[Stem photosynthesis and its main influencing factors of Haloxylon ammodendron and Tamarix ramosissima.] / æ¢­æ¢­å’Œå¤šæžæŸ½æŸ³çš„æžå¹²å ‰åˆåŠå ¶ä¸»è¦å½±å“å› å­.

Stem photosynthesis (Pg) is an alternative and significant carbon source, playing a crucial role in plant survival under extreme environment. The main aims of this study were to quantify stem and leaf photosynthesis, find out the main drivers of Pg, and estimate the contributions of Pg to plant individual carbon balance of two dominant species Haloxylon ammodendron and Tamarix ramosissima in Gurbantunggut Desert. A Li-Cor 6400 portable photosynthesis system and a special chamber were used to measure leaf and stem photosynthesis. Ancillary measurements included leaf/stem functional trait (chlorophyll content, water content, leaf/stem area, carbon/nitrogen content, etc.) and environmental factors (air temperature and humidity, photosynthetically active radiation, soil temperature, and soil water content). Our results showed that Pg of H. ammodendron and T. ramosissima was 2.37 and 0.98 µmol·m-2·s-1, Pg refixation CO2 of stem respiration by 65%-76% and 57%-77% in H. ammodendron and T. ramosissima. Pg was influenced by photosynthetically active radiation, air temperature, soil temperature and water vapor deficit. Pg assimilation CO2 accounted for 8.2%-16.6% and 3.6%-8.3% of CO2 assimilation of H. ammodendron and T. ramosissima, respectively. The maximum value appeared at noon when temperature was high. There might be fundamental defects if we ignore the contribution of branch photosynthesis when predicting carbon process of desert ecosystem under the background of climate change.

CIP2A Causes Tau/APP Phosphorylation, Synaptopathy, and Memory Deficits in Alzheimer's Disease.

Protein phosphatase 2A (PP2A) inhibition causes hyperphosphorylation of tau and APP in Alzheimer's disease (AD). However, the mechanisms underlying the downregulation of PP2A activity in AD brain remain unclear. We demonstrate that Cancerous Inhibitor of PP2A (CIP2A), an endogenous PP2A inhibitor, is overexpressed in AD brain. CIP2A-mediated PP2A inhibition drives tau/APP hyperphosphorylation and increases APP ß-cleavage and Aß production. Increase in CIP2A expression also leads to tau mislocalization to dendrites and spines and synaptic degeneration. In mice, injection of AAV-CIP2A to hippocampus induced AD-like cognitive deficits and impairments in long-term potentiation (LTP) and exacerbated AD pathologies in neurons. Indicative of disease exacerbating the feedback loop, we found that increased CIP2A expression and PP2A inhibition in AD brains result from increased Aß production. In summary, we show that CIP2A overexpression causes PP2A inhibition and AD-related cellular pathology and cognitive deficits, pointing to CIP2A as a potential target for AD therapy.

Liposarcoma of the stomach: Report of two cases and review of the literature.

Liposarcoma of the stomach is extremely rare, and only 37 cases have been reported worldwide. We herein report two cases of liposarcoma of the stomach. The first patient was referred to our hospital with upper abdominal discomfort. The endoscopic examination revealed a tumor mass about 3 cm in diameter. The patient underwent a partial gastrectomy and had an uneventful recovery. The histopathological examination revealed a well-differentiated liposarcoma. The second patient had symptoms of upper abdominal discomfort combined with nausea and anorexia. Several palpable masses were found with endoscopy. Endoscopic submucosal dissection was the treatment used, and the postoperative course was uneventful. The histopathological diagnosis was a well-differentiated liposarcoma. The two patients did not undergo any adjuvant therapy. They are both currently in good condition without recurrence. Therefore, we believe that the outcome of liposarcoma of the stomach is positive, and surgical resection may be the first choice for treatment at present.

Extrasynaptic NMDA receptor-induced tau overexpression mediates neuronal death through suppressing survival signaling ERK phosphorylation.

Intracellular accumulation of the hyperphosphorylated tau is a pathological hallmark in the brain of Alzheimer disease. Activation of extrasynaptic NMDA receptors (E-NMDARs) induces excitatory toxicity that is involved in Alzheimer's neurodegeneration. However, the intrinsic link between E-NMDARs and the tau-induced neuronal damage remains elusive. In the present study, we showed in cultured primary cortical neurons that activation of E-NMDA receptors but not synaptic NMDA receptors dramatically increased tau mRNA and protein levels, with a simultaneous neuronal degeneration and decreased neuronal survival. Memantine, a selective antagonist of E-NMDARs, reversed E-NMDARs-induced tau overexpression. Activation of E-NMDARs in wild-type mouse brains resulted in neuron loss in hippocampus, whereas tau deletion in neuronal cultures and in the mouse brains rescued the E-NMDARs-induced neuronal death and degeneration. The E-NMDARs-induced tau overexpression was correlated with a reduced ERK phosphorylation, whereas the increased MEK activity, decreased binding and activity of ERK phosphatase to ERK, and increased ERK phosphorylation were observed in tau knockout mice. On the contrary, addition of tau proteins promoted ERK dephosphorylation in vitro. Taking together, these results indicate that tau overexpression mediates the excitatory toxicity induced by E-NMDAR activation through inhibiting ERK phosphorylation.

Crystal structure of 4,4',4''-(1,3,5-triazine-2,4,6-tri-yl)tripyridinium trichloride 2.5-hydrate.

The asymmetric unit of the title compound, C18H15N6 (3+)·3Cl(-)·2.5H2O, contains two independent (1,3,5-triazine-2,4,6-tri-yl)tripyridinium cations. Both cations are approximately planar, the r.m.s. deviations of fitted non-H atoms being 0.045 and 0.051 Å. In the crystal, extensive O-H⋯Cl, O-H⋯O, N-H⋯Cl and N-H⋯O hydrogen bonds and weak C-H⋯Cl and C-H⋯O inter-actions link the organic cations, Cl(-) anions and water mol-ecules into a three-dimensional supra-molecular architecture. π-π stacking between the pyridine rings of adjacent cations is also observed, the centroid-to-centroid distance being 3.7578 (8) Å.

Mononuclear gold(I) acetylide complexes with urea group: synthesis, characterization, photophysics, and anion sensing properties.

A series of mononuclear gold(I) acetylide complexes with urea moiety, R'(3)PAuC≡CC(6)H(4)-4-NHC(O)NHC(6)H(4)-4-R (R' = cyclohexyl, R = NO(2) (2a), CF(3) (2b), Cl (2c), H (2d), CH(3) (2e), (t)Bu (2f), OCH(3) (2g); R' = phenyl, R = NO(2) (3a), OCH(3) (3b); R' = 4-methoxyphenyl, R = H (4a), OCH(3) (4b)), have been synthesized and characterized. The crystal structures of Ph(3)PAuC≡CC(6)H(4)-4-NHC(O)NHC(6)H(4)-4-NO(2) (3a) and (4-CH(3)OC(6)H(4))(3)PAuC≡CC(6)H(4)-4-NHC(O)NHC(6)H(5) (4a) have been determined by X-ray diffraction. Complexes 2a-2g, 3b, and 4a-4b show intense luminescence both in the solid state and in degassed THF solution at 298 K. Anion binding properties of complexes 2a-2g, 3a-3b, and 4a-4b have been studied by UV-vis and (1)H NMR titration experiments. In general, the log K values of 2a-2g with the same anion in THF depend on the substituent R on the acetylide ligand of 2a-2g: R = NO(2) (2a) > CF(3) (2b) ≥ Cl (2c) > H (2d) > CH(3) (2e) ≈ (t)Bu (2f) ≥ OCH(3) (2g). Complex 2a with NO(2) group shows the dramatic color change toward F(-) in DMSO, which provides an access of naked eye detection of F(-).

5,6,7-Trichloro-2-meth-oxy-8-hy-droxy-quinoline.

In the title compound, C(10)H(6)Cl(3)NO(2), a mean plane fitted through all non-H atoms has an r.m.s. deviation of 0.035 Å. In the crystal, adjacent mol-ecules are connected by O-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distance = 3.650 (1) Å], resulting in an infinite chain which propagates in the b-axis direction.

Constructions of 1D helical chains with left-handed/right-handed helicity: a correlation between the helicity of 1D chains and the chirality of building blocks.

The reactions of [Ni(alpha-SS-L)](ClO(4))(2)/[Ni(alpha-RR-L)](ClO(4))(2) with dca(-) gave two enantiomers of [Ni(SS-L)](dca)(2) (S-) and [Ni(RR-L)](dca)(2) (R-) in acetonitrile/water, and two supramolecular stereoisomers of {[Ni(SS-L)](2)(dca)(3)(ClO(4)).DMF}(n) (Delta-) and {[Ni(RR-L)](2)(dca)(3)(ClO(4)).DMF}(n) (Lambda-) in acetonitrile/DMF, respectively (L = 5,5,7,12,12, 14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, dca = dicyanamide, N(CN)(2)(-)). While the reaction of racemic [Ni(alpha-rac-L)](ClO(4))(2) (containing an equal amount of SS and RR enantiomers) with dca(-) in acetonitrile/water or acetonitrile/DMF produced a trimer of [Ni(rac-L)(dca)](3).(dca).(ClO(4))(2).MeCN () rather than S-/R- or Delta-/Lambda-. X-ray single-crystal analysis reveals that S-/R- and Delta-/Lambda- crystallize in a chiral space group P2(1), while crystallizes in a centrosymmetric space group C2/c. In S-/R-, the [Ni(SS-L)](dca)(2)/[Ni(RR-L)](dca)(2) monomers are linked through intermolecular hydrogen bonds to form a two-dimensional sheet. While the intermolecular hydrogen bonding linking of {[Ni(SS-L)](2)(dca)(3)}(+)/{[Ni(RR-L)](2)(dca)(3)}(+) leads to the formation of a 1D right-handed helical chain of Delta- and 1D left-handed helical chain of Lambda-, respectively, demonstrating there is a correlation between the helicity of 1D chains and the chirality of building blocks. Complex forms a triangular structure of {[Ni(rac-L)(dca)](3)}(3+), in which the macrocyclic ligand L adopts unsymmetrical RR/RR/SS or RR/SS/SS configurations. The homochiral nature of S-/R- and Delta-/Lambda- are confirmed by the results of solid circular dichroism (CD) spectra measurements. The magnetic properties of chiral Delta-/Lambda- and achiral were investigated.

Three-dimensional lanthanide anionic metal-organic frameworks with tunable luminescent properties induced by cation exchange.

Three 3D lanthanide anionic metal-organic frameworks {K(5)[Ln(5)(IDC)(4)(ox)(4)]}(n) x (20H(2)O)(n) with 1D channels were synthesized under hydrothermal conditions [Ln = Gd (1), Tb (2), and Dy (3)]. The K(+) ions within the 1D channel are easily exchanged with various cations. The emission intensities of Tb(III) in 2 increased significantly upon the addition of Ca(2+) ions, while the introduction of other metal ions caused the intensities to be either unchanged or weakened.

Vanadium polyoxoanion-bridged macrocyclic metal complexes: from one-dimensional to three-dimensional structures.

The reactions of four-coordinated transition metal macrocyclic complexes [ML](ClO(4))(2) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, M = Ni, Cu) with NH4VO3 under different conditions gave four coordination polymers of {[(CuL)(0.5)(H2L)(1.5)][H2V10O2)] x 6H(2)O}(n) (1x6H(2)O), {[NiL](3)[V16O38(H2O)] x 6H(2)O}(n) (2 x 6H(2)O), {[NiL][VO(3)](2) x 0.33H2O}(n) (3.0.33H(2)O), and {[CuL][VO(3)](2) x 0.33H(2)O}(n) (4 x 0.33H2O). Single crystal X-ray diffraction analyses reveal that four diverse vanadium polyoxoanions, [H2V1oO28)(4-) cluster, [V16O38(H2O)](6-) cage, [V6O18](6-) ring, and [VO(3)](n)(n-) chain, were obtained from the same reactant NH(4)VO(3) under different conditions. In 1, the cluster anion [H2V10O28](4-) alternately bridges [CuL]2+/[H2L]2+ to form a one-dimensional chain, and the [V16O38(H2O)](6-) cage in 2 links three [NiL]2+ into a two-dimensional sheet. Compounds 3 and 4 show three-dimensional structures, which are constructed by the connections of hexanuclear [V6O18](6-) rings with [NiL]2+ in 3 and [VO3](n)(n-) chains with [CuL]2+ in 4, respectively, generating one-dimensional channels occupied by guest water molecules.

Gerardianin A, a new abietane diterpenoid from Isodon lophanthoides var. gerardianus.

A new abietane diterpenoid, gerardianin A (1), along with a known compound 6,7-dehydroroyleanone (2), has been isolated from the aerial parts of Isodon lophanthoides var. gerardianus [Bentham] H. Hara. The structure of 1 was determined on the basis of spectroscopic methods and X-ray single-crystal diffraction analysis.

The supramolecular isomerism based on argentophilic interactions: the construction of helical chains with defined right-handed and left-handed helicity.

The reactions of racemic and enantiopure macrocyclic compounds [Ni(alpha-rac-L)](ClO(4))(2) (containing equal amounts of SS and RR enantiomers), [Ni(alpha-SS-L)](ClO(4))(2), and [Ni(alpha-RR-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile/water afford three 1D helical chains of {[Ni(f-rac-L)][Ag(CN)(2)](2)}(n) (1), {[Ni(f-SS-L)](2)[Ag(CN)(2)](4)}(n) (Delta-2), and {[Ni(f-RR-L)](2)[Ag(CN)(2)](4)}(n) (Lambda-2); one dimer of [Ni(f-rac-L)][Ag(CN)(2)](2) (3); and one trimer of [Ni(f-rac-L)Ag(CN)(2)](3).(ClO(4))(3) (4) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Compounds 1, Delta-2, Lambda-2, and 3, which are supramolecular isomers, are constructed via argentophilic interactions. In 1, [Ni(f-RR-L)][Ag(CN)(2)](2) enantiomers alternately connect with [Ni(f-SS-L)][Ag(CN)(2)](2) enantiomers through intermolecular argentophilic interactions to form a 1D meso-helical chain, and the 1D chains are further connected through the interchain hydrogen bonds to generate a 2D network. When chiral [Ni(alpha-SS-L)](ClO(4))(2) and [Ni(alpha-RR-L)](ClO(4))(2) were used as building blocks, two supramolecular stereoisomers of Delta-2 and Lambda-2 were obtained, which show the motif of homochiral right-handed and left-handed helical chains, respectively, and the 1D homochiral helical chains are linked by the interchain hydrogen bonds to form a 3D structure. In 3, a pair of enantiomers of [Ni(f-RR-L)][Ag(CN)(2)](2) and [Ni(f-SS-L)][Ag(CN)(2)](2) connect with each other through intermolecular argentophilic interactions to form a dimer. The reaction of [Ni(alpha-rac-L)](ClO(4))(2) with K[Ag(CN)(2)] in acetonitrile gives a trimer of 4; each trimer is chiral with unsymmetrical RR, RR, and SS, or RR, SS, and SS configurations. The homochiral nature of Delta-2 and Lambda-2 was confirmed by the results of solid circular dichroism spectra measurements. The solid samples of 1-4 show strong fluorescent emissions at room temperature.

Anion recognition of chloride and bromide by a rigid dicobalt(II) cryptate.

The crystal structures of [Co 2L(Cl)](ClO 4) 3 ( 1), [Co 2L(Br)](ClO 4) 3 ( 2), [Co 2L(OH)(OH 2)]I 3 ( 3), and [Co 2L (1)(Cl)](ClO 4) 3 ( 4), the density functional theory calculations, as well as the binding constants of [Co 2L] (4+) toward Cl (-) and Br (-) and of [Co 2L (1)] (4+) toward Cl (-), are reported in this paper (L = N[(CH 2) 2NHCH 2(C 6H 4- p)CH 2NH(CH 2) 2] 3N, L (1) = N[(CH 2) 2NHCH 2(C 6H 4- m)CH 2NH(CH 2) 2] 3N). The rigid dicobalt(II) cryptate [Co 2L] (4+) shows the recognition of Cl (-) and Br (-) but not of F (-) and I (-), because of the size matching to its rigid cavity. We also found that the relative rigid tripodal skeleton of L than that of L (1) results in the higher affinity of [Co 2L] (4+) toward Cl (-). Magnetic susceptibility measurements of 1 and 2 indicate that the two Co(II) atoms in the cryptates are antiferromagnetically coupled through the Cl (-)/Br (-) bridge, with g = 2.19, J = -13.7 cm (-1) for 1, and g = 2.22, J = -17.1 cm (-1) for 2.

Spontaneous resolution of a racemic nickel(II) complex and helicity induction via hydrogen bonding: the effect of chiral building blocks on the helicity of one-dimensional chains.

The reactions of a racemic four-coordinated nickel(II) complex [Ni(alpha-rac-L)](ClO4)2 (containing equal amount of SS and RR enantiomers) with l- and d-phenylalanine in acetonitrile/water gave two less-soluble six-coordinated enantiomers of {[Ni( f-SS-L)(l-Phe)](ClO4)}n (Delta-1) and {[Ni(f- RR-L)(d-Phe)](ClO4)}n (Lambda-1), respectively. Evaporation the remaining solutions gave two six-coordinated diastereomers of {[Ni 3(f- RR-L)3(l-Phe)2(H 2O)](ClO4)4}n (a-2) and {[Ni3(f- SS-L)3(d-Phe)2(H2O)](ClO4)4}n (b-2), respectively (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, Phe(-) = phenylalanine anion). The reaction of [Ni(alpha-rac-L)](ClO4)2 with dl-Phe(-) gave a conglomerate of c-1; in which, the SS and RR enantiomers preferentially coordinate to l- and d-Phe(-) respectively to give a racemic mixture of Delta-1 and Lambda-1, and the spontaneous resolution occurs during the reaction, in which each crystal crystallizes to become enantiopure. Removing Phe(-) from Delta-1 and Lambda-1 using perchloric acid gave two enantiomers of [Ni(alpha-SS-L)](ClO4)2 (S-3) and [Ni(alpha-RR-L)](ClO4)2 (R-3). Dissolving S-3 and R-3 in acetonitrile gave two six-coordinated enantiomers of [Ni( f-SS-L)(CH3CN)2](ClO4)2 (S-4) and [Ni( f- RR-L)(CH3CN)2](ClO4)2 (R-4), while dissolving [Ni(alpha-rac-L)](ClO4)2 in acetonitrile gave a racemic twining complex [Ni(f-rac-L)(CH3CN)2](ClO4)2 (rac-4). Delta-1 and Lambda-1 belong to supramolecular stereoisomers, which are constructed via hydrogen bond linking of [Ni( f-SS-L)(l-Phe)](+) and [Ni(f-RR-L)(d-Phe)](+) monomers to form 1D homochiral right-handed and left-handed helical chains, respectively. The reaction of S-3 with d-Phe(-) gave {[Ni(f-SS-L)(d-Phe)](ClO4)}n (5), which shows a motif of a 1D hydrogen bonded zigzag chain instead of a 1D helical chain. Compound a-2/ b-2 contains dimers of [{Ni(f-RR-L)}2(l-Phe)(H2O)](3+)/[{Ni( f- SS-L)}2(d-Phe)(H2O)](3+) and 1D zigzag chains of {[Ni(f-RR-L)(l-Phe)](+)}n /{[Ni(f-SS-L)(d-Phe)](+) n . The homochiral nature of Delta-1/Lambda-1, a-2/b-2, S-3/R-3, and S-4/R-4 are confirmed by the results of circular dichroism (CD) spectra measurements.

CO2 fixation and transformation by a dinuclear copper cryptate under acidic conditions.

CO2 fixation and transformation by metal complexes continuously receive attention from the viewpoint of carbon resources and environmental concerns. We found that the dinuclear copper(II) cryptate [Cu2L1](ClO4)4 (1; L1 = N[(CH2)2NHCH2(m-C6H4)CH2NH-(CH2)2]3N) can easily take up atmospheric CO2 even under weakly acidic conditions at room temperature and convert it from bicarbonate into carbonate monoesters in alcohol solution. The compounds [Cu2L1(mu-O2COH)](ClO4)3 (2), [Cu2L1(mu-O2COR)](ClO4)3 (3: R = CH3; 4: R = C2H5; 5: R = C3H7; 6: R = C4H9; 7: R = C5H11; 8: R = CH2CH2OH), [Cu2L1(mu-O2CCH3)](ClO4)3 (9), and [Cu2L1(OH2)(NO3)](NO3)3 (10) were characterized by IR spectroscopy and ESI-MS. The crystal structures of 2-6 and 10 were studied by single-crystal X-ray diffraction analysis. On the basis of the crystal structures, solution studies, and DFT calculations, a possible mechanism for CO2 fixation and transformation is given.

Interchain-solvent-induced chirality change of 1D helical chains: from achiral to chiral crystallization.

Three helical supramolecular stereoisomers of meso-2, Delta-2, and Delta-3 with the formula of cis-[Ni(f-rac-L)][Ni(CN)4] were successfully constructed based on the [Ni(f-rac-L)2+ and [Ni(CN)4]2- building blocks (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). In all three supramolecular stereoisomers, cis-[Ni(f-rac-L)]2+ cations are alternately bridged by [Ni(CN)4]2- anions through two cis (in meso-2 and Delta-2) or trans (in Delta-3) cyano groups to form one-dimensional (1D) helical chains of cis-[Ni(f-rac-L)][Ni(CN)4]. In meso-2, the right/left-handed chirality of the originally formed chain is transferred oppositely to adjacent chains through the interchain hydrogen-bonding interactions of hexameric water clusters, leading to the formation of meso-2 with a central symmetrical space group, P21/n, in which the 1D helical chains are packed in an alternating right- and left-handed chirality. In Delta-2 and Delta-3, the right/left-handed chirality of the original chain is transferred uniformly to adjacent chains through the zipper-like interchain hydrophobic interactions, resulting in the formation of Delta-2 and Delta-3 with chiral space groups of P212121 and P3121, respectively, in which all of the 1D helical chains are arranged in the same right/left-handed chirality.

Syntheses, structures, and magnetic properties of the face-centered cubic clusters [Tp(8)(H(2)O)(12)M(6)Fe(8)(CN)(24)](4+) (M = Co, Ni).

Reactions between K[TpFe(CN)3] (Tp- = hydrotris(1-pyrazolyl)borate) and M(ClO4)2 x 6H2O (M = Co or Ni) in a mixture of acetonitrile and methanol afford, upon crystallization via THF vapor diffusion, [Tp8(H2O)12Co6Fe8(CN)24](ClO4)4.12THF x 7H2O (1) and [Tp8(H2O)12Ni6Fe8(CN)24](ClO4)4.12THF x 7H2O (2). Both compounds contain cyano-bridged clusters with a face-centered cubic geometry, wherein octahedral CoII or NiII centers are situated at the face-centering sites. The results of variable-temperature magnetic susceptibility measurements indicate the presence of ferromagnetic exchange coupling within both molecules to give ground states of S = 7 and 10, respectively. Low-temperature magnetization data reveal significant zero-field splitting, with the best fits for the Co6Fe8 and Ni6Fe8 clusters yielding D = -0.54 and 0.21 cm-1, respectively; ac magnetic susceptibility measurements performed on both samples showed no evidence of the slow relaxation effects associated with single-molecule magnet behavior.

A robust microporous 3D cobalt(II) coordination polymer with new magnetically frustrated 2D lattices: single-crystal transformation and guest modulation of cooperative magnetic properties.

A microporous 3D cobalt(II) coordination polymer featuring pillared layers [Co(2)(ma)(ina)](n) x 2nH(2)O (1 x 2H(2)O) (ma = malate, ina = isonicotinate) was generated by hydrothermal treatment with a void volume of 25.8%, in which the in-situ generated ma ligands connect the Co(II) ions into a 2D lattice with mixed and multiple exchange-bridges, affording a new geometrical topology different from the Kagomé lattice and leading to spin frustration. The rigid ina-pillared metallic-layered structure could retain 3D structural ordering upon guest removal and exchange. By soaking guest-free host in MeOH and methanamide (HCONH(2)) solutions, single crystals of dehydrated were transformed into single crystals of 1 x MeOH and 1 x HCONH(2), respectively, without apparent host-structural changes. 1 can also be rehydrated into 1 x 2H(2)O'. The guest-inclusion crystals have been characterized by X-ray single-crystal diffraction at 293 K and 93 K, confirming the single-crystal-to-single-crystal transformations and providing detailed information of the guest molecules confined in the subnanospace and host-guest and/or guest-guest hydrogen-bonding interactions. The magnetic behaviours of this family of porous magnetic materials are complex due to the influences of multiple metal sites, intra- and inter-layer exchanges, spin-orbit coupling, as well as geometrical frustration, which show magnetic ordering at <2 K, 3.5 K, 3.5 K, and 8 K for 1, 1 x MeOH, 1 x HCONH(2), and 1 x 2H(2)O, respectively, due to the different size of guest molecules along with the different host-guest interaction, which may slightly modify the path of magnetic exchange, decrease the intensity of the spin-frustration in the 2D lattice, and cooperatively enhance the magnetic ordering temperature.

Synthesis, structures, and magnetic properties of a series of cyano-bridged Fe-Mn bimetallic complexes.

The preparation and crystal structures of five cyano-bridged Fe-Mn complexes, [(bipy)2Fe(II)(CN)2Mn(II)(bipy)2]2(ClO4)4 (1), [(bipy)2Fe(II)(CN)2Mn(II)(DMF)3(H2O)]2(ClO4)4 (2), {[(Tp)Fe(III)(CN)3]2Mn(II)(DMF)2(H2O)}2 (3), {[(Tp)Fe(III)(CN)3]2Mn(II)(DMF)2}n (4), and Na2[Mn(II)Fe(II)(CN)6] (5) (bipy = 2,2'-bipyridine, Tp = tris(pyrazolyl)hydroborate), are reported here. Compounds 1-4 contain the basic Fe2(CN)4Mn2 square building units, of which 1-3 show the motif of discrete molecular squares of Fe2(CN)4Mn2 and 4 possesses a 1D double-zigzag chain-like structure, while compound 5 is a 3D cubic framework analogous to that of Prussian blue. Compounds 1 and 2 show weak ferromagnetic interactions between two Mn(II) ions through the bent -NC-Fe(II)-CN- bridges. Compound 3 shows weak antiferromagnetic coupling between the Fe(III) and Mn(II) ions, while compound 4 displays a metamagnetic-like behavior with TN = 5.2 K and Hc = 10.5 kOe. Compound 5 exhibits a ferromagnetic ordering with Tc= 3.5 K, coercive field, Hc, = 330 G, and a remnant magnetization of 503 cm3 Oe mol(-1).

Two supramolecular isomers of molecular squares and 1D helical chains with alternating right- and left-handed chirality.

The reaction of [Ni(alpha-rac-L)](ClO4)2 with K2[Ni(CN)4] gives a cyanide bridged [2+2] type of molecular square, {cis-[Ni(f-rac-L)][Ni(CN)4]}2 (1). By slightly changing the reaction conditions, the reaction of [Ni(alpha-rac-L)](ClO4)2 with KCN leads to a metastable compound, cis-[Ni(f-rac-L)(CN)2] (2), and an unexpected 1D helical chain, {cis-[Ni(f-rac-L)][Ni(CN)4]}n (3). In 3, the 1D helical chains are packed in an alternating right- and left-handed chirality due to the oppositely twisted arrangements of two adjacent [Ni(CN)4]2- anions. The metastable compound 2 can be converted to 3 in a CH3CN/CH3OH solution. Compounds 1 and 3 are classified as supramolecular isomers, and isomer 3 can be considered to be formed by the ring-opening polymerization of the square precursor 1. Magnetic susceptibility measurements of 1 and 3 show that the adjacent six-coordinated Ni(II) atoms are antiferromagnetically coupled through the bent -NC-Ni-CN- bridges of the diamagnetic [Ni(CN)4]2- anions, with g = 2.08 and J = -0.426 cm(-1) for 1 and g = 2.08 and J = -0.278 cm(-1) for 3. The correlation between the structures and the J values is discussed.