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)]center dot H2O (1), [La2Cu(NIPH)(4)(H2O)(6)] (2), [La2Cu(NIPH)(4)(H2O)(2)] (3) and [LaCu(NIPH)(2)(HNIPH)(H2O)(2)]center dot 2H(2)O (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.