Crystal structure determination of two pyridine derivatives: 4-[(E)-2-(4-meth-oxy-phen-yl)ethen-yl]-1-methyl-pyridin-1-ium hexa-fluoro-λ6-phosphane and 4-{(E)-2-[4-(di-methyl-amino)-phen-yl]ethen-yl}-1-phenyl-1λ5-pyridin-1-ylium hexa-fluoro-λ6-phosphane.

The title mol-ecular salts, C16H16NO+·PF6 -, (I), and C21H21N2 +·PF6 -, (II), are pyridine derivatives. In compound (I), the cation comprises a methyl N-substituted pyridine ring and a meth-oxy-substituted benzene ring connected by a C=C double bond. The F atoms of the PF6 - anion are disordered over two sets of sites with refined occupancy factors of 0.614 (7):0.386 (7). In compound (II), the cation comprises a pyridine ring attached to unsubstituted phenyl ring and a di-methyl-aniline ring, which are connected by a C=C double bond. The anion is PF6 -. In both salts, the cation adopts an E configuration with respect to the C=C bond. The pyridine ring makes a dihedral angle of 9.86 (12)° with the meth-oxy-substituted benzene ring in compound (I) and 11.2 (3)° with the di-methyl-amine-substituted benzene ring in compound (II). In compound (I), the crystal packing is stabilized by weak C-H⋯F inter-molecular inter-actions which result in R 4 3(14) ring motifs, forming mol-ecular sheets running parallel to (03). These are further stabilized by weak P-F⋯π interactions. In compound (II), the crystal packing is stabilized by C-H⋯F inter-actions, which result in R 6 6(40) ring motifs, forming mol-ecular sheets running parallel to (101) and these are further connected by π-π inter-actions.

Comparative Studies on the Aqueous Synthesis and Biocompatibility of L-Cysteine and Mercaptopropionic Acid Capped CdSe/CdS/ZnS Core/Shell/Shell Quantum Dots.

Quantum dots have now become the most important candidates and widely exploited as promising architectures for use as diagnostic and imaging agents in biomedicine and as semiconductors in the electronics industry. This article emphasizes on the aqueous synthesis of water soluble CdSe/CdS/ZnS core/shell/shell quantum dots with L-cysteine and mercaptopropionic acid as capping agent and their observed properties have been compared. The biocompatibility of the assynthesized quantum dots have also been analyzed through the cytotoxicity study using MTT assay. The structural, morphological and optical properties of these quantum dots have been examined through X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-Visible absorption spectroscopy (UV-Vis) and Photoluminescence spectroscopy (PL). The capping of L-cysteine and mercaptopropionic acid on the quantum dots has been confirmed from Fourier transform infrared spectroscopy (FTIR). XRD results demonstrated the formation of hexagonal wurtzite structure for L-cysteine and cubic zinc blende structure for mercaptopropionic acid capped CdSe/CdS/ZnS quantum dots. From the optical measurements, it is observed that there is a considerable increase in the photoluminescence intensity of L-cysteine capped quantum dots than MPA. The HRTEM images revealed the narrow size distribution and in addition, L-cysteine capped quantum dots were found to be more biocompatible than mercaptopropionic acid capped quantum dots which would provide new opportunities for applications in bioimaging and biolabelling.

Crystal structures of two stilbazole derivatives: bis-{(E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium} tetra-iodido-cadmium(II) and (E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium 4-meth-oxy-benzene-sulfonate monohydrate.

The title mol-ecular salts, (C18H23N2)2[CdI4], (I), and C18H23N2 +·C7H7O4S-·H2O, (II), are stilbazole, or 4-styryl-pyridine, derivatives. The cation, (E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium, has a methyl group attached to pyridine ring and a diethyl amine group attached to the benzene ring. The asymmetric unit of salt (I), comprises one cationic mol-ecule and half a CdI4 dianion. The Cd atom is situated on a twofold rotation axis and has a slightly distorted tetra-hedral coordination sphere. In (II), the anion consists of a 4-meth-oxy-benzene-sulfonate and it crystallizes as a monohydrate. In both salts, the cations adopt an E configuration with respect to the C=C bond and the pyridine and benzene rings are inclined to each other by 10.7 (4)° in (I) and 4.6 (2)° in (II). In the crystals of both salts, the packing is consolidated by offset π-π stacking inter-actions involving the pyridinium and benzene rings, with centroid-centroid distances of 3.627 (4) Šin (I) and 3.614 (3) Šin (II). In the crystal of (II), a pair of 4-meth-oxy-benzene-sulfonate anions are bridged by Owater-H⋯Osulfonate hydrogen bonds, forming loops with an R 2 4(8) motif. These four-membered units are then linked to the cations by a number of C-H⋯O hydrogen bonds, forming slabs lying parallel to the ab plane.

Investigating the photocatalytic degradation property of Pt, Pd and Ni nanoparticles-loaded TiO2 nanotubes powder prepared via rapid breakdown anodization.

The present study was performed to investigate the photocatalytic efficiency of the titania (TiO2) nanotubes (NTs) powder prepared via rapid breakdown anodization sensitized individually with Ni, Pd and Pt metal nanoparticles (NPs). The TiO2 NTs powder had the length of 5-6 µm, with the outer diameter between 20 and 25 nm and the wall thickness of 3-4 nm as observed in the scanning and transmission electron microscopes. The crystal structure analysis employing X-ray diffraction indicated the presence of Pt, Pd and Ni NPs in face-centered cubic phase over the anatase TiO2 NTs powder. The photocatalytic degradation of methylene blue (MB) was carried out with these photocatalysts. As a result, the performance of the 2 at.% Pt-loaded Pt-TiO2 NTs nanocomposite was determined to be superior on comparison to other photocatalysts under the current investigation. Fourier-transform infrared spectra confirmed the absence of any adsorption of MB or degraded products onto the surface of all the photocatalysts. The electron paramagnetic resonance analysis substantiated the e- transfer interaction from the conduction band of TiO2 NTs to Fermi level of Pt NPs has resulted in the better photodegradation process. The possible degradation mechanism using Pt-TiO2 NTs nanocomposites is discussed.

Bulk size crystal growth, spectroscopic, dielectric and surface studies of 4-N,N-dimethylamino-4-N'-methylstilbazolium m-nitrobenzenesulfonate (DSMNS): A potential THz crystal of stilbazolium family.

The synthesis and growth of a potentially useful and efficient nonlinear optical organic single crystal of 4-N,N-dimethylamino-4-N'-methylstilbazolium m-nitrobenzenesulfonate (DSMNS) is reported. The growth experiment involved the slope nucleation method coupled with slow cooling as well as slow solvent evaporation techniques. Single crystal X-ray diffraction (XRD), Fourier transform infrared (FT-IR), FT-Raman and nuclear magnetic resonance (NMR) techniques have been employed to ascertain the structure and composition of the crystal. Second harmonic generation (SHG) efficiency of the sample has been examined by Kurtz and Perry powder test. Thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) techniques are employed to investigate the thermal behavior of the grown crystal. The frequency/temperature dependent dielectric properties of the organic crystal of DSMNS are studied. The surface features of the grown crystal are investigated by chemical etching study and atomic force microscopy (AFM).

Crystal structure of bis-(thio-cyanato-κS)bis-(thio-urea-κS)mercury(II).

In the title complex, [Hg(NCS)2(CH4N2S)2], the Hg(II) atom is four-coordinated having an irregular four-coordinate geometry composed of four thione S atoms of two thio-cyanate groups and two thio-urea groups. The S-Hg-S angles are 172.02 (9)° for the trans-thio-cyanate S atoms and 90.14 (5)° for the cis-thio-urea S atoms. The mol-ecular structure is stabilized by an intra-molecular N-H⋯S hydrogen bond, which forms an S(6) ring motif. In the crystal, mol-ecules are linked by a number of N-H⋯N and N-H⋯S hydrogen bonds, forming a three-dimensional framework. The first report of the crystal structure of this compound appeared in 1966 [Korczynski (1966 ▶). Rocz. Chem. 40, 547-569] with an extremely high R factor of 17.2%, and no mention of how the data were collected.

Linear and nonlinear optical, mechanical, electrical and surface studies of a novel nonlinear optical crystal - manganese mercury thiocyanate (MMTC).

The highly efficient nonlinear optical single crystal of manganese mercury thiocyanate has been grown from slow evaporation solvent technique. The second harmonic generation and optical transmittance of the grown crystal are studied by Kurtz and Perry powder technique and spectroscopic absorbance spectrum. Mechanical behaviour is analyzed using Vickers microhardness test. The dielectric response of the grown crystal is studied as a function of the temperature and the results are discussed. Further, electronic properties such as plasma energy, Penngap, Fermi energy and electronic polarizability are evaluated. Third order nonlinear optical studies are performed using by single beam Z-scan technique using Nd:YAG laser and parameters such as nonlinear refractive index n2, absorption co-efficient ß and nonlinear optical susceptibility χ((3)) are evaluated for the grown crystal. The surface of the grown crystal is analyzed with field emission scanning electron microscope and atomic force microscope analyses.

4-Methyl-anilinium 4-hy-droxy-benzene-sulfonate.

In the crystal of the title molecular salt, C7H10N(+)·C6H5O4S(-), the benzene-sulfonate units are linked through phenol-sulfonate O-H⋯O hydrogen bonds, forming chains along the c-axis direction. These chains are linked via N-H⋯O hydrogen bonds involving two of the three H atoms of the ammonium group of the 4-methyl-anilium cation, giving rise to two-dimensional networks parallel to the bc plane which are further connected through an additional N-H⋯O inter-action in which the third ammonium H atom is involved, generating a three-dimensional network.

Growth and physicochemical properties of L-phenylalaninium maleate: a novel nonlinear optical crystal.

Single crystals of novel organic nonlinear optical material, L-phenylalaninium maleate (LPM) having dimensions up to 10 × 6 × 6 mm(3) were grown by slow evaporation solution growth technique at room temperature. The grown crystals were confirmed by single crystal X-ray diffraction studies and the various functional groups were identified by FT-IR spectroscopic analysis. The optical properties were studied by optical absorption, second harmonic generation (SHG), photoconductivity and photoluminescence (PL) studies and reported for the first time. The optical band gap energy and SHG efficiency were found to be 4.85 eV and 1.5 times higher than KDP crystals. Negative photoconducting nature was confirmed by photoconductivity studies. Photoluminescence studies confirm the suitability of the sample for blue and green radiations. The title compound was also subjected to TG/DTA analysis and dielectric studies. Layer like growth pattern was analyzed by SEM micrograph.

Synthesis, growth and characterization of new borate-mixed crystals of type (NH4)1-xKxB5O8.

New borate-mixed crystals of type (NH4)1-x KxB5O8 were grown from aqueous solution by slow solvent evaporation method. The mixed crystals were confirmed by atomic absorption studies (AAS) and characterized by X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), optical absorption and solubility studies. The second harmonic generation efficiencies of the parent and mixed crystals were studied and compared with that of KDP.