Volume 84, Issue 12

In 2005 at the centennial anniversary of Fudan University, Shanghai, China, a new conference venue began [1]. This venue, the International Conference on Novel Materials and Synthesis (NMS) together with the International Symposium on Fine Chemistry and Functional Polymers (FCFP), is targeted to provide high-level academic exchange for both local and international chemists, materialists, physicists, engineers, and technologists in the fields of materials and synthesis. The year 2011 was the International Year of Chemistry, and it is well known that chemistry is an essential creative science for the sustainable development of humankind. As a result, the joint NMSVII/ FCFP-XXI event (www.nms-iupac.org), held in Shanghai, China, 16-21 October 2011, was more important than ever. The Conference received much support from IUPAC, The National Natural Science Foundation of China, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, the Science and Technology Commission of the Shanghai Municipality, and the National Basic Research Program of China (2007CB209700), and was carried out under the auspices of IUPAC. The Conference was attended by 430 participants from 40 countries and areas. The scientific program comprised 10 plenary lectures, 56 keynote lectures, 206 invited lectures, and 94 posters. Detailed, active, and lively discussions were covered by the following themes: - innovative chiral and achiral compounds - innovative bio- and biobased materials and composites - innovative polymers such as conducting, semiconducting ones, supramolecular (supermolecular, dynamers) - innovative energy systems including fuel cells, solar cells, lithium batteries, and supercapacitors - innovative nanomaterials such as 1D, 2D, and 3D nanomaterials - new ceramic materials such as superconductors, electronic, diaelectronic, ferroelectric, piezoelectric, optoelectric, and magnetic materials - new metallic materials including alloys - other novel materials including drugs, perfumes, agricultural chemicals, and photosensitive materials, displaying materials and fine ceramics; and - neutron scattering and its application in fundamental and applied research on new materials. The program served to emphasize that novel materials and their preparation are dynamic research areas that are attracting growing interest from researchers, engineers, industries, and policy-makers. Furthermore, novel materials continue to find applications that serve the needs and interests of producers and consumers. A selection of 13 papers based on specially invited presentations at NMSVII/ FCFP-XXI is published in this issue to demonstrate the quality and scope of the themes of this Conference. During the Conference, the role and contributions of this high-level academic platform to novel materials and their synthesis are well realized by the participants, sponsors, and exhibitors. In addition, the organization committee established the Distinguished Award 2011 for Novel Materials and their Synthesis along with IUPAC; Prof. Guoxiu Wang (Australia), Dr. Dr. Fusayoshi Masuda (Japan), Prof. Dr. André-Jean Attias (France), and Prof. Bao-Lian Su (Belgium) received the award for their excellent work. The IUPAC Prof. Jiang Novel Materials Youth Prize was awarded to two winners, Prof. Zhibo Li (China) and Dr. Jr-Hau He (Taiwan, China), for the first time. This will next be awarded in 2013. Three winners for the IUPAC Poster Prize were also awarded. Yuping Wu, Shiyou Guan, and Guoxiu Wang Conference Editors [1] Y. P. Wu. Pure Appl. Chem. 78 (10), iii (2006).

A composite film of tantalum carbide (TaC)-graphite was synthesized on etched Si using thermal evaporation of Ta followed by C/H chemical vapor deposition (CVD). In the present study, Ta wire 0.5 mm in diameter was electrically heated without carburizing. Under high current conditions, filaments were thermally evaporated and interacted with chemically decomposed C, forming a composite film of TaC-graphite deposits on the substrates. The influence of chamber pressure, substrate temperature, and methane concentration on the film properties has been studied. By increasing chamber pressure from 25 to 100 torr in a gas mixture of H and methane (containing 3 % methane), the morphology of films changed with an increased growth rate and surface roughness. Increasing the methane concentration in the mixture resulted in broadening of X-ray diffraction (XRD) peaks, increase in film thickness, and coarsening of grains, along with formation of clusters. The growth rates of the films produced at a substrate temperature of 950 °C were lower than those deposited at 850 °C. Their grain sizes were bigger and exhibited a dense structure with higher surface roughness.

Based on our studies on the hybrid catalysts of nanosized ( ns ) oxide with zeolite, products obtained from the isomerization and hydrocracking of heavier n -paraffins and the role of ns oxide were investigated using a tricomponent catalyst of [Ni-Mo/γ-Al 2 O 3 ], ns oxide, and H-beta zeolite catalyst, which showed high activity, high isomerization selectivity, and mild cracking ability. A concerted effect of the three components was observed. From the observed hybridization state of the catalyst, it was suggested that the concerted effect was obtained because the components become attached to each other. The individual and concerted effects of each component and two components, respectively, were investigated based on the ratio of [Ni-Mo/γ-Al 2 O 3 ]/[H-beta zeolite], the content of ns oxide, the amount of metal, the type of ns oxide species, and the reduction state of metal. It was confirmed that in order to obtain the highest concerted effect, the ratios of [Ni-Mo/γ-Al 2 O 3 ]/[H-beta zeolite] and/or ns oxide/zeolite are important. Furthermore, among the ns oxide species, ns Al 2 O 3 - ns TiO 2 displayed the highest activity and cracking ability with an over-cracking suppression. In addition to increasing the concerted effect in the tricomponent catalyst, the performance of this catalyst could also be further increased by controlling the amount and reduction state of metal.

The association of natural polymers with silica is a fruitful strategy to design novel hybrid structures with potential applications in the fields of biotechnology, medicine, and environmental sciences. Here we illustrate the principles of formation, the structure, and the properties of such biohybrid systems by the specific example of silica–pectin porous materials. The influence of the silica source, i.e., aqueous silicates and tetraethoxysilane (TEOS), was more specifically addressed. The alkoxide precursor may be associated with the polysaccharide in a wide range of concentrations. In contrast, the high initial viscosity and fast condensation rate of silicates limits the range of accessible compositions. Owing to weak interactions between the mineral and organic components, silicification does not improve the thermal stability of the polymer but has a strong impact on the water stability of the materials, which depends on the silica source. It is shown that the stability of the silica–pectin hybrid materials during enzymatic degradation is optimum for low carbohydrate content and high silica content, independently of the inorganic precursor.

The influence of different modifiers, P 2 O 5 , K 2 O, Al 2 O 3 , SiO 2 , CeO 2 , and ZrO 2 , on the optical properties and photostability of rutile titanium dioxide was studied. The research was aimed at obtaining pigmentary rutile titanium dioxide with the enhanced photostability. The optical properties such as brightness, white tone, and gray tone were improved when titanium dioxide samples were modified with zirconium instead of cerium. Titanium dioxide products modified additionally with Al 2 O 3 displayed improved optical properties by comparison with appropriate titanium dioxide products lacking introduced aluminum. In comparison with unmodified material (∆ E * = 21.8), a considerable increase of the photostability of modified titanium dioxide was observed. The lowest photoactivity, in the range of ∆ E * = 0.96–2.45, was measured for the TiO 2 -PKAlSiCe series. A selective leaching method and X-ray diffraction (XRD) analysis were used to determine the distribution of modifiers in titanium dioxide materials. It was concluded that the differences in both photoactivity and optical properties of modified titanium dioxide depend on its phase composition.

Tetrapod-shaped nanocrystals have attracted increasing interest for optoelectronic applications in recent years due to their rich morphologies. With unique properties such as a direct band-gap and excellent photoelectrical characteristics, CdSe nano-tetrapods are promising nanostructures for applications in such fields as photodetectors, field emitters, and photovoltaic devices. This review mainly describes the remarkable progress made in synthesis and hybrid photovoltaic applications of CdSe nano-tetrapods over the last few years. In particular, the “blinking” effect observed from these nano-tetrapods in chloroform solution is highlighted. This overview covers the current state of the art as well as an outlook on possibilities and limitations.

A novel thermotropic liquid-crystalline (LC) biocopolymer, poly{ trans -3-methoxyl-4-hydroxycinnamic acid (MHCA: ferulic acid)- co - trans -3,4-dihydroxycinnamic acid (DHCA: caffeic acid)}, was synthesized by a thermal acidolysis-polycondensation of MHCA and DHCA, efficiently catalyzed by Na 2 HPO 4 . When the MHCA composition of poly(MHCA- co -DHCA) was 60, 75, and 90 mol %, the copolymers showed a nematic LC phase although individual homopolymers such as polyMHCA and polyDHCA did not exhibit LC phase. Poly(MHCA- co -DHCA)s showed high molecular weight ( M w ) ranged between M n 2.6 × 10 4 to 3.7 × 10 4 and M w 8.2 × 10 4 to 13.1 × 10 4 , respectively, high glass-transition temperature ( T g ) with the range of 115 to 140 °C and high degradation temperature T 10 , from 315 to 356 °C. In the adhesive test of copolymers against the surface of carbon substrate, the copolymers showed high shear strength at fracture.

A new type of hetero-grafted molecular bottlebrush with polypeptide as backbone was synthesized using graft-onto strategy. Poly(γ-propargyl-L-glutamate) (PPLG) as backbone was firstly synthesized via ring-opening polymerization (ROP) of γ-propargyl-L-glutamate (PLG) N-carboxyanhydride (NCA). Next, polystyrene-N 3 (PS-N 3 ) and monomethoxy poly(ethylene glycol)-N 3 (mPEG-N 3 ) as side chains were grafted onto the PPLG backbone using copper-catalyzed click reaction, which afforded good grafting density and efficiency. Two polypeptide bottlebrushes with PS-to-mPEG molar ratio at 70/30 and 30/70 were prepared. The self-assembly behaviors of these two polypeptide bottlebrushes were investigated using the cosolvent method, and their supramolecular structures were characterized using light scattering (LS) and electron microscopy.

Bionanocomposites are a novel class of nanosized materials. They contain the constituent of biological origin and particles with at least one dimension in the range of 1–100 nm. There are similarities with nanocomposites but also fundamental differences in the methods of preparation, properties, functionalities, biodegradability, biocompatibility, and applications. The article includes two parts. Bionanocomposite definition and classification along with nanoparticles, biomaterials, and methods of their preparation are initially reviewed. Then, novel approaches developed by our team are presented. The first approach concerns the preparation of bionanocomposites from chitosan and nanoparticles. It is based on the regulated charging of polysaccharide by the gradual shift of solution pH. When charges appear, the biomacromolecules come into the electrostatic interactions with negatively charged nanoparticles that cause the jellification of solutions. It is also applied to form films. They have a nacre-like structure from stacked planar nanoparticles separated by aligned biomacromolecules. The second approach deals with the biomimicking mineralization of biopolymers by using a novel silica precursor. Its advantage over the current sol-gel processing is in the compatibility and regulation of processes and structure of generated silica. Another example of the mineralization is presented by titania. Syntheses are performed in anhydrous ethylene glycol. Processes and structure of bionanocomposites are regulated by water that is added in an amount to only hydrate functional groups in the carbohydrate macromolecule.

Recently, nucleophilic addition reactions to imino functions have been utilized in many crucial steps for the synthesis of bioactive and functional materials. This article summarizes the integrated “umpolung” reactions of α-imino esters and the use of iminium salts as reactive electrophiles. Regarding the umpolung reactions, the following five reactions are discussed: (1) N -alkylation/homocoupling; (2) tandem N -ethylation/ C -allylation; (3) tandem N -ethylation/ C -cyanation; (4) reduction of imines with tris(trimethylsilyl)aluminum; and (5) N -alkylation and Claisen rearrangement. Moreover, the generation and reactions of alkoxycarbonyl iminium species are also discussed. These are prepared easily from trisubstituted amino ketene silyl acetals by oxidation, and the subsequent nucleophilic addition of various nucleophiles readily affords the addition products.

The process of axial and radial Si–Ge heterostructure formation during nanowire growth by vapor–liquid–solid (VLS) mechanism was studied using Monte Carlo (MC) simulation. It was demonstrated that radial growth can be stimulated by adding chemical species that decrease the activation energy of precursor dissociation or the solubility of semiconductor material in catalyst drop. Reducing the Si adatom diffusion length also leads to Si shell formation around the Ge core. The influence of growth conditions on the composition and abruptness of axial Ge–Si heterostructures was analyzed. The composition of the Ge x Si 1– x axial heterojunction (HJ) was found to be dependent on the flux ratio, the duration of Si and Ge deposition, and the catalyst drop diameter. Maximal Ge concentration in the HJ is dependent on Ge deposition time owing to gradual changing of catalyst drop composition after switching Ge and Si fluxes. The dependence of junction abruptness on the nanowire diameter was revealed: in the adsorption-induced growth mode, the abruptness decreased with diameter, and in the diffusion-induced mode it increased. This implies that abrupt Ge–Si HJ in nanowires with small diameter can be obtained only in the chemical vapor deposition (CVD) process with negligible diffusion component of growth.

Hybrid inorganic/nanocarbon solar cells represent low-cost solutions for the large-scale manufacturing of energy conversion devices. Here we discuss results that relate to the electronic interactions of nanocarbon materials with freestanding and surfactant-free silicon nanocrystals (Si-ncs) with quantum confinement effects, integrated in bulk-heterojunction solar cells. In particular, we demonstrate the feasibility of bulk-heterojunction photovoltaic solar cells that consist of Si-ncs combined with fullerenes or with semiconducting single-walled carbon nanotubes (SWCNTs). We show that the energy levels between Si-ncs with energy gap exceeding 1.75 eV and fullerenes are adequate for exciton dissociation and carriers (electrons/holes) generation and that hybrid solar cells formed by Si-ncs and semi-conducting SWCNTs favor exciton dissociation only when a distinct chiral index [i.e., (7,5)] is used. While fullerenes show energy conversion capabilities in the visible spectral region (1.7–3.1 eV), the cells containing the SWCNTs, in comparison, have a considerably expanded optical response covering a broad range of the spectrum (0.9–3.1 eV).

New kinds of bifunctional antioxidant enzyme mimics were prepared, and their superoxide anion radical (O 2 •– ) and hydroxyl radical (•OH) scavenging activity was investigated. These conjugates were prepared by binding insoluble salphen [ N , N -(phenylene)salicylidene] Schiff-base metal complexes (HO-salphen-M, M = Co, Mn, Cu) with bovine serum albumin (BSA). They were characterized by UV–vis spectra, circular dichroism (CD), and native polyacrylamide gel electrophoresis (PAGE). It showed that the binding mode was an axial coordination between HO-salphen-Co and amino acid residue of BSA. The structure of BSA was maintained when the binding amount of HO-salphen-Co was less than 10. After combining HO-salphen-Co into BSA, the low solubility of HO-salphen-Co was overcome, and the O 2 •– and •OH scavenging activity of BSA was improved two orders of magnitude. In similar inhibitory value, the scavenging rate of salphen-Co20@BSA was far higher than -others. The scavenging activity of different proportion salphen-Co@BSA was salphen-Co20@BSA > salphen-Co10@BSA > salphen-Co5@BSA > salphen-Co2@BSA. But salphen-Cu@BSA and salphen-Mn@BSA did not show •OH scavenging activity.

Nanostructured solar cells have attracted increasing attention in recent years because their low cost and ease of preparation offer unique advantages and opportunities unavailable with conventional single-crystalline solar cells. The efficiencies of this kind of solar cell largely depend on the interfacial structure owing to the large specific interface areas and the inherent high density of interface states. In this review article, strategies of interface engineering will be introduced in detail. The up-to-date progress and understanding of interface engineering and its role in influencing the efficiency of nanostructured solar cells will be discussed. Some of the representative examples of the interface engineering method will be presented wherever necessary. Continued boosting of the energy conversion efficiency for nanostructured solar cells is anticipated in the coming years and will bring this kind of solar cell to the status of commercialization.