Chemiluminescence determination of ultramicro DNA with a flow-injection method

A high sensitive flow-injection chemiluminescence method for determination of calf thymus DNA and herring sperm DNA has been developed. The method is based on the chemiluminescence reaction of Rhodamine B-cerium(IV)-thermally denatured DNAs in sulfuric acid media. The proposed procedure allows quantitation of DNAs in the range 2.6×10⁻⁵ to 0.26 μg ml⁻¹ for calf thymus DNA and 5.0×10⁻⁸ to 5.0×10⁻⁵ μg ml⁻¹ for herring sperm DNA with correlation coefficients 0.9998 and 0.9996 (both n=11), respectively. The detection limits (3σ) are 6.5×10⁻⁶ μg ml⁻¹ for calf thymus DNA and 4.3×10⁻⁸ μg ml⁻¹ for herring sperm DNA. The possible mechanism of chemiluminescence in the system is discussed.     

Synthesis and Molecular Structure of Binuclear Tin(IV) Complex Bridged by Terephthalate Anion

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Synthesis of New Reagent 2‐Acetylthiophenethiocynate and its Use in Extraction of Pt(IV) Spectrophotometrically

2‐Acetyl thiophenethiocynate (ATT) was synthesized and its characterization study was carried out using elemental analysis, IR and NMR techniques. The new reagent was proposed as an extractant for the development of the extractive spectrophotometric method for determination of Pt(IV) metal. The reagent complexes with the metal to produce a yellow colored complex which was then extracted into ethyl acetate at pH 11.2–11.6 having an absorption maxima at 400 nm. The thermal study showed that the extraction reactions are exothermic in nature with the reagent, and the stoichiometric ratio of Pt(IV) to 2‐acetyl thiophenethiocynate in the organic phase was 1:2. The method permits separation and determination of platinum from real and binary mixtures. The separation of Pt(IV) from bivalent metal ions has been also studied.     

Facile synthesis of 1-(arylimino)naphthalen-2(1H)-ones from anilines and 2-naphthols promoted by NaBr/K2S2O8/CAN

An efficient method has been developed for the synthesis of 1-(arylimino)naphthalen-2(1H)-ones through the cascade reaction of anilines and 2-naphthols promoted by NaBr/K₂S₂O₈/Ce(NH₄)₂(NO₃)₆. Using this protocol, a series of 1-(arylimino)naphthalen-2(1H)-ones was obtained in good to excellent yields (17 examples, 70–92% yields). The reactions may proceed through the following steps: bromination of 2-naphthols by in-situ-generated bromine from NaBr and K₂S₂O₈ to afford 1-bromonaphthalen-2-ols, coupling of 1-bromonaphthalen-2-ols with anilines to afford the corresponding amines, and subsequent oxidation of the amines into the products by Ce(NH₄)₂(NO₃)_6. These newly obtained α-imine ketones have great potentials for synthesis of special optical materials bearing naphthalene moiety.     

Nitrosubstituted hydroxamate ligands in new triphenyltin(IV) complexes as prospective antimicrobial agents

New triphenyltin(IV) hydroxamate complexes, [Ph₃Sn(4-NO₂CnH)] and [Ph₃Sn(4-NO₂BzH)] have been synthesized by the reactions of Ph₃SnCl with potassium 4-nitrocinnamo hydroxamate [4-NO₂C₆H₄CHCHCONHOK] (KHL¹) and potassium 4-nitro benzohydroxamate [4-NO₂C₆H4CONHOK] (KHL²). The complexes were synthesized in 1:1 molar ratio in MeOH?+?C₆H₆ and characterized by physicochemical and IR, ¹H NMR, and mass spectrometry. The bidentate hydroxamate involving bonding through carbonyl and hydroxamic oxygen (O, O coordination) has been inferred from IR spectra. The electrochemical behavior of complexes has been analyzed. Quasi-irreversible two electron metal-centered cathodic process of type Sn^IV/Sn^II redox couple was indicated by cyclic voltammetric technique. The thermal behavior of 1 and 2 studied by TGA has shown continuous decomposition to yield Sn + 0.5SnO₂ and SnO₂ as final residues. The in vitro antimicrobial activity assays of 1 and 2 against pathogenic Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gram-negative bacteria (Salmonella typhi and Pseudomonas aeruginosa), and fungi (Aspergillus fumigatus and Alternaria alternata) were done by MIC method. The complexes have exhibited appreciable antimicrobial activity relative to the respective standard Gentamycin and Nystatin drugs.     

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis,characterization, antioxidant activity,DNA binding and in vitro cytotoxicity

A series of new complexes of oxovanadium(IV) [VO(L)(B)] and ruthenium(II) [Ru(CO)(PPh₃)₂(L)] ( 1.1- 1.3,  2.1–2.3 ) (H₂L = dehydroacetic acid Schiff base of S‐methyldithiocarbazate, H₂smdha ( 1 ) or S‐benzyldithiocarbazate, H₂sbdha ( 2 ); B = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen)) have been synthesized. The structure of these complexes was authenticated using elemental analyses and spectroscopic techniques, and their magnetic properties and electrochemical behaviour were studied. The molecular structures of oxovanadium(IV) complexes [VO(smdha)(bpy)]?CH₂Cl₂ ( 1.1 ) and [VO(sbdha)(phen)]?2H₂O ( 2.2 ) were confirmed using single‐crystal X‐ray crystallography. Analytical data showed that the ligands 1 and 2 are chelated to the metal centres in a bi‐negative tridentate fashion through azomethine N, thiol S and deprotonated hydroxyl group. The antioxidant activity of the synthesized compounds was tested against 2,2‐diphenyl‐1‐picrylhydrazyl) radical, which showed that the complexes demonstrate a better scavenging activity than their corresponding ligands. The cupric ion reducing antioxidant capacity method was also employed and the total equivalent antioxidant capacity values were found to be higher for the oxovandium(IV) complexes. DNA binding affinity of the compounds was determined using UV–visible and fluorescence spectra, revealing an intercalation binding mode. Higher cytotoxicity for the complexes compared to their ligands was found against human liver hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF7) cell lines using MTT assay.     

Structure‐cytotoxicity relationship for apoptotic inducers organotin(IV) derivatives of mandelic acid and L‐proline and their mixed ligand complexes having enhanced cytotoxicity

Structure‐cytotoxicity relationship of di?/tri‐organotin(IV) derivatives of mandelic acid ( 1 – 4 ), L‐proline ( 5 – 7, 15, 16 ), and mixed ligand complexes of latter with 1,10‐phenanthroline ( 8 – 14 ) investigated on the basis of MTT assay against human cancer cell lines, viz. MCF‐7 (mammary cancer), HepG2 (liver cancer) and PC‐3 (prostate cancer) in vitro indicated that all complexes except methyl‐ and octyl‐ analogues displayed potential cytotoxicity. The most active one is dibutyltin(IV) mandelate ( 2 ) exhibiting IC₅₀ 2.03 ± 0.40, 0.98 ± 0.23 and 3.86 ± 1.68 μM against MCF‐7, HepG2 and PC‐3, respectively, which is ≈ 15 and 2.5 times against MCF‐7, 20 and 5 times against HepG2 and 5 and ≈ 3 times against PC‐3 more cytotoxic than cis‐platin and 5‐fluorouracil, respectively. Diorganotin(IV) derivatives of mandelic acid are more cytotoxic than triorganotin analogues. Organotin(IV) derivatives of L‐proline (except Bu₃Sn(Pro) 16 ) are less cytotoxic than those of mandelic acid but their cytotoxicity is enhanced by complexion with 1,10‐phenanthroline. This may be due to the structural planarity and extended π system of 1,10‐phenanthroline which facilitates their transportation across the cell membrane and enhances the possibility of DNA intercalation over the planar L‐proline ring, and eventually, their DNA binding affinity so as to interfere with the cellular functions of DNA leading to apoptosis. Various biophysical experiments such as DNA fragmentation, acridine orange and comet assays, and flow cytometry assay using annexin V–fluorescein isothiocyanate (FITC) and propidium iodide (PI) have been carried out in order to ascertain their mode of action. The observed results indicated that the major cause of cancer cell death is apoptosis, but a minor role played by necrosis cannot be excluded. It is concluded on the basis of the observed results that the nature and number of organic groups bonded to tin as well as the nature of counter anions play an important role in determining the cytotoxicity of organotin(IV) compounds.     

Oxotitanium(IV) complexes of some bis‐unsymmetric Schiff bases: Synthesis,structural elucidation and biomedical applications

A number of oxotitanium(IV) complexes of the type TiOL with bis‐unsymmetric dibasic tetradentate Schiff base (LH₂) containing ONNO donor atoms have been synthesized. Mono‐Schiff base (OPD‐HNP) was prepared by the condensation of 1:3 molar ratio of 2‐hydroxy‐1‐naphthaldehyde (HNP) with o‐phenylenediamine (OPD). Dibasic unsymmetric tetradentate diamine Schiff bases were prepared by the reaction of OPD‐HNP with 2‐hydroxyacetophenone, 2‐hydroxypropeophenone, benzoylacetone, acetylacetone and ethylacetoacetate. Further, titanylacetylacetonate was reacted with these ligands to obtain their metal complexes. On the basis of analytical and physiochemical data, the formation of complexes as TiOL was suggested having square pyramidal geometry. Quantum mechanical approach also confirmed this geometry. The assessment of the synthesized ligands and their complexes showed that some behave as good inhibitors of mycelial growth against selected phytopathogic fungi but weak inhibitors against some selected bacteria. A few of them also showed antioxidant properties.     

Sensing and photocatalytic properties of nanosized Cu(I)CN organotin supramolecular coordination polymer based on pyrazine

Orange prismatic crystals of the supramolecular coordination polymer (SCP) _∞³[Cu(CN)₂(Me₃Sn)(Pyz)], SCP 1 , were synthesized using a self‐assembly method under ambient conditions. Nanosized 1 was obtained using the same molar ratio in water by ultrasonic irradiation. SCP 1 was characterized using single‐crystal X‐ray diffraction, elemental analysis, thermal analysis and Fourier transform infrared spectroscopy. SCP 1 and its nanosized 1 particles were also examined using powder X‐ay diffraction and scanning electron microscopy. The luminescence emission of SCP 1 was studied as well as its use as a sensor for the detection of common organic solvents and metal ions. Also, the catalytic activities of nanosized 1 towards various organic dyes were investigated under ambient conditions, UV irradiation and ultrasonic irradiation. Nanosized 1 as a heterogeneous nanoparticle catalyst exhibits high catalytic activity for the degradation of eosin‐Y and acid blue dyes. The mechanism of degradation investigated using various scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals.