Tb(III) complexes with nonyl-substituted calix[4]arenes as building blocks of hydrophilic luminescent mixed polydiacetylene-based aggregates

The present work for the first time introduces PDA-based vesicles as convenient supporters of luminescent water insoluble Tb³⁺ complexes. The specific cyclophanic structure of the ligands, where upper and lower calix[4]arene rims are decorated by nonyl- and chelating groups correspondingly provides both complex formation with Tb³⁺ ions with the coordination of the latter via two 1,3-diketonate groups and self- or mixed aggregation of the complexes. The conditions of the self-aggregation of the Tb³⁺ complexes are revealed, although the self-aggregates are unstable being converted into the nanosized precipitates which tend to further aggregation and phase separation. The complexes exhibit Tb(III)-centered luminescence which tends to change in time following the phase separation processes. The embedding of the Tb³⁺ complexes into the PDA-based vesicles results in the mixed aggregates with significant Tb(III)-centered luminescence and significant colloidal stability. The latter arises from high negative electrokinetic potential values due to exterior carboxylic/carboxylate groups of the PDA vesicles.