Elżbieta Luboch

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

New 21-membered lipophilic crown ethers, each incorporating a pyrrole unit and two azo groups as macrocyclic ring components, have been synthesized. The complexation behavior of these and two further macrocycles has been investigated in acetonitrile. These ligand systems have been employed as ionophores in transport experiments involving the competitive transport behavior of an equimolar mixture of Co2 + , Ni2 + , Cu2 + , Zn2 + , Cd2 + , Ag+ and Pb2 + across a water (pH 4.9)/chloroform/water (pH 3) bulk membrane system. In each case transport selectivity for lead(II) was obtained. The macrocycles have been incorporated in solvent polymeric membrane electrodes and their behavior towards a selection of metal ions, including those mentioned above, is reported.

Chromogenic azocrown ethers with peripheral alkyl, alkoxy, hydroxy or dimethylamino group

Abstract New derivatives of azobenzene crown ethers have been obtained. They include compounds with alkyl, alkoxy, hydroxy or dimethylamino group in aromatic residue(s) as side substituents. Their chromoionophoric properties and properties in ion-selective membrane electrodes have been studied. Structures of two azocrown ethers with peripheral hydroxy group in benzene ring were confirmed by X-ray analysis. Effect of metal ion complexation by hydroxyazobenzocrown ethers on hydroxyazo-quinone hydrazone tautomerism was studied.

Na+-selective ChemFETs based on a novel ionophore: bis(phenylbenzo)-13-azocrown-5

Abstract This paper presents performances of ChemFETs based on a novel sodium ionophore bis(phenylbenzo)-13-azocrown-5. The main feature of the ionophore is its increased lipophilicity. This study shows that ChemFETs based on the novel ionophore exhibit a relatively high selectivity coefficient for sodium over lithium ions K (Na + /Li + ) pot , and that it is elevated for ChemFETs with PVC membrane containing o -nitrophenyl octyl ether ( o NPOE) as a plasticizer. Moreover, a significant difference in selectivity coefficients for Na + over Ca 2+ ions, also depending on a plasticizer, was observed. In addition, procedure of synthesis of the ionophore is also described. A good stability of the output signal was obtained for Na + -ChemFETs based on Siloprene membrane.

STEREOCHEMISTRY OF 16-MEMBERED AZO- AND AZOXYCROWN ETHERS. STRUCTURES OF THEIR SANDWICH POTASSIUM IODIDE COMPLEXES

Abstract16-Membered dibenzoazo- and dibenzoazoxycrown ethers have been synthesized. The Z and E isomers of the azocrown compound have been separated and the geometry of the –N=N– and –-N(O)=N–- groups determined. Potassium iodide complexes of the azo- and azoxycrown ethers were obtained and their structures were determined by the X-ray method. The crystal of the azocrown ether complex is triclinic, space group P¯1, a = 21.071(5), b = 12.112(4), c = 8.757(2) Å α = 81.28(2), β = 84.66(2), γ = 107.49(2)°. The azoxycrown ether complex is monoclinic, space group C2/c, a = 15.648(3), b = 19.597(4), c = 14.651(3) Å; β = 111.30(3).

Novel Calix[4]resorcinarenes with Side Azobenzo-15-crown-5 Residues

Abstract New calix[4]resorcinarenes having two or four azobenzo-15-crown-5 residues on the lower rim have been synthesized by the condensation of resorcinol with the corresponding aldehyde (acetal).

Cyclodextrin Combinations with Azocompounds

Cyclodextrins (CDs) are cyclic oligosaccharides consisting of various numbers of -1,4linked glucose units (α-CD, β-CD and γ-CD for hexa-, heptaand octamers, respectively). Larger homologues are recently described, cf., [1,2]. CDs form inclusion complexes with a variety of organic compounds [3]. Complexation influences solubility of organic guests in water, and stabilizes the guest molecules towards oxidation and other unwanted reactions. Also CDs catalyze some reactions playing role of microreactors or serve as building blocks for nanotubes. For latest papers or books dealing with cyclodextrin chemistry see [4-7] . In this review are considered combinations of CDs and their derivatives, in which compounds bearing azo unit are chemically bonded or mechanically associated with the host. In this case, the binding properties are modified by light when the guest molecule undergoes trans cis isomerization [6a].

Azo group(s) in selected macrocyclic compounds

Azobenzene derivatives due to their photo- and electroactive properties are an important group of compounds finding applications in diverse fields. Due to the possibility of controlling the trans–cis isomerization, azo-bearing structures are ideal building blocks for development of e.g. nanomaterials, smart polymers, molecular containers, photoswitches, and sensors. Important role play also macrocyclic compounds well known for their interesting binding properties. In this article selected macrocyclic compounds bearing azo group(s) are comprehensively described. Here, the relationship between compounds’ structure and their properties (as e.g. ability to guest complexation, supramolecular structure formation, switching and motion) is reviewed.

Correction to: Azo group(s) in selected macrocyclic compounds

In the original publication of the article, a part of the scheme 12 was missed. The correct version of the scheme 12 was provided in this correction article. The original article has also been corrected.