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Ligands with flexible conformations add to the structural diversity of metal-organic frameworks but, at the same time, pose a challenge to structural design and prediction. Representative examples include Zr-tetracarbox-ylate-based MOFs, which afford assorted structures for a wide range of applications, but also complicate the structural control. Herein, we systematically studied the formation mechanism of a series of (4,8)-connected Zr-tetracarbox-ylate-based MOFs by altering the substituents on different positions of the organic linkers. Different ligand rotamers give rise to three types of structures with flu, scu, and csq topologies. A combination of experiment and molecular simulation indicate that the steric hindrance of the substituents at different positions dictates the resulting MOF structures. Additionally, the controllable formation of different structures was successfully implemented by a combination of linkers with different steric effects at specific positions. [ABSTRACT FROM AUTHOR]

Herein, 15 lanthanide coordination complexes based on three di-, tri-, and tetra-carboxylic ligands with imidazolyl groups have been solvothermally designed, synthesized, and characterized. All the complexes exhibit high thermal stabilities and can remain stable in the open air more than 7 days. Luminescent spectra of Eu3+ and Tb3+ complexes at room temperature indicate that the three carboxylic ligands H2L¹, H3L², and H4L³ are promising potential light sensitizers for lanthanide ions based on their suitable triplet energy levels. Luminescent lifetimes and quantum yields of these compounds were further measured and compared. The correlations between their structural features and photophysical properties are discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Four isostructural lanthanide(III) complexes, [Ln2(HL)2(H2O)4]n·2nH2O (H4L=3,3′,6,6′-tetracarboxyl-2,2′-bipyridine) (Sm (1), Eu (2), Gd (3), Tb (4)), have been synthesized under the hydrothermal condition and characterized by single-crystal X-ray diffractions, powder X-ray diffractions (PXRD), thermal analyses (TGA) and elemental analyses (EA). These four complexes all exhibit 1D chain-like structures containing di-nuclear lanthanide(III) units, which are further linked by hydrogen bonding into 3D supramolecules. To further investigate the properties of the above complexes, the photoluminescent properties of 2 and 4 are also discussed. [Copyright &y& Elsevier]

A synthetic strategy to construct discrete indium-organic polyhedra has been illustrated based on small three-membered windows from a 2,5-pyridinedicarboxylate (PDC) ligand with an angle of 120°. [Et2NH2]6[In6(PDC)12] (InOF-10) is a high-symmetry octahedron with eight three-membered windows, and [Et2NH2]18[In18(BPDC)6(PDC)30] (InOF-11) is a complex polyhedron derived from 3-edge-removed octahedra with an auxiliary biphenyl-3,3'-dicarboxylate (BPDC) ligand. Moreover, the sorption behavior of the latter is also well investigated. [ABSTRACT FROM AUTHOR]

Eu2PQC6 has been developed to detect Al3+ by monitoring the quenching of the europium-based emission, with the lowest detection limit of ~32 pM and the quantitative detection range to 150 μM. Eu2PQC6 is the first ever example that the europium(III) complex serves as an Al3+ fluorescent sensor based on "competition-displacement" mode. [ABSTRACT FROM AUTHOR]