Waldemar Iwanek

Self-Assembly of 2,8,14,20-Tetraisobutyl-5,11,17,23-tetrahydroxyresorc[4]arene

We report herein the observation of a hexameric structure of a hydroxyresorc[4]arene in the solid state, enclosing a large interior space. This artificial molecular container is stabilized only by hydrogen bonds. The tendency to form aggregates in solution is demonstrated mainly by means of ESI-MS methods.

Ground state and excited state association: chiral recognition between 2,2′-dihydroxy-1,1′-binaphthyl and amines

Abstract Stability constants of complexes in the ground state of S(−)-2,2′-dihydroxy-1,1′-binaphthyl(binaphthol, BiOH) with S(−)- and R(+)-1-phenylethylamine (PEA), S(+)- and R(−)-1-cyclohexylethylamine (CHEA), S(−)- and R(+)- N,N -dimethylphenylethylamine (DMPEA), S(−)- and R(+)-(1-naphthylethylamine) (NEA), (1S,2R)-(+)- and (1R,2S)- (−)-2-dimethylamine-1-phenylpropanol ( N -methylephedrine, NME) were determined in a series of solvents. Differences were found in complexation in the system S(−)-BiOH-R(−)- CHEA-chiral alcohols in acetonitrile. The S(−)- and R(+)-BiOH fluorescence quenching in the presence of chiral ameines mentioned above was studied in some solvents. Distinct differences were only found in acetonitrile. Weak fluorescence of the excited ion pair with hydrogen bond was observed for all investigated systems in all solvents used. A mechanism is proposed involving charge-transfer complexes as well as exciplexes. The influence of chiral solvents indicates the participation of trimolecular intermediates in the ground state. In the excited state proton transfer leading to an ion pair may explain the chiral discrimination in acetonitrile.

Chiral calixarenes derived from resorcinol II. Functionalization by mannich reaction with α-aminoalcohols

Abstract A new type of chiral resorc[4]arene is described. The formation of both enantiomers of 4 is controlled by the α-aminoalcohols 3 used in the Mannich reaction. Although 1,3-oxazine rings could be formed analogously to the condensation reaction with amines only the formation of 1,3-oxazolidine derivatives is observed.

The complexes of tetramethylresorc[4]arene with amines, amino alcohols and pyridine

The solid complexes of resorc[4]arenes with amines, amino alcohols, and pyridine were obtained. Their composition was determined by H-1-NMR and spectrophotometric methods. For selected compounds, the composition was confirmed by the mass spectra. The crystallographic composition of the complex of calixresorcarene with pyridine was determined

Synthesis of enantiomerically and diastereomerically pure oxazaborolo-benzoxazaborininone derivatives of resorcinarene from l-proline

Abstract The novel oxazaborolo-benzoxazaborininone derivatives of resorcinarene were synthesised from l -proline in high diastereomeric excess (>98%). The boron compounds were used as an element linking the carboxy group, the hydroxy group as well as the lone electron pair of the nitrogen atom.

The synthesis of octamethoxyresorc[4]arenes catalysed by Lewis acids

Abstract Lewis acids catalyse the condensation of isovaleraldehyde with 1,3-dimethoxybenzene. All conformers formed in this reaction were isolated and analysed spectroscopically. SnCl4, when used in this reaction, catalysed selective formation of the rccc conformer in high yield. Its selectivity was compared to other aliphatic aldehydes.

The template synthesis and complexation properties of methoxypyrogallo[4]arene

A template method for the synthesis of methoxypyrogallo[4]arene was presented. A complexation of MPA with strong electron acceptors was observed. The ESI-MS analysis showed strong complexing properties of MPA towards alkali metal cations. The ionophore properties of MPA were investigated. The quantum-mechanical calculations were performed for the resulting complexes.

Synthesis and structural studies of 5, 11, 17, 23-tetrahydroxyresorc[4]arenes

Hydroxyresorc[4]arenes are bowl-shaped calixarene compounds. Herein we report the synthesis and the results of X-ray diffraction examinations of six hydroxyresorc[4]arenes, one of them could be crystallized in two conformations. All compounds co-crystallize with different solvent molecules, linked together by hydrogen bonds. It is known that hydroxyresorc[4]arenes are capable of forming large aggregates, a number of different compounds have been prepared, some of them could be crystallized and investigated by single crystal methods. Most of the compounds tend to form polarity-induced double layers.

Lewis Acid-Induced Synthesis of Octamethoxyresorcarenes

Abstract The Lewis acids catalyze the condensation of isovaleraldehyde with 1,3-dimethoxybenzene. All conformers formed in this reaction were isolated and analyzed spectrally. SnCLi, when used in this reaction, catalyzed selectively formation of the rccc conformer in high yield.

Complexation of fullerenes by calix[n]arenes: molecular dynamic simulations and benesi-hildebrandequilibrium constants

Abstract MD simulations using a combination of AMI and AMBER are performed to elucidate the origin of complexation between fullerenes and calix[n]arenes (n = 4,6,8). Only calix[6]arenes and calix[8]arenes are suitable for complex formation. By introducing benzyl substitutents on the upper rim of the calixarenes the interaction energy between host and guest is even improved. Analysis of the data also reveals a strong stabilization by t-butyl or benzyl substitutents beside π-π interactions between the arene units of the calixarene and fullerenes. The calculated data perfectly correlate with the experimentally observed equilibrium constants.