Role of refractive index in sum frequency generation intensity of salt solution interfaces

Sum frequency generation spectroscopy (SFG) has been widely used to study the interfacial chemistry of aqueous salt solutions of biological or environmental importance. Most of the SFG data analysis used the same bulk refractive index for different salt concentrations despite of the variations of the refractive indices. Here we systematically investigate the influence of the refractive index on the SFG intensities at various experimental conditions. It is discovered that the SFG intensities are the most sensitive to the refractive index at solid/liquid interfaces nearby the total internal reflection geometries. At air/liquid interfaces, the effect of the refractive indices is also nonegligible. Consequently some important SFG results, such as the response of water structures to the ionic strength at the SiO₂/aqueous interfaces, are necessary to be reevaluated. These conclusions on the effect of the small variations of the refractive index are generally useful for the common practice of SFG data analysis.     

Development of a triple channel detection probe for hydrogen peroxide

The rapid and reliable measurement of hydrogen peroxide (H₂O₂) is imperative for many areas of technology, including pharmaceutical, clinical, food industry and environmental applications. In this work, a novel multifunctional complex, [Ru(bpy)₂(luminol-bpy)](PF₆)₂ (bpy: 2,20'-bipyridine), was designed and synthesized by incorporating a Ru(II) complex with a luminal group. In the presence of horseradish peroxidase (HRP), reaction of [Ru(bpy)₂(luminol-bpy)]²⁺ with H₂O₂ can be monitored by three sensing channels including photoluminescence (PL), chemiluminiscence (CL) and eletrochemiluminiscence (ECL). The quantitative assays for H₂O₂ in aqueous solutions using [Ru(bpy)₂(Luminalbpy)]( PF₆)₂ as a probe were established with PL, ECL and CL signal output modes, respectively.     

Stereochemical determination of tetrahydropyran-substituted xanthones from fungus Chaetomium murorum

Chaetoxanthone D (1), a new tetrahydropyran-substituted xanthone originated from polyketide pathway, together with the four known natural products chaetoxanthone C (2), alternariol methyl ether (3), alternariol (4) and 2,5-dimethyl-7-hydroxychromone (5) was isolated from a strain of Chaetomium murorum. The structures of these compounds were elucidated based on extensive spectroscopic analyses. The absolute configurations of 1 and 2 were determined by using quantum chemical electronic circular dichroism (ECD) calculations.     

Particulate capillary precolumns with double-end polymer monolithic frits for on-line peptide trapping and preconcentration

In this work,a novel kind of particulate capillary precolumns with double-end polymer monolithic frits has been developed.Firstly,the polymer monolithic frit at one end was prepared via photo-initiated polymerization of a mixture of lauryl methacrylate and ethyleneglycol dimethacrylate with 1-propanol and 1,4-butanediol as porogens and 2,2-dimethoxy-2-phenylacetophenone as a photo-initiator in UV transparent coating capillary(100 μm i.d.).Subsequently,C18 particles(5 μm,100 A) were packed into the capillary,and sealed with the polymer monolithic frit at another end.To prevent the reaction of monomers and C18 particles,the packed C18 particles were masked during UV exposure.The loading capacity of such a precolumn was determined to be about 9 μg by frontal analysis with a synthetic peptide APGDR1 YVHPF as a model sample.Furthermore,two parallel precolumns were incorporated into a two-dimensional nano-liquid chromatography(2D nano-LC) system with dual capillary trap columns for peptide trapping and concentration.Compared to 2D nano-LC system with a single trap column,such two dimensional separations could be operated simultaneously to improve the analysis throughput.All these results demonstrated that such capillary precolumns with double frits would be promising for high-throughput proteome analysis.     

[12] ane N_3-based BODIPY as a selective and sensitive off–on sensor for the sequential recognition of Cu~(2+) ions and ADP

A novel [12]aneN3-based BODIPY sensor 1 can be applied in the sequential recognition of Cu2 and ADP in aqueous solution and living cells with high selectivity and sensitivity     

BioLeT: A new design strategy for functional bioluminogenic probes

By integrating photoinduced electron transfer (PET) into the design of functional bioluminogenic probes, Urano and his coworkers recently developed a new rational design strategy, BioLeT. It is expected that this BioLeT strategy will enable us to design and develop new bioluminescence probes for detecting various biomolecules with no catalytic or reactive activity.     

Tris(Znsalen) cryptand minimizes Znsalen aggregation arising from intermolecular Zn…O interaction

Exploring the factors to control Znsalen aggregation is of importance to design functional materials in catalysis, optical materials and biological imaging. In this work, we synthesized and characterized four cryptand type triZnsalen complexes and found that cryptand structure could efficiently minimize intermolecular Zn···O interaction. More importantly, encapsulated by PLGA nanoparticles, cryptand triZnsalen 1 displayed visible intracellular fluorescence whereas monomeric Znsalen 5 could not. These results provide a new access to design new luminescent materials with the potential application in optics and biological studies.     

Palladium-catalyzed ortho-selective C–H bond chlorination of aromatic ketones

A palladium-catalyzed ortho-selective C–H bond chlorination reaction for the preparation of 2-chloro aromatic ketones was described. Both electron-withdrawing and electron-donating groups on the aromatic rings are well tolerated under the optimized conditions. The 2-chloro aromatic ketones obtained by our method could be applied to synthesize the derivatives of 1H-indazole or benzo[d]isoxazole.     

Medium effect on dielectric relaxation behaviors of 4A zeolite bulk dispersion system

Dielectric spectra of 4A zeolite particles bulked in deionized water (4A/W) or cyclohexane (4A/C) were measured respectively under different temperatures, and two dielectric relaxations were found in both of 4A/W and 4A/C. Because of existence of water molecules in pores, both low and high frequency relaxation times (τ_LFR and τ_HFR) of 4A/Wdecreasedmore sharply than 4A/C with increasing temperature. According to the temperature dependence of τ_LFR and τ_HFR, the activation energies of Na⁺ interacting with framework under hydrated and dehydrated environments were calculated respectively, and the original properties of Na⁺ in dehydrated zeolite were obtained by analyzing the dielectric properties of 4A/C. Furthermore, a transient state of Na⁺ motion with temperature was found in 4A/C system.