Ninety Years of Using Azo Compounds of the Pyridine Series as Analytical Reagents

First Synthesis of 2-Amino-5-hydroxy-4H-chromene-3-carbonitriles from 4-(2-Pyridylazo)resorcinol

“…4-(2-Pyridylazo)resorcinol (PAR, 4), available in the form of sodium salt monohydrate, has long been actively used in analytical chemistry as a non-selective tridentate complexing agent for the extraction and concentration of heavy metal ions, as a metallochromic indicator for complexometric titration, reagent for the photometric determination of analytes (for reviews, see [19][20][21][22][23]). In recent years, PAR has been actively used to create optical sensors and test materials for the determination and extraction of heavy metals [24][25][26][27], spectrophotometric analysis of transition metals in catalysts [28], extraction of Rh 3+ [29], Ga 3+ [30], Ir 4+ [31], and Co 2+ ions [32], obtaining charge-transfer complexes with aromatic nitro compounds [33], etc.…”

Traditional, One pot Three Component Synthesis and Anti-Bacterial Evaluations of Some New Pyrazoline Derivatives

“…Aromatic azo compounds are frequently used in a wide range of applications. They're utilized as organic dyes [7,8], indicators [9], radical reaction initiators [10], medicinal [11], and drug delivery agents [12], Nonlinear optics [13], optical storage media [14], chemosensory [15], and photochemical switches [16].…”

Complex Formation in a Liquid-Liquid Extraction System Containing Co(II), 4-(2-Thiazolylazo)resorcinol and Monotetrazolium Salt

“…[5][6][7][8][9] The complex formation with azo derivatives of resorcinol via phenolic oxygen, azo nitrogen and thiazolyl or pyridylazo nitrogen, gives colored chelates with metal cations. [10][11][12][13][14][15][16][17][18][19] Tetrazolium salts are used as reagents for the extraction-spectrophotometric determination of metals, e.g. Mo(VI), W(VI), Ge(IV), Tl(III), Nb(V), V(IV), V(V), Ga(III).…”