Chromogenic proton-dissociable azocrown ether reagents for lithium ions

Chromogenic azole diazothiacrown ethers

“…The 18-and 21-membered pyrrole or imidazole azothiacrown ethers were obtained in two consecutive reactions [3,7] (Figure 1), i.e. i) alkylation of 2-aminobenzenethiol with the respective 1,5-dichloro-3-oxapentane or 1,8-dichloro-3,6-dioxaoctane to form diaminodithioethers; and ii) diazotization of the diamine, followed by coupling of the bisdiazonium salts with pyrrole or imidazole with simultaneous macrocyclization.…”

“…Within azochromoionophores [2] a special attention was paid to macrocyclic compounds with inherent -N=N-unit. Previously, we showed that 18-and 21-membered chromogenic derivatives of p-alkylphenol with inherent azo unit can be used for detection of small concentration of lithium cations [3]. Crown ethers, in which "hard" oxygen atoms of the ether chain are replaced with "soft" sulfur atoms show complementary properties, i.e.…”

Pyrrole Azocrown Ethers. Synthesis, Complexation, Selective Lead Transport and Ion-Selective Membrane Electrode Studies

“…1) as the ionophores. Palmitic acid was added to the chloroform membrane in four-fold excess (4 x 10 -3 mol dm 3 ) relative to the concentration of crown ether (10 -3 mol dm 3 ) present. The presence of the palmitic acid avoids the need to co-transport nitrate ion from the aqueous source phase (the palmitic acid loses a proton to the aqueous phase).…”

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 , v = 0.01 cm 3 ). The initial spectrum (1) was obtained two minutes after addition of the salt solution.…”

“…Recently, we have described the synthesis and properties of 18-and 21-membered azomacrocyclic chromoionophores (compounds 1 and 2) that contain a pyrrole residue [2]. In these compounds the pyrrole moiety replaces the phenol residue used previously [3,4]. It was found that in acetonitrile the 18-membered pyrrole derivative 1 ( Fig.…”