A unique purely lanthanide-based single-molecule magnet (SMM) with an oxalate bridge has been designed through a rational synthetic approach. This strategy opens up new opportunities to design SMMs through the premeditated choice of a blocking ligand and suitable oxalate bridge.

Multiple switchable physical properties have been demonstrated in one single niccolite structural metal-organic framework, [(CH CH ) NH ][Fe Fe (HCOO) ] (1), including (i) a reversible ferroelastic phase transition triggered by freezing the disordered (CH CH ) NH cations, (ii) a thermally switchable dielectric constant transition accompanied by phase transition, and (iii) thermal and positive magnetic field driven magnetic poles reversal at low temperatures, attributed to different responses of the magnetization of Fe and Fe sublattices to external stimuli. More interestingly, the exchange anisotropy between the two sublattices can also give rise to tunable positive and negative exchange bias fields. Straightforwardly, such diverse demonstrations of bistability in one single material (depending on the specific tuning way) will provide extra freedom and flexibility for the design of switcher devices.

Three new Ln(III) complexes based on 2,2'-bipyridine [Ln(hfac)3(bpy)] (Ln = Dy (1), Tb (2), or Ho (3); hfac = hexafluoroacetylacetonate; and bpy = 2,2'-bipyridine) have been synthesized and characterized structurally and magnetically. Single-crystal X-ray analysis shows that all these complexes contain one [Ln(hfac)3(bpy)] unit in which a center Ln(III) ion is surrounded with a slightly distorted square-antiprismatic LnO6N2 coordination sphere formed by three bischelate hfac anions and one bpy ligand. Both static and dynamic magnetic properties were studied for complex 1, which is proved to be a new single-ion magnet. The luminescence characterizations of complexes 1 and 2 are also studied in this paper.

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Five new one-dimensional rare earth-nitronyl nitroxide radical complexes [Ln(hfac)3(NIT-3BrPhOMe)]n (Ln = Nd (1), Sm (2), Gd (3), Tb (4), Dy (5); hfac = hexafluoroacetylacetonate; NIT-3BrPhOMe = 2-(3'-bromo-4'-methoxyl)-4,4,5,5-tetramethyl-imidazolyl-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. Five complexes possess linear chain structure in which the NIT-3BrPhOMe radical ligands link Ln(hfac)3 units through the oxygen atoms of nitronyl nitroxide groups. DC magnetic studies show that Nd, Sm and Gd complexes are paramagnetic above 2.0 K, whereas Tb and Dy complexes show antiferromagnetic ordering with T(N) = 19.9 K and 6.4 K, respectively. Moreover, Tb and Dy complexes exhibit frequency-dependence of ac magnetic susceptibilities, suggesting the presence of slow magnetic relaxation. This work demonstrated that the substituents of the nitronyl nitroxide radical and the lanthanide ion can play a crucial role in modulating the magnetic behavior for one-dimensional lanthanide-radical systems.

On the basis of the carboxylic structure of trimesic acid (TMA) and 5-borono-1,3-benzenedicarboxylic acid (B-BDC), here two hydrogen-bonded organic frameworks (HOFs), HOF 1 (MA-TMA) and HOF 2 (MA-B-BDC), were prepared by reacting melamine (MA) with trimesic acid and 5-borono-1,3-benzenedicarboxylic acid, respectively. The as-prepared HOF 1 and HOF 2 with 3D supramolecular structure exhibit excellent performance in proton transport. AC impedance test shows that the proton conductivities of HOF 1 and HOF 2 reach 3.11 × 10 −4 S•cm −1 (343 K, 98% RH) and 4.32 × 10 −4 S•cm −1 (323 K, 98% RH), respectively. To increase the proton conductivity, Im@HOF 1 and Im@HOF 2 were obtained by introducing imidazole (Im), which acts as a jumping site for proton transfer. The proton conductivities of Im@HOF 1 and Im@HOF 2 reached 4.12 × 10 −4 S•cm −1 (333 K, 98% RH) and 1.20 × 10 −3 S•cm −1 (353 K, 98% RH), respectively. This is the first time that guest molecules were introduced into HOFs. The stability and proton conductivity of the HOFs are improved due to the interaction of imidazole with carboxyl groups and water molecules.

The reaction of polydentate ligand Bis-tris propane {(CH 2 OH) 3 CNH(CH 2 ) 3 NHC(CH 2 OH) 3 } with Ln(NO 3 ) 3 ·6H 2 O and Fe 3 O precursor resulted in the formation of a series of Fe 6 Ln 2 nanoclusters. Magnetic measurements indicate that the Fe 6 core exhibits ferrimagnetic behavior and slow magnetic relaxation was observed in Fe 6 Dy 2 and Fe 6 Tb 2 .

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