MOLECULAR RECOGNITION OF PHENETHYLAMINE, TYRAMINE AND DOPAMINE WITH NEW ANIONIC CYCLOPHANES IN AQUEOUS-MEDIA

Water-soluble cyclophanes functionalized by amide groups and pendant c arboxymethyl groups have been synthesized, in a single step, by a cond ensation reaction between ethylenediaminetetraacetic (EDTA) dianhydrid e and bis(4-aminophenyl) ether or bis(4-aminophenyl)methane: cyclophan es obtained are 30,33-octaaza-17,40-dioxa[10.1.10.1]paracyclophane (I) and ,7,10,24,27,30,33-octaaza[10.1.10.1]paracyclophane (2). Their com plexation with 2-phenylethylamine (phenethylamine), 2-(4-hydroxyphenyl )ethylamine (tyramine) and 2-(3,4-dihydroxyphenyl)ethylamine (dopamine ), which have biologically important activities, has been studied by H -1 NMR spectroscopy in aqueous media, The formation constants of 1:1 h ost-guest complexes, K= [HG]/[H][G], have been determined as: log K= 0 .8 for I-phenethylamine; 1.2 for l-tyramine; 1.2 for I-dopamine; 1.6 f or 2-phenethylamine; 2.0 for 2-tyramine. Dopamine and 2 form a complex with low water-solubility, The chemical shifts of aromatic protons of the host and guest molecules suggest the formation of inclusion compl exes in solutions, The formation of the host-guest complexes is assist ed by a hydrogen bond and/or an electrostatic interaction between the pendant -CH2CO2- group of the host and the -CH2CH2NH3+ arm of the gues t molecule, The two types of molecular recognition sites of the new cy clophanes result in the selective complex formation. with the aromatic amines.