A family of six new homo-lanthanide coordination polymers incorporating a conjugated ligand of 2,5-di(2′,4′-dicarboxylpheny)pyridine, namely, {[Ce(μ₃₋ddpp)]·4H₂O}_n (1), {[Nd(μ₃₋ddpp)]·2H₂O}_n (2), {[Sm(μ₆₋ddpp)]·H₂O}·H₂O}_n (3), {[Eu(μ₆₋ddpp)]·H₂O}_n (4), {[Tb(μ₆₋ddpp)]·H₂O}_n (5), and {[Er(μ₆₋ddpp)]·H₂O}_n (6) (H₃ddpp = 2,5-di(2′,4′-dicarboxylpheny)pyridine acid), has been prepared successfully through solvothermal reactions. Polymers 1–6 exhibit various coordination environments and different multi-dimensions, but they are all assembled in a one dimensional (1-D) Ln–carboxylate chain. Polymer 1 only shows a 1-D ribbon chain, while polymer 2 exhibits a binodal (3, 8)-connected topology net. Heavy lanthanide polymers 4–6 possess 3D frameworks based on a rare (4, 8)-connected msw framework. Thermogravimetric and different thermal analysis measurements indicate that they all display high thermal stability. The luminescence emission spectra display characteristic f–f transition emissions of Ln(III) polymers in visible or near infrared (NIR) regions. The fluorescent ligand H₂ddpp provides efficient energy transfer for the sensitization of Eu(III) and Tb(III) ions in the visible region, among which a Tb(III) polymer may be employed as a fluorescence ratiometric probe for the pollutant CrO₄ ²⁻ anion.

A family of heteronuclear metal organic frameworks (MOFs) using lanthanide and transition metal ion based on a rigid ligand of substituted imidazoledicarboxylic acid, namely, {[Ln₂Zn₂ (μ₃-Hmimda)₂ (μ₃-mimda)₂·4H₂O]_n·mn H₂O}, Ln = Nd, m = 2 (1), Ln = Ho, m = 3 (2), Ln = Er, m = 2 (3), Ln = Yb, m = 3 (4), [Tb₂Co₂(μ₃-Hmimda)₂ (μ₃-mimda)₂·4H₂O]_n·2nH₂O} (5) and [Dy₂Co₂ (μ₃-Hmimda)₂ (μ₃-mimda)₂·4H₂O]_n·nH₂O} (6), (H₃mimda = 1H-2-methyl-4,5-imidazole-dicarboxylic acid), have been developed and characterized. All the complexes (except for a little disparity for 1) are isostructural, and all crystallize in the monoclinic system. They possess an extended reticular-like porous structure constructed from corrugated 2D layers. Direct current (dc) magnetic susceptibility measurements for 1–5 indicated depopulation of the Stark components at low temperature and/or possible weak anti-ferromagnetic interactions within hetero-nuclear MOFs. Alternating current (ac) susceptibility studies reveal that the Dy(III)–Co(II) complex exhibits both possible ferromagnetic couplings and frequency-dependent out-of-phase signals, behaviour of single-ion magnet nature. Fluorescence properties of series complexes both in near-infrared (NIR) and visible regions have been comparatively studied.

A series of coordination polymers {[Ln(aobtc)(H₂O)₄]·Hbipy·H₂O}_n (H₄aobtc = azoxybenzene-2,2′,3,3′-tetracarboxylic acid, bipy = 4,4′-bipyridine, and Ln = Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Er(6)) have been synthesized and characterized systematically. The cationic Hbipy⁺ guest incorporated polymers are isostructural sets, featuring a one-dimensional (1D) zigzag double chain edifice composed of binuclear clusters [Ln₂(H₄aobtc)₂], with the Hbipy⁺ guest being located on two sides. These 1D chains are further interlinked into a 2D layer structure, and further extended into a 3D framework through hydrogen bonding interactions. The luminescence emission spectra of polymers 2 and 3 are based on the H₄aobtc acid ligands, while 1 and 4 display the characteristic f–f transitions of Ln(III) ions. Magnetic measurements revealed the presence of ferromagnetic behavior in polymer 3. The magnetic behaviors of 4 and 6 are ascribed to the depopulation of the Stark levels and/or weak antiferromagnetic interactions within MOFs at lower temperature. Slow relaxation is observed through the alternating-current susceptibility measurements for 5 at lower temperature, and the coexistence of weak ferromagnetism corresponding to the spin-canting-like behavior.

A family of highly stable lanthanide coordination polymers incorporating fluorine-substituted carboxylate tectonics and the rigid ligand phenanthroline, namely, {[Ln_m(Tfbda)_n(Phen)₂·2H₂O]·2H₂O}_z, (Ln = Pr (1), Ho (4) and Gd (7), m = 2, n = 3); {[Ln₃ (Tfbda) m₁ (Tfba) m₂ (Phen)_n·2H₂O]·H₂O}_z (z > 1, Ln = Dy (3), Er (5) and Yb (6), m₁ = 4, m₂ = 1, n = 3); [Ln₂(H₂Tfbda)₄(Phen)₂·(H₂O)₂]·Phen (Ln = Nd (2)), Tfbda = 3,4,5,6-tetrafluoro-benzene-1,2-dioic acid, Tfba = 2,3,4,5-tetrafluorobenzoic acid have been afforded under hydrothermal conditions. The series of coordination polymers exhibited diverse structural motifs, from dinuclear cluster to 1-D chain arrary, displaying efficiently sensitized luminescence over a spectral range from visible to near-infrared (NIR) region and a long lifetime, due to efficient energy transfer from fluorine-substituted ligands to Ln(III) centers in solid state. Slow relaxation magnetization and significant frequency- and temperature-dependent peaks were observed in trinuclear Dy(III)-based coordination polymer 3. DC magnetic susceptibility studies reveal the existence of weak ferromagnetic interaction within 7.