Click chemistry‐based synthesis of azo polymers for second‐order nonlinear optics

Four linear polymers containing pendant azo moiety were synthesized through click chemistry for second‐order nonlinear optical study. The polymers were found soluble in most of the polar organic solvents such as tetrahydrofuran (THF), chloroform, and dimethyl formamide (DMF). The polymers showed thermal stability up to 300 °C and glass transition temperatures (T_g) in the range of 120–140 °C. The molecular weights (M_w) of these polymers (measured by gel permeation chromatography) were in the range 37,900–55,000 g/mol. The polymers were found to form optically transparent films by solution casting from THF solution. Order parameters were calculated from UV–vis absorption spectra. The morphology changes in the films after poling were characterized by atomic force microscopy. The angular dependence, temperature dependence, and time dependence of second harmonic generation (SHG) intensity were obtained by using 1064 nm Nd:YAG laser. The SHG intensity remained unchanged up to 95 °C. At room temperature, it remained stable up to 8 days after initial drop of about 14%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Optical investigations of conducting polypyrrole under pressure

Abstract

The changes in the characteristics of vibrational and optical properties of the conducting form of polypyrrole under pressure is studied.     

Polymer complexes. LXX. Synthesis,spectroscopic studies,thermal properties and antimicrobial activity of metal(II) polymer complexes

The monomer 3‐allyl‐5‐(phenylazo)‐2‐thioxothiazolidine‐4‐one (HL) was prepared by the reaction of allyl rhodanine with aniline through diazo‐coupling reaction. Reaction of HL with Ni(II) or Co(II) salts gave polymer complexes ( 1 – 8 ) with general stoichiometries [M(HL)(Cl)₂(OH₂)₂]_n, [M(HL)(O₂SO₂)(OH₂)₂]_n, [M(L)(O₂NO)(H₂O)₂]_n and [M(L)(O₂CCH₃)(H₂O)₂]_n (where M = Ni(II) or Co(II)). The structures of the polymer complexes were identified using elemental analysis, infrared and electronic spectra, molar conductance, magnetic susceptibility, X‐ray diffraction and thermogravimetric analysis. The interaction between the polymer complexes and calf thymus DNA showed a hypochromism effect. HL and its polymer complexes were tested against bacterial and fungal species. Co(II) polymer complex 2 is the most effective against Klebsiella pneumoniae and is more active than penicillin. The results showed that Ni(II) polymer complex 5 is a good antibacterial agent against Staphylococcus aureus and Pseudomonas aeruginosa. Molecular docking was used to predict the binding between the monomer with the receptors of prostate cancer (PDB code: 2Q7L Hormone) and breast cancer (PDB code: 1JNX Gene regulation). Coats–Redfern and Horowitz–Metzger methods were applied for calculating the thermodynamic parameters of HL and its polymer complexes. The thermal activation energy of decomposition for HL is higher than that for the polymer complexes.     

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Homogeneity of variance and correlation coefficients is one of assumptions in the analysis of longitudinal data.However, the assumption can be challenged. In this paper, we mainly propose and analyze nonlinear mixed effects models for longitudinal data with exponential correlation covariance structure, intend to introduce Huber's function in the log likelihood function and get robust estimation (M-estimation) by Fisher scoring method. Score test statistics for homogeneity of variance and correlation coefficient based on M-estimation are then studied. A simulation study is carried to assess the performance of test statistics and the method we proposed in the paper is illustrated by an actual data example.     

The role of delay times in subcycle-resolved probe retardation measurements

The delay in the nonlinear response of matter to intense laser pulses has been studied since a long time regarding its nuclear contribution. In contrast, the electronic part of the nonlinear response in wide-band-gap dielectrics, which is usually dominant, is not well explored regarding its delay, and previous studies have revealed that the timescale is below 1 fs. Here, the influence of delay times on the recently introduced method of subcycle-resolved probe retardation measurements is investigated using a simulation. In the model assumed, the electronic nonlinearity is divided into the third order Kerr effect and the plasma contribution due to conduction band population in the strong laser field. In the regime of close-to-collinear pump-probe geometries, the probe retardation shows both π- and 2π-oscillations in the pump-probe delay. Sub-femtosecond delay times influence the phase of the oscillations significantly, but it remains difficult to distinguish the influence of the Kerr response from the plasma contribution.     

On the Rayleigh-Plateau instability

In this paper,we study the surface instability of a cylindrical pore in the absence of stress. This instability is called the Rayleigh-Plateau instabilty. We consider the model developed by Spencer et ...     

Some MnIII-porphyrins with de-polymerization activity toward humic acid

Four Mn^III-porphyrin complexes, chloro(tetraphenylporphinato)Mn^III(1,6-diaminohexane), bromo(tetraphenylporphinato)Mn^III(1,6-diaminohexane), azido(tetraphenylporphinato)Mn^III(1,6-diaminohexane), and thiocyanato(tetraphenylporphinato)Mn^III(1,6-diaminohexane), have been synthesized. These complexes have been characterized using UV-Vis, IR, ESI-mass spectra, elemental analyses, magnetic susceptibility measurements, and conductivity measurement. The molar conductance values of these complexes in ethanol indicate non-electrolytes. The utility of these complexes in de-polymerization of coal using humic acid as the coal model has been tested by the optical density method.     

A mixed-ligand approach for building a N-rich porous metal-organic framework for drug release and anticancer activity against oral squamous cell carcinoma

Abstract

A new Zn(II) metal-organic framework (MOFs), [Zn(BTC)(HME)]·(DMAc)(H₂O) (1, H₃BTC =1,3,5-benzenetricarboxylic acid, HME?=?protonated melamine, DMAc?=?N,N-dimethylacetamide), has been synthesized under solvothermal conditions. In the structure of 1, the four-coordinate Zn(II) ions are connected by BTC^3? ligands into a 3-D framework with (3)-connected utg-type topology. This MOF shows permanent porosity after lattice solvent removal with a calculated pore size distribution around 0.72?nm. With abundant N-donor sites and suitable pore size, the desolvated 1 (1a) was used as a drug carrier for the loading of anticancer drug 5-fluorouracil (5-Fu) molecules. Moderate 5-Fu loading capacity and long drug release time were observed for 1a. The computational simulation results reveal that strong H-bond interactions between the 5-Fu molecules and the nitrogen sites allow slow release of the drug 1a. In addition, the in vitro cytotoxicity of 1 and 5-Fu loaded 1a were also evaluated using MTT assays against human oral squamous cell carcinoma (SCC-251 and HSC-4).     

Spectral characterization and biocidal activity of organotin(IV) (E)-3-[(2′,6′-dichlorophenylamido)]propenoates

Biocidal and spectroscopic aspects of organotin(IV) complexes with (E)-3-[(2′,6′-dichlorophenylamido)]propenoic acid are described with support of elemental analysis. IR, ¹H, ¹³C, ¹¹⁹Sn NMR and mass spectral data suggest that the ligand is bidentate, coordinating through oxygen atoms and that diorganotin(IV) complexes are six-coordinate. Triorganotin(IV) carboxylates exist as pentacoordinated trigonal bipyramidal complexes in the solid state and tetrahedral ones in solution. The complexes have been screened against bacteria, fungi and brine-shrimp larvae to assess their biological activity.     

A 2D Co(II) coordination polymer based on 1,3,5-tris(1H-imidazol-1-yl)benzene: photocatalytic properties and theoretical analysis

Abstract

A new 2D Co(II) based coordination polymer (CP), {[Co₂(tib)₂(NO₃)₃(H₂O)₂·NO₃]_n (1), has been synthesized using 1,3,5-tris(1-imidazolyl)benzene (tib) ligand. The single crystal X-ray diffraction study indicates that 1 possesses an infinite 2D layer, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding interactions. Additionally, the thermogravimetric analysis (TGA) of CP indicates its decomposition temperature was about 268?°C. The UV/Vis diffuse-reflection spectrum of 1 indicates its semiconducting nature on the basis of which the photocatalytic properties of 1 against photodecomposition of organic dyes have been studied. The possible mechanism associated with the photocatalytic activity of 1 against organic dyes is addressed using density of states (DOS) calculations.