Three tetrahydroisoquinolinedione derivatives

N‐(2‐Chloro­benzyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₆H₁₂ClNO₂, crystallizes in P2₁/n with three crystallographically independent mol­ecules in the asymmetric unit, which differ slightly in conformation, N‐(2‐bromo‐4‐methyl­phenyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₆H₁₂BrNO₂, crystallizes in P2₁/n with one mol­ecule in the asymmetric unit andN‐(2,3‐di­chloro­phenyl)‐1,2,3,4‐tetra­hydro­iso­quinoline‐1,3‐dione, C₁₅H₉Cl₂NO₂, crystallizes in P2₁/c with one mol­ecule in the asymmetric unit. In all three structures, the heterocyclic rings adopt approximately planar conformations. The pyridine rings are orthogonal to the substituted phenyl rings. In all three structures, the crystal packing is stabilized by intermolecular C—H?O hydrogen bonds.     

Sol-gel-coated oligomers as novel stationary phases for solid-phase microextraction

Amphiphilic and hydrophilic oligomers were synthesized and coated on fused silica capillaries using a sol-gel technique. Sol-gel-coated capillaries were evaluated for the solid-phase microextraction and preconcentration of a wide variety of non-polar and polar analytes. Both types of coatings were stable under high temperature (up to 280 degrees C). The extraction efficiency of the sol-gel coatings was evaluated for the extraction of both non-polar and polar analytes, including organochlorine pesticides, triazine herbicides, estrogens and alkylphenols (APs) and bisphenol-A (BPA). Compared with commercially available solid-phase microextraction (SPME) adsorbents such as poly(dimethylsiloxane)divenylbenzene and polyacrylate, the new materials showed comparable selectivity and sensitivity towards both non-polar and polar analytes. The new coatings gave good linearity and detection limits. For example with triazines, a detection limit of <0.005 microl l(-1), precision from 5.0 to 11.0% (n = 6) and linearity of the calibration plots (0.5 to 50 microl l(-1)) were obtained. The sol-gel coated SPME capillaries were used for the determination of triazine herbicides in reservoir water samples collected in Singapore.     

Effect of s-, p-, d-, and f-block elements on the structure and properties of ammonium dihydrogen phosphate crystals

The influence of the s-, p-, d-, and f-block elements (Cs, Sb, Pd, and Ce) doping on the properties of ammonium dihydrogen phosphate (ADP) crystals has been described. Incorporation of small quantity of dopants into the crystalline matrix is well confirmed by energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma (ICP) techniques. The reduction in the intensity observed in powder X-ray diffraction (XRD) of doped specimens and slight shifts in vibrational frequencies confirm the lattice stress. Surface morphological changes due to doping of metals are observed by scanning electron microscopy (SEM). The differential scanning calorimetry (DSC) curves show only a slight variation in endothermic peak temperatures. The sharpness of the DSC peaks shows the good degree of crystallinity of the material. The cell parameters have been determined using single crystal XRD analysis of pure ADP and ADP:Cs/ADP:Sb/ADP:Pd/ADP:Ce specimens. The influence of metals on the second harmonic generation (SHG) efficiency is also investigated.     

Synthesis and Characterization of Homoleptic and Heteroleptic Complexes Involving Dithiocarbamates,Triphenylphosphine, and Nickel(II)

Abstract

Six new nickel complexes of two dithiocarbamate ligands (cyfdtc = N-cyclohexyl-N- furfuryldithiocarbamate and bztpedtc = N-benzyl-N-[2-thiophenylethyl]dithiocarbamate) namely, (Ni[cyfdtc]₂) (1), (Ni[bztpedtc]₂) (2), (Ni[cyfdtc][NCS][PPh₃]) (3), (Ni[bztpedtc] [NCS][PPh₃]) (4), (Ni[cyfdtc][PPh₃]₂)ClO₄ (5), and (Ni[bztpedtc][PPh₃]₂)ClO₄ (6) have been prepared and characterized using IR, electronic, and NMR (¹H and ¹³C) spectra. A single crystal X-ray structural analysis was carried out for complex 3 and showed that nickel is in a distorted square planar arrangement with the NiS₂PN chromophore. The shift in ν_C?N of the heteroleptic complexes to higher frequencies compared with the parent complex is assigned to mesomeric delocalization of electron density from the

dithiocarbamate ligand toward the metal atom, which increases the contribution of polar thioureide form in mixed ligand complexes. Electronic spectral studies suggest square planar geometry for the complexes. In the ¹³C NMR spectra, the upfield shift of NCS₂ carbon signal for 3 and 4 from the chemical shift value of 1 and 2 is due to effect of PPh₃ on the mesomeric drift of electron density toward nickel throughout thioureide C?N bond.     

Growth, structure, and characterization of tris(thiourea)silver(I) nitrate

Single crystals of tris(thiourea)silver(I) nitrate have been grown by slow evaporation solution growth technique from an aqueous solution at 25 °C. The single crystal X-ray diffraction study reveals that the crystal belongs to tetragonal system and cell parameters are a = b = 14.2790(4) Å, c = 24.8900(7) Å, and V = 5074.8(2) Å³. The various functional groups present in the molecule are confirmed by Fourier transformed infrared spectroscopy (FT-IR). The structure and the crystallinity of the materials were further confirmed by powder X-ray diffraction analysis. Thermogravimetric and differential thermal analysis reveal the purity of the sample and no decomposition is observed up to the melting point. The crystal is further characterized by UV–Vis and Vickers microhardness analysis.     

Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid supported montmorillonite K-10 clay-catalysed one-pot multi-component synthesis of chromeno[2,3-b]indoles

One-pot three-component synthesis of twelve different chromeno[2,3-b]indole derivatives were achieved by the condensation of β-naphthol, oxindole and various substituted aldehydes. Two more chromeno[2,3-b]indole derivatives were also synthesized through one-pot two-component condensation of salicylaldehyde with oxindole/chlorooxindole. Both the condensations were achieved by using Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid, H₄[PVMo₁₁O₄₀] supported on montmorillonite K-10 clay for about 10% as catalyst under environmentally benign solvent-free reaction condition. Shorter reaction time, excellent yield of product, sustainability of catalytic material and simple workup procedure under green experimental conditions are the advantages of this protocol.

     

Os(VIII)-catalysed oxidation of sulfides by sodium salt of N-chlorobenzenesulfonamide

Catalytic activity of Os(VIII) in the oxidation of some twenty organic sulfides with sodium salt of N-chlorobenzenesulfonamide (CAB) has been investigated in alkaline (pH8.7) t-butanol–water (1:1 v/v) medium. Significant retarding influence of [OH⁻] on the reactivity is exhibited. The catalysed reaction is strongly accelerated in the presence of Hg(II). Imperfections are observed in the linear Hammett relationship in the case of –NO₂ substituents.     

Effect of chelating agent (1,10-phenanthroline) on potassium hydrogen phthalate crystals

The influence of a new organic additive, chelating agent 1,10-phenanthroline (Phen) (∼5.0·10⁻³ M L⁻¹) on potassium hydrogen phthalate (KHP) single crystals at 30° is investigated. The crystals were grown from the aqueous solutions of pH ∼4.5 at constant temperature by solvent evaporation technique. The chelating agent leads to an increase in metastable zone width and assists the bulk growth process. The growth rate of crystals in the presence of Phen decreases considerably with an increase in impurity concentration. Not much variation is observed in FTIR and cell parameter values, determined by XRD analysis. It appears that the growth promoting effect (GPE) of Phen is caused by the adsorption of the organic additive on the prism of KHP crystals. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed up to the melting point. Scanning electron microscope (SEM) photographs exhibit the effectiveness of the impurity in changing the surface morphology of KHP crystals. Contrary to expectations, Phen depresses the NLO efficiency of KHP, suggesting that the molecular alignments in the presence of Phen results in cancellation effects disturbing the non-linearity.     

Effect of anthracene doping on potassium hydrogen phthalate crystals

The influence of the highly fluorescent dopant, anthracene (over a concentration range from 5 × 10^?4 to 1.2 × 10^?2 mol dm^?3) on the nonlinear optical properties and fluorescence intensity of potassium hydrogen phthalate (KHP) single crystals grown at 30 °C by a slow evaporation solution growth technique (SEST) has been investigated. Powder XRD and FTIR spectral analyses confirm the slight distortion of the structure of crystal because of doping. UV–Visible study shows that the transparency is not affected much by the dopant. The SEM investigation reveals that KHP suffers from crack development. Thermal analysis indicates that there is no decomposition of the crystal up to the melting point. It is interesting to observe that additions of small quantity anthracene to KHP results in the enhancement of fluorescence intensity. The fluorescence intensity dependence on dopant concentration is observed. Interestingly, second harmonic generation (SHG) efficiency of KHP is dramatically improved by doping with small quantities of anthracene.