Two novel Er(III) metal–organic frameworks, namely, {[Er 5 (bptc) 3 (Hbptc)(H 2 O) 12 ]·4H 2 O} n (1) and {[Er(bptc′)]} n (2) have been synthesized through the hydrothermal reaction of H 4 bptc with trivalent erbium salts in different temperatures (H 4 bptc=2,2′-bipyridine-3,3′,6,6′-tetracarboxylic acid, H 3 bptc′=2,2′-bipyridine-3,6,6′-tricarboxylic acid). The hydrothermal decarboxylation of H 4 bptc into H 3 bptc′ in 2 was found in higher temperature. Compound 1 reveals a 2-D layered structure and 2 exhibits a 3-D framework structure. The near-infrared luminescent properties of compounds 1–2 have been investigated at 77K.