Diversification of hydrothermal reaction products induced by temperature: syntheses, structures and properties of four La(III)-Cu(II) metal frameworks constructed from rod-shaped molecular building blocks

The hydrothermal reaction of La(III), Cu(II) and 5-nitroisophthalic acid (H2NIPH) at different temperatures produced four novel coordination polymers, [LaCu(NIPH)(ONIPH)(H2O)4].H2O (1), [La2Cu(NIPH)4(H2O)6] (2), [La2Cu(NIPH)4(H2O)2] (3) and [LaCu(NIPH)2(HNIPH)(H2O)2].2H2O (4), (HONIPH = 2-hydroxy-5-nitroisophthalate), these 2D and 3D frameworks are the first La(III)-Cu(II) heterometallic frameworks based on infinite rod-shaped molecular building blocks. In 1, a 2D layer is composed of infinite La-O-C-O-Cu rods consisting of alternating [La2O14(CO2)2] and [Cu2O8] units by corner sharing. The 3D frameworks of 2-4 are constructed from different rod-shaped molecular building blocks, which are linked by NIPH ligands to form a pcu-type rod packing arrangement. Interestingly, HONIPH came from the in situ hydroxylation of H2NIPH in the hydrothermal reaction.