1D, 2D and 3D Coordination Polymers of Aromatic Carboxylate Tb III : Structure, Thermolysis Kinetics and Fluorescence

Reactions of TbCl 3 · 6H 2 O with aromatic acids, namely, pyridine‐2,3‐dicarboxylic acid (H 2 pda), isophthalic acid (H 2 ipa) and isonicotinic acid (Hina) gave rise to three new coordination polymers {[Tb(pda)(Hpda)] · 3H 2 O} n ( 1 ), {[KTb(ipa) 2 (H 2 O) 3 (μ‐H 2 O)] · 2H 2 O} n ( 2 ) and [Tb(ina) 3 (H 2 O) 2 ] n ( 3 ), respectively. Complex 1 constructed by eight‐coordinate Tb III nodes connected with completely and half‐deprotonated pda and Hpda spacers is a novel 3D metal–organic architecture with nanosized hexagonal 1D channels hosting guest water, whereas complex 2 is a 2D heterometal sheet built by completely deprotonated ipa spacers bridging eight‐coordinate K I and nine‐coordinate Tb III . As for 3 , deprotonated monoacid ina anions link eight‐coordinate Tb III centres into a 1D double‐chain structure. As excited at 320 nm, complexes 1 – 3 all display a serial of emissions centred at about 486, 545, 582 and 620 nm, which is assigned to the characteristic 5 D 4  →  7 F j (j = 6; 5; 4; 3) electronic transitions of Tb III . The overall fluorescence nature of 1 – 3 is extremely alike, but their fluorescence intensity and lifetime are affected by the architectures. Very interestingly, the fluorescence intensity of 2 , especially emitting at 545 nm, is largely enhanced owing to the coordination of alkali metal K I in the Tb III –carboxylate network. Furthermore, thermal behaviours of 1 – 3 under a nitrogen atmosphere as well as the thermolysis nonisothermal kinetics of 2 are researched.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)