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1.
The electronic spectra of three azo cinnoline derivatives have been studied in pure and mixed organic solvents of different characteristics as well as the effect of concentration of the compounds in the different solvents. The different bands observed have been assigned to the proper electronic transition. The longer wavelength band displayed by the para nitro cinnoline derivative in dimethylformamide (DMF) solution is assigned to an intermolecular CT transition. The solvated H-bonding complexes formed between DMF and the para nitro derivative were investigated. DeltaG and K(f) values of these complexes have been determined. The acidity constants of the para nitro compound were determined from the spectra in aquous-methanolic solution of varying pH values. The effect of temperature on the longer wavelength visible band of p-NO(2) has been investigated.  相似文献   

2.
An easily accessible in situ catalyst composed of [{RuCl(2)(p-cymene)}(2)] and terpyridine has been developed for the selective transfer hydrogenation of aromatic nitro and azo compounds. The procedure is general and the selectivity of the catalyst has been demonstrated by applying a series of structurally diverse nitro and azo compounds (see scheme).  相似文献   

3.
An indirect gravimetric method for the determination of organic nitro, nitroso and azo compounds has been investigated. The amount of nitro, nitroso, and azo compound present is calculated from the loss in weight of copper metal during the reduction of the compound to the amine. Interferences are discussed in detail. No standard solutions are required and only commonly available equipment is used Accuracy is of the order of ± 0 5%  相似文献   

4.
Reduction of the nitro group in 5-nitromethyl-1,4,8,11-tetraazacyclotetradeca-11-enenickel(II) complexes 1 leads to 5-aminomethyl-substituted macrocyclic nickel(II) complexes. Orange, protonated “arm off” (3 and 5) and violet “arm on” (2 and 4) complexes were isolated and characterized. Relative configurations of substituents and conformations of the macrocyclic ligands are proposed on the basis of NMR evidence. The isolation of free ligands is also described.  相似文献   

5.
Differential thermal analysis was employed as a new method to observe the formation of complexes of dibenzo-18-crown-6 polyether and macrocyclic nitro derivatives with potassium iodide. DTA thermograms of polyethers, of solid complexes, and mixtures of polyether and potassium iodide were obtained in an atmosphere of dry nitrogen.  相似文献   

6.
The redox behaviour of copper(II) complexes with the open chain ligand, benzilbisthiosemicarbazone, and the macrocyclic one [3,4,10,11-tetraphenyl-1,2,5,8,9,12,13-octaazacyclotetradeca-7,14- dithione- 2,4,9,11-tetraene] has been explored by cyclic voltammetry. The half-wave potential values for the copper(II)/copper(I) redox couple and the spectral data obtained on dimethylsulfoxide (DMSO) solution agree with the superoxide dismutase (SOD)-mimetic activity of the complexes. The macrocyclic complexes show more positive reduction potential and more activity than the open chain derivatives. From our results it follows that the structure and conformation of ligand has influence on the redox potential of central atom in coordination compound. The changes in the coordination sphere are connected with the change of biological function of compounds represented by SOD-mimic activity. In addition, the L1H6 derivatives show quasireversible waves associated to Cu(II)/Cu(III) process.  相似文献   

7.
A general and efficient method for synthesis of both symmetric and asymmetric aromatic azo compounds in one single step has been developed. The nitro compounds were reduced and the substituted anilines were oxidized by each other without any metal in the base condition. Various azo compounds with halogen, methyl and methoxy functional group were obtained by using available, cheap nitro compounds and substituted anilines. In addition, the electronic effect and substituent effect of the compounds have been discussed.  相似文献   

8.
The coprecipitation of azo compounds based on 4-nitrophenyl- and 4-sulfophenyldiazonium naphthol sulfonates as their diphenylguanidinium ion-pair complexes with analogous compounds of naphthalene-2-sulfonic acid and 4-phenylsulfodiazonium is investigated. The optimization of the coprecipitation is considered based on the notions of the driving force of the cocrystallization of impurities. The optical characteristics of colored ion-pair complexes are measured. It is found that the water solubility is decreased most substantially for azosulfonates with hydrophobic nitro groups and with no more than two sulfo groups in different aromatic nuclei, which can lead to a decrease in the detection limit due to preconcentration by coprecipitation, which stimulates the thermodynamic flux of concentrate elution. Coprecipitation is combined with flow-injection analysis in the on-line mode, and new procedures are developed for determining naphthol sulfonates and related azo compounds with the detection limit equal to 0.003–0.006 mg/50 mL.  相似文献   

9.
New Mn(II), Ni(II), Co(II) and Cu(II) complexes of an azo dye ligand based on p ‐phenylenediamine with 5‐nitro‐8‐hydroxyquinoline were synthesized and characterized using elemental analysis, inductive coupled plasma analysis, molar conductance, powder X‐ray diffraction, thermogravimetric analysis, magnetic moment measurements, and infrared, 1H NMR, electron ionization mass and UV–visible spectral studies. The spectral and analytical data reveal that the azo dye ligand acts as a monobasic bidentate ligand via deprotonated OH and nitrogen atom of the quinoline ring. The data support the formulation of all complexes with a 2:1 ligand‐to‐metal ratio, except the Mn(II) complex that has a mononuclear formula. All complexes have an octahedral structure. The molar conductance data reveal that all the metal complexes are non‐electrolytic in nature. From the X‐ray data, the average particle size of the ligand and its complexes is 0.32–0.64 nm. The colour fastness to light, washing, perspiration, sublimation and rubbing of the prepared ligand and its complexes on polyester fabrics and colorimetric properties were measured. The results reveal that the ligand and its complexes have a good to moderate affinity to polyester fibres.  相似文献   

10.
The demetallation in acidic solution of the Cu(II) complexes with open-chain and cyclic tetramines containing a piperazine unit (2 and 3) has been investigated in terms of its kinetic aspects and compared with the behaviour of unsubstituted counterparts (tetramines 1 and 4). The presence of the piperazine fragment slows demetallation of the open-chain-ligand complex owing to the activation barrier associated with the conformational change from boat-to-half-boat; however, it does not affect the demetallation of the macrocyclic complex, which involves the spontaneous boat-to-twist conformational change. Thus, lateral reinforcement of a cyclam-like ligand does not add any further contribution to the typical inertness in demetallation of macrocyclic complexes.  相似文献   

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