Synthesis Of Iodides Pyridylazo Amines Reagents And Its Application To The Spectral Analysis And Electrochemical Analysis

This paper summarizes the classification, the relationship between their structure and properties and the application of pyridylazo reagents. Due to the high sensitivity, the complex stability and selectivity, the pyridylazo reagents have been widely used in many fields, and have become the hotspot of color reagent research. In order to further explore the spectroscopic qualities and the relations between their structure and properties and to find more sensitive, selective reaction systems, two new reagents, 5-(5-iodine-2-pyridyla -zo)-2,4-diaminotoluene(5-I-PADAT) and 2-(5-iodine-2-pyridylazo)-5-dimethylaminoa -aniline(5-I-PADMA) were designed and synthesized in this paper. The structures and compositions are characterized by nuclear magnetic resonance spectroscopy(1HNMR), elemental analysis and infrared spectroscopy(IR). And also the application of 5-I-PADAT and 5-I-PADMA in spectrophotometric analysis and electrochemistry have been studied in detail.In this paper, the color reactions of 5-I-PADAT and 5-I-PADMA with Rh(III), Co(II), Ru(II), Pd(II) have been studied, and a series of new photometric have been established. The experimental results follow below: (1) 5-I-PADAT reacts with Rh(III) and Co(II) to form violet-red and red purple complex with molar ratio of 2:1 in HAc-NaAc solution. The molar absorptivity of 5-I-PADAT-Rh(III) and 5-I-PADAT-Co(II) is 1.81×105 L·mol-1·cm-1 at 580 nm and 1.24×105 L·mol-1·cm-1 at 580 nm respectively. Beer's law are obeyed in range of 0 ~ 0.8μg·mL-1 and 0 ~ 0.4μg·mL-1 for them. (2) In HAc-NaAc and HClO4 solution 5-I-PADAT reacts with Ru(II) and Pd(II) to form orange-red and blue-violet complex with molar ratio of 1:2 and 1:1 respectively. The molar absorptivity of 5-I-PADAT-Ru(II) and Pd(II) is 5.72×104 L·mol-1·cm-1 at 509 nm and 7.2×104 L·mol-1·cm-1 at 583 nm respectively. Beer's law are obeyed in range of 0 ~ 0.5μg·mL-1 and 0 ~ 1.0μg·mL-1 for Ru(II) and Pd(II) respectively. (3) In HAc-NaAc solution, 5-I-PADMA reacts with Rh(III) and Co(II) to form blue and violet-red complex. The molar absorptivity of Rh(III) and Co(II) is 1.86×105 L·mol-1·cm-1 at 613 nm and 1.21×105 L·mol-1·cm-1 at 614 nm. Beer's law are obeyed in the range of 0 ~ 0.56μg·mL-1 and 0 ~ 0.5μg·mL-1 for them. (4) In HAc-NaAc and HClO4 solution 5-I-PADMA reacts with Ru(II) and Pd(II) to form orange-red and blue complex with molar ratio of 2:1. The apparent molar absorptivity is 5.72×104 L·mol-1·cm-1 at 618 nm and 8.82×104 L·mol-1·cm-1 at 613 nm respectively. Beer's law are obeyed in range of 0 ~ 1.0μg·mL-1 and 0 ~ 0.6μg·mL-1 for Ru(II) and Pd(II) respectively.In electrochemical analysis, the polarographic catalytic wave of the Rh(III) and Co(II) with two reagents have been studied. The experimental results follow below: (1) In HAc-NaAc, NaH2PO4-Na2HPO4 buffer solution, Rh(III)-5-I-PADAT and Co(II)-5-I-PADAT complexes cause sensitive polarographic wave at the potential of -1.02 V and -1.20 V. The first-order derivative peak current are linear in the range of 1.0×10-12 ~ 4.0×10-10 g·mL-1 and 1.0×10-9 ~ 4.0×10-8 g·mL-1 for Rh(III) and Co(II), respectively. The detection limit are 3.1×10-13 g·mL-1 and 1.2×10-10 g·mL-1 for Rh(III) and Co(II), respectively. (2) In HAc-NaAc, Hexamethylenetetramine solution, Rh(III)-5-I-PADMA and Co(II)-5-I-PADMA complexes cause sensitive polarographic wave at the potential of - 1.01 V and - 1.25 V. The first-order derivative peak current is linear in the range of 4.0×10-11 ~ 4.0×10-10 g·mL-1 and 3.0×10-9 ~ 4.0×10-8 g·mL-1 for Rh(III) and Co(II) respectively. The detection limit are 1.42×10-11 g·mL-1 and 4.7×10-10 g·mL-1 for Rh(III) and Co(II), respectively.Compared with previous methods, the new methods have been improved obviously in sensitivity and selectivity and have been applied to analysis of real samples to get satisfactory results.