光学特异材料的设计(英文)

In this contribution we review our latest achievements of combined experimental and theoretical studies to tailor the properties of optical metamaterials(MMs) at will. We give three examples of metamaterial designs that have been realized by means of electron-beam lithography and whose spectroscopic characteristics have been comprehensively investigated. In every case, our experiments are complemented by rigorous numerical simulations. Particular emphasis is put on the significance of such tailored effectiv...     

Electronic Tuning of Host-Guest Interactions within the Cavities of Fluorophore-Appended Calix[4]arenes

A series of fluorescent calix[4]arene scaffolds bearing electron-rich carbazole moiety conjugated at the lower rim have been prepared. Studies of the fluorescence quenching in the presence of the N-methyl pyridinium guest revealed that the electronic properties of the distal phenolic ring play a major role in the host–guest complexation. In particular, placing an electron-donating piperidine fragment at that ring significantly increased the host–guest interactions, while introducing the same fragment into the proximal phenolic ring weakened the fluorescence response. These results suggest that the dominant interactions between the guest and calixarene cavity involve the oxygen-depleted fluorophore-bearing aromatic ring and not the more electron-rich unsubstituted phenolic fragments.     

On the wave dispersion in microstructured solids

Continuum Mechanics and Thermodynamics - In this paper, elastic wave propagation in a one-dimensional micromorphic medium characterized by two internal variables is investigated. The evolution...     

The Coordination Behavior of Oxygen-depleted Calixarenes towards d10 Noble Metal Ions

A calix[4]arene, in which two of the phenol functions are replaced by pyrazole units, [H₂(bpzCal)], was investigated as a ligand for Cu⁺, Ag⁺ and Au⁺ ions. Using [Cu(MeCN)₄]BF₄ and AgSbF₆ as the precursors, complexes [MH₂(bpzCal)]X (M = Cu, X = BF_4; M = Ag, X = SbF₆) were formed, where the calixarene ligands adopt a 1,3-alternate structure and the metal ions are coordinated linearly by the two pyrazolyl donors. [CuH₂(bpzCal)]BF₄ displayed a – for copper(I) complexes – unusual stability towards O₂, which is due to the steric protection of the Cu^I center. By contrast a dinuclear copper(I) complex [Cu₂(bpzCal)] that was obtained through treatment of [H₂(bpzCal)] with two equivalents of Cu(HMDS) is rather sensitive towards O₂. The preparation of a gold complex required the employment of a gold precursor, which contains one labile and one stabilizing neutral ligand, namely [(PPh₃)Au(NCMe)]SbF₆, which led to the formation of [(PPh₃)AuH₂(bpzCal)]SbF₆. In this complex [H₂(bpzCal)] acts only as a monodentate ligand for the gold center. Taken together, the results demonstrate the potential of [H₂(bpzCal)] in providing rather different coordination spheres for metal ions.     

Single-site catalysis by bimetallic zinc calixarene inclusion complexes

[reaction: see text] Bimetallic alkylzinc calixarene inclusion complexes were prepared and used in the ring-opening polymerization of L-lactide. Polymers with high molecular weight and a low degree of polydispersity were obtained. 1H NMR and diffusion NMR experiments suggest that a single-site mechanism is operative.     

Measurement of nanomolar diphenols by substrate recycling coupled to a pH-sensitive electrode

A new enzyme amplification scheme based on the measurement of the pH-change generated in the laccase/glucose dehydrogenase substrate recycling reaction has been established. Quinone species formed after oxidation of diphenols by laccase are reduced by glucose dehydrogenase in the presence of glucose. Catalytic oxidation of glucose to gluconic acid via gluconolactone leads to a pH-decrease. The utility of the very simple pH-sensitive antimony electrode for monitoring the bienzyme reaction has been shown. The detection limit for norepinephrine and p-aminophenol measured by the bienzyme-modified antimony electrode was 1 nmol/L in the presence of glucose. The enhancement in sensitivity and analytical applications of the proposed scheme are discussed. Permanent address: Department of Biosensors, Research Center for Molecular Diagnostics and Therapy, Simpheropolsky Blvd. 8, 113149 Moscow, Russia     

Synthesis of the elusive (R3P)2MF2 (M = Pd, Pt) complexes

The synthesis and characterization of previously unknown palladium(II) and platinum(II) difluoro phosphine complexes are described. These complexes can be obtained either via a halide metathesis reaction with AgF in dichloromethane or by reacting the corresponding dimethyl complexes with XeF2. While the Pt(II) complexes can be prepared with both aryl- and alkyl-phosphine ligands, the stability of the Pd(II) complexes is limited to those having cis-oriented trialkyl phosphine ligands.     

A bienzyme electrode for tyrosine-containing peptides determination

A bienzyme electrode for monitoring biologically important peptides containing tyrosine has been established on the basis of mushroom tyrosinase and quinoprotein glucose dehydrogenase (GDH). Tyrosine residues bound in the peptide chain are oxidized by tyrosinase resulting in consumption of oxygen. Subsequently, the dopaquinone residues are reduced in the GDH catalysed reaction which is driven by an excess of glucose. This reaction cycle leads to a considerable increase of sensitivity. Both enzymes were entraped in poly(vinyl)alcohol matrix and placed on the surface of a Clark-type oxygen electrode (the working platinum electrode was potentiostated at −600 mV) (vs. Ag/AgCl reference electrode) between a polypropylene and cellulose membrane. The bienzyme-modified Clark-type oxygen electrode has a lower detection limit of 0.2 μM for the opioid peptides Tyr-D-Ser-Gly-Phe-Leu-Thr, Leu-enkephalin, Tyr-D-Ala-Gly-Phe-D-Leu and morphiceptin. The dependence of response of the electrode on the length of peptide chain and position of tyrosine residue is discussed. The new electrode has been applied to the quality control of tyrosine containing peptides from pharmaceutical formulations and from peptide synthesis.