Dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes with lanthanum metal

It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels-Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels-Alder adducts of o-quinodimethane with dienophiles were obtained, in the reaction of α,α′-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles.     

Physicochemical features of poly-o-phenylenediamine modification with palladium microparticles

A new method is developed to prepare alladium dispersed in a polymeric matrix. Exposure of poly-o-phenylenediamine films in PdCl₂ solution showed palladium cations strongly linked by the polymeric matrix to enable reduction of the metal accumulated in the polymer bulk. Optical absorption spectra were studied for poly-ophenylenediamine saturated with palladium ions and poly-o-phenylenediamine with palladium electroreduced upon impregnation. Method of X-ray photoelectron spectroscopy confirmed the presence of palladium cations in unreduced poly-o-phenylenediamine film and palladium metal upon reduction in polymeric matrix.     

Structure and behavior of organic analytical reagents : Chelates of 2-(o-hydroxyphenyl)-benzoxazole, 2-(o-hydroxyphenyl)-benzothiazole and 2-(o-hydroxyphenyl)-benzothiazoline.

The reactions of the chelating reagents named in the title, with a number of metal ions, have been studied in order to evaluate the behavior of reagents containing reactive groupings analogous to those of 8-hydroxyquinoline, but so arranged as to form six-membered ring chelates with metal ions. All three reagents have been found to give less stable chelates than 8-hydroxyquinoline, indicating that for this type of reagent, six-membered ring chelates are less stable than five. 2-(o-Hydroxy-phenyl)-benzoxazole and 2-(o-hydroxyphenyl)-benzothiazole have been found to be potentially useful as organic precipitating agents for metal ions, being more selective than 8-hydroxyquinoline, which they somewhat resemble in behavior. In contrast to the oxazole and thiazole, 2-(o-hydroxyphenyl)-benzothiazoline was found to react with most of the metal ions tried. Because of the solubility of its chelates in organic solvents, 2-(o-hydroxyphenyl)-benzothiazoline may be a useful solvent extraction agent for metal ions.     

A spectrophotometric study of o,o'-dihydroxyazobenzene and its chelates with aluminum,gallium and indium

The composition of the chelates of aluminum, gallium and indium with o,o'-dihydroxyazobenzene has been established in acidic alcoholic -water mixtures to be pH dependent by means of spcctrophotometric measurements. Only chelates with a 1 : 1 and 2. : 1 ratio of o,o'-dlihydroxyazobenzene to metal are formed. The first acid dissociation constant of o,o'-dlihydroxyazobenzene and the formulas and stability constants for -the chelates were determined, The stability of the chelates increased in tle order indium, aluminum, gallium.     

Zinc and cadmium complexes based on 3,6-di-tert-butyl-o-benzoquinone

Zinc and cadmium bis-o-semuquinolate and catecholate complexes are synthesized by the reduction of 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) with amalgamated metals in a medium of various solvents. The oxidation of the metal catecholate derivatives results in the corresponding mono-o-semiquinone complexes, which undergo symmetrization to form the metal bis-o-semiquinolates. The molecular structures of the complexes (3,6-SQ)₂Zn · Py, (3,6-SQ)₂Zn · H₂O, and (3,6-SQ)₂Cd · α,α′-Bipy (3,6-SQ is the radical anion of 3,6-Q) are studied by X-ray diffraction analysis. Magnetochemical studies are carried out for the zinc and cadmium bis-o-semiquinone complexes.     

Tin oxidation with 3,6-di-tert-butyl-o-benzoquinone

The kinetics of tin oxidation with 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) in toluene was studied. The scheme of formation of tin o-quinone complexes during metal oxidation with 3,6-Q in different aprotic solvents was suggested on the basis of the kinetic, EPR, and IR data.     

Mechanism of thermal dehydrochlorination

Co(II), Ni(II), Cu(II) and Zn(II) complexes ofo-hydroxyacetophenone Girard-P hydrazone were prepared by using the organic ligand and the corresponding transition metal chlorides. The protonation and formation constants were evaluated for the organic ligando-hydroxyacetophe-none Girard-P hydrazone and its transition metal complexes, respectively. The thermal behaviour of the test materials was established by means of DTA. Their semiconducting parameters were evaluated through DC-conductivity measurements, and their thermodynamic parameters were evaluated, assigned and interpreted. The mechanism of thermal dehydrochlorination of the metal chloride complexes was proposed.     

The suitability of various calcium electrodes based on metal salts of di-(n-octylphenyl)phosphoric acid and some derivatives for the measurement of calcium in sea water

The calcium salts of di-(n-octylphenyl)-phosphoric acid, di-(p-n-octyl-o-nitrophenyl)-phosphoric acid and di-(p-n-octyl-o-bromophenyl)-phosphoric acid have been investigated as calcium sensors in membrane electrodes. The electrodes have been used for potentiometric titrations of calcium in sea water. The effect of varying the membrane solvent and the chelate metal has been studied.     

Fluorescence quenching of alternant and non-alternant polycyclic hydrocarbons by electron transfer

Rate constants of fluorescence quenching by electron acceptors are greater for alternant than for non-alternant hydrocarbons with equal E_oo. The reverse is true for quenching by electron donors. This is consistent with the lowering of the π-orbital energies of non-alternant compared to alternant polycyclic hydrocarbons of equal E_oo.     

Aluminum,gallium and indium chelates of salicylidene-o-aminophenol

Conditions necessary to determine spectrophotometrically the composition of the chelates of aluminum, gillium, and indium with salicylidene-o-aminophenol have been determined. Under these conditions, in each case a chelate containing a 2 : 1 ratio of salicylidene-o-aminophenol to metal is formed.     

Highly specific-glucose fluorescence sensing based on boronic anthraquinone derivatives via the GOx enzymatic reaction

The boronic acid anthraquinones, oHAQB and pHAQB, have been designed, and demonstrated to serve as fluorogenic biosensors for glucose. The sensory molecule, oHAQB, has exhibited the specific-glucose sensing via the GOx enzymatic reaction. In this contribution, the fluorescence changes of oHAQB reasonably correspond to the concentration of glucose upon the conversion of boronic acid to hydroxy based sensor by H₂O₂ generated from glucose along with GOx enzymatic reaction. Our sensing ensemble was then successfully applied to determine the glucose concentration in the range of 0.08–0.42 mM. The limit of detection (LOD) of oHAQB for glucose detection using the GOx enzymatic probe is approximately 0.011 mM.     

A photo-responsive cholesterol capable of inducing a morphological transformation of the liquid-ordered microdomain in lipid bilayers

An azobenzene-modified cholesterol was designed and synthesized for photo-induced domain transformation in lipid bilayer membranes. Upon UV-light irradiation, the cholesterol derivative changes the conformation through photoisomerization of the azobenzene moiety from trans- to cis-form. The photoisomerization effectively occurred both in liquid-ordered (L_o) and liquid-disordered (L_d) phases. Phase-contrast and fluorescence microscopic observation revealed that photoisomerization of the azobenzene-modified cholesterol induced the shape transformation of giant unilamellar vesicle (GUV) and the reorganization of L_o domain structure. Such a photo-induced transformation of lipid domain gave two different pathways dependent on the lipid composition of GUV; disappearance of the L_o domain or appearance of a small L_d domain with in the L_o domain.     

p-Toluenesulfonic acid catalyzed regiospecific nitration of phenols with metal nitrates

Highly regiospecific mononitration of phenols and substituted phenols is accomplished employing a metal nitrate and a catalytic amount of p-toluenesulfonic acid in acetone. An exclusive ortho-selectivity was observed with excellent yields. A variety of metal nitrates were used to obtain o-nitrophenols exclusively in good to excellent yields. The use of p-toluenesulfonic acid is key for the selectivity observed.     

The properties of some organic molecules as free species and as ligands in ruthenium(II) complexes

The electron affinities and polarizabilities of imidazole, pyrazine, 2,2′-bipyridine and o-benzoquinone diimine were calculated by the density functional method. It was demonstrated that in transition metal complexes the π¹-accepting ability of the ligand is determined mainly by its electron affinity. Our calculations showed that o-benzoquinone diimine (bqdi) is a very strong acceptor of π electrons, but that this ability depends on the composition of the complex.     

A generalized form of the extraction constant for the partition of a metal chelate between immiscible aqueous and organic phases

The theory underlying the partition of sparingly soluble reagents and their formally neutral metal chelates between an aqueous phase and any immisicible organic phase leads to a generalized extraction constant K^*_ex=K_exSⁿ_r,0/S_c,o where K_ex is the conventional extraction constant and S_r,oS_c,o are the molar solubilities of reagent and metal complex, respectively, in the same organic solvent. The predicted constancy of K^*_ex is confirmed for measurements in seven solvents and for systems involving mono-, di- and tridithizonates of Ag⁺, Zn²⁺ and Bi³⁺, respectively.     

手性方酰化哒嗪衍生物的合成及荧光特性研究

以3,6-二甲酰基哒嗪和丙氨酸、α-氨基苯酚、方酸为原料合成了一种新的手性方酰化哒嗪胺衍生物, 利用IR, ¹H NMR及元素分析对其结构进行了表征, 并研究了金属离子对化合物的荧光性的影响. 结果表明, Cu^2＋, Ni^2＋等金属离子对化合物产生明显的荧光猝灭作用.     

ESR investigation of copper(I) complexes with o-semiquinolate ligands

Solutions of o-semiquinolatecopper(I) complexes with neutral ligands, such as PPh₃, P(OEt)₃, AsPh₃, AsEt₃, cyclooctadiene-1,5, PhCCPh, PhCCH and CO, were investigated by ESR. The spectra of the complexes are characterised by high specificity and sensitivity to configuration of ligand surroundings. The radical character of the o-semiquinolate ligand remains constant over the chemical transformation in the metal coordination sphere. These properties allow the use of o-semiquinolate ligands as a special “spin mark” in the chemistry of coordination compounds.     

Hyperfine splitting of the odd 4 F J o , 2 P J o and 4 S J o LaI multiplets

High resolution spectra of LaI lines recorded in the R6G region by laser-induced resonance fluorescence method show well resolved hyperfine structures. The analysis of the hyperfine structure of seven LaI transitions is presented here. It has allowed the deduction of magnetic dipole and electric quadrupole constants of all levels belonging to the excited odd parity multiplets: ⁴ F ^o (J = 3/2-9/2), ² P ^o (J = 1/2,3/2), and ⁴ S ^o (J = 3/2). Some of the results are new and some of them present improved values of the hyperfine splitting constants.     

Simple imine linked colorimetric and fluorescent receptor for sensing Zn ions in aqueous medium based on inhibition of ESIPT mechanism

Herein, we report the highly selective binding of Zn²⁺ ion by the salicylaldimine based Schiff base chromogenic receptor 1 [(N,N′-bis (salicylidine)-o-phenylenediamine]. Receptor 1 senses Zn²⁺ ion in aqueous medium by colorimetric and fluorescent response in the presence of other metal ions like Pb²⁺, Hg²⁺, Sn²⁺, Cd²⁺. Receptor 1 on binding with Zn²⁺ ion exhibits fluorescence enhancement which is due to the inhibition of the (ESIPT) mechanism.     

The structure of intramolecular charge-transfer excited states of derivatives of p-cyano-N,N-dimethylaniline. Some inconsistencies of the TICT model

The photophysical properties of o-methyl-p-cyano-N,N-dimethylaniline were studied. Additionally, the radiative lifetimes of charge-transfer fluorescence for several other derivatives of p-cyano-N,N-dimethylaniline were estimated. New evidence indicates that excited o-methyl-p-cyano-N,N-dimethylaniline in non-polar solvents relaxes to an intramolecular charge-transfer state. It has been shown that the twist angle of the amino group around the CN bond in this state is remarkably smaller than the 90° postulated for the TICT (twisted intramolecular charge-transfer) model.