Photoconduction in [Fe(Htrz)2(trz)](BF4)·H2O nanocrystals

Sub-micron-sized [Fe(Htrz)(2)(trz)](BF(4))·H(2)O nanoparticles that exhibit a spin crossover transition are positioned between Au electrodes with sub-100 nm separation. After voltage poling, samples exhibit unexpected large conductivity, with photoconductance and photovoltaic behavior.     

1,2,4‐Triazole Controlled CdII/MnII Complexes with Discrete Mononuclear,Polymeric 1D Chain,and 2D Layer Motifs

Three Htrz‐based metal complexes, [Cd(trz)(CH₃OH)(nb)]_n ( 1 ), [Cd(Htrz)(H₂O)(nb)₂]_n ( 2 ), and {[Mn(Htrz)₂(H₂O)₄] · 2nb} ( 3 ) (Htrz = 1,2,4‐triazole, Hnb = 4‐nitrobenzoic acid), have been synthesized by diffusion or solvent evaporation method and structurally characterized by single crystal X‐ray crystallography, elemental analysis, IR and fluorescence spectroscopy, and TG‐DTA. Structural determinations revealed that complex 1 has a two‐dimensional (2D) layer structure constructed by tridentate μ_N1,N2,N4‐bridging trz anions and Cd^II ions. Complex 2 presents a 1D polymeric chain structure bridged by bidentate μ_N1,N4‐bridging Htrz molecule and Cd^II ions, whereas compound 3 is a supramolecular assembly containing a mononuclear [Mn(Htrz)₂(H₂O)₄]²⁺ dication and two free nb anions for charge compensation. Thus, the structural diversity of the three complexes is significantly governed by the coordination modes of the neutral/deprontated Htrz ligand, rather than the terminal/lattice nb anion. Additionally, the thermal stability of the complexes is observed to be dependent on the polymeric or discrete structure nature. At room temperature, the three solid complexes show Htrz‐based intraligand fluorescent emission.     

Three novel organic-inorganic complexes based on decavanadate [V10O28]6- units: special water layers, open 3D frameworks and yellow/blue luminescences

Three unusual polyoxovanadate-based inorganic-organic hybrid complexes, [Zn(Im)(2)(DMF)(2)](2)[H(2)V(10)O(28)]·Im·DMF (1), [Zn(3)(Htrz)(6)(H(2)O)(6)][V(10)O(28)]·10H(2)O·Htrz (2) and {[Zn(3)(trz)(3)(H(2)O)(4)(DMF)](2)[V(10)O(28)]·4H(2)O}(n) (3) (Im = imidazole, Htrz = 1,2,4-triazole, DMF = N,N'-dimethylammonium) have been synthesized at room temperature via evaporative crystallization, and characterized by single-crystal X-ray diffraction. Complex 1 shows the structure of a discrete [V(10)O(28)](6-) cluster grafted by two [Zn(Im)(2)(DMF)(2)](2+) fragments through two bridged oxygen atoms, representing a rarely observed coordination mode. Complex 2 consists of a linear trinuclear Zn(II) unit bridging six Htrz ligands and a [V(10)O(28)](6-) cluster as the counter anion, where the extensive hydrogen-bonding interactions lead to {Zn(3)-V(10)}(SMF) and a special water layer involving (H(2)O)(36) rings, and consequently forms a unique 3D metal-organic-water supramolecular network. Complex 3 can be described as a 3,4-connected fsc-type network, and is the first example of open coordination 3D framework based on [V(10)O(28)](6-) and the other two different secondary building units, involving mononuclear and binuclear Zn(II)-Htrz motifs. The optical properties of complexes 1-3 in the solid state are investigated at room temperature. The results show that complexes 1 and 3 emit intense blue luminescences attributed to the ligands, while complex 2 exhibits an infrequent fluorescent property, emitting both blue and yellow luminescences at 472 and 603 nm simultaneously. Furthermore, powder X-ray diffraction and thermogravimetric analyses of 1-3 are also investigated, which demonstrate their high purities and thermal stabilities.     

A facile route for the preparation of nanoparticles of the spin-crossover complex [Fe(Htrz)2(trz)](BF4) in xerogel transparent composite films

Films and monoliths containing the spin crossover complex [Fe(Htrz)(2)(trz)](BF(4)) (trz = 1,2,4-triazole) as nanoparticles have been obtained. The dispersion and consecutive inclusion of the Fe complex in a silica matrix prepared from tetramethoxysilane or tetraethoxysilane afford monoliths or films with a violet colour at room temperature, which turns white above 380 K. This change of colour is reversible. This thermochromic behaviour has been characterized by measuring the magnetic properties together with thermogravimetric studies and Raman spectroscopy, the result of which all demonstrate that both films and monoliths undergo a spin crossover. Microscopy studies confirm the occurrence of the Fe complex as nanoparticles, in both the monoliths and the films. The facile synthesis of these materials as nanoparticles in transparent films should open the possibility of the synthesis of high quality films.     

One-dimensional CuBr4(2-) ion array and CuBr3- ion chain included in the pi conducting framework composed of bis(methylthio)tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide molecules

The reaction of a new donor molecule having a planar but largely bent skeleton, bis(methylthio)tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide (1), with CuBr(2) in CH(3)CN/CS(2) afforded a black-colored crystal with a formula of 1(4).CuBr(4).2CuBr(3). In the crystal 1 molecules are one-dimensionally stacked to form half-cut pipelike columns, which are arranged to construct two different shapes of channels included by a one-dimensional array of CuBr(4)(2)(-) ions and a bibromide-bridged linear chain of CuBr(3)(-) ions with a square-pyramidal geometry at the Cu atom, [CuBr(3)(-)](n)(), respectively. The room-temperature electrical conductivity on the single crystal of 1(4).CuBr(4).2CuBr(3) was 2.0 x 10(-)(2) S cm(-)(1), and the temperature dependence of electrical conductivity was semiconducting with a large activation energy of 160 meV. The interactions between the neighboring Cu(II) d spins in the one-dimensional S = 1/2 spin systems due to CuBr(4)(2)(-) ions and CuBr(3)(-) ions in [CuBr(3)(-)](n)() were both antiferromagnetic, and the magnitudes were moderate (Weiss temperature, THETAV; = -18 K) in the former spin system and fairly large (coupling constant, J/k(B) = -120 K) in the latter spin system, which was in marked contrast to a moderate and ferromagnetic [CuBr(3)(-)](n)() chain in the cyclohexylammonium salt already known.     

Synthesis,X-ray diffraction structures,spectroscopic properties,and in vitro antitumor activity of isomeric (1H-1,2,4-triazole)Ru(III) complexes

Three ruthenium(III) complexes containing 1H-1,2,4-triazole (Htrz), viz., (H(2)trz)[cis-RuCl(4)(Htrz)(2)], 1, (H(2)trz)[trans-RuCl(4)(Htrz)(2)], 2, and (Ph(3)PCH(2)Ph)[trans-RuCl(4)(Htrz)(2)], 3, have been synthesized by reaction between RuCl(3) and excess of the triazole in 2.38 M HCl (1 and 2), while 3 was obtained by metathesis of 2 and [Ph(3)PCH(2)Ph]Cl in water. The products were characterized by IR, UV-vis, electrospray mass spectrometry, cyclic voltammetry, and X-ray crystallography (1 and 3). X-ray diffraction study revealed cis and trans arrangements of the triazole ligands in 1 and 3, correspondingly, and unprecedented monodentate coordination of the triazole through N2 and stabilization of its 4H tautomeric form, which is the disfavored one for the free triazole. The cytotoxicity of 1 and 2 has been assayed in three human carcinoma cell lines SW480, HT29 (colon carcinoma), and SK-BR-3 (mammary carcinoma). Both compounds exhibit antiproliferative activity in vitro. Time-dependent response of all three lines to 1 and 2 and a structure-activity relationship, i.e., higher activity of the trans-isomer 2 than that of cis-species 1, have been observed.     

Thermal-transport studies on two-dimensional quantum spin liquids

Quantum spin liquids (QSLs) are fluidlike states of quantum spins in which the long-range ordered state is destroyed by quantum fluctuations. The ground state of QSLs and their exotic phenomena, which have been extensively discussed for decades, have yet to be identified. We employ thermal-transport measurements on newly discovered QSL candidates κ-(BEDT-TTF)(2)Cu(2)(CN)(3) and EtMe(3)Sb[Pd(dmit)(2)](2), and report that the two organic insulators have different QSLs characterized by different elementary excitations. In κ-(BEDT-TTF)(2)Cu(2)(CN)(3), heat transport is thermally activated at low temperatures, and this suggests the presence of a spin gap in this QSL. In stark contrast, in EtMe(3)Sb[Pd(dmit)(2)](2), a sizable linear temperature dependence of thermal conductivity is clearly resolved in the zero-temperature limit, and shows gapless excitation with a long mean free path (ca. 1000 lattice distances). Such a long mean free path demonstrates a novel feature of QSL as a quantum-condensed state with long-distance coherence.     

新型"分子合金"类Fe(II)配合物的合成和自旋转换性能

合成了Fe[(Htrz)~9~/~4(NH~2trz)~3~/~4](BF~4)~2.H~2O(1)和Fe[(Htrz)~3~/~2(NH~2trz)](BF~4).3H~2O(2)两个"分子合金"类自旋转换配合物。其变温光谱表明,它们在室温附近具有自旋转换行为,同时还伴有热致变色及滞后现象。     

自旋转换-氧化石墨烯纳米复合材料的制备及磁性

利用氧化石墨烯（GO）表面具有丰富含氧基团的特点,采用原位生长法将经典的亚铁三氮唑自旋转换（SCO）配位聚合物[Fe（Htrz）₂（trz）]（BF₄）负载到二维材料GO的表面。利用X射线粉末衍射（PXRD）、红外光谱（FTIR）、SEM、TEM、拉曼等手段对自旋转换-氧化石墨烯（SCO-GO）纳米复合材料进行了表征。通过光谱表征发现,复合材料的FTIR和PXRD特征峰为GO和[Fe（Htrz）₂（trz）]（BF₄）特征峰的叠加,初步证明了自旋转换-氧化石墨烯纳米复合材料已成功制备。SEM和TEM分析直观地显示立方体状的[Fe（Htrz）₂（trz）]（BF₄）纳米颗粒均匀地分散在氧化石墨烯表面,且随着原位生长时间的增加,GO表面的[Fe（Htrz）₂（trz）]（BF₄）的负载量增加、尺寸增大。拉曼图谱表明[Fe（Htrz）₂（trz）]（BF₄）负载到GO表面后,氧化石墨烯特征拉曼峰的强度比（ID/IG）增大,说明氧化石墨烯的缺陷密集程度增大,[Fe（Htrz）₂（trz）]（BF₄）纳米颗粒与石墨烯之间的作用力增强。磁性测试表明不同自组装时间（1、6、12 h）的SCO-GO复合材料的T_1/2↑分别为381.1、381.5和382.4 K,T_1/2↓分别为345.9、345.0和344.8 K,其磁滞回线宽度分别为35.2、36.5和37.6 K,这是由于不同自组装时间的SCO-GO复合材料中[Fe（Htrz）2（trz）]（BF4）的负载量和尺寸的差异导致的。DSC分析结果和磁性结果一致,证实了SCO-GO复合材料自旋转变温度向高温区移动。     

Transition metal bisdithiolene complexes based on extended ligands with fused tetrathiafulvalene and thiophene moieties: new single-component molecular metals

The gold and nickel bisdithiolene complexes based on new highly extended ligands incorporating fused tetrathiafulvalene and thiophene moieties (alpha-tdt=thiophenetetrathiafulvalenedithiolate and dtdt=dihydro- thiophenetetrathiafulvalenedithiolate), were prepared and characterised by using cyclic voltammetry, single crystal X-ray diffraction, EPR, magnetic susceptibility and electrical transport measurements. These complexes, initially obtained under anaerobic conditions as diamagnetic gold monoanic [nBu(4)N][Au(alpha-tdt)(2)] (4), [nBu(4)N][Au(dtdt)(2)] (3) and nickel dianionic species [(nBu(4)N)(2)][Ni(alpha-tdt)(2)] (8), [(nBu(4)N)(2)][Ni(dtdt)(2)] (7), can be easily oxidised to the stable neutral state just by air or iodine exposure. The monoanionic complexes crystallise in at least two polymorphs, all of which have good cation and anion segregation in alternated layers, the anion layers making a dense 2D network of short SS contacts. All of the neutral complexes, obtained as microcrystalline or quasi amorphous fine powder, present relatively large magnetic susceptibilities that correspond to effective magnetic moments in the range 1-3 mu(B) indicative of high spin states and very high electrical conductivity that in case of the Ni compound can reach sigma(RT) approximately 250 S cm(-1) with a clear metallic behaviour. These compounds are new examples of the still rare single-component molecular metals.     

Synthesis and structural characterization of a TCNQ based organic semi-conducting material with a 2:5 stoichiometry

The tetrabutylammonium complex with a 2:5 stoichiometry, (n-Bu(4)N)(2)(TCNQ)(5), has been prepared and structurally characterized by X-ray crystallography. Diagnostic bands in the Raman spectrum and signature features in the electrochemistry confirm that the TCNQ moieties are partially charged in the solid state. EPR, magnetic susceptibility, and electrical conductivity measurements are all consistent with (n-Bu(4)N)(2)(TCNQ)(5) behaving as a quasi-one-dimensional organic semiconductor.     

Structure determination and magnetic studies of triazole chelated Co(II) coordination polymers

Two cobalt(II) halide complexes with 1,2,4-triazole as a ligand were synthesized. Their structures were determined by extended x-ray absorption fine structure (EXAFS) and powder x-ray diffraction (XRD). Both complexes [Co(Htrz)Cl₂]_n ( 1 ) and {[Co(Htrz)₂(trz)]BF₄}_n ( 2 ) form one-dimensional polymeric chain and the distances of Co⋯Co are 3.3521(2) Å and 3.8629(2) Å, respectively. The Htrz and Cl⁻ are bridging ligands to connect two Co(II) ions in 1 , and the local environment of Co site is in a distorted octahedron with {CoN₂Cl₄} core. In complex 2 , two Htrz and one trz are bridging ligands to connect two Co(II) ions, and the local geometry of Co is in a pseudo octahedron with {CoN₆} core. The analysis of Co L_II,III-edge XAS indicates that the Co(II) of both complexes are at high spin state with t_2g⁵e_g² configuration and the crystal field strength (10Dq) is about 1.2 eV. The broken-symmetry DFT calculations indicate that antiferromagnetic coupling state of Co⋯Co is the most stable state in both complexes; and the coupling constants of 1 and 2 are −0.32 cm⁻¹ and −3.70 cm⁻¹, respectively. Based on the distances of Co⋯Co and coupling constants, such antiferromagnetic interaction is achieved through triazole ligands.     

Tuning of redox potentials for the design of ruthenium anticancer drugs -- an electrochemical study of [trans-RuCl(4)L(DMSO)](-) and [trans-RuCl(4)L(2)](-) complexes, where L = imidazole, 1,2,4-triazole, indazole

The electrochemical behavior of [trans-RuCl(4)L(DMSO)](-) (A) and [trans-RuCl(4)L(2)](-) (B) [L = imidazole (Him), 1,2,4-triazole (Htrz), and indazole (Hind)] complexes has been studied in DMF, DMSO, and aqueous media by cyclic voltammetry and controlled potential electrolysis. They exhibit one single-electron Ru(III)/Ru(II) reduction involving, at a sufficiently long time scale, metal dechlorination on solvolysis, as well as, in organic media, one single-electron reversible Ru(III)/Ru(IV) oxidation. The redox potential values are interpreted on the basis of the Lever's parametrization method, and particular forms of this linear expression (that relates the redox potential with the ligand E(L) parameter) are proposed, for the first time, for negatively (1-) charged complexes with the Ru(III/II) redox couple center in aqueous phosphate buffer (pH 7) medium and for complexes with the Ru(III/IV) couple in organic media. The E(L) parameter was estimated for indazole showing that this ligand behaves as a weaker net electron donor than imidazole or triazole. The kinetics of the reductively induced stepwise replacement of chloride by DMF were studied by digital simulation of the cyclic voltammograms, and the obtained rate constants were shown to increase with the net electron donor character (decrease of E(L)) of the neutral ligands (DMSO < indazole < triazole < imidazole) and with the basicity of the ligated azole, factors that destabilize the Ru(II) relative to the Ru(III) form of the complexes. The synthesis and characterization of some novel complexes of the A and B series are also reported, including the X-ray structural analyses of (Ph(3)PCH(2)Ph)[trans-RuCl(4)(Htrz)(DMSO)], [(Ph(3)P)(2)N][trans-RuCl(4)(Htrz)(DMSO)], (H(2)ind)[trans-RuCl(4)(Hind)(DMSO)], and [(Hind)(2)H][trans-RuCl(4)(Hind)(2)].     

自旋转换氧化石墨烯纳米复合材料的制备及磁性

利用氧化石墨烯(GO)表面具有丰富含氧基团的特点,采用原位生长法将经典的亚铁三氮唑自旋转换(SCO)配位聚合物[Fe(Htrz)2(trz)](BF4)负载到二维材料GO的表面。利用X射线粉末衍射(PXRD)、红外光谱(FTIR)、SEM、TEM、拉曼等手段对自旋转换-氧化石墨烯(SCO-GO)纳米复合材料进行了表征。通过光谱表征发现,复合材料的FTIR和PXRD特征峰为GO和[Fe(Htrz)2(trz)](BF4)特征峰的叠加,初步证明了自旋转换-氧化石墨烯纳米复合材料已成功制备。SEM和TEM分析直观地显示立方体状的[Fe(Htrz)2(trz)](BF4)纳米颗粒均匀地分散在氧化石墨烯表面,且随着原位生长时间的增加,GO表面的[Fe(Htrz)2(trz)](BF4)的负载量增加、尺寸增大。拉曼图谱表明[Fe(Htrz)2(trz)](BF4)负载到GO表面后,氧化石墨烯特征拉曼峰的强度比(ID/IG)增大,说明氧化石墨烯的缺陷密集程度增大,[Fe(Htrz)2(trz)](BF4)纳米颗粒与石墨烯之间的作用力增强。磁性测试表明不同自组装时间(1、6、12 h)的SCO-GO复合材料的T1/2↑分别为381.1、381.5和382.4 K,T1/2↓分别为345.9、345.0和344.8 K,其磁滞回线宽度分别为35.2、36.5和37.6 K,这是由于不同自组装时间的SCO-GO复合材料中[Fe(Htrz)2(trz)](BF4)的负载量和尺寸的差异导致的。DSC分析结果和磁性结果一致,证实了SCO-GO复合材料自旋转变温度向高温区移动。     

Electrical conductivity modulation coupled to a high-spin-low-spin conversion in the molecular system [FeIII(qsal)2][Ni(dmit)2]3.CH3CN.H2O

The synergy between the electrical conductivity within the stacks of Ni(dmit)2 in the newly electrocrystallized [Fe(qsal)2][Ni(dmit)2]3.CH3CN.H2O and the spin conversion of Fe(qsal)2 is evidenced. In addition, the presence of a light-induced excited spin state trapping effect suggests that this complex is a prototypal photoswitchable spin-crossover molecular conductor.     

Hydrothermal synthesis, structural chemistry, and magnetic properties of materials of the MII/triazolate/anion family, where MII = Mn, Fe, and Ni

Hydrothermal chemistry has been exploited in the preparation of a series of manganese(II), iron(II), and nickel(II) triazolate frameworks, [Mn7(trz)8(CH3CO2)4(OH)2].2.5H2O (1.2.5H2O), [Mn5(Htrz)2(SO4)4(OH)2] (2), [Fe5(Htrz)2(SO4)4(OH)2] (3), [Fe3(Htrz)3(HSO4)(SO4)2(OH)].H2O (4.H2O), [Ni3(trz)3(OH)3(H2O)4].5H2O (5.5H2O), and [Ni3(trz)5(OH)].2.5H2O (6.2.5H2O). The materials all exhibit three-dimensional structures, reflecting the tendency of triazole/triazolate ligands to bridge multiple metal sites. A prominent characteristic of the structures is the presence of embedded metal clusters as building blocks: heptanuclear MnII units in 1, pentanuclear MII sites in 2 and 3, and trinuclear MII clusters in 4 and 5. The presence of the pentanuclear and trinuclear clusters of magnetic metal cations in 2-5 is reflected in the unusual magnetic characteristics of these materials, all of which exhibit spin frustration. The compound 5.5H2O reversibly desorbs/sorbs solvent. However, the dehydrated phase does not adsorb methanol, N2, O2, or H2, presumably as a consequence of the highly polar void volume and the narrow channels connecting the larger cavities of the void structure.     

Nonvolatile rewritable memory effects in graphene oxide functionalized by conjugated polymer containing fluorene and carbazole units

A new polymer, poly[{9,9-di(triphenylamine)fluorene}(9,9-dihexylfluorene)(4-aminophenylcarbazole)] (PFCz) was synthesized and used in a reaction with graphene oxide (GO) containing surface-bonded acyl chloride moieties to give a soluble GO-based polymer material GO-PFCz. A bistable electrical switching effect was observed in an electronic device in which the GO-PFCz film was sandwiched between indium-tin oxide (ITO) and Al electrodes. This device exhibited two accessible conductivity states, that is, a low-conductivity (OFF) state and a high-conductivity (ON) state, and can be switched to the ON state under a negative electrical sweep; it can also be reset to the initial OFF state by a reverse (positive) electrical sweep. The ON state is nonvolatile and can withstand a constant voltage stress of -1 V for 3 h and 10(8) read cycles at -1 V under ambient conditions. The nonvolatile nature of the ON state and the ability to write, read, and erase the electrical states, fulfill the functionality of a rewritable memory. The mechanism associated with the memory effects was elucidated from molecular simulation results and in-situ photoluminescence spectra of the GO-PFCz film under different electrical biases.     

Fe(II)自旋交叉分子材料

自旋交叉配合物具有理想的分子双稳态,可用作新型的热开关、光开关和信息存储器件。本文对近三年来Fe(II)自旋交叉分子材料的重要研究进展进行了综述,主要讨论了转变温度在室温附近的Fe(II)自旋交叉配合物以及具有光致激发自旋态捕获(LIESST)效应和多功能的Fe(II)自旋交叉分子材料,并对Fe(II)自旋交叉分子材料的应用前景作了探讨。     

Synthesis and Characterization of [Fe(Htrz)2(trz)](BF4)] Nanocubes

Compounds that exhibit spin-crossover (SCO) type behavior have been extensively investigated due to their ability to act as molecular switches. Depending on the coordinating ligand, in this case 1H-1,2,4-triazole, and the crystallite size of the SCO compound produced, the energy requirement for the spin state transition can vary. Here, SCO [Fe(Htrz)₂(trz)](BF₄)] nanoparticles were synthesized using modified reverse micelle methods. Reaction conditions and reagent ratios are strictly controlled to produce nanocubes of 40–50 nm in size. Decreases in energy requirements are seen in both thermal and magnetic transitions for the smaller sized crystallites, where, compared to bulk materials, a decrease of as much as 20 °C can be seen in low to high spin state transitions.     

A New Two‐Dimensional Coordination Polymer of Mercury(II) with very High Thermal Stability

A 2D Hg^II coordination polymer containing ligands 1,2,4‐triazole (Htrz) and thiocyanate, [Hg(μ₃‐trz)(SCN)]_n ( 1 ) has been synthesized and characterized by elemental analysis and IR spectroscopy. The single‐crystal X‐ray data show the coordination number of Hg atoms is four and the ligand trz^? acts as a three‐fold donor. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses. The composition and formation of the complex in methanol solution were found to be in support of its solid state structure.