A NEW AND SHORT SYNTHESIS OF 7 H-BENZO[a]CYCLOHEPTEN-7-ONE AND SOME DERIVATIVES: OXIDATION OF 7-BROMO-5H-BENZO[a]CYCLOHEPTENE

Oxidation of 7-bromo-5H-benzo[a]cycloheptene with some oxidation reagents has been studied. Several 2,3- and 4,5-benzotropone derivatives has been obtained. The structures of the products were determined by ¹H-, ¹³C NMR data and chemical transformation.     

Carboxy Group as a Remote and Selective Chelating Group for C−H Activation of Arenes

The first example of carboxy group assisted, remote‐selective C(sp²)?H activation with a Pd^II catalyst has been developed and proceeds through a possible κ² coordination of the carboxy group, thus suppressing the ortho‐C?H activation through κ¹ coordination. Besides meta‐C?H olefination, direct meta‐arylation of hydrocinnamic acid derivatives with low‐cost aryl iodides has been achieved for the first time. These findings may motivate the exploration of novel reactivities of the carboxy assisted C?H activation reactions with intriguing selectivities.     

Complexes of a New N3S2 Macrocycle: Synthesis,Structure and Electrospray Mass Spectrometry

The silver(I) complex of a 15-membered macrocyclic ligand with an N₃S₂ donor set (L¹) has been prepared by the reaction of 2,6-diacetylpyridine with 1,8-diamino-3,6-dithiaoctane in the presence of silver(I) ions. A reduced form (L²) of the ligand, in which the imine groups are converted to amines, was prepared by the reduction of the silver(I) complex by sodium borohydride. The ligand L² has been characterised by various spectroscopic techniques and the copper(II) complex has been prepared. The metal complexes of L¹ and L² have been characterised by electrospray mass spectrometry and UV-visible spectroscopy. The copper(II) complex of L¹ has been synthesised from [AgL¹]⁺ via metal exchange. [CuL¹](ClO₄)₂ crystallises in the orthorhombic space group Pna2₁ with a = 14.374(5) Å, b = 12.947(3) Å, c = 11.824(3) Å with Z= 4. The geometry about the metal centre approximates trigonal bipyramidal with the pyridinyl nitrogen and the sulfur donors in the equatorial positions and the imine nitrogen donors in the axial positions. Metal ion exchange and the relative stabilities of metal complexes of the macrocyclic ligands were studied by electrospray mass spectrometry.     

Reactor neutron activation analysis by a triple comparator method

The single comparator method has been extended to a triple comparator method, using⁶⁰Co,^114m In and¹⁹⁸Au. In this technique, thek-ratios of the elements to be analyzed, now determined against the three comparators, are corrected for each new ratio of thermal to epithermal reactor neutron flux. These flux ratios are calculated from the absolute activities of the three comparators. The thermal neutron activation cross-section and the resonance integral for the reaction¹¹³In(n,γ)^114m In have been determined.     

Complete analysis of the 1H NMR spectra of acetylated glycals—a conformational study

The complete analysis of the ¹H NMR spectra of the six acetylated glycals as well as that of tetra-O-acetyl-2-hydroxy-D -glucal has been carried out. The conformation of these compounds, as determined from the proton couplings (±0.05Hz) obtained, has been interpreted in terms of a rapid interconversion equilibrium between the two possible dihydropyran half-chair conformations. A computer treatment of all observed couplings has been carried out to obtain optimized values for the populations and couplings characteristic of the two alternative half-chair conformations. The rotamer populations of the acetoxy–methyl group are discussed on the basis of the measured ⁵J₁₆ and ⁵J₃₆ couplings.     

一个新的具有大的吸收截面的双光子引发剂的合成和非线性光学性质

E,E-1,4-Bis（4＇-N,N-diphenylaminostyryl）-2,5-dimethoxybenzene （DPAMOB） has been synthesized by a simple and effective solid phase Wittig reaction and characterized by 1^H NMR spectra and elemental analysis, Linear absorption, single-photon induced fluorescence and two-photon induced fluorescence spectra were experimentally studied. The new dye has a large two-photon absorption （TPA） cross-section of σr= 1007,2 GM [1 GM= 1 × 10^-50 cm^4·s/（photon molecule）] at 800 nm measured by the two-photon induced fluorescence method. The experimental results confirm that DPAMOB is a good TPA chromophore and can successfully initiate two-photon photopolymerization of ethoxylated trimethylolpropane triacrylate esters （SR454）. Finally, a microstructure has been fabricated by use of DPAMOB as initiator.     

Anharmonicity of a molecular oscillator

The phenomenon of anharmonicity has been proved to be an effect of coupling between the change of nuclear positions in molecular vibrations ( Q ) and the electronic degrees of freedom as represented by the chemical potential (μ) at constant number of electrons (N). The coupling parameters have well‐founded meaning in the conceptual density functional theory (DFT), first approximations to their numerical values have recently become available. The effect of coupling between normal vibrational modes also appears to be the direct consequence of the electron‐nuclear coupling. To show the pure anharmonic effect, calculations for a collection of diatomic molecules have been presented. The anharmonicity, described in the present work as d³E/d Q ³ ≠ 0, has been proved to be the intrinsic property of every oscillating molecular system. A small anharmonic contribution exists even for the “strong harmonic” oscillator, when for the force constant k both a = (?k/? Q )_N = 0 and λ = (?k/?N) _Q = 0. The latter derivative of the force constant appears to be primary factor determining the anharmonic property of a molecule. An estimate of its values has been provided from the experimental data on the anharmonicity of diatomic molecules. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

QSAR based modeling on a series of α-hydroxy amides as a novel class of bradykinin B1 selective antagonists

G-protein coupled receptors like Bradykinin (BK) B₁ represent a potential treatment route for chronic pain and inflammation. Quantitative structure activity relationship has been performed on a series of α-hydroxy amides as a novel class of bradykinin B₁ selective antagonists, using different physicochemical parameters along with appropriate indicator variables. It has been found that physicochemical parameters such as connectivity indices ³χ, ⁴χ and ⁵χ, molecular weight, molar refractivity, density along with indicator variables are significantly correlated with activity. In this paper best results were obtained by using multiple regression analysis. Different models were generated with high values of R² and low values of PRESS/SSY ratio. The significant equations were statistically tested by using leave one out (LOO) technique and cross validation methods.     

Efficient production of electronically excited BiF(AO+) via collisions with NF(a1Δ)

An efficient process for converting the energy stored in electronically excited NF(a¹Δ) into blue-green BiF (A? X) band emissions has been discovered. Bismuth atoms are converted to BiF and then repeatedly pumped to the (AO⁺) state in two steps via collisions with NF(a¹Δ). A model has been formulated that predicts BiF emission intensities that are in excellent agreement with the observed values. Some of the rate coefficients required for this model are estimated by means of charge-transfer theories. The cyclic nature of this system, along with its other basic properties, suggests that it has a strong potential to be an efficient blue-green laser system.     

Synthesis,structure and electrochemical properties of a dioxomolybdenum(VI) complex with a ferrocene-containing ligand

Summary Bis[ferrocene aldehyde benzoylhydrazonato(1-)-N ¹,O]- dioxomolybdenum(VI) has been synthesized and characterized by x-ray diffraction and i.r.,¹H n.m.r. and electronic spectroscopies. The CH₂Cl₂/hexane solvate crystallizes in space group P2₁/n witha=11.149(6),b=20.463(8),c= 15.541(5) Å, =90.40(3)° andZ=4. The structure has been refined to R_w=0.049 based on 2886 independent reflections. The complex has distorted octahedral geometry with the two bidentate ligands coordinated through the oxygen and the azomethine nitrogen atoms. The MoO ₂ ²⁺ unit has the expectedcis geometry and the Mo-N bonds aretrans to the oxo-groups. The chelate rings are nearly planar but the cyclopentadienyl and phenyl rings are twisted out of the chelate rings. The electrochemical behaviour of the compound is also discussed: the two ferrocenyl groups appear to be independent with respect to oxidation and the molybdenum centre displays a nearly reversible one-electron reduction.     

Amberinone,a new guaianolide from Amberboa ramosa

The Amberboa is a medicinally important genus present in the family Asteraceae; members of this genus are mainly distributed in Pakistan and India. It has been used in different systems of traditional medicines for different diseases. Amberinone (1), a new sesquiterpene lactone, has been isolated from the ethyl acetate (EtOAc) soluble fraction of Amberboa ramosa together with chrysin (2), quercitine (3), eriodictyol (4) and keamferol (5). This is the first report of these compounds from this species. The structures of the isolated compounds have been elucidated by 1D and 2D ¹H ¹³C NMR spectroscopy.     

Isolation and Structural Determination of a Hexacoordinated Antimony(V) Dication

The hexacoordinated antimony(V) dication [(ppy)₃Sb]²⁺ ([ 1 ]²⁺; ppy=2-(2-pyridyl)phenyl), stabilized by three intramolecular donor–acceptor interactions, has been isolated as its hexachloroantimonate salt [ 1 ][SbCl₆]₂, prepared by the oxidative addition of chlorine to the neutral stibine [(ppy)₃Sb] ( 1 ), followed by the abstraction of chloride. Air-stable [ 1 ][SbCl₆]₂ exhibits remarkable thermal stability and the three ppy ligands on the antimony atom are shown to be magnetically inequivalent in the ¹H and ¹³C NMR spectra. A hexacoordinated, meridional octahedral bonding geometry has been determined for [ 1 ][SbCl₆]₂ by X-ray crystallographic analysis. Theoretical calculations were performed to investigate why the meridional form was generated preferentially over the facial form. In addition, the dynamics of the ppy ligands were investigated by variable-temperature ¹H NMR spectroscopy. The potential to generate dications by using a single-electron-transfer reagent has also been investigated. The dication [ 1 ]²⁺ is the first [12–Sb–6]²⁺ chemical species to have been structurally determined.     

Synthesis and complexation of a novel soluble vic-dioxime with hydroxyethyl pendant arms

A new soluble vic-dioxime ligand namely 1,4-bis(2′-hydroxyethyl)-2,3-bis(hydroxyimino)-5,6-diphenylpiperazine, (LH₂) containing optically active centers has been prepared as a mixture of isomers from (CNO)₂ and N,N-bis(2-hydroxyethyl)stilbendiamine (1) which has been made by the reduction of the condensation of the product of benzaldehyde and 2-aminoethanol in the presence of aluminum amalgam. N,N-coordinated planar metal complexes of this ligand have been synthesized with Ni^II, Cu^II, Co^II, Pd^II and U^VIO₂. Oxidation of (LH)₂Co in the presence of a base, such as pyridine, leads to an octahedral complex (LH)₂CopyCl containing pyridine and chloride as axial ligands in addition to vic-dioxime ligands. The structures of the ligand and its complexes are proposed on the basis of elemental analysis, ¹H-n.m.r., mass, i.r. and u.v.–vis. spectral data. This revised version was published online in June 2006 with corrections to the Cover Date.     

Thermodynamics of binary mixtures of non-electrolytes containing a salt

Molar excess volume V ^E and enthalpy H ^E data have been measured at 25°C for pyridine A saturated with anhydrous cupric chloride (S) [A(S)]+ B [where B is aniline or o-toluidine (OT) or formamide (FD) or N, N-dimethylformamide (NND)] mixtures on the assumption that while the standard state of B is that of pure components B, the standard state of A(S) is that of A saturated with the salt S. The excess volume or enthalpy data for an equimolar mixture at a given temperature have been utilized to evaluate the interactional parameter X₁₂ of the Sanchez and Lacombe theory of fluid mixtures at that temperature, and the same has been combined with V ^E (x _A ) data for a good prediction not only of the coresponding H ^E (x _A ) data for the mixture but also the extent of unlike interactions between the A(S) and B components of these A(S)+B mixtures.     

The unimolecular chemistry of protonated glycine and the proton affinity of glycine: a computational model

The potential energy hypersurface of protonated glycine, GH⁺, has been investigated. The calculated G2(MP2) value for the proton affinity (PA) of glycine, PA _calc=895kJ mol⁻¹, is in good agreement with the experimental value which has been estimated to lie in the range 864kJ mol⁻¹ < PA _exp <891kJ mol⁻¹. Ab initio quantum chemical calculations of relevant parts of the potential energy surface of GH⁺ give a reaction model which is consistent with the observed mass spectrometric fragmentation pattern. The lowest energy unimolecular reactions of GH⁺ are two distinct processes: (1) loss of CO, which has a substantial barrier for the reverse reaction, and (2) loss of CO plus H₂O, which has no barrier for the reverse reaction. Received: 15 November 1996 / Accepted: 6 May 1997     

Oxidation of electron deficient olefins using a copper(II) complex based on a bis-benzimidazole diamide ligand

New bis-benzimidazole based diamide ligands N, N′-bis(2-methyl benzimidazolyl)-benzene-1,3-dicarboxamide [GBBA] and N-Octyl-N, N′-bis(2-methyl benzimidazolyl)-benzene- 1,3-dicarboxamide [O-GBBA] have been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(GBBA)X ₂] · nH₂O and [Cu(O-GBBA)X₂] · n H₂O, where X is an exogenous anionic ligand (X = Cl⁻, NO₃⁻, SCN⁻). The oxidation of electron deficient olefins has been investigated using [Cu(O-GBBA)X₂] · nH₂O as catalyst and TBHP as an alternate source of oxygen. The respective ketonic products have been isolated and characterized by ¹H-NMR. The complex [Cu(GBBA)(NO₃)₂] · 4H₂O has been characterized structurally. It crystallizes in a monoclinic space group C2/c. Low temperature EPR spectra have been obtained for the complexes that shows g_II > g_I > 2.0024, indicating a tetragonal geometry in the solution state. The complexes display a quasi reversible redox wave due to the Cu(II)/Cu(I) reduction process. The E_1/2 values shift anodically as NO₃⁻ < SCN⁻ < Cl⁻.     

Synthesis, structure and spectral characterisation of a hydrogen-bonded polymeric manganese(III) Schiff base complex

A new hydrogen-bonded polymeric Mn(III) complex C₁₉H₂₀Mn₁N₃O₃S₁ (1) has been synthesised by conventional procedure with a new Schiff base ligand (2Z,3Z)-N ¹,N ²-bis(1-(2-hydroxyphenyl)ethylidene)ethane-1,2-diamine (H ₂ L) bearing a tetradentate N₂O₂ donor site. The complex has been characterised with several spectroscopic techniques like FT-IR, UV/Vis and EPR and also well supported by variable temperature magnetic susceptibility study. The structure of the co-ordination complex has been unequivocally confirmed from single crystal X-ray diffraction study. The redox stability of the metal chelate complex has been investigated with a slow scan cyclic voltammetry.     

The Extractive-Spectrophotometric Determination of Iron(III) As a Mixed-Ligand Complex with N-Hydroxy-N,N′DI-p-Tolyl-p-Toluamidine and Thiocyanate

The extractive-photometric determination or iron(III) as a mixed-ligand complex with N -hydroxy-N, N′ -di-p -tolyl-p -toluamidine (HDTTA) and thiocyanate is described. The orange-red Waterinsoluble 1:1:2 (metal: HDTTA: SCN^?) ternary complex formed in 0.1–0.6 M hydrochloric acid solutions is quantitatively extractable into benzene. The wavelength of maximum absorption, molar absorptivity and sensitivity of the colour system are 460nm, 12000 l. mole^?1 cm^?1 and 0.0046 μg Fe/cm ²respectively. The influence or foreign ions on the determination of iron has been studied. This method has also been applied to determine the iron content of several alloys.     

Preconcentration of 198Au in a green alga, Rhizoclonium</p> </p>

Summary The bioaccumulation of ¹⁹⁸Au radionuclide, by Rhizoclonium riparium a member of Chlorophyceae has been studied. It has been observed that accumulation of gold on Rhizoclonium is almost pH independent and slightly higher at basic pH. Accumulation of gold was studied with ¹⁹⁸Au radiotracer, 0.1, 1 and 5 ppm concentrations of gold. It has been concluded from the biochemical analysis that the gold accumulation is due to adsorption in the cellulose and not in protein, fat and carbohydrate. Accumulated gold was recovered when washed with conc. HNO₃.</p> </p>     

Synthesis of a novel copolymer using glycogen and poly(lactide) as a carrier of dual drugs—ornidazole and ofloxacin

Biodegradability and biocompatibility are two crucial prerequisites for a promising therapeutic vehicle. Herein, a novel biocompatible copolymer has been synthesized using glycogen and polylactide (PLA). Glycogen, a naturally occurring biopolymer has been functionalized by methacrylation. On the other hand, lactide has been polymerized through ring opening polymerization (ROP), initiated by hydroxyethyl methacrylate (HEMA) and catalyzed by tin (II) 2‐ethyl hexanoate. Finally, the synthesized two substrates (i.e., glycogen methacrylate and PLA‐HEMA) are covalently connected by free‐radical polymerization, initiated by AIBN. The structure of the developed copolymer has been confirmed using ¹H and ¹³C NMR spectral analyses. The gel characteristics have been evaluated by rheological studies, while the morphological assessment has been investigated by FESEM analysis. In vitro cytocompatibility study reveals that the hydrogel (Gly‐co‐PLA) is biocompatible. The in vitro and in vivo release studies demonstrate the excellent pH‐sensitive control release profile of dual drugs: ornidazole and ofloxacin. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1697–1703