M. V. Churakova

Building up of Macroring in the New Synthesis of Azacrown Ethers. Structure and Complex Formation of Nitrobenzoazacrown Ethers

A cyclization of azapodand haloderivatives into nitrobenzoazacrown ethers under treatment with various bases and in their absence was investigated. The nitrobenzoazacrown ethers obtained and their complexes with metal cations were studied by X-ray diffraction method and by 1H NMR titration. In nitrobenzoaza-15-crown-5 a capability to complex Ca2+ cation was found that significantly exceeded similar ability of nitrobenzocrown ether with the same size of the macroring.

Host-guest complexes of nitro-substituted N-alkylbenzoaza-18-crowns-6

A number of N-alkyl(nitrobenzo)aza-18-crowns-6 in which the nitrogen atom in the macroring is conjugated with the benzene ring were synthesized, and their complexing power was compared with that of model nitro derivatives of benzo-18-crown-6 and N-phenylaza-18-crown-6 using 1H NMR spectroscopy and DFT/PBE quantum-chemical calculations. The stability constants of the complexes formed by crown ethers with NH4/+, EtNH3/+, Li+, Na+, and K+ in CD3CN were determined by 1H NMR titration. The complexing power of N-alkyl(nitrobenzo)aza-18-crowns-6 toward metal and ammonium cation was considerably higher than that of N-(4-nitrophenyl)aza-18-crown-6 and N-alkyl(nitrobenzo)aza-15-crown-5 and was comparable or higher than that of nitrobenzo-18-crown-6.

New methodology for the synthesis of benzoazacrown ethers by transformation of the macrocycle of benzocrown ethers

The review summarizes the results of studies aimed at constructing new promising macrocyclic ligands that bind metal and ammonium ions. A new approach to the synthesis of formyl and nitro derivatives of 1-aza-2,3-benzocrown ethers possessing considerable synthetic potential is described. The review presents a radically new methodology for the synthesis of such benzoazacrown ethers based on stepwise transformations of the macrocycle of readily accessible benzocrown ethers. The main structural factors and necessary conditions enabling stepwise transformations of the macrocycle of crown ethers into azacrown ethers were revealed. For the first time, the ability of N-methylbenzoazacrown ethers to form complexes was found, which is much superior to that of widely used N-phenylazacrown ethers and benzocrown ethers with the same size of the macrocycle.