Andrzej Cygan

Synthesis, x-ray structure and electrochemical properties of a new crown ether with a cis azo unit in the macrocycle

Abstract A chromogenic 13-membered crown ether with a cis azo unit in the macrocycle has been obtained as a side product during the reduction of 1,5-bis (2′-nitrophenoxy)-3-oxapentane. The electrochemical properties of this compound have been studied by the voltammetric method. Its behaviour as an ionophore in ion-selective membrane electrodes has also been investigated. The X-ray structures of the new crown ether 3 and the parent compound 1 have been determined.

Macrocyclic polyfunctional lewis bases. VII. Size and structure controlled stabilities of polyaza-crown ether complexes with Co2+−Zn2+ ions

Stability constants have been determined at 25 °C in aqueous 0.1 M Et4NClO4 medium by potentiometric method of the following ligands: 1,7-dioxa-4,10-diazacyclododecane 5, 1,4,10-trioxa-7,13-diazacyclopentadecane 6, 1,4,7,13-tetraoxa-10,16-diazacyclooctadecane 7, 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane 8, 1,4,7-trioxa-10,13-diazacyclopentadecane 9 and 1,10-dioxa-4,7,13,16-tetraazacyclooctadecane 10 with Co2+, Ni2+, Cu2+ and Zn2+ ions. The values of the stability constants are discussed in terms of the relative size of the metal ion and macrocyclic cavities, the spatial arrangement of the donor nitrogen atoms and the macrocyclic effect.

The synthesis of some aromatic crown ether derivatives and their ion-selective electrode properties

Abstract The synthesis of alkyl, nitro and halogeno derivatives of benzo-15-crown-5, benzo- 18-crown-6 and naphtho-15-crown-5 has been reported. Also some novel ester type bis(crown ether)s have been prepared. Some of the compounds have been characterized as electroactive substances in PVC membrane Ion-selective electrodes.

Macrocyclic polyfunctional Lewis bases. XI: Structure of trichlorocuprates of Crown-complexed sodium

Abstract The structures of trichlorocuprates of benzo-15-crown-5 complexed sodium and dibenzo-18-crown-6 complexed sodium were determined from diffractometer data by direct methods and refined by least-squares to R(F) = 0.059 and 0.039 respectively. Both complexes, (C 14 H 20 O 5 ) 2 Na 2 Cu 2 Cl 6 and(C 20 H 24 O 6 ) 2 Na 2 Cu 2 Cl 6 , are centrosymmetric and consist of very similar Cu 2 Cl 6 2− units lying across the centre of symmetry. Two Na + cations, surrounded individually by crown ether ligands, are located on opposite sides of the anion. The dimeric structure of the anion is very characteristics for chlorocuprates of very bulky cations and resembles the anions present in tetraphenylphosphonium and tetraphenylarsonium chlorocuprates. This gives a further supportto the «super heavy” alkali metal cations concept.

A 13-membered crown ether with an azoxy subunit in the macrocycle: Synthesis and X-ray structure

The presented azoxy compound is an example of a new crown ether analogue. It has been synthesized by the reduction of an open chain dinitro compound with stannite under strongly alkaline conditions. A method for the separation of the azo and azoxy compounds formed simultaneously has been proposed. The structures of two crystallographically independent molecules of compound2 have been determined. In spite of the small size of the macroring in compound2, the phenyl residues around the azoxy group have atrans orientation.

Bis(benzocrown ether)s with polymethylene bridges and their appilication in ion-selective electrodes

Abstract Synthetic procedures based on the condensation of benzocrown ether derivatives leading to bis (benzocrown ether)s with nonhydrolyzable polymethylene bridges have been elaborated. The obtained compounds may have identical or different macrocyclic units. Methods for introducing lipophilic substituents into these compounds also have been described. The synthesized compounds have been applied in ion-selective electrodes and exhibit high selectivities for potassium, rubidium and cesium ions.

The effect of substituents in macrocyclic polyethers containing aromatic rings on ion-selective electrode properties

Ion-selective electrodes, containing derivatives of crown ethers with aromatic rings, have been investigated. The electrodes were characterized by determining their detection limits and selectivity coefficients. Thet-butyl derivative of naphtho-15-crown-5 was found to exhibit the best properties (Ld=1×10−5,KNa/K=6×10−4).

The X-ray structure of the trichlorocuprate of naphtho-15-crown-5 complexed potassium

The structure of the trichlorocuprate of naphtho-15-crown-5 complexed potassium has been determined by X-ray analysis. The crystal contains the complex cations [K(naphtho-15-crown-5)2]+, the anion [Cu2Cl6]2− and water molecules. The full composition of the compound in the solid state is represented by the formula [K(naphtho-15-crown-5)2]2[Cu2Cl6]·nH2O), wheren≌3. The sandwich type cations are similar to those found previously for potassium complexes with benzo-15-crown-5. The coordination number of potassium is equal to 10; the coordination polyhedron is a 15-crown-5. The coordination number of potassium is equal to 10; the coordination polyhedron is a pentagonal antiprism. The water molecules are disordered and occupy six symmetrically independent positions with a probability of ∼0.5 in the crystal. The lack of close contacts between water molecules and the remaining components enabled the treatment of the complex as a clathrate.

The Stability Constants of Some Benzo-15-Crown-5 And Naphtho-15-Crown-5 Derivatives

Abstract The stability constants for the complexes of several benzo-15-crown-5 and naphtho-15-crown-5 derivatives containing various substituents in the aromatic ring have been determined in methanol. The potentiometric method with glass ion-selective electrodes has been employed. The stability constants have been compared to the selectivity coefficients (log kpot K,Na ) of membrane electrodes based on the mentioned compounds. No significant relationship has been stated.

New macrocycles containing the azoxy subunit and their properties

Abstract A new macroring closure reaction leading to crown-like macrocycles containing the azoxy group as a new macroring subunit has been introduced. The possibility of complex formation with cations has been examined by studying these compounds in membrane ion-selective electrodes.