Spectrophotometric Determination of Diphenylamine,Pyrrole, and Indole - A Kinetic Study

Abstract

The use of p-dimethylaminocinnamaldehyde (p-DAC) has been described for the colorimetric determination of diphenylamine (DPA), Pyrrole (Py) and Indole (In) in acidic media. The kinetics of the reactions were studied and a mechanism for the reactions has been proposed. The reaction products were isolated, and identified using IR, NMR and elemental analysis.     

Simultaneous Determination of Timolol Maleate and Pilocarpine Hydrochloride in Ophthalmic Solutions by First Derivative UV Spectrophotometry and PLS-1 Multivariate Calibration

ABSTRACT

The use of UV spectrophotometry (first-derivative/zero-crossing and zero-order spectra/multivariate calibration) is reported for the analysis of two miotic agents in ophthalmic solutions. The resolution of these mixtures has been accomplished without prior separation or derivatisation by using: 1) first-derivative measurements at two appropriate zero-crossing points: λ₁ = 222 nm, where the absorption corresponding to excipients is negligible, and λ₂ = 307 nm, where the contribution of pilocarpine and excipients to the overall absorption is negligible, and 2) partial least squares (PLS-1) regression analysis of zero-order spectral data. Although the components show an important degree of spectral overlap, they have been simultaneously determined with high accuracy, and with no interference from ophthalmic solution excipients.     

Identification of Organic Compounds Solvent Extracted from Paper and Glass Soxhlet Thimbles

Abstract

Organic compounds leached from paper and glass soxhlet thimbles have been identified by computerized high resolution gas chromatography /mass spectrometry. Nineteen specific organics have been tentatively identified from paper thimbles. The analysis of glass thimbles have not demonstrated these contaminants. The use of glass thimbles as a substitute for paper is advantageous in preparation of samples for trace organic analysis. This is an improvement but not a panacea as cross-contamination must still be evaluated by the analytical chemist.     

Ion Chromatographic Analysis of Sulfate and Nitrate in Ambient Aerosols

Abstract

Ion exchange has been known to provide excellent separation of ions since 1850, and ion exchange chromatography has been in use since 1940. However, ion exchange chromatography has not been widely used for the automated analysis of eluted ions because of the background produced by the electrolyte used for elution. H. Small, T. S. Stevens, and W. C. Bauman, (Anal. Chem., 47, 1801 (1975)) recently developed a technique whereby the background is reduced to a minimum with eluant suppression. Eluant suppression allows the use of ion exchange chromatography with conductimetric detection as a sensitive and selective means for the analysis of practically all ionic species. This communication describes the first successful application of ion chromatography (IC) to the analysis of total water soluble sulfate and nitrate in ambient aerosols. Analytical conditions and data on sensitivity, selectivity, accuracy and repeatability are described.

The application of this technique to the analysis of atniospheric anions and cations and their precursors is to be investigated in future studies.     

A theoretical study of the intramolecular interaction between proximal atoms in planar conformations of biphenyl and related systems

The nature of the interaction between proximal hydrogens in planar biphenyl has been recently a matter of debate as arguments in favor of and against the existence of “H–H” bonding have been recently put forward. This issue is addressed here through the study of both the electron density ρ(r) and the electron localization function (ELF) η(r) obtained in quantum calculations on molecular systems with F atoms replacing hydrogens in the moiety that presents this interaction. The analysis of geometries and properties of ρ(r) and η(r) at both planar and twisted equilibrium conformations of those systems along with biphenyl, permits to get information on this intramolecular interaction that is compared with the use of the traditional chemical concepts (steric hindrance and π-resonance effects) involved. It is shown that although the ELF gives information compatible with these classical terms, this does not preclude the existence of bonds between proximal atoms with features rather similar to those of well-established intramolecular hydrogen bonds.     

Spectrophotometric and First Derivative Spectrophotometric Determination of Magnesium with 1-Hydroxy-2-Carboxyanthraquinone

Abstract

1-Hydroxy-2-carboxyanthraquinone reacts with magnesium in ethanol-water mixtures to form a red complex having an absorption maximum at 490 nm in alkaline medium. A detailed study of the characteristics of this complex has been carried out and a spectrophotometric method for the determination of magnesium at the 0.4–4.0 μg ml^?1 level is proposed. The method has been sensitized by employing first derivative spectrophotometry. By the use of the derivative approach magnesium can be determined between 0.08–0.40 μg ml^?1. Statistical analysis of the results is also described.     

Tris(N-methylferrocenyl-N-(2-phenylethyl)dithiocarbamato-S,S′)cobalt(III) for anion sensing and preparation of cobalt-iron sulfide nanoparticles: A new photocatalyst for the degradation of dyes

Tris(N-(pyrrol-2-ylmethyl)-N-butyldithiocarbamato-S,S′)cobalt(III) (1) and tris(N-methylferrocenyl-N-(2-phenylethyl)dithiocarbamato-S,S′)cobalt(III) (2) have been synthesized and characterized by elemental analysis and spectroscopy (IR, UV-vis and NMR). The elemental analysis and IR, ¹H and ¹³C NMR spectra are consistent with the formation of the cobalt(III) complexes with dithiocarbamate ligands. The anion binding properties of 1 and 2 based on host-guest interaction have been examined with the use of cyclic voltammetry.This study showed that both complexes preferred to bind with I^-compared to other halides. 2 has been used as precursors for the preparation of cobalt-iron sulfide nanoparticles. TEM image of cobalt-iron sulfide nanoparticles showed that the particles are spherical. The elemental compositions of the nanoparticles were confirmed by energy dispersive X-ray spectroscopy. IR spectral studies on nanoparticles confirm the presence of capping agent (triethylenetetramine). The nanoparticles were explored as photocatalysts to study the degradation of dyes using methylene blue and rhodamine-B in aqueous solution under UV irradiation. The cobalt-iron sulfide works as an efficient photocatalyst for degradation of rhodamine-B.     

Synthesis and Bioactivities of Clopyralid Hydrazide-Hydrazones

A series of clopyralid hydrazide-hydrazone derivatives (4a–p) have been synthesized. Their structures were confirmed by elemental analysis, infrared, and ¹H NMR spectra. The bioactivities of compounds 4a–p were tested with barnyard grass, rape, and S. aureus, but the results showed that they could not be considered the promising herbicidal or antibacterial agents.     

调控发光波长:新型2-取代8-羟基喹啉衍生物金属锌配合物的合成与特性研究

设计合成了2-[(2'-芴基)-乙烯基]-8-羟基喹啉(6)、2-[(2'-菲基)-乙烯基]-8-羟基喹啉(7)及其金属锌配合物8和9; 用UV-Vis, FT-IR, ESI-MS, ¹H NMR和元素分析确认了化合物6和7的结构; 并用四甲基偶氮唑盐微量酶反应比色法(MTT法)研究了其调控骨髓间质干细胞增殖的作用, 结果表明, 化合物6和7对干细胞有明显的增殖作用. 用FT-IR, FAB-MS和元素分析表征了金属锌配合物结构, 光致发光光谱测试结果表明, 化合物8的发光峰值为602 nm, 发黄光; 化合物9的发光峰值为628 nm, 发橙红色光.     

The synthesis and characterization of new metal-free and metallo phthalocyanines substituted with four dithiatetraoxa macrocyclic moieties

New metal-free phthalocyanine (7) fused symmetrically in peripheral positions with four dithiatetraoxa macrocycles, has been synthesized by cyclotetramerization of the isoindolinediimine derivative of macrocyclic 6. Metallophthalocyanine (8) was synthesized by reaction of phthalonitrile derivative (5) with anhydrous nickel(II) chloride. The new compounds were characterized by elemental analysis, ¹H and ¹³C-NMR, IR UV–Vis and mass spectroscopies.     

多叠氮基三唑类高氮化合物的合成与晶体结构

2,5,2'-三氯-1,1'-偶氮-1,3,4-三唑(1)与叠氮化钠反应首次合成含有多叠氮和四氮烯(N—N＝N—N)结构的高氮化合物2,5,2'-三叠氮-1,1'-偶氮-1,3,4-三唑(3). 在相同条件, 2,5,2',5'-四氯-1,1'-偶氮-1,3,4-三唑(2)与叠氮化钠反应没有得到2,5,2',5'-四叠氮-1,1'-偶氮-1,3,4-三唑(b), 而是得到其分解产物3,5-二叠氮基-1,2,4-三唑(4). 用X 射线单晶衍射测定了化合物3和4的晶体结构. 晶体2b通过分子间氢键的相互作用形成具有9元环的三聚体,并由于三唑环共轭体系使氮上的H原子具有酸性,从而导致互变现象发生.     

Synthesis and evaluation of multitopic bisbenzothiazolyl calix[4]arenes for ionic toxicants

Abstract

Two new benzothiazolyl calix[4]arene-based multitopic molecular receptors L-1 and L-2 have been synthesised and evaluated for recognition of ionic toxicants. The receptors selectively interact with copper, silver and fluoride ion toxicants as assessed through UV-visible, NMR and colorimetric techniques. The stability of L-1:Cu⁺² and L-2:Cu⁺² complexes was found to be higher than that of complexes formed with Ag⁺ and F^– complexes in the presence of trifluoroacetic acid. Superiority of L-1 over L-2 for analysis of identified toxicants has been determined by measurement of binding constants.     

Crystal structure studies and antimicrobial activities of transition metal complexes of pyridine-2,6-dicarboxylic acid and imidazole containing water clusters

Two new copper(II) and chromium(III) complexes of tridentate 2,6-pyridinedicarboxylic acid (H₂pydc) with imidazole (im), (Him)[Cu(Hpydc)(pydc)]?H₂pydc?5H₂O (1) and (Him)[Cr(pydc)₂]?H₂pydc?5H₂O (2), have been prepared and characterized by elemental analysis, TGA measurements, FT-IR, and UV–Vis spectroscopy, powder and single crystal X-ray crystallography. Crystal structure analyses reveal that both copper(II) and chromium(III) ions are in a distorted octahedral environment. The optimized geometrical parameters were calculated using methods based on the density functional theory (DFT). These calculations agree closely with the X-ray structure. The antimicrobial activities of the ligand and the complexes were evaluated in vitro and compared with drugs in use. The results show that the complexes had stronger antibacterial activity than the corresponding ligand and the effectiveness was confirmed against Bacillus subtilis (gram positive) and Klebsiella pneumoniae (gram negative) for 1, and Escherichia coli and K. pneumoniae (gram negative) for 2 by the well diffusion method.     

Lignans and secoiridoid glycosides from the stem barks of Jasminum tortuosum

This paper reports on the first phytochemical analysis ever performed on Jasminum tortuosum Willd. This analysis, mainly carried out by means of column chromatography separation, NMR spectroscopy and mass spectrometry, led to the isolation and the identification of four compounds, namely the lignans ginkgool (1) and olivil-4′-O-β-glucopyranoside (2) and the secoiridoids oleoside dimethyl ester (3) and oleoside 11-methyl ester (4). The presence of these compounds is significant from a chemotaxonomic point of view, confirming the correct botanical classification of the species and, from a phytochemical standpoint, may suggest its possible use in the ethno-medicinal field.     

Synthesis and Characterization of S-Triazine Cored Tripodal Keto-oxime and Its Trinuclear Complexes

2,4,6-Tris(4-hydroxybenzimino)-1,3,5-triazine (II) has been synthesized by the reaction of 1 equiv. melamine (I) and 3 equiv. 4-hydroxybenzaldehyde and characterized by means of elemental analysis, ¹H NMR, Fourier transform–infrared spectroscopy, and liquid chromatography–mass spectrometry (LC-MS). 2,4,6-tris(4-(2-phenyl-2-keto-hydroxyiminoyloxy)benzimino)-1,3,5-triazine L (III) has been synthesized by the reaction of 1 equiv. II and 3 equiv. chloroisonitrozoacetophenone and characterized by means of the same methods. Four novel trinuclear Fe(III) and Cr(III) complexes involving tetradentate Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(salophen H₂) with L (III) have been synthesized and characterized by means of elemental analysis, Fourier transform–infrared spectroscopy, LC-MS (ESI⁺), and thermal analyses. The metal ratios of the prepared complexes have been determined using atomic absorption spectroscopy. The aim of the present study is to synthesize novel tridirectional-trinuclear systems and to present their effects on magnetic behavior of [salen or salophenFe(III)/Cr(III)] capped complexes. The complexes have also been characterized as low-spin distorted octahedral Fe(III) and as distorted octahedral Cr(III) bridged by keton-oxime group.     

The synthesis and characterization of new phthalocyanines containing hexaazadithia macrobicyclic moieties

The new metal-free and metallo phthalocyanines (4) and (5) bearing four tetrasubstituted hexaazadithia macrobicycles on peripheral positions, have been synthesized. Phthalonitrile (3) has been synthesized from the reaction of (1,3,6,9,11,14 hexaazatricyclo [12.2.1.1^6,9]) (1) and 1,2-bis(2-iodomercaptoethyl)-4,5-dicyanobenzene (2). The new compounds were characterized by elemental analysis, and IR, ¹H, ¹³C-NMR, UV-Visible and mass spectral data.     

The Synthesis and Properties of New Metal-free and Metallophthalocyanines Containing Four Diloop Macrocyclic Moieties

The synthesis and characterization of new metal-free (9) and metal-containing (Zn, Ni or Cu 10, 11, 12) derivatives of a symmetrically octasubstituted phthalocyanine derived from 21,22-dicyano-2,3,5,6,8,9,11,12,15,17,18,25,26,28-tetradecahydro[1,4,7,12] benzodioxadithiacyclotetradeceno[6,7-b][1,4,7,10,13]benzopentaoxacyclopentadecene (7), which was synthesized in a multi-step reaction sequence, have been described. The novel compouds have been characterized by a combination of elemental analysis, ¹H and ¹³C NMR, IR, UV–vis and MS spectral data.     

Characterization of Molecular Structures Using Topological Indices

Abstract

The characterization of molecular structure using structural invariants has increased greatly over the last ten years. Specifically, topological indices have become more widely used in the quantification of molecular structure for use in quantitative structure-activity relationship studies, chemical documentation, and molecular similarity studies. The basis, calculation, and utility of topological indices has been examined, with an eye to the specific advantages and problems in their use. In addition, variable clustering and principal component analysis are examinee as two potential solutions to the problem of index intercorrelation.     

Synthesis,characterization, and biological activity of five new mixed-ligand palladium(II) complexes with ethylenediamine and 4-toluenesulfonyl-L-amino acid dianion

Five new palladium(II) complexes with 4-toluenesulfonyl-L-amino acid dianion and en, [Pd(en)(TsserNO)] (1), [Pd(en)(TsglyNO)] (2), [Pd(en)(TsalaNO)]?·?1.5H₂O (3), [Pd(en)(TsleuNO)]?·?H₂O (4), and [Pd(en)(TspheNO)]?·?2H₂O (5), have been synthesized and characterized by elemental analysis, IR, UV, ¹H NMR, and mass spectrometry. Crystal structure of 1 has been determined by X-ray diffraction analysis. The cytotoxicity was tested by MTT and SRB assays. The results indicate 1–5 exert cytotoxic effects against HL-60, Bel-7402, BGC-823, and KB cell lines and 5 displays the best cytotoxicity. The structure–activity relationships suggest that both amino acid and N-containing ligands have important effects on cytotoxicity.