Oldrich Kocian

RuII-Polypyridine Complexes Covalently Linked to Electron Acceptors as Wires for Light-Driven Pseudorotaxane-Type Molecular Machines

The photophysical properties of wire-type compounds based on a photosensitizing RuII complex linked to an electron-accepting bipyridinium or diazapyrenium group have been studied with the aim of designing light-driven molecular machines based on pseudorotaxanes (shown schematically). As an outcome, the photoinduced dethreading of a pseudorotaxane formed by a crown ether ring and one of the investigated wire-type compounds has been realized.

Cyclophanes and [2]catenanes as ligands for transition metal complexes: Synthesis, structure, absorption spectra, and excited state and electrochemical properties

Two tetracationic cyclophanes and two [2]catenanes containing paraquat-type units together with one or two transition metal chelating 2,2′-bipyridyl moieties have been synthesized. The metal-binding units have been used to generate novel mono- and binuclear ruthenium(II), rhenium(I), silver(I) (right), and copper(I) complexes.

Syntheses, coordination, spectroscopy and electropolymerisation studies of new alkynyl and vinyl linked benzo- and aza-crown ether–bipyridyl ruthenium(II) complexes. Spectrochemical recognition of group IA/IIA metal cations

New alkynyl and vinyl linked benzo- and aza-crown ether–bipyridyl ruthenium(II) complexes have been prepared and electropolymerised onto platinum and optically transparent conducting glass electrodes to produce novel films capable of spectrochemically recognising alkali and alkaline earth metal guest cations.

Novel polytopic macrocyclic receptor molecules containing multiple bipyridyl and dibenzo-18-crown-6 units

Abstract New polytopic macrocycles (7)-(11) containing multiple 4,4′-disubstituted-2,2′-bipyridyl and dibenzo-18-crown-6 units are described. Preliminary coordination studies reveal these novel ligands form polymetallic complexes with ruthenium and potassium guest cations.

Cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and bismethoxyphenyl-vinyl–bipyridyl ruthenium(II) complexes. Electrochemical polymerization studies and supporting electrolyte effects

The cyclic voltammetry of benzo-15-crown-5 ether-vinyl-bipyridyl ligands, their ruthenium(II) complexes and the ‘model’ bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complexes has been investigated in acetonitrile. The benzo-15-crown-5 ether units of the solution complexes are sensitive to supporting electrolyte, being more difficult to electro-oxidize on binding of sodium or magnesium cations. The tris(ligand) ruthenium(II) complexes can be reductively electropolymerized to form smooth, adherent electroactive orange films. For these electropolymerized films, the benzo-15-crown-5 ether irreversible electro-oxidation is electrocatalysed by RuIII sites and is only observed on the first cyclic voltammogram. RuIII/II redox potentials are insensitive to changes in the supporting electrolyte, apparent differences being due to variable liquid-junction potentials at the interface between the reference electrode and the supporting electrolyte solutions. Electropolymerized bismethoxyphenyl-vinyl-bipyridyl ligand ruthenium(II) complex films exhibit transparent/orange electrochromicity.

Electrochemical polymerisation studies of aza-15-crown-5 vinyl-2,2′-bipyridine ruthenium(II) complexes

Abstract The electrochemical polymerisation of the mono(ligand) and tris(ligand) ruthenium(II) complexes, [RuL 1,2 (bipy) 2 ] 2+ and [RuL 1,2 3 ] 2+ (bipy = 2,2′-bipyridine, L 1 = 4-methyl-4′-( N -styryl-aza-15-crown-5)-2,2′-bipyridine, L 2 = 4,4′-bis( N -styryl-aza-15-crown-5)-2,2′-bipyridine), has been investigated in acetonitrile. Preparation of electroactive polymer films was established on reductive electropolymerisation of the tris(ligand) ruthenium(II) complexes. Electropolymerisation of [RuL 1 (bipy) 2 ] 2+ did not take place, suggesting that the polymer formation mechanism involves radical-radical hydrodimerisation for pairs of vinyl groups rather than ‘polyvinyl-type’ chain propagation. Lack of electropolymerisation for [RuL 2 (bipy) 2 ] 2+ , with two vinyl linkages on the same ligand, is explained by steric constraints preventing repeated linkages between aza-15-crown-5 vinyl-pyridine units. While polymer formation via the alternative route of oxidative coupling of the N -styryl-aza-15-crown-5 moieties might be anticipated, electro-oxidation for the [RuL 2 (bipy) 2 ] 2+ and [RuL 1,2 3 ] 2+ complexes led only to the formation of electroinactive orange films with concurrent electrode passivation.

New polyaza tris-ferrocene and tris-2,2′-bipyridyl macrobicyclic cryptand molecules. Isolation of homo- and hetero-polymetallic zinc(II) and copper(I) cryptates containing externally coordinated ruthenium(III) cations

New multisite ligands containing either three peripherally linked ferrocene redox centres (L1,L3) or three externally orientated 2,2′-bipyridyl transition metal recognition sites (L2,L4) have been prepared and their homo- and hetero-polymetallic zinc(II) and copper(I) cryptates incorporating in the case of L2 and L4 externally coordinated ruthenium(II) cations have been isolated.

Synthesis of unsymmetrical 4,4'-disubstituted 2,2'-bipyridines containing benzo crown ether and ferrocene moieties

A simple one-pot synthesis of unsymmetrical 4,4′-disubstituted 2,2′-bipyridine ligands containing benzo crown ether and redox-active ferrocene moieties is described.

Self-assembly in the metallation of bis(aminoaryl) ethers

Abstract The dilithiation of 2,2′-bis(2-methoxyethylamino)diphenyl ether ( 4 ) and 2,2′-bis( N , N -dimethylethylenediamino)diphenyl ether ( 7 ) in the absence of any Lewis base donor resulted in the formation of dimeric complexes 8 and 9 , respectively, containing the unprecedented Li 4 O 2 N 4 “adamantanoid” metal core as a consequence of the self-recognition and self-assembly involving the two metallated subunits. In contrast, on monometallation using particular conditions, e.g. sodium hydride in the presence of Lewis base donor, the same ligands undergo a Smiles-type rearrangement, providing the first example of such a reaction involving an amine and a deactivated aromatic system. The conditions needed to promote this rearrangement have been investigated.

Monometallation of a di(aminoaryl) ether induces a Smiles rearrangement leading to a sodium aryloxide complex: the synthesis and crystal structure of [(MeOCH2CH2)(C6H4NHCH2CH2OMe)NC6H4O·Na]2

The title compound was synthesised by 1 : 1 reaction of sodium hydride with a di(aminoaryl) ether ligand in toluene–hexamethylphosphoramide (HMPA) solution; X-ray crystallography revealed that an in situ Smiles rearrangement of the ligand had taken place to give a dimeric aryloxide sodium complex, which is in stark contrast to previous results obtained by 2 : 1 reaction of BunLi with the ligand in the absence of HMPA.