The step-economical synthesis of lobelanine involving a ring closing double aza-Michael (RCDAM) reaction is revisited and successfully extended to the synthesis of various configurationally more stable analogues. Owing to the presence of a configurationally labile β-aminoketone subunit, lobelanine is prone to self-catalyze mutarotation in solution. Through the synthesis of original lobelanine a...

The title compound (systematic name: cis-anti-cis-2,5,8,15,18,21-hexa-oxatri-cyclo-[20.4.0.0(9,14)]hexa-cosane aceto-nitrile disolvate), C20H36O6·2CH3CN, crystallizes from an aceto-nitrile solution of di-cyclo-hexane-18-crown-6 on evaporation. The mol-ecule is arranged around a center of symmetry with half the crown ether mol-ecule and one mol-ecule of aceto-nitrile symmetry independent. All O-...

Photochemistry, Fluorescence, Crown Ethers, Biology The complexing of thallous ions (T1+), with the crown ether dibenzo 18 crown-6 polyether (DB) has been studied by NMR, fluorescence, and pulse radiolysis techniques. NMR data show a strong interaction of the T1+ ions with the aromatic moieties. This is also illustrated by a static quenching of the aromatic fluorescence by Tl+. The rates of rea...

A crown ether-functionalized poly(tetraphenylethene) (AP-TPE) is synthesized and the rotation of the TPE group is successfully restricted via the complexation of crown ether and organic ammonium salts, leading to a stepwise enhanced fluorescence accompanied by a morphological transition from micellar to vesicular.

A bolaamphiphilic low-molecular-weight gelator based on crown ether, which could self-assemble into organogels and hydrogels, was prepared. The contribution of each part of the structure to the gelation property was investigated by designing a series of analogues. A simple framework (crown ether-hydrophobic linkage-ammonium salt) was proposed.

In addition to the ammonium-crown ether recognition, pi-stacking interactions between the C60 sphere and the porphyrin moiety have been evidenced in a supramolecular complex obtained from a porphyrin-crown ether conjugate and a fullerene derivative bearing an ammonium unit.

Crystalline complexes of S-tert-butylisothiuronium perchlorate ( t-BuSC(NH2),C104) and 18-crown-6 (18C6) and 1,3-xylyl-18-crown-5 (1,3X18C5) with a 1:l stoichiometry were obtained via extraction. X-ray diffraction analysis showed that in the solid state the guest molecule is coordinated via one of the two NH, groups to the crown ether. The second NH2 group is bound to the anion. 'H NMR spectros...

Two simple, rapid and sensitive sensors for the assay of dopamine hydrochloride have been developed. The methods are based upon the formation of the membrane sensors 12-crown-4-phosphotungestic acid (crown ether-PTA)-dopamine and 12-crown-4-tetraphenylborate (crown ether-TPB)-dopamine as neutral carriers. The sensors were stable and showed fast potential responses of 10 s, and near-Nernstian ca...

The interaction between benzo-15-crown-5 (B15C5), dibenzo-18-crown-6 (DB18C6), dibenzyl-daza-18crown-6 (DBzDA18C6), N-phenyl-aza-15-crown-5 (NPhA15C5) and dibenzopyridine-18-crown-6 (DBPy18C6) with π-acceptor 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) in chloroform solution was studied spectrophotometrically. The interaction of B15C5-DDQ and DB18C6-DDQ caused the formation...