Chemical transformations and changes in free volume holes in high-energy proton irradiated low-density polyethylene (LDPE)

Low-density polyethylene (LDPE) was irradiated with 4 MeV protons at different ion fluences. Chemical modifications were studied by UV–vis and Fourier transformed infrared (FT-IR) spectroscopy. Further, the changes in free volume holes were studied using positron annihilation lifetime spectroscopy. The different UV–vis absorption spectra show the maximum absorption at around 280 nm for the lower fluences whereas at the highest fluence a red shift is observed. This indicates formation of chromophoric groups that have the maximum absorption in that region. The formation of vinylidine, trans-vinylene, end-vinyl group, unsaturated linkage and carbonyl group were detected from FT-IR spectra. Positron annihilation lifetime spectroscopy reveals that the free volume hole size and their relative fraction first decrease, attaining a minimum value and subsequently increases with increase in ion fluence. These changes in free volume holes have been well correlated with the observed chemical transformations.     

Synthesis of N-TiO2: Stability and Visible Light Activity for Aqueous Styrene Degradation

Nitrogen-doped TiO₂ (N-TiO₂) were prepared by the impregnation method using urea as a nitrogen source and TiO₂-P25 as precursor. N-TiO₂ was characterized by x-ray diffraction (XRD), UV–vis diffusion reflectance spectra (UV–vis DRS), Fourier transform infrared spectroscopy (FTIR), and x-ray photoelectron spectroscopy (XPS) techniques. XPS analysis indicates the incorporation of nitrogen in TiO₂ lattice as O–Ti–N linkage. DRS spectra reveal the extended absorption to the visible range. Photocatalytic performance of the N-TiO₂ was studied by testing the degradation rate of aqueous styrene under visible light. Also, the degradation kinetics of aqueous styrene and possibility of cyclic usage of N-TiO₂ were investigated.     

Hydrothermal synthesis of nitrogen-doped carbon dots as a sensitive fluorescent probe for the rapid,selective determination of Hg2+

In the present work, a green synthetic method for producing nitrogen-doped carbon dots (NCDs) by using ammonium citrate and urea is introduced. The obtained NCDs were characterised by transmission electron microscopy, Fourier transform infrared spectra, UV–vis absorption and fluorescence spectra. The results showed that the prepared NCDs were spherical with a size of about 3.5 nm, emitting strong and stable blue fluorescence when excited at 352 nm. It was noting that the NCDs enable sensitive and selective determination of Hg²⁺ in tap water with a linear range of 0.01–5 mg L^?1 based on a possible charge transfer process. The detection limit was 9.4 µg L^?1.     

Spectroscopic and electrochemical properties of thin solid films of yttrium bisphthalocyanine

Langmuir—Blodgett (LB) and evaporated thin solid films of the yytrium bisphthalocyanine complex (YPc₂) have been prepared on various substrates. Cyclic voltammograms of films are discussed and the electrochromic effect on LB films is reported. A detailed spectroscopic characterization of the YPc₂ material is given using resonance Raman scattering (RRS), surface-enhanced resonance Raman scattering (SERRS), transmission and reflection absorption FT-IR spectroscopy and UV—vis spectra. The spectroscopic characterization of the chemical and electrochemical oxidations products of YPc₂ films and solutions was carried out by in situ UV—vis spectroscopy. Potential applications are discussed.     

Microwave-hydrothermal synthesis and photocatalytic properties of biomass charcoal/TiO2 nanocomposites

Biomass charcoal-doped titanium dioxide (C/TiO₂) composites were proposed by microwave-hydrothermal and calcination method using tetrabutyl titanate as the titanium source and lignin as the carbon source. TiO₂ crystals with different morphologies could be successfully adsorbed onto the surface of biomass charcoal. These products were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric (DTG), UV–vis diffuser flection spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), and Brunauer–Emmett–Teller (BET). The photocatalytic activities of the as-obtained composites were checked under visible light irradiation. The results showed that both the microwave-hydrothermal temperature and time played an important role in the microstructure and photocatalytic activity of the samples. The rapid microwave-hydrothermal with the thermal post-treatment provides a promising route for the fabrication of biomass charcoal-doped nanocomposites materials.     

Facile preparation and characterization of anatase TiO2/nanocellulose composite for photocatalytic degradation of methyl orange

Anatase TiO₂/nanocellulose composite was prepared for the first time via a one-step method at a relatively low temperature by using cellulose nanofibers as carrier and tetrabutyl titanate as titanium precursor. The morphology, structure and element composition of the composite were characterized by SEM, EDS, TEM, XRD, XPS and UV–vis DRS. The specific surface area and thermal stability of the composite were investigated by N₂ adsorption–desorption and thermogravimetric analysis, respectively, and the band gaps of the prepared photocatalysts were calculated based on the UV–vis DRS results. In addition, the prepared composite was used for the photocatalytic degradation of methyl orange (aqueous solution, 40 mg L⁻¹). It was found that the composite had a good morphology and anatase crystal structure, and Ti-O-C bond was formed between TiO₂ and nanocellulose. The specific surface area of composite was increased and the thermal stability was decreased compared with the cellulose nanofiber. Moreover, the degradation rate of methyl orange was achieved as 99.72% within 30 min, and no obvious activity loss was observed after five cycles. This work might give some insights into the design of efficient photocatalysts for the treatment of organic dye wastewater.     

Enhancement of Antibacterial Capability of Cotton Textiles Coated with TiO2–SiO2/Chitosan Using Hydrophobization

Since textiles have a porous and hydrophilic structure, they are ideal substrates for the settlement and growth of pathogenic bacteria. Therefore, fabrication of hydrophobic textiles to reduce their humidity has the potential to inhibit the growth of bacteria. On this basis, we report here an improvement of the antibacterial capability of textiles coated with TiO₂–SiO₂/chitosan using hydrophobization. Synthesis of TiO₂–SiO₂ clusters with chitosan was carried out using the sol–gel technique. In addition, hydrophobization of the textiles using hexadecyltrimethoxysilane (HDTMS) was carried out using a dip‐spin coating method. In addition, their characteristics were examined using X‐ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectra (UV‐DRS), Fourier transform infrared (FTIR), water contact angle, and antibacterial activity. XRD, SEM, UV‐DRS, FTIR, and water contact angle confirmed the physical and chemical properties of the modified textiles. In summary, the present work shows that the hydrophobization of textiles using HDTMS can enhance the antibacterial capability of cotton textiles.     

DNA-binding properties studies and spectra of a novel fluorescent Zn(II) complex with a new chromone derivative

A new chromone derivative (6-ethoxy chromone-3-carbaldehyde benzoyl hydrazone) ligand (L) and its two transition metal complexes [Zn(II) complex and Ni(II) complex] have been prepared and characterized on the basis of elemental analysis, molar conductivity, mass spectra, UV–vis spectra and IR spectra. The Zn(II) complex exhibits light blue fluorescence under UV light, and the fluorescent properties of Zn(II) complex and the ligand in solid state and in different solutions (MeOH, DMF, THF and H₂O) were investigated. In addition, the interactions of the Zn(II) complex and the ligand with calf thymus DNA were investigated using UV–vis absorption, fluorescence, circular dichroic spectral methods and viscosity measurement. It was founded that both two compounds, especially the Zn(II) complex, strongly bind with calf thymus DNA, presumably via an intercalation mechanism.     

2-氨基-2-甲基丙醇化学修饰试剂用于气相色谱-质谱分析不饱和脂肪酸

以2-氨基-2-甲基丙醇为脂肪酸的化学修饰试剂,将不饱和脂肪酸羧基化学修饰成含氮杂环,从而避免了链烯基中碳碳双键在EI源中的移动,并使质谱呈现显示双键位置的规范信息。通过解析不饱和脂肪酸2-氨基-2-甲基丙醇化学修饰产物的EI质谱图,得到了不饱和脂肪酸中碳碳双键的定位规则,从而为分析不饱和脂肪酸精细结构提供了手段。用脂肪酸2-氨基-2-甲基丙醇化学修饰气相色谱-EI质谱法分析了螺旋藻脂肪酸,鉴定出9种不饱和脂肪酸,确定了螺旋藻脂肪酸中碳碳双键的位置,结果与文献一致。     

DNA interaction and cytotoxicity studies of ruthenium(III) complexes containing 3-(benzothiazol-2-yliminomethyl)-naphthalen-2-ol ligand

A new Schiff base, 3-(benzothiazol-2-yliminomethyl)-naphthalen-2-ol, has been synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy (FT-IR), UV–vis, nuclear magnetic resonance, and single-crystal X-ray diffraction. Ruthenium(III) complexes of the Schiff base were synthesized and characterized by analytical and spectroscopic (FT-IR, UV–vis, and electron paramagnetic resonance) data as well as magnetic susceptibility measurements. DNA-binding properties of the ligand and its ruthenium(III) complexes have been investigated by electronic absorption spectroscopy. The three ruthenium(III) complexes were tested for DNA cleavage. Further in vitro study of the cytotoxity of the ligand and the complexes on human cervical cancer cell line and human laryngeal epithelial carcinoma cell line were carried out.     

Novel hybrids of Cu2+ ternary complexes of salicylidene-amino acid Schiff base with phenanthroline（or bipyridine） intercalated in Mg/Al-NO3-layered double hydroxide

Four Cu²⁺ complexes of salicylidene-amino acid Schiff base with 1,10-phenanthroline（Phen） or 2,2’- bipyridine（Bipy） were successfully intercalated in interlayer galleries of Mg/Al-NO₃-layered double hydroxide（LDH） by the swelling-restored method.The hybrids were characterized by elemental analysis,X-ray diffraction,FT-IR spectra,UV-vis DRS,TG-DTA and SEM observation.Good protection of the complexes by LDH in neutral and weak acidic solutions was revealed by UV spectra,cyclic voltammograms and luminescence spectra.     

Investigation of the interaction between colloidal TiO(2) and bovine hemoglobin using spectral methods

The interaction between bovine hemoglobin (BHb) and TiO(2) colloid was investigated by UV/vis absorption, UV/vis diffuse reflectance spectrum, IR, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. TiO(2) effectively quenched the intrinsic fluorescence of BHb via static quenching. The process of binding TiO(2) on BHb was a spontaneous molecular interaction procedure. The thermodynamic parameters, DeltaH degrees and DeltaS degrees were estimated to be -78.07 kJ mol(-1), -110.93 J mol(-1)K(-1) according to the van' Hoff equation. This indicates that the van der Waals and hydrogen bonds interactions played a major role in stabilizing the TiO(2)-BHb complex. The effect of TiO(2) on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy.     

Hybrid material based on ST–AA photonic crystal core and ZnO particle shell

The aim of this study was to obtain a hybrid material based on a polymer photonic crystal core and inorganic ZnO shell with potential applications in optoelectronic devices or photocatalysts. For this reason, ZnO particles were obtained both in the absence and presence of ST–AA particles using a chemical reduction method for metal salts. The inhibited growth mechanism of inorganic particles generated in the presence of polymer latex was noticed. The products were characterized by SEM, EDX, TEM, DLS, and UV–vis.     

Porphyrin–TiO2 nanoparticle heterostructure assembly by Langmuir–Blodgett method

Surface pressure–area (π–A) isotherm characteristics of 5,10,15-(4-hydroxyphenyl)-20-(4-hexadecyloxyphenyl) porphyrin monolayers on both the water and TiO₂ hydrosol subphases, the UV–vis absorption and fluorescence spectra of the monolayers deposited onto CaF₂ substrates are investigated. π–A isotherms find that the porphyrin ring extends to lie more flat on a TiO₂ hydrosol surface than on a water surface. The UV–vis absorption spectra of the deposited monolayers prove that the porphyrin TiO₂ nanoparticle heterostructure assembly is formed, in which the J-aggregated effect of porphyrin is weakened, comparing with that in the monolayer deposited from water subphase. The fluorescence spectra show that the fluorescent emission quenching by the photoinduced electron transfer from the excited porphyrin molecule to TiO₂ nanoparticle, occurs under excitation in the Soret band region of porphyrin.     

Crosslinkable poly(p‐phenylenevinylene) derivative

To simplify the fabrication of multilayer light‐emitting diodes, we prepared a p‐phenylenevinylene‐based polymer capped with crosslinkable styrene through a Wittig reaction. Insoluble poly(p‐phenylenevinylene) derivative (PPVD) films were prepared by a thermal treatment. The photoluminescence and ultraviolet–visible (UV–vis) absorbance of crosslinked films and noncrosslinked films were studied. We also studied the solvent resistance of crosslinked PPV films with UV–vis absorption spectra and atomic force microscopy. Double‐layer devices using crosslinked PPVD as an emitting layer, 2‐(4‐tert‐butylphenyl)‐5‐phenyl‐1,3,4‐oxadiazole (PBD) in poly(methyl methacrylate) as an electron‐transporting layer, and calcium as a cathode were fabricated. A maximum luminance efficiency of 0.70 cd/A and a maximum brightness of 740 cd/m² at 16 V were demonstrated. A 12‐fold improvement in the luminance efficiency with respect to that of single‐layer devices was realized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2124–2129, 2004     

The oxyfunctionalization of 4‐methylcoumarins using dimethyldioxirane

The kinetic study of the efficient regioselective oxidation of the C? C double bond of 4‐methylcoumarins with isolated dimethyldioxirane was investigated using UV–vis spectroscopy methods. In the excess of dimethyldioxirane, the pyrone ring of a coumarin skeleton is selectively epoxidated and hydroxylated in neutral media, in high yields. Kinetic analyses demonstrate two independent reaction pathways, epoxidation and hydroxylation, respectively, which was also confirmed using kinetic isotope effect methods. Both reaction products were isolated, and their structures were determined by NMR and mass spectra. The position of methyl groups attached at the aromatic part of coumarin molecule shows significant influence on kinetic rate constants and activation parameters. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 414–420, 2009     

全氟萘烷的化学还原与电化学还原

全氟碳化合物 ( PFCs)是分子中与碳原子相连的氢 (官能团中的除外 )全部被氟原子取代的有机氟化合物 .由于氟元素的电负性最大 ,所以 C— F键的键能很大 ( 4 80～ 5 30 k J/mol) ;PFCs与相应的碳氢化合物相比 ,C— F键的键长 ( 0 .1 3nm)与 C— H键的键长 ( 0 .1 nm)接近 ,而且氟原子的范德华半径( 0 .1 5 nm)与氢原子的范德华半径 ( 0 .1 2 nm)也非常接近 ,所以当碳氢化合物中的氢原子被氟原子取代而形成全氟碳化合物后 ,结构上不会发生太大的变化 [1] ;但是全氟碳化合物的物理化学性质与原来碳氢化合物的物理化学性质有显著差异 ,表…     

Preparation and photocatalytic antibacterial property of nitrogen doped TiO2 nanoparticles

Nitrogen doped TiO₂ (N-TiO₂) nanoparticles with about 30 nm in size were produced by a sol–gel method and characterized respectively by UV–vis, X-ray diffraction (XRD), Transmission electron microscopy, X-ray photoelectron spectroscopy (XPS). Their photocatalytic antibacterial properties were evaluated by the antibacterial ratio against Escherichia coli in dark and under simulated sunlight respectively. The XRD pattern showed that the doped nano-TiO₂ was mainly composed of anatase phase. The XPS spectra of the N-TiO₂ sample indicated that TiO₂ was doped by nitrogen atom. The nitrogen doping created a new N 2p state slightly above the valence band top consists of O 2p state, and this pushes up the valence band top and decreased the band gap. Which leaded to the absorption edge was red-shifted to the visible light region of UV–vis spectra of nitrogen doped nano-TiO₂ comparing with pure nano-TiO₂. The antibacterial percentage of N-TiO₂ against E. coli reached to 90 % under simulated sunlight for 2 h, which was much better than that in dark, also than that of pure nano-TiO₂. The photo-catalytic antibacterial activity was activated under visible light. The structure and integrity of cell wall and cell membrane were destructed, and even caused the bacteria death.     

Ab initio Hartree-Fock and density functional theory study on characterization of 3-(5-methylthiazol-2-yldiazenyl)-2-phenyl-1H-indole

The optimized molecular structures, vibrational frequencies, corresponding vibrational assignments, thermodynamic properties, UV–vis spectra and atomic charges of 3-(5-methylthiazol-2-yldiazenyl)-2-phenyl-1H-indole molecule have been investigated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods at 6–31G (d,p) basis set. The obtained bond lengths and bond angles have been seen to be good agreement with the experimental data. After calculated vibrational frequencies have been compared with each other, the correlation coefficient has been determined. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and energy band gap. Infrared intensities and Raman activities have been also reported.     

General and Efficient Intermolecular [2+2] Photodimerization of Chalcones and Cinnamic Acid Derivatives in Solution through Visible‐Light Catalysis

[2+2] Photocycloaddition, for example, the dimerization of chalcones and cinnamic acid derivatives, is a unique strategy to construct cyclobutanes, which are building blocks for a variety of biologically active molecules and natural products. However, most attempts at the above [2+2] addition have focused on solid‐state, molten‐state, or host–guest systems under ultraviolet‐light irradiation in order to overcome the competition of facile geometric isomerization of nonrigid olefins. We report a general and simple method to realize the intermolecular [2+2] dimerization reaction of these acyclic olefins to construct cyclobutanes in a highly regio‐ and diastereoselective manner in solution under visible light, which provides an efficient solution to a long‐standing problem.