Hao-Ling Sun

An organometallic single-ion magnet.

An organometallic single-ion magnet is synthesized with only 19 non-hydrogen atoms featuring an erbium ion sandwiched by two different aromatic ligands. This molecule displays a butterfly-shaped hysteresis loop at 1.8 K up to even 5 K. Alternating-current (ac) susceptibility measurement reveals the existence of two thermally activated magnetic relaxation processes with the energy barriers as high as 197 and 323 K, respectively.

Unique (3,12)-Connected Porous Lanthanide−Organic Frameworks Based on Ln4O4 Clusters: Synthesis, Crystal Structures, Luminescence, and Magnetism

Three porous lanthanide-organic frameworks, [Ln(4)(OH)(4)(3-SBA)(4)(H(2)O)(4)].nH(2)O [Ln = Eu(III) (1), n = 10; Gd(III) (2), n = 10; Tb(III) (3), n = 8; 3-SBA = 3-sulfobenzoate], have been prepared by a hydrothermal synthesis method. They are isomorphous and crystallize in a tetragonal system with space group P 42(1)c. The structure can be considered to be built up by cubanelike [Ln(4)(OH)(4)](8+) secondary building units, which are further connected by 3-SBA to form a 3D coordination framework with 1D pores along the c direction for accommodation of novel T8(3) water tapes or zigzag water chains. Furthermore, in these compounds, the [Ln(4)(OH)(4)](8+) units and 3-SBA ligands serve as 12-connected and 3-connected nodes, respectively, resulting in a unique (3,12)-connected framework with the Schlafli symbol of (4(3))(4)(4(20).6(28).8(18)). The luminescent properties of the Eu(III) (1) and Tb(III) (3) complexes have been studied, showing characteristic emissions at room temperature. Variable-temperature magnetic susceptibility studies indicate that the Gd(III) complex 2 displays weak antiferromagnetic coupling through mu(3)-OH(-) pathways.

Elucidation of slow magnetic relaxation in a ferromagnetic 1D dysprosium chain through magnetic dilution

A novel ferromagnetic 1D dysprosium chain was synthesized. It exhibits slow magnetic relaxation, originating from the single-ion behaviour of Dy(3+) as indicated by dc and ac magnetic data of both diluted and un-diluted samples.

Magnetic properties of EuS nanoparticles synthesized by thermal decomposition of molecular precursors

Europium(II) sulfide nanoparticles with an average particle size of 5.5 nm and a narrow size distribution were synthesized by the direct and facile thermal decomposition of a molecular precursor Eu(Phen)(Ddtc)3 (Phen = 1,10-phenanthroline, Ddtc = diethyldithiocarbamate) at the relatively low temperature of 200 °C. Compared with EuS samples of 50–120 nm in size, which show bulk ferromagnetic ordering, the EuS nanocrystals of 5–6 nm in size show a cluster glass-like behavior. Moreover, a quasi-ferrimagnetic behavior was observed in the smallest EuS sample upon oxidation of the surface.

Linking cyano-bridged ladders by azide to form a layered metamagnetElectronic supplementary information (ESI) available: crystal structure plots, more magnetic data and plots for 1 and 2. See http://www.rsc.org/suppdata/cc/b4/b405167j/

Cyano-bridged corrugated ladder-like chains are connected by mu(1,1)-N(3) (end-on, EO) bridges to form a layered coordination polymer, [Mn(N(3))(CH(3)OH)[Cr(phen)(CN)(4)].CH(3)OH (2), which is the first mixed cyano-azide bridged compound, and shows metamagnetism below 21.8 K, a temperature much higher than that (3.4 K) of the crossed double chain [Cr(phen)(CN)(4)](2) [Mn(H(2)O)(2)].4H(2)O (1) based on the same building block [Cr(phen)(CN)(4)](-).

Phosphorescent cocrystals constructed by 1,4-diiodotetrafluorobenzene and polyaromatic hydrocarbons based on C–I⋯π halogen bonding and other assisting weak interactions

The cocrystals were assembled with 1,4-diiodotetrafluorobenzene (1,4-DITFB) as the halogen bonding donor and the polycyclic aromatic hydrocarbons (PAH), biphenyl (Bp), naphthalene (Nap), phenanthrene (Phe), as the π-type halogen bonding acceptors, corresponding to cocrystals 3 (Bp-DITFB), 4 (Nap-DITFB) and 5 (Phe-DITFB), respectively. The single crystal X-ray diffraction analysis reveals that the two-dimensional layer in 3 or the one-dimensional chain structures in 4 and 5 are formed by C–I⋯π halogen bonds, and that the C–I⋯π bonding occurs in both above-the-carbon and above-the-bond models of DITFB to PAHs. Other intermolecular interactions in cocrystals such as C–F⋯F–C contacts, edge-to-edge type π–π stacking and C–H⋯I hydrogen bonding are also significant in maintaining the stability of supramolecular structures. The stoichiometry of all three cocrystals is 1:2 of PAH to DITFB. The PAHs with smaller conjugation systems and linear (not more than two benzene rings) or bent structures may be apt to form cocrystals with 1,4-DITFB by C–I⋯π halogen bonding. The cocrystals are well characterized by various spectroscopic methods. Additionally, the cocrystals 4 and 5, as expected, produce strong green and orange phosphorescence, respectively, due to strong spin-orbital coupling of iodine atoms. Phosphorescence of Phe in cocrystal 5 appears to be largely red-shifted compared with regular emission in solution or on general solid-supports. The phosphorescence decay of cocrystals 4 and 5 both obey a mono-exponential form with lifetimes of 0.067 ms and 1.449 ms, respectively.

3D Self-penetrating coordination network constructed by dicyanamide and 1,2-bis(4-pyridyl)ethane-N,N′-dioxide (bpeado)

The complexes of formulae M(dca)2(bpeado) (M = Mn (1), Fe (2), Co (3), Ni (4), Cu (5); dca = dicyanamide; bpeado = 1,2-bis(4-pyridyl)ethane-N,N′-dioxide) have been synthesized and characterized by X-ray single crystal diffraction. Compounds 1–5 contain 3D self-penetrating networks, in which bidentate dca ligands bridge the octahedral metal ions to form square-grid like M(dca)2 sheets and these sheets are further connected by criss-crossing bpeado to give a 3D self-penetrating network. Variable temperature magnetic susceptibility studies have shown that these compounds generally display very weak antiferromagnetic coupling because of the long bpeado and μ1,5-dca pathways. Consequently, no magnetic ordering was found.

Europium Pyrimidine-4,6-dicarboxylate Framework with a Single-Crystal-to-Single-Crystal Transition and a Reversible Dehydration/Rehydration Process

In this paper, a novel three-dimensional (3D) porous lanthanide-organic framework, Eu2(μ4-pmdc)2(OH)2·3H2O (1), which is stable up to 400 °C, has been hydrothermally synthesized and characterized. It shows intriguing single-crystal-to-single-crystal transformation and reversible dehydration/rehydration phenomenon upon removal and rebinding of the lattice water molecules, which is supported by single-crystal X-ray diffraction, powder X-ray diffraction, and photoluminescence data.

Cyclic water pentamer in a tape-like structure

A novel water tape consisting of fused cyclic water pentamers has been observed in a supramolecular compound.

Lanthanide-pyridyl-2,5-dicarboxylate N-oxide frameworks with rutile topology

Four novel lanthanide-organic frameworks Ln(2,5-pdco)(CH3COO)(H2O) [Ln = La (1), Eu (2), Gd (3), Tb (4); 2,5-H2pdco = pyridyl-2,5-dicarboxylic acid N-oxide] have been synthesized and characterized. The coordination networks are similarly constructed viaLn2(μ-CH3COO)2 dinuclear secondary building units (SBUs), which are further linked by six 3-connected 2,5-pdco tectons to result in a novel 3D (3,6)-connected framework with rutile topology. Compound 2 shows the characteristic red emissions of Eu3+ at room temperature with the life time of 0.42(1) ms and emission quantum yield of 32.1%. The variable-temperature magnetic susceptibility studies indicate the presence of weak antiferromagnetic coupling between Gd3+ in 3 while weak ferromagnetic like one between Tb3+ in 4 through chelating-bridging acetate anions, despite their similar crystal structures.