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A tricoordinated gold(I) chloride complex, tBuXantphosAuCl, supported by a sterically bulky 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene ligand (tBuXantphos) was synthesized. This complex features a remarkably longer Au-Cl bond length [2.632(1) Å] than bicoordinated linear gold complexes (2.27-2.30 Å) and tricoordinated XantphosAuCl [2.462(1) Å]. Single-crystal X-ray diffraction analysis of a cocrystal of tBuXantphosAuCl and pentafluoronitrobenzene (PFNB) and UV-vis spectroscopic titration experiments revealed the existence of an anion-π interaction between the Cl anion ligand and PFNB. Stoichiometric reaction between PFNB and tBuXantphosAuOtBu, after replacement of Cl by a more nucleophilic tBuO anion ligand, showed higher reactivity and para selectivity in the transformation of C-F to C-OtBu bond, distinctively different from that when only KOtBu was used (ortho selectivity) under the identical condition. Mechanistic studies including density functional theory calculations suggested a gold-mediated nucleophilic ligand attack of the C-F bond pathway via an SNAr process. On the basis of these results, using trimethylsilyl derivatives TMS-X (X = OMe, SEt, NEt2) as the nucleophilic ligand source and the fluorine acceptor, catalytic transformation of the C-F bond of aromatic substrates to the C-X (X = O, S, N) bond was achieved with tBuXantphosAuCl as the catalyst (up to 20 turnover numbers).

Molecular spintronics, which combines spintronics and molecular electronics, is an emerging field of research. Low-dimensional molecular magnets such as single molecule magnets (SMMs) and single chain magnets (SCMs) can potentially be used as spin carriers in spintronic devices, and hence have attracted considerable interest. By using different bridging ligands, a number of L.-M. Zheng (*) • M. Ren School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, People’s Republic of China e-mail: lmzheng@nju.edu.cn J. Tang State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, People’s Republic of China e-mail: tang@ciac.ac.cn H.-L. Sun Department of Chemistry, Beijing Normal University, Beijing, People’s Republic of China # Springer Science+Business Media Dordrecht 2016 Y. Xu et al. (eds.), Handbook of Spintronics, DOI 10.1007/978-94-007-6892-5_26 617 compounds showing SMM or SCM behaviors have been reported. This review article covers the following aspects: (1) SMMs based on the oxo-bridged transition metal clusters with the main focus on the Mn-O and Fe-O clusters; (2) SMMs based on single metal (lanthanide, actinide, transition metal) ions as well as polynuclear lanthanide clusters; (3) single chain magnets; and (4) recent development of spintronics based on SMMs such as molecular spin transistors and spin valves.

Two novel complexes of CoL1(SCN)2(H2O)2 4H2O (1) and CoL2(SCN)2(H2O)2 2H2O (2) (L1 = bis(4-pyridinecarboxamide)-1,2-ethane-N,N′-dioxide and L2 = bis(4-pyridinecarboxamide-1,6-hexane)-N,N′-dioxide) constructed by pre-designed ligands of bis(4-pyridinecarboxamide)alkanes-N,N′-dioxide have been synthesized and structurally characterized. Both compounds contain similar 1D chains bridged by the ligands. However, the chains in 1 and 2 are connected by different interchain hydrogen bonds to form different 2D layers, which depend on the flexibility and length of the ligands. Furthermore, the thermal stability of 1 and 2 were studied by using thermogravimetric analysis and temperature dependent powder X-ray diffraction method.

By the reaction of Zn(OAc)(2)·2H(2)O with Ozagrel, (E)-3-(4-((1H-imidazol-1-yl)methyl)phenyl)acrylic acid (Himpaa), a novel coordination polymer [Zn(impaa)(2)](n)(1) was synthesized and was characterized by IR, elemental analysis, single-crystal X-ray diffraction analysis, photoluminescence spectroscopy, and thermogravimetric and differential thermal analysis. The four-coordinate Zn(II) ions are linked into 1D double-helical chain by the deprotonated impaa(-), which is extended into a 3D supramolecular structure through intermolecular C-H···O hydrogen bonds.

Two isostructural compounds [M(hpmc)(phen)(H 2 O)] [M = Mn (1), Co (2); H 2 hpmc = 6-hydroxypyrimidine-4-carboxylic acid, phen = 1,10-phenanthroline] were synthesized by the in-situ hydrothermal reactions of 6-chloropyrimidine-4-carboxylic acid (Clpmc) with Mn II and Co II ions, in which the metal centers are bridged by pyrimidine ring to form 1D chain. Magnetic studies indicate pyrimidine can transmit antiferromagnetic coupling and the Co II complex shows spin-canting behavior below 3.5 K.

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.

Two supramolecular cocrystals, 1, pyrene/1,4-diiodotetrafluorobenzene (1,4-DITFB), and 2, pyrene/1,2-diiodotetrafluorobenzene (1,2-DITFB), have been prepared and characterized using X-ray diffraction analysis and multiple spectroscopic methods. Several intermolecular interactions such as C–I⋯I–C, C–I⋯π, π–π and C–H⋯F were observed in cocrystal 1 and/or 2, in which DITFB molecules act simultaneously as an isolator to prevent the pyrene molecule from aggregating and also as a heavy atom effect agent to induce phosphorescence emission from pyrene. The spectral results demonstrate that the two cocrystals both display strong phosphorescence at room temperature with decay rates of 1.7 × 103 s−1 and 0.22 × 103 s−1, respectively. The differences in the phosphorescence behavior between 1 and 2 are relevant to the local molecular environment created by 1,4- or 1,2-DITFB in cocrystals.

The neutral dimer complex Re2(CO)6(BIZ)2 was directly obtained from a simple reaction between Re(CO)5Cl and N∩OH-type ligand 2-(1-phenyl-1H-benzoimidazol-2-yl)phenol (HBIZ). The further reaction of...

We have developed a new protocol in- volving the "copper(II) chloride-cesium carbonate" system for the aerobic oxidation of primary alco- hols. Cesium carbonates and the solvents such as toluene and 1,2-dichloroethane play important roles to form a catalytically active intermediate contain- ing a m-hydroxyl-bridged trinuclear copper moiety (complex 1). From the X-ray crystal structure of complex 1, an electrostatic interaction between chloride anions and cesium cations was observed, which stimulated us to understand the roles of cesium carbonate in this reaction as a base, stabiliz- ing and "solvating" intermediates in toluene and 1,2-dichloroethane.

A new pillared-layer coordination polymer, [Co(3)(pybz)(2)(pico)(2)](n) (1; pybz = 4-(pyridin-4-yl)benzoate, pico = 3-hydroxypicolinate), contains rare 2D [Co(3)(pico)(2)](n)(2n+) layers formed by linear cobalt(II) trimers through the unusual mu(4)-kappaN,O:kappaO'-mu(2):kappaO''-mu(2) bridging mode of pico ligands, which are further cross-pillared by exotridentate bridging pybz ligands to form a three-dimensional structure with an unusual uninodal 8-connected body-centered-cubic topology. The bulk magnetic behavior of 1 exhibits ferrimagnetic long-range ordering below 2.6 K, which mainly arises from the cooperative magnetic effect of the intra- and intertrimer arrangements in the 2D magnetic system based on the nature of the exchange modes of mu(2)-hydroxyl, mu(2)-carboxylate oxygen, and 1,1,3-mu(3)-carboxylate bridges.

Single-chain magnets (SCM) are a novel class of molecular magnetic materials exhibiting slow magnetic relaxation, which arises from large uniaxial type magnetic anisotropy, strong intrachain and very weak or negligible interchain magnetic interactions. Although more than 20 examples of SCM have been reported, the controlled synthesis of SCM is still a challenge. Here we review the three strategies for the construction of SCM, highlight typical examples, discuss the role of intrachain and interchain interactions on the overall magnetic behavior of SCM as well as how to control or tune these interactions. For each strategy we present the advantages/shortcoming and then point out the main directions that remain to be developed in the field.

Correction for ‘Isostructural lanthanide-based metal–organic frameworks: structure, photoluminescence and magnetic properties’ by Li-Lin Luo et al., Dalton Trans., 2018, 47, 925–934.

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.

Field cultivation practices affected soil temperature that influenced the crop development of winter crops. This study was undertaken to determine the effects of different mulch materials, tillage depths and planting methods on spike differentiation of winter wheat (Triticum aestivum L.). The field experiment was consisted of three tests: (i) polythene mulch, straw mulch and no mulch; (ii) ridge planting and furrow planting; (iii) conventional tillage and shallow tillage. The results showed that soil temperature was affected by different practices. The higher soil temperature under polythene mulch resulted in the earlier initiation of spike differentiation, while straw mulch decreased soil temperature in spring that delayed the initiation compared with the non-mulch treatment. The spike initiation under ridge planting started earlier than that of furrow planting. Reduced tillage delayed the initiation compared with the conventional tillage. Duration of spike differentiation lasted longer under earlier starting of initiation that increased the grain numbers per spike. Other yield component characters were not affected by soil temperature. It was concluded that in the North China Plain where grain-filling duration of winter wheat was limited, agricultural practices that increased soil temperature in spring were favorable for grain production.

A unique two-dimensional layer-based material [Cu(μ1,1-N3)2(H2O)][CuL2] (1, L = 2-methylpyrazine-5-carboxylate) was produced by a stepwise, microwave-assisted synthesis, featuring linear Cu(II)-μ1,...

Two related CoII 5-aminoisophthalate coordination frameworks [Co5(μ3−OH)2(5-NH2-bdc)4(H2O)2]·7.5H2O (1, 5-NH2-bdc = 5-aminoisophthalate) and [Co5(μ3−OH)2(5-NH2-bdc)4(bpy)0.5(H2O)]·3H2O (2, bpy = 4,4′-bipyridine) based on [Co5(μ3−OH)2] clusters have been synthesized by hydrothermal reaction, structurally described, as well as properties characterized, that have unusual 3D networks with high connectivity (3,12) and (3,13)-connected, respectively. Notably, the unique (3,13)-connected framework is constructed from the (3,12)-connected network analogue and 4,4′-bipyridyl spacer. Magnetic studies show that a dominant antiferromagnetic coupling between Co(II) ions, and the generation of relatively effective noncompensated moments at very low temperature, mainly arises from the cooperative magnetic effect of the intercluster arrangement in the Td−SP-3Oh mixed-geometry-based pentamer.

Treatment of Ln(NO3)3 · 6H2O with 1, 2-phenylenedioxydiacetic acid (H2PDOA) in ethanol leads to the unusual 1-D double chain complexes {[Ln(PDOA)1.5 (H2O)3] · H2O}n (Ln = Sm (1), Eu (2), Dy (3)), in which the Ln3+ ions are linked by pentadentate and bideatate PDOA ligands in two different directions. The chain looks like a ladder containing two –Ln–O–C–O–Ln– chains and PDOA spacers, which has never been observed in the lanthanide carboxylate complexes, and they exhibit different photoluminescence properties.

The magnetic and photo-magnetic properties of Co dinuclear compounds were studied. The Co compounds, [{Co(tpa)} 2 (dhbq)](BF 4 ) 3 · 2H 2 O and [{Co(tpa)} 2 (dhbq)](ClO 4 ) 3 · 2H 2 O, have the structure [(tpa)Co III-LS –(μ-dhbq) 3− –Co III-LS (tpa)] 3− (where LS, H 2 dhbq, tpa denote low-spin, 2,5-di-hydroxy-1,4-benzoquinone and tris(2-pyridylmethyl)amine, respectively) at room temperature. On heating, these compounds exhibit valence-tautomeric inter-conversion; [(tpa)Co III-LS –(μ-dhbq) 3− –Co III-LS (tpa)] 3− ⇆ [(tpa)Co II-HS –(μ-dhbq) 2− –Co III-LS (tpa)] 3− (where HS denotes high-spin). Furthermore, both of these compounds exhibit photo-induced valence tautomerism at low temperature (

The complexes [Ln2(PDOA)3(phen)2(H2O)2] · 2H2O (Ln = Eu (1), Tb (2), and Dy (3); H2PDOA = 1,2-phenylenedioxydiacetic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single crystal X-ray diffraction methods. The three complexes are all binuclear molecules. The two Ln(III) centers are linked by only one PDOA ligand through its two bidentate-chelating carboxylate groups. PDOA also acts as a terminal ligand using one carboxylate oxygen and ether oxygen atoms to chelate the Ln(III) ion. 3-D supramolecular frameworks are built up by the hydrogen bonds and π–π stacking interactions. The fluorescent spectra of the three complexes show the characteristic emission of the Eu(III) for 1, Tb(III) for 2, and Dy(III) for 3, respectively.

The present article investigates a reversible structural phase transition, and related physical properties change in a new quasi-one-dimensional (1D) organic semiconductor crystal, DBA(TCNQ)2 [DBA = dibutylammonium, TCNQ = 7,7,8,8-tetracyanoquinodimethane]. Differential scanning calorimetry traces reveal the DBA(TCNQ)2 single crystal undergoes a first-order reversible phase transition at around 260−270 K, which is accompanied by a dramatic change in both conductivity and magnetic susceptibility. A direct correlation of physical properties with crystal structure is established. Detailed X-ray structure analyses indicate a reversible structural change related to dimer−tetramer transition along the TCNQ chain and disruption of the hydrogen-bonding chains as the temperature decreases from 270 to 253 K, which is the origin of the electronic and magnetic transition.

Straw mulching is an effective measure to conserve soil moisture. However, the existence of straw on the soil surface also affects soil temperature, which in turn influences crop growth, especially of winter crops. Five-year field experiments (2000–2005) investigated the effects of straw mulching and straw mass on soil temperature, soil evaporation, crop growth and development, yield and water use efficiency (WUE) of winter wheat (Triticum aestivum L.) at Luancheng Station on the North China Plain. Soil is a moderately well-drained loamy soil with a deep profile at the station. Two quantities of mulch were used: 3000 kg ha−1 [less mulching (LM)] and 6000 kg ha−1 [more mulching (MM)], representing half and all of the straw from the previous crop (maize). In the control (CK), the full quantity of mulch was ploughed into the top 20 cm of soil. The results showed that the existence of straw on the soil surface reduced the maximum, but increased the minimum diurnal soil temperature. When soil temperature was decreasing (from November to early February the next year), soil temperature (0–10 cm) under straw mulching was on average 0.3°C higher for LM and 0.58°C higher for MM than that without mulching (CK). During the period when soil temperature increased (from February to early April, the recovery and jointing stages of winter wheat), average daily soil temperature of 0–10 cm was 0.42°C lower for LM and 0.65°C lower for MM than that of CK. With the increase in leaf area index, the effect of mulching on soil temperature gradually disappeared. The lower soil temperature under mulch in spring delayed the development of winter wheat up to 7 days, which on average reduced the final grain yield by 5% for LM and 7% for MM compared with CK over the five seasons. Mulch reduced soil evaporation by 21% under LM and 40% under MM compared with CK, based on daily measuring of microlysimeters. However, because yield was reduced, the overall WUE was not improved by mulch.

Carbon nanotube (CNT) mediated delivery system of drugs etc. has currently aroused a large interest. Because the delivery system will be ultimately introduced into the human body, the information about the in vivo biological behavior and consequences of CNTs becomes very important. Here, using [14C-taurine]-multi-walled CNTs (MWCNTs) as tracers, we show the biodistribution and translocation pathways of MWCNTs in mice by three different routes. After mice were exposed by intravenous injection, MWCNTs predominately accumulated in liver and retained for long time. Transmission electron micrographs clearly show the remarkable entrapment of MWCNTs in hepatic macrophages (Kupffer cells). The biological index examinations indicate low liver acute toxicity of MWCNTs. Some favorable aspects of MWCNTs being used as a drug nanovehicle are also discussed.

2D dysprosium complex exhibiting slow magnetic relaxation originating from the strong Ising anisotropy of single Dy3+ ions has been reported., A new 2D dysprosium layer compound has been successfully synthesized from reaction with 2-(3-pyridyl) pyrimidine-4-carboxylic acid (H3-py-4-pmc), in which the Dy3+ ions reside in square antiprismatic coordination environments and are connected by carboxylate/oxalate/hydroxyl bridges. Magnetic studies reveal ferromagnetic interactions between Dy3+ ions, slow magnetic relaxation with an effective energy barrier U eff of 186 K under zero dc field and pronounced hysteresis loops at low temperatures. Further dilution magnetic study suggests that the slow magnetic relaxation originates from the single-ion magnetic behavior of Dy3+ ion and that magnetic coupling suppresses the quantum tunneling of magnetization at low temperature. In addition, theoretical calculation indicates strong Ising anisotropy of the Dy3+ ion that is due to the strong interaction between Dy3+ ions and hydroxyl groups.

The introduction of NaBPh(4) into a methanolic solution of CoCl(2)·(6)H(2)O and 2-[(pyridine-2-ylimine)-methyl]phenol (Hpymp) afforded {[Co(II)(3)(pymp)(4)(MeOH)(2)][BPh(4)](2)}·(2)MeOH (1) with a centro-symmetrically linear trinuclear structure. Magnetic analysis of 1 exhibited significant intracluster ferromagnetic exchange (2.4 cm(-1)) and slow relaxation of magnetization in both zero and non-zero static fields below 5 K, giving the first [Co(II)(3)] single molecule magnet with an effective energy barrier of 17.2(3) cm(-1) under a 500 Oe dc field.

Granular C/Co/C films have been prepared by magnetron sputtering from C and Co onto glass substrates at room temperature and subsequent in situ annealing. It has been found that the structure and magnetic properties of the C/Co/C films depend strongly on the Co layer thickness. Vibrating sample magnetometer measurements indicate that the in-plane coercivities reach maximum in 20 nm Co thickness of both as-deposited and annealed films. The squareness ratio of annealed films was more than 0.8. X-ray diffraction shows that majority Co nanograins are formed as the hexagonal-close-packed (HCP) structure in 20 nm Co thickness with annealing at 400 °C. Scanning probe microscope was used to scan surface morphology and magnetic domain structures. The values of the surface roughness were lower than 0.6 nm in all annealed samples. The average magnetic cluster size was estimated to be about 10 nm in annealed 20 nm Co thickness films.

Mono-, bis-, and trismaleimides (MM-2, BM-4, and TM-6, respectively) bearing electron-donating chromophores generally displayed strong fluorescence quenching. The quenching mechanism of fluorescence was revealed by electrochemical studies. On the basis of the electrochemical data, an energy level diagram was established for these maleimides. The electron-donating ability increased in the order of TM-6 < BM-4 < MM-2. The electron-accepting ability increased in the opposite order, that is, from MM-2 to BM-4 to TM-6. The copolymerization of multimaleimides with diamine could be well monitored by fluorescence spectroscopy. Compared with fluorescence probe techniques, the fluorescence monitoring could directly reflect the consumption of C=C bonds. Furthermore, a novel trismaleimide resin was preliminarily studied, in which TM-6 was a dual-purpose functional monomer acting not only as a crosslinker but also as an intrinsic fluorophore to monitor its crosslinking or cure process.

The synthesis, X-ray data, and electronic structures of two manganese(III) 1D polymers ligated by tetrachlorocatechol, [Mn2III(H2L1)(Cl4Cat)4·2H2O]∞ (1) and [Mn2III(H2L2)(Cl4Cat)4·2CH3CN·2H2O]∞ (2), are reported. The electronic structures of the complexes have been determined by UV−vis−near-IR, IR, electron paramagnetic resonance (EPR), and magnetic susceptibility measurements. Both 1 and 2 are air stable in the solid state and in solution, unlike most of the previously reported o-quinone-chelated transition-metal complexes. Electronic spectroscopy exhibits a strong near-IR band near 1900 nm for both, suggesting the presence of a mixed-valence semiquinone−catecholate oxidation state of the catechol ligands, Mn2III(Cl4Cat)2(Cl4SQ)2, together with the pure catecholate forms. The presence of this isomer was further supported by EPR and magnetic susceptibility measurements. The complexes undergo intramolecular electron transfer (valence tautomerism) upon an increase of the temperature involving the equilibriu...

A three-dimensional (3D) Cu(II)-containing Prussian Blue analogue with two types of [Cr(CN)6]3- units, [Cu(2,2‘-dpa)]3[Cr(CN)6]2·3H2O (2,2‘-dpa = 2,2‘-dipicolylamine), was synthesized and character...

A 1D water tape consisting of vertex-sharing cyclic water hexamers has been observed, which represents a subunit of ice structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The synthesis, structures, and magnetic properties of four cyano-bridged MIIRuIII2 compounds prepared from the paramagnetic RuIII building blocks, trans-[Ru(salen)(CN)2]- 1 [H2salen = N,N‘-ethylenebis(salicylideneimine)] and trans-[Ru(acac)2(CN)2]- (Hacac = acetylacetone), are described. Compound 2, {Mn(CH3OH)4[Ru(salen)(CN)2]2}·6CH3OH·2H2O, is a trinuclear complex that exhibits antiferromagnetic coupling between MnII and RuIII centers. Compound 3, {Mn(H2O)2[Ru(salen)(CN)2]2·H2O}n, has a 2-D sheetlike structure that exhibits antiferromagnetic coupling between Mn and Ru, leading to ferrimagnetic-like behavior. Compound 4, {Ni(cyclam)[Ru(acac)2(CN)2]2}·2CH3OH·2H2O (cyclam = 1,4,8,11-tetraazacyclotetradecane), is a trinuclear complex that exhibits ferromagnetic coupling. Compound 5, {Co[Ru(acac)2(CN)2]2}n, has a 3-D diamond-like interpenetrating network that exhibits ferromagnetic ordering below 4.6 K. The density functional theory (DFT) method was used to calculate the molecular magnetic orbitals and the ma...

A phthalate-bridged copper(II) complex {[Cu(phth)(Phen)(H2O)] ⋅ H2O}n (H2phth: phthalic acid, Phen: 1,10-phenanthroline) has been synthesized by the reaction of CuCl2 and phthalic acid in the presence of 1,10-phenanthroline in aqueous solution. The crystal structure of the complex has been determined by X-ray diffraction analysis to be orthorhombic, with the centrosymmetric space group Pbcm, where a = 11.6652(3) A, b = 11.1709(3) A, c = 14.0532(4) A, V = 1831.28(9) A3, Z = 4. The L2− (the acid radical of H2phth) ion is coordinated to the Cu2+ ion as a monodentate ligand. Each L2− ion bridges two adjacent Cu2+ ions with its two oxygen atoms from two carboxylic groups to form a one-dimensional zigzag chain. The coordination water and uncoordinated carboxylic oxygen atoms from neighboring chains are linked through hydrogen bonds to form a two-dimensional structure. There is a weak interaction between the coordination water molecule and the Cu2+ ion in the neighboring chain.

Ternary terbium complexes with p-aminobenzoic acid (HL), [TbL3(DMSO)(H2O)]2 (1), [TbL3(DMF)(H2O)]2 (2) and [TbL3(Bpy)(H2O)]2·2H2O (3) (DMSO=dimethyl sulfoxide, DMF=N, N- dimethylformamide, Bpy=2, 2′- bipyridyl) have been synthesized, and their crystal structures determined. The luminescence properties of these complexes, including both the emission quantum yield and the fluorescence lifetime, have been investigated. The effect of a second ligand on the crystal structure and luminescence property of the ternary terbium p-aminobenzoic acid complexes, and the relationship between luminescence properties and crystal structure, including coordination mode of the L− ligand and the characteristics of a second ligand, are discussed.

In our paper, the cubic magnetocrystalline anisotropy was first considered while measuring the critical in-plane field range [Hip0, Hip2] of which vertical Bloch lines (VBLs) annihilated in the hard domains (Hip0 is the maximal critical in-plane field of which hard domains remain stable, Hip2 is the minimal critical in-plane-field of which all of the hard domains convert to soft bubbles (SBs) without VBLs). It was found that the critical in-plane fields change periodically when the crystal direction changes in plane, and their changes are opposite to the domain-erasing field. A six-fold symmetry of the critical in-plane field in the sample plane was observed. Applying in-plane field in different directions, the influence of crystal direction on the annihilation of VBLs in hard domain walls is of only a small magnitude.

Three coordination polymers of Co(II) with dicyanamide (dca) were obtained by adding coligands of 2,5-dimethylpyrazine-dioxide (2,5-dmpdo), 2,3,5-trimethylpyrazine-dioxide (2,3,5-tmpdo), or 2,3,5,6-tetramethylpyrazine-dioxide (2,3,5,6-tmpdo) to the binary system of Co-dca. Co2(dca)(4)(2,5-dmpdo)2 (1) crystallizes in the triclinic space group P with a=7.4962(2), b=9.0364(2), c = 10.4783(4) A, alpha = 72.567(1), beta = 72.557(1), gamma = 68.814(2) degrees , V = 616.61(3) A(3), Z = 1, and R1 = 0.0345. [Co3(dca)6(H2O)4].2(2,3,5-tmpdo) (2) is in the monoclinic space group C2/c with a = 29.477(1), b = 7.3735(2), c = 17.4631(7) A, beta = 93.652(1) degrees , V = 3787.9(2) A(3), Z = 4, and R1 = 0.0532. [Co(dca)2(H2O)2].2(2,3,5,6-tmpdo) (3) is in the monoclinic space group P2(1)/c with a = 9.4739(3), b = 11.3876(3), c = 12.1778(3) A, beta = 98.967(1) degrees , V = 1297.74(6) A(3), Z = 4, and R1 = 0.0481. 1 contains an unusual (4,4) Co-dca layer, representing a rare example of metal-dca coordination polymers with mixing 1,3-mu(2)- and 1,5-mu2-dca bridges. The Co-dca (4, 4) layers are connected by 2,5-dmpdo to give an alpha-Po-type network, which displays antiferromagnetic ordering below 10.8 K. 2 is a unique 3D framework composed of 2D twinned 1,5-mu2-dca bridged layers, which are connected by Co-H2O-Co linkages. The noncoordinated 2,3,5-tmpdo units and the coordination water molecules form hydrogen-bonded chains that thread the framework. 3 has alternating stacks of usual Co-dca (4, 4) layers through 1,5-mu2-dca bridges and organic layers of noncoordinated 2,3,5,6-tmpdo. Weak antiferromagnetic and weak ferromagnetic coupling was observed in 2 and 3, respectively.

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.

The reaction of MnCl2·4H2O and 2,5-dimethylpyrazine-dioxide (2,5-dmpdo) with various anions in H2O affords different complexes, the solid structures of which are controlled by the choice of counteranions. Reaction of MnCl2·4H2O and 2,5-dmpdo with NH4NCS yields [Mn(NCS)2(2,5-dmpdo)1.5(H2O)2]·0.5(2,5-dmpdo)·H2O (1), which contains Mn(II) dimers bridged by 2,5-dmpdo. However, with the replacement of NH4NCS with NaN3 or sodium dicyanamide (Na(dca)) in the above reaction, Mn(N3)2(2,5-dmpdo)(H2O)2 (2) or Mn(dca)2(2,5-dmpdo) (3) was isolated. Compound 2 consists of a one-dimensional zigzag chain constructed by 2,5-dmpdo bridging ligands. Compound 3 is comprised of two-dimensional layers constructed by bridging 2,5-dmpdo and dca ligands. These results unequivocally indicate that the nature of the counteranions, which play different roles in each complex, is the key factor governing the structural topologies of them. While using 2,3-dimethylpyrazine-dioxide (2,3-dmpdo) instead of 2,5-dmpdo, [Mn(dca)2(2,3-dmpdo)]·H...

Three new rare earth p-aminobenzoic acid complexes, [Tb2L6(H2O)2]n (1), [Tb2L6(H2O)4]·2H2O (2) and [ Tb ( phen ) 2 L 2 ( H 2 O ) 2 ] ( phen ) L · 4 H 2 O (3) (HL: p-aminobenzoic acid; phen: 1, 10-phenanthroline), with different structural forms are reported in this paper. Complex 1 is a polymolecule with a two-dimensional plane structure. Compound 2 is a binuclear molecule, and 3 appears to be a mononuclear complex. The fluorescence intensity, the fluorescence life-time and emission quantum yield of 2, which has two coordination water molecules, is better than those of 1, which has only one coordination water molecule. This is an unusual phenomenon for general fluorescent rare earth complexes. The fluorescence performance of 3 is the most unsatisfactory among the three complexes. Their crystal structures show that the coordination mode of the ligand is an important factor influencing the luminescence properties of a fluorescent rare earth complex.

A series of rare earth complexes with p-aminobenzoic acid (HL) have been synthesized: [RE2L6(H2O)2]n [RE=La (1), Ce(2), Pr(3), Sm(4), Eu(5), Tb(6), Dy(7), Er(9)] and [RE2L6(H2O)4]·2H2O [RE=Tb(6′), Ho(8), Yb(10), Lu(11), Y(12)]. The crystal structures of 1, 2, 6, 6′, 7, 9 and 12 have been determined and the isomorphous relationships of the others have been identified. Their structures change from two-dimensional (2D) array (the coordination number of the metal ions is nine for 1 and eight for 2–7 and 9) to double-nuclear structure (the metal ions are eight-coordinated) for 6′, 8 and 10–12, as controlled by lanthanide contraction. The structural type has been found influenced by the pH value of the reaction mixtures.

Series of lanthanide coordination polymers of Ln(pzdo)4(ClO4)3 (La 1, Ce 2, Pr 3, Sm 4, Eu 5, Gd 6, Tb 7, Y 8) were synthesized by addition of pzdo (pzdo=pyrazine-dioxide) into aqueous solution of Ln(ClO4)3. X-ray single crystal structure analysis reveals that all of them are isomorphous and crystallize in space group I4(1)/acd with a=b=15.4976(1) A, c=23.0985(3) A, Z=8 for exemplified Pr complex. Each Ln ion is coordinated by eight pzdo ligands, and each pzdo ligand bridges two metal ions, resulting in an eight-connected three-dimensional coordination network with square channels along c-direction.

Influence of rotating in-plane field on vertical Bloch lines in the walls of second kind of dumbbell domains (IIDs) was investigated, and a critical in-plane field range [H-ip(1),H-ip(2)] of which vertical-Bloch lines (VBLs) annihilated in IIDs is found under rotating in-plane field (H-ip(1) is the maximal critical in-plane-field of which hard domains remain stable, H-ip(2) is the minimal critical in-plane-field of which all of the hard domains convert to soft bubbles (SBs, without VBLs)). It shows that the in-plane field range [H-ip(1), H-ip(2)] changes with the change of the rotating angle Deltapsi. H-ip(1) maintains stable, while H-ip(2) decreases with the decreasing of rotating angle Deltapsi. Comparing it with the spontaneous shrinking experiment of IIDs under both bias field and in-plane field, we presume that under the application of in-plane field there exists a direction along which the VBLs in the domain walls annihilate most easily, and it is in the direction that domain walls are perpendicular to the in-plane field. (C) 2004 Elsevier B.V. All rights reserved.

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.