Abstract
Picolinate-based segmented dianionic ligands L(1)(2-) (5-((4-carboxyphenyl)ethynyl)picolinate) and L(2)(2-) (5,5'-(ethyne-1,2-diyl)dipicolinate) have been used in the synthesis of the highly robust and luminescent europium(III) coordination polymers [(CH(3))(2)NH(2)][Eu(H(2)O)(2)(L(1))(2)] (1) and [(CH(3))(2)NH(2)][Eu(L(2))(2)]·H(2)O·CH(3)COOH (2). Both 1 and 2 exhibit high selectivity for detection of nitroaromatic compounds since they act as quenchers of the Eu(3+) emission. Stern-Volmer plots, using nitrobenzene as a quencher, yielded values of K(SV) = 150 M(-1) and 160 M(-1) for 1 and 2, respectively. Luminescence studies in the presence of different metal ions indicate a high selectivity for Fe(3+) detection, with K(SV) values of 471 M(-1) and 706 M(-1) for 1 and 2, respectively. Both 1 and 2 possess extremely robust extended structures, leading to emissive properties that are stable in a wide pH range.