Robust Lanthanoid Picolinate-Based Coordination Polymers for Luminescence and Sensing Applications

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.