Photochromism of several synthesised 1,3-diazabicyclo[3,1,0]hex-3-ene derivatives

Sensitive and selective detection of trace copper in standard alloys, food and biological samples using a bulk optode based on N,N'-(4,4'-ethylene biphenyl) bis(3-methoxy salicylidine imine) as neutral carrier

In this paper, an optical sensing film has been proposed for sensitive determination of copper (ІІ) ion in aqueous solutions. The copper sensing membrane was prepared by incorporating N,N'-(4,4'-ethylene biphenyl) bis(3-methoxy salicylidine imine) as ionophore in the plasticized PVC membrane containing bis(2-ethylhexyl) sebacate (DOS) as plasticizer. This proposed membrane works on the basis of a cation-exchange mechanism and shows a significant absorbance signal change on exposure to acetate buffer solution of pH 4.0 containing copper ion. The proposed sensing film displays a linear range of 0.01-32.0 μg mL(-1) with a limit of detection 0.008 μg mL(-1). Moreover, upon the introduction of a negatively charged lipophilic additive (oleic acid) into the membrane, the optode displayed enhanced sensitivity. In addition, satisfactory analytical sensing characteristics for determining copper (II) ion were obtained in terms of the selectivity, stability and reproducibility. The response time of the optode was less than 3 min, depending on the concentration of Cu(ІІ) ions. The optode membrane has been applied to determine Cu(II) in various real samples.

Potentiometric membrane sensor based on 6-(4-nitrophenyl)-2,4-diphenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene for detection of Sn(II) in real samples

A Sn2+ ion-selective electrode which was prepared with a polymeric membrane based on 6-(4-nitrophenyl)-2,4-diphenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene (NDDBH) as a ionophore. Effects of experimental parameters such as membrane composition, nature and amount of plasticizer, the amount of additive and concentration of internal solution on the potential response of Sn2+ sensor were investigated. The electrode exhibited a Nernstian slope of 28.8+/-1.1 mV/decade of Sn2+ over a concentration range of 1.0 x 10(-5) to 1.0 x 10(-1) M of Sn2+ in an acidic solution (pH 1). The limit of detection was 4.0 x 10(-6) M. The results show that this electrode can be used in ethanol media until 20% (v/v) concentration without interference. It can be used for more than 6 weeks without any considerable divergence in the potentials. The proposed membrane electrode revealed very good selectivity for Sn(II) ions over a wide variety of other cations and could be used in acidic media. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficient of the electrode. The stability constant (log K(s)) of the Sn(II)-ionophore complex was determined at 25 degrees C by potentiometric titration in mixed aqueous solution. It was used as indicator electrode in potentiometric determination of Sn(II) ion in real samples.