Structurally versatile cadmium coordination polymers based on bis(1,2,4-triazol)ethane and rigid aromatic multicarboxylates: syntheses, structures and properties

Abstract

Nine Cd(II) coordination polymers {[Cd(bte)(NO₂-bdc)(H₂O)]·H₂O}_n (1), {[Cd(bte)(I-bdc)(H₂O)]·H₂O}_n (2), {[Cd(bte)_0.5(OH-bdc)(H₂O)]·H₂O}_n (3), {[Cd(bte)₂(H₂O)₂]·(SO₃-Hbdc)·4H₂O}_n (4), {[Cd(bte)_0.5(1,4-bdc)(H₂O)]·2H₂O}_n (5), {[Cd₂(bte)₂(btec)(H₂O)₂]·11H₂O}_n (6), [Cd(btre)(obc)₂]_n (7), {[Cd(btre)_0.5(NO₂-bdc)(H₂O)₂]·H₂O}_n (8) and {[Cd₃(btre)₂(SO₃-bdc)₂]·4H₂O}_n (9) (bte = 1,2-bis(1,2,4-triazol-1-yl)ethane, btre = 1,2-bis(1,2,4-triazol-4-yl)ethane, NO₂-bdc = 5-nitroisophthalate, I-bdc = 5-iodoisophthalate, OH-bdc = 5-hydroxyisophthalate, SO₃-bdc = 5-sulfoisophthalate, 1,4-bdc = 1,4-benzenedicarboxylate, btec = 1,2,4,5-benzenetetracarboxylate, obc = 4-hydroxybenzenecarboxylate) have been synthesized and structurally characterized. 1 and 2 are independent 1D MONTs. An interesting structural feature of 1 and 2 is that the NO₂ or I groups of each 1D MONT polythread into two adjacent 1D MONTs to form a (1D → 2D) polythreaded array. 3 is a (3,4)-connected 2D network with the point symbol (4²·6)(4²·6³·8). 4 shows the double chain cation [Cd(bte)₂(H₂O)₂]_n²ⁿ⁺ and 3D hydrogen bond architecture. The structure of 5 is an unusual (4,4)-connected 3D network with the point symbol (4·6·8⁴)(4·6³·8²)₂. 6 is an unusual (3,4)-connected 3D network with the point symbol (8³)₂(8⁶). The structures of 7 and 8 are the 1D chain and 1D ladder, respectively. 9 exhibits an unusual (3,5,5,6)-connected three-dimensional network with the point symbol (4²·8)₂(4³·8³·10³·12)₂(4³·6·8³·10³)₂(4⁴·6³·8⁶·10²). The luminescence and thermal stability of 1–9 were investigated.