W Tungsten

Possessing high H₂ capacities and interesting dehydrogenation behavior, metal amidoborane ammoniates were prepared by reacting Ca(NH₂)₂, MgNH, and LiNH₂ with ammonia borane to form Ca(NH₂BH₃)₂⋅2 NH₃, Mg(NH₂BH₃)₂⋅NH₃, and Li(NH₂BH₃)₂⋅NH₃ (LiAB⋅NH₃). Insight into the mechanisms of amidoborane ammoniate formation and dehydrogenation was obtained by using isotopic labeling techniques. Selective ¹⁵N and ²H labeling showed that the formation of the ammoniate occurs via the transfer of one H(N) from ammonia borane to the [NH₂]⁻ unit in Ca(NH₂)₂ giving rise to NH₃ and [NH₂BH₃]⁻. Supported by theoretical calculations, it is suggested that the improved dehydrogenation properties of metal amidoborane ammoniates compared to metal amidoboranes are a result of the participation of a strong dihydrogen bond between the NH₃ molecule and [NH₂BH₃]⁻. Our study elucidates the reaction pathway involved in the synthesis and dehydrogenation of Ca(NH₂BH₃)₂⋅2 NH₃, and clarifies our understanding of the role of NH₃, that is, it is not only involved in stabilizing the structure, but also in improving the dehydrogenation properties of metal amidoboranes.

Amidoborane ammoniate formation is investigated by using isotopic labeling techniques. The formation of Ca(NH₂BH₃)₂⋅2 NH₃ is initiated by proton transfer from NH₃BH₃ to NH₂⁻ (amide), forming Ca(NH₃)²⁺ and anionic [NH₂BH₃]⁻ groups. The dehydrogenation of the ammoniate, which occurs at lower temperatures, is a result of the participation of NH₃ in the dehydrogenation process via the combination of (NH₃)H^δ+⋅⋅⋅H^δ−(NH₂BH₃⁻).

A sheltered existence: Direct liquid-membrane crystallization is used as a low-cost, low-waste, yet highly effective method to prepare a catalyst encapsulated by a H-β zeolite. Through vapor–liquid exchange, a continuous and sufficient, but not excessive supply of both water and template is the key part of this method.

The ring-fused thiophene derivatives benzo[c]thiophene and its precursor bicyclo[2.2.2]octadiene (BCOD) have been introduced as π-conjugated spacers for organic push–pull sensitizers with dihexyloxy-substituted triphenylamine as donor and cyanoacrylic acid as acceptor (OL1–OL6). The effects of the fused ring on the spectroscopic and electrochemical properties of these sensitizers and their photovoltaic performance in dye-sensitized solar cells have been evaluated. Introduction of a binary benzo[c]thiophene and ethylenedioxy thiophene as π bridge caused a significant red shift of the characteristic intramolecular charge-transfer band to 642 nm. It is found that the sensitizer OL3, which contains one benzo[c]thiophene unit as π linker, gives the highest overall conversion efficiency of 5.03 % among all these dyes.

Sensitive souls: A series of sensitizers for dye-sensitized solar cells features ring-fused thiophene bridges between donor and acceptor moieties. The absorption spectra of the push–pull sensitizers all exhibit intense intramolecular charge transfer bands in the visible region (see picture), and solar cells based on the dyes show good incident photon to current conversion efficiencies.

A carboxylic acid appended naphthalenediimide (NDI) derivative exhibits hydrogen-bonding-mediated, lamellar-type, self-assembly in the nonpolar solvent methyl cyclohexane (MCH). Such a self-assembled material shows bright and almost pure white-light emission in contrast to the blue-emitting monomeric NDI building block. For more information see the Communication by S. Ghosh and M. R. Molla on page 1290 ff.

We have developed a novel application for DNA oligonucleotide-stabilized Ag nanoclusters in fluorescent imaging of human serum proteins after native polyacrylamide gel electrophoresis (PAGE). Oligonucleotide-stabilized Ag nanoclusters were used as fluorescent probes for direct detection of proteins after native PAGE. Some relatively low-abundance proteins, such as α-1-antichymotrypsin (ACT) and α-2-glycoprotein 1, zinc (ZAG) were easily detected by oligonucleotide-stabilized Ag nanocluster-based fluorescent imaging and identified by MS and MS/MS techniques, without the need of expensive antibodies or tedious immunoassay procedures. The pH condition for the oligonucleotide-stabilized Ag nanocluster solution was optimized and the possible mechanism of interaction between proteins and DNA oligonucleotide-stabilized Ag nanoclusters was analyzed. As a novel fluorescent detection method it is simple, fast, nontoxic and sensitive, and it shows great analytical potential in proteome research and in biochemistry.

PAGE proof: Direct detection of human serum proteins after native PAGE was accomplished by using DNA oligonucleotide-stabilized Ag nanoclusters as a fluorescent probe (see figure). Compared with staining methods, it is simple, fast, nontoxic, and offers higher sensitivity and resolution.

Novel amine-terminated silicon (Si) quantum dots (QDs) were synthesized and applied for the detection of human serum proteins on gels directly after polyacrylamide gel electrophoresis (PAGE). The diameter of these stable amine-terminated Si QDs was in the range of 0.5–2.0 nm. In this study, the fluorescent imaging conditions, such as the buffer solution, pH value, buffer concentration and quantity of Si QDs, were optimized and the possible mechanisms of Si QDs–protein interaction were analyzed. The mode of Si QDs and human serum albumin association was found to occur by hydrogen bond interactions; this was probably attributed to the interaction between the amino group of amine-terminated Si QDs and the carboxyl group of proteins. Meanwhile, human serum proteins separated by native 1D and native 2D electrophoresis were detected by Si QD-based fluorescent imaging. Some proteins, such as isoform 1 of α-1-antitrypsin, complement C3 (Fragment) and hemopexin, which were identified by mass spectrometry (MS), were easily detected by using Si QDs, but not with CBB-R250 staining. The Si QDs-based fluorescent imaging technique with high resolution is a sensitive and dependable method for direct detection of human serum proteins, and has enormous potential in clinical diagnosis.

Tuning PAGE: Photoluminescent imaging of human serum proteins after PAGE by using amine-terminated silicon quantum dots as fluorescent probes, is reported (see scheme). By using this nontoxic, simple method, high sensitivity and resolution can be achieved.

Carbon nanotubes (CNTs) were non-covalently functionalized by 1-pyrenecarboxaldehyde (PCA) via ππ stacking interactions. PCA not only acts as the reductant for the deposition of PtRu nanoparticles, but the oxidation product of PCA can also effectively anchor and stabilize the in-situ-produced PtRu NPs on the surface of CNTs. Transmission electron microscopy demonstrates that PtRu NPs are uniformly dispersed on the surface of CNTs with small particles sizes of about 1.7 nm. The obtained PtRu-NP/CNT composites have higher electrochemical surface areas, electrocatalytic activities, and better stability towards methanol oxidation compared to PtRu NPs supported on pristine CNTs.

NP and tuck: A strategy using the non-covalent functionalization of carbon nanotubes (CNTs) with 1-pyrenecarboxaldehyde (PCA) for the high dispersion of noble-metal nanoparticles (NPs) onto CNTs was developed. The oxidation product of PCA can effectively anchor and stabilize the in situ produced PtRu NPs on the surface of the CNTs. The obtained PtRu-NP/CNT-PCA nanohybrids show excellent electrocatalytic performance for methanol oxidation.