abstract
For functional nitrogen-bridged calix(hetero)aromatic platforms to be further used in the design of more sophisticated receptors, the azacalix[2]arene[2]triazine nitrogen bridges were functionalised with methyl bromoacetate. Three new macrocycles with four N-methyl ester pendant arms were straightforwardly prepared in good yields from the undecorated azacalix[2]arene[2]triazine precursors with chlorine, dimethylamine or dihexylamine substituted triazines. These intermediate macrocycles exhibited different reactivity towards the nucleophilic replacement, which was rationalized from the computed electrostatic potential for these molecules. Subsequently, the N-methyl ester appendages were hydrolyzed with each dialkylamine derivative providing a single macrocycle with four carboxylic groups. In contrast the hydrolysis of the dichlorinated azacalix[2]arene[2]triazine analogue yielded a mixture of three isomeric macrocycles having two N-methyl esters and two carboxylmethyl pendant arms and the triazine chlorine atoms replaced by hydroxyl groups. The coordination ability of two macrocycles with four carboxylic groups for transition metals was evaluated with copper(II) by UV-vis titrations.
keywords
SUPRAMOLECULAR CHEMISTRY; PI INTERACTIONS; TRIAZINE; MOLECULES; CAVITY; DERIVATIVES; COMPLEXES; SILICA
subject category
Chemistry
authors
Caio, JM; Esteves, T; Carvalho, S; Moiteiro, C; Felix, V
our authors
João Miguel da Cruz Morgado Agostinho Caio
PhD Student
Sílvia Cristina Ferreira de Carvalho
Post-doc Fellowship
Vítor Félix
Associate Professor with Aggregationacknowledgements
The authors are grateful for funding from QREN-FEDER, through the Operational Program Competitiveness Factors - COMPETE, and National Funds through the FCT under project PTDC/QUI-QUI/101022/2008 and Pest-OE/QUI/UI0612/2013. J.M.C. and S.C. thank FCT for PhD scholarship SFRH/BD/66789/2009 and postdoctoral grant SFRH/BPD/42357/2007 respectively. We also acknowledge Paula Branco from ASAE for the mass spectra.