alkaline water oxidation reaction.

In recent years, several novel strategies for speeding up the slow kinetics of the water oxidation reaction have attracted considerable attention for generation of O2. This is particularly important from the environmental perspective. Here we report a SBA-15 type, 2D-hexagonal functionalized mesoporous organosilica material as support for small Ag nanoparticles (NPs) by grafting the silica surface with 3-aminopropyltriethoxysilane, followed by chemical impregnation of Ag NPs at its surface, to obtain a AgNPs@SBA-NH2 material. The AgNPs@SBA-NH2 has been thoroughly characterized using several instrumental tools, such as powder X-ray diffraction, ultra-high resolution transition electron microscopy, N2 sorption, FT-IR spectroscopy, thermogravimetric and differential thermal analysis and X-ray photoelectron spectroscopy. High Brunauer-Emmett-Teller (BET) surface area and fine dispersion of Ag NPs throughout the surface of the amine-functionalized mesoporous material could enhance the rate of oxygen evolution reaction (OER) activity for AgNPs@SBA-NH2 in the electrochemical water splitting reaction.

A high performance catalyst of shape-specific ruthenium nanoparticles for production of primary amines by reductive amination of carbonyl compounds.

The creation of metal catalysts with highly active surfaces is pivotal to meeting the strong economic demand of the chemical industry. Specific flat-shaped pristine fcc ruthenium nanoparticles having a large fraction of atomically active {111} facets exposed on their flat surfaces have been developed that act as a highly selective and reusable heterogeneous catalyst for the production of various primary amines at exceedingly high reaction rates by the low temperature reductive amination of carbonyl compounds. The high performance of the catalyst is attributed to the large fraction of metallic Ru serving as active sites with weak electron donating ability that prevail on the surface exposed {111} facets of flat-shaped fcc Ru nanoparticles. This catalyst exhibits a highest turnover frequency (TOF) of ca. 1850 h-1 for a model reductive amination of biomass derived furfural to furfurylamine and provides a reaction rate approximately six times higher than that of an efficient and selective support catalyst of Ru-deposited Nb2O5 (TOF: ca. 310 h-1).

Visible Light-Driven Water Oxidation on an In Situ N2 -Intercalated WO3 Nanorod Photoanode Synthesized by a Dual-Functional Structure-Directing Agent.

With a view to developing a photoanode for visible light-driven water oxidation in solar water splitting cells, pure-monoclinic WO3 nanorod crystals with N2 intercalated into the lattice were synthesized by using hydrazine with a dual functional role-as an N atom source for the in situ N2 intercalation and as a structure-directing agent for the nanorod architecture-to gain higher incident photon-to-current conversion efficiency at 420 nm than with most previously reported WO3 electrodes.

Superior Inorganic Ion Cofactors of Tetraborate Species Attaining Highly Efficient Heterogeneous Electrocatalysis for Water Oxidation on Cobalt Oxyhydroxide Nanoparticles.

A heterogeneous catalyst incorporating an inorganic ion cofactor for electrochemical water oxidation was exploited using a CoO(OH) nanoparticle layer-deposited electrode. The significant catalytic current for water oxidation was generated in a Na2B4O7 solution at pH 9.4 when applying 0.94 V versus Ag/AgCl in contrast to no catalytic current generation in the K2SO4 solution at the same pH. HB4O7- and B4O72- ions were indicated to act as key cofactors for the induced catalytic activity of the CoO(OH) layer. The Na2B4O7 concentration dependence of the catalytic current was analyzed based on a Michaelis-Menten-type kinetics to provide an affinity constant of cofactors to the active sites, Km = 28 ± 3.6 mM, and the maximum catalytic current density, Imax = 2.3 ± 0.13 mA cm-2. The Imax value of HB4O7- and B4O72- ions was 1.4 times higher than that (1.3 mA cm-2) for the previously reported case of CO32- ions. This could be explained by the shorter-range proton transfer from the active site to the proton-accepting cofactor because of the larger size and more flexible conformation of HB4O7- and B4O72- ions compared with that of CO32- ions.

Dual-Functional Surfactant-Templated Strategy for Synthesis of an In Situ N2 -Intercalated Mesoporous WO3 Photoanode for Efficient Visible-Light-Driven Water Oxidation.

N2 -Intercalated crystalline mesoporous tungsten trioxide (WO3 ) was synthesized by a thermal decomposition technique with dodecylamine (DDA) as a surfactant template with a dual role as an N-atom source for N2 intercalation, alongside its conventional structure-directing role (by micelle formation) to induce a mesoporous structure. N2 physisorption analysis showed that the specific surface area (57.3 m2 g-1 ) of WO3 templated with DDA (WO3 -DDA) is 2.3 times higher than that of 24.5 m2 g-1 for WO3 prepared without DDA (WO3 -bulk), due to the mesoporous structure of WO3 -DDA. The Raman and X-ray photoelectron spectra of WO3 -DDA indicated intercalation of N2 into the WO3 lattice above 450 °C. The UV/Vis diffuse-reflectance spectra exhibited a significant shift of the absorption edge by 28 nm, from 459 nm (2.70 eV) to 487 nm (2.54 eV), due to N2 intercalation. This could be explained by the bandgap narrowing of WO3 -DDA by formation of a new intermediate N 2p orbital between the conduction and valance bands of WO3 . A WO3 -DDA-coated indium tin oxide (ITO) electrode calcined at 450 °C generated a photoanodic current under visible-light irradiation below 490 nm due to photoelectrochemical water oxidation, as opposed to below 470 nm for ITO/WO3 -bulk. The incident photon-to-current conversion efficiency (IPCE=24.5 %) at 420 nm and 0.5 V versus Ag/AgCl was higher than that of 2.5 % for ITO/WO3 -bulk by one order of magnitude due to N2 intercalation and the mesoporous structure of WO3 -DDA.

Carbonate Ions Induce Highly Efficient Electrocatalytic Water Oxidation by Cobalt Oxyhydroxide Nanoparticles.

Synthetic models of oxygen evolving complex (OEC) are used not only to gain better understanding of the mechanism and the roles of cofactors for water oxidation in photosynthesis, but also as water oxidation catalysts to realize artificial photosynthesis, which is anticipated as a promising solar fuel production system. However, although much attention has been paid to the composition and structure of active sites for development of heterogeneous OEC models, the cofactors, which are essential for water oxidation by the photosynthetic OEC, remain little studied. The high activity of CoO(OH) nanoparticles for electrocatalytic water oxidation is shown to be induced by a CO32- cofactor. The possibility of CO32- ions acting as proton acceptors for O-O bond formation based on the proton-concerted oxygen atom transfer mechanism is proposed. The O-O bond formation is supposed to be accelerated due to effective proton acceptance by adjacent CO32- ions coordinated on the CoIV center in the intermediate, which is consistent with Michaelis-Menten-type kinetics and the significant H/D isotope effect observed in electrocatalysis.

Characterization of Interfacial Charge-Transfer Photoexcitation of Polychromium-Oxo-Electrodeposited TiO2 as an Earth-Abundant Photoanode for Water Oxidation Driven by Visible Light.

Polychromium-oxo-deposited TiO2 (CrIII x Oy /TiO2 ) electrodes were fabricated by a simple electrochemical technique by using different TiO2 basal electrodes (anatase, rutile, and mixed polymorphic phases P25) as earth-abundant photoanodes for visible-light-driven water oxidation. The high-resolution transmission electron microscopy (HR-TEM) observation illustrated that an CrIII x Oy layer with approximately 2-3 nm thickness was formed on the surface of the crystalline TiO2 particles. Upon visible-light irradiation of the electrodes, the photoanodic current based on water oxidation was generated at the CrIII x Oy /TiO2 electrodes. However, the wavelength (below 620 nm) for photocurrent generation at CrIII x Oy /TiO2 -rutile was longer than that (below 560 nm) at CrIII x Oy /TiO2 -P25 by 60 nm, which is in agreement with the difference (0.2 eV) in the conduction band (CB) edge energy between rutile and anatase TiO2 . This gives a quantitative account for the photocurrent generation based on interfacial charge transfer (IFCT) from Cr 3d of the deposited CrIII x Oy layer to the TiO2 CB. The photocurrent generated for CrIII x Oy /TiO2 -rutile was higher than that for CrIII x Oy /TiO2 -anatase, which is ascribed to 1) more effective CrIII x Oy deposition on the rutile particles, 2) a larger electrolyte/CrIII x Oy interface for water oxidation as a result of smaller rutile particles (ca. 30-40 nm) compared with larger P25 particles (ca. 40-80 nm), and 3) more effective use of visible light owing to the low energy IFCT transition of rutile.

Open pore architecture of an ordered mesoporous IrO2 thin film for highly efficient electrocatalytic water oxidation.

We report the first accessible channel-like open pore architecture of ordered 2D hexagonal mesoporous IrO2 films and its utilization as an efficient anode for electrocatalytic water oxidation. A well-ordered mesostructure of circa 7 nm pores were obtained by a facile one-pot soft-templating strategy, employing a [Ir(OH)6](2-) precursor stabilized by a triblock copolymer "Pluronic F127" as a pore-directing template. A mesoporous IrO2 film calcined at 400 °C (∼70 nm thick) affords a high surface area of 512 m(2) cm(-3) and 2 times higher O2 evolution during the electrocatalytic water oxidation relative to an untemplated IrO2 coating film.

Unique and facile solvothermal synthesis of mesoporous WO3 using a solid precursor and a surfactant template as a photoanode for visible-light-driven water oxidation.

Mesoporous tungsten trioxide (WO3) was prepared from tungstic acid (H2WO4) as a tungsten precursor with dodecylamine (DDA) as a template to guide porosity of the nanostructure by a solvothermal technique. The WO3 sample (denoted as WO3-DDA) prepared with DDA was moulded on an electrode to yield efficient performance for visible-light-driven photoelectrochemical (PEC) water oxidation. Powder X-ray diffraction (XRD) data of the WO3-DDA sample calcined at 400°C indicate a crystalline framework of the mesoporous structure with disordered arrangement of pores. N2 physisorption studies show a Brunauer-Emmett-Teller (BET) surface area up to 57 m(2) g(-1) together with type IV isotherms and uniform distribution of a nanoscale pore size in the mesopore region. Scanning electron microscopy (SEM) images exhibit well-connected tiny spherical WO3 particles with a diameter of ca. 5 to 20 nm composing the mesoporous network. The WO3-DDA electrode generated photoanodic current density of 1.1 mA cm(-2) at 1.0 V versus Ag/AgCl under visible light irradiation, which is about three times higher than that of the untemplated WO3. O2 (1.49 µmol; Faraday efficiency, 65.2%) was evolved during the 1-h photoelectrolysis for the WO3-DDA electrode under the conditions employed. The mesoporous electrode turned out to work more efficiently for visible-light-driven water oxidation relative to the untemplated WO3 electrode.

Ligand-assisted fabrication of small mesopores in semi-crystalline titanium oxide films for high loading of Ru(II) dyes.

Small mesoporous (2-3 nm) and optically uniform titania films with high surface areas were fabricated by employing the ligand-assisted templating approach using designed surfactants that contain strong N-donor sites around the hydrophilic headgroup. Two N atoms, located in a pyridine ring and in the attached alkyl chain, can strongly interact with one Ti atom via covalent ligation and reduce the reactivity (hydrolysis and condensation) of soluble Ti species. The as-made films were treated with UV-ozone irradiation, before calcination to crystallize the titania frameworks. Condensation of the titania frameworks proceeded during the UV-ozone treatment that also destroyed the binding sites between the designed surfactants and Ti atoms with partial decomposition of the surfactants. The titania surfaces were then covered with resultant charred organic species and stabilized, which was helpful for the retention of the mesostructures even after partial crystallization of the titania frameworks during calcination at 400 °C. The small mesopores were more useful for effective accommodation of Ru(II) bipyridyl dyes (∼1 nm) than were common mesopores (∼10 nm). Almost 2 times higher dye loadings were achieved over the small mesoporous titania films than other porous titania films due to the high surface areas, and consequently a high density of the photosensitive dye molecules was achieved even in the thin film fabricated in one pot.

Connectivity of PS-b-PEO templated spherical pores in titanium oxide films.

Titania films having relatively uniform spherical pores were successfully fabricated using polystyrene-block-poly(ethylene oxide) (PS(n)-b-PEO(m)) diblock copolymers. Depending on the molecular weight of PS(n)-b-PEO(m), the spherical pores were varied from large mesopores (n = 40,000, m = 53,000; ∼40 nm) to macropores (n = 58,600, m = 71,000; ∼60 nm, n = 100,000, m = 150,000; ∼100 nm) in diameter. It was confirmed that the porous structures were thermally stable with crystallization of the titania frameworks. Interconnectivity between the spherical pores was reliant on the micellar arrangement of hydrophobic PS cores, while the amount of isolated pores was increased in the films prepared using low molecular weight PS(n)-b-PEO(m). The presence of such isolated pores was confirmed on the basis of adsorption experiments by using a globular hemoprotein cytochrome c (ca. 3.1 nm). Highly interconnected spherical pores, which were preferentially fabricated using high molecular weight PS(n)-b-PEO(m), were quite helpful for smooth diffusion-adsorption of bulky proteins inside the porous films.

Template directed synthesis of mesoporous ZnO having high porosity and enhanced optoelectronic properties.

A simple route for the synthesis of a novel mesoporous zinc oxide material having wurtzite like nanocrystalline pore walls by using Schiff-base amine as template is reported, which shows very high BET surface area (456 m(2) g(-1)) and remarkably enhanced photoconductivity and photoluminescence at room temperature under visible light irradiation vis-à-vis bulk ZnO material.