Organometallic Ionic Liquids Containing Sandwich Complexes: Molecular Design,Physical Properties,and Chemical Reactivities

Ionic liquids (ILs) are salts with low melting points and are useful as electrolytes and solvents. We have developed ILs containing cationic metal complexes, which form a family of functional liquids that exhibit unique physical properties and chemical reactivities originating from metal complexes. Our study explores the liquid chemistry in the field of coordination chemistry, where solid-state chemistry is currently the main focus. This review describes the molecular design, physical properties, and reactivities of organometallic ILs containing sandwich or half-sandwich complexes. This paper mainly covers stimuli-responsive ILs, whose magnetic properties, solvent polarities, colors, or structures change by the application of external fields, such as light, heat, and magnetic fields, or by reaction with coordinating molecules.     

基于三吡啶烯烃配体的一维配位聚合物:合成、结构及光电性质

在室温下,用三吡啶烯烃配体dipyridin-2-yl-(4-(2-pyridin-4-yl-vinyl)-phenyl)-amine(ppvppa)与银盐溶液反应,分别得到3个具有类似的一维链结构的配位聚合物{[Ag(ppvppa)]BF4}n(1)、{[Ag(ppvppa)]PF6}n(2)和{[Ag(ppvppa)]NO3}n(3)。在溶剂热条件下,用ppvppa与Ni(Ⅱ)反应,得到另一个以辅助羧酸配体桥联的一维配位聚合物{[Ni(ppvppa)(2,3-NDC)(H2O)]·2H2O}n(4)。对配合物1～4分别进行了元素分析、红外、热重、粉末X射线衍射、单晶X射线衍射等结构表征。配合物1～3呈现出由ppvppa连接Ag(Ⅰ)形成的阳离子一维双股链结构。配合物4呈现出由2,3-NDC配体桥联2个相邻的[Ni2(ppvppa)2(H2O)2]单元形成的中性一维双股链结构。含有Ag(Ⅰ)的配合物1～3表现出良好的荧光性质,而含Ni(Ⅱ)的配合物4没有荧光响应。选取配合物1和4作为代表,研究了它们的光电流响应性质。配合物1和4均表现出灵敏的阳极光电流响应,且在多次循环后仍保持稳定且可重复,其光电流值分别为2和6μA,明显强于空白ITO电极的光电流响应。     

含1，3，5-三-((4-吡啶)-1，2-乙烯基)苯的配位聚合物的合成、结构及性质

用三烯烃三吡啶配体1,3,5三-((4-吡啶)-1,2-乙烯基)苯(tpeb)和M(NO_3)_2(M=Co,Ni,Zn,Cd)以及4种不同的有机羧酸(3,5-二溴苯甲酸(3,5-HDBB)、2,5-噻吩二羧酸(2,5-H_2TDC)、2,5-呋喃二羧酸(2,5-H_2FDC)、2,5-二溴对苯二甲酸(2,5-H_2DBTP))进行溶剂热反应,得到了[Zn(tpeb)(3,5-DBB)_2]_n(1)、[Co_2(tpeb)_2(2,5-TDC)_2]_n(2)、[Co_2(tpeb)_2(2,5-FDC)_2]_n(3)、[Co(tpeb)(2,5-DBTP)]_n(4)、[Ni(tpeb)(2,5-DBTP)]_n(5)、[Cd(tpeb)_(0.5)(2,5-DBTP)]_n(6)六个配位聚合物。对配合物1～6分别进行了单晶X射线衍射、粉末X射线衍射、红外、元素分析、热重、荧光等结构表征。配合物1～6结构独特且多样。配合物1是由[Zn(3,5-DBB)_2]单元通过配体tpeb桥联构筑的一维zigzag链状结构;配合物2和3是由一维梯状[Co(tpeb)]_n链分别与2种不同的五元杂环二取代羧酸桥联构筑而成的二维双层结构;配合物4和5均是由一维[M(2,5-DBTP)]_n(M=Co,Ni)链通过tpeb交叉连接而成的三维网络结构;配合物6则是由二维的[Cd(2,5-DBTP)]_n层状结构通过tpeb连接而成的三维互穿拓扑网络结构。配合物1～6的热稳定性较好,它们在固态时表现出不同的荧光性质。     

Syntheses and Crystal Structures of Two One-dimensional Coordination Polymers Constructed from a Flexible Hinge-like Ligand

By using the flexible hinge-like ligand 2,2＇-bis（3-hydroxy-l,4-naphthoquinone） （H2bhnq）, two isomorphous one-dimensional zigzag chain coordination polymers have been obtained. Single-crystal X-ray analyses revealed that the metal centers in these two complexes are distorted octahedra involving four oxygen atoms of two bhnq2 anions, and two oxygen atoms of two DMF molecules situated in trans positions to one another. Crystal data for [Mn（bhnq）（DMF）2]n 1： C26H22MnN2O8, Mr = 545.40, monoclinic, space group C2/c, a = 14.936（3）, b = 10.362（2）, c = 15.901（3）A., β = 99.86（3）°, V = 2424.7（8）A3, Z = 4, Dc = 1.494 g/cm^3, F（000） = 1124,μ = 0.599 mm^-1, final GOOF = 1.025, R = 0.0654 and wR = 0.1537. Crystal data for [Cd（bhnq）（DMF）2]n 2： C26H22CdN2O8, Mr = 602.86, monoclinic, space group C2/c, a = 14.839（3）, b = 10.493（2）, c = 16.034（3）A, β = 99.40（3）°, V = 2463.1（9）A^3, Z = 4, Dc = 1.626 g/cm^3, F（000） = 1216,μ = 0.941 mm^-1, final GOOF = 1.069, R = 0.0358 and wR = 0.0944.     

基于双苯并咪唑及二羧酸配体配合物的合成、结构及抗菌活性

利用双苯并咪唑基配体4,4′-二(苯并咪唑-1-甲基)联苯(bbmb)与V形二羧酸配体4,4′-二羧苯基醚(H2dcpe)合成了配合物{[Ni(bbmb)(dcpe)(H_2O)]·2H_2O}_n(1)和{[Mn_2(bbmb)(dcpe)_2(H_2O)]·1.5H_2O}_n(2)。通过红外、元素分析、X射线单晶衍射、热重分析等检测手段对配合物结构进行了表征。配合物1是具有sql拓扑构型的二维层状化合物。配合物2呈现出含有四核锰构型的二维层状结构。体外抗菌实验证明2个配合物都表现出良好的抗菌活性。     

(1‐Butyl‐4‐methyl‐pyridinium)[Cu(SCN)2]: A Coordination Polymer and Ionic Liquid

The compound (C₄C₁py)[Cu(SCN)₂], (C₄C₁py=1‐Butyl‐4‐methyl‐pyridinium), which can be obtained from CuSCN and the ionic liquid (C₄C₁py)(SCN), turns out to be a new organic–inorganic hybrid material as it qualifies both, as a coordination polymer and an ionic liquid. It features linked [Cu(SCN)₂]^? units, in which the thiocyanates bridge the copper ions in a μ_1,3‐fashion. The resulting one‐dimensional chains run along the a axis, separated by the C₄C₁py counterions. Powder X‐ray diffraction not only confirms the single‐crystal X‐ray structure solution but proves the reformation of the coordination polymer from an isotropic melt. However, the materials shows a complex thermal behavior often encountered for ionic liquids such as a strong tendency to form a supercooled melt. At a relatively high cooling rate, glass formation is observed. When heating this melt in differential scanning calorimetry (DSC) and temperature‐dependent polarizing optical microscopy (POM), investigations reveal the existence of a less thermodynamically stable crystalline polymorph. Raman measurements conducted at 10 and 100 °C point towards the formation of polyanionic chain fragments in the melt. Solid‐state UV/Vis spectroscopy shows a broad absorption band around 18 870 cm^?1 (530 nm) and another strong one below 20 000 cm^?1 (<500 nm). The latter is attributed to the d(Cu^I)→π*(SCN)‐MLCT (metal‐to‐ligand charge transfer) transition within the coordination polymer yielding an energy gap of 2.4 eV. At room temperature and upon irradiation with UV light, the material shows a weak fluorescence band at 15 870 cm^?1 (630 nm) with a quantum efficiency of 0.90(2) % and a lifetime of 131(2) ns. Upon lowering the temperature, the luminescence intensity strongly increases. Simultaneously, the band around 450 nm in the excitation spectrum decreases.     

一个锰的二维配位聚合物的合成及其性质

本文用2-咪唑乙酸(Hiaa),2,2′-联吡啶,氢氧化钠和六水合高氯酸锰在水和乙醇中反应合成了1个二维配位化合物{[Mn(iaa)(2,2′-bipyridine)(H₂O)](ClO₄)}_n (1)。单晶结构表明化合物1是1个新颖的二维双核锰配位聚合物,锰离子的配位构型为扭曲的八面体。每一个锰离子与3个配体配位,而每个配体与3个锰离子桥连。磁性研究表明1中Mn(Ⅱ)离子间存在弱的反     

对苯二甲酸及双酚A衍生物构筑的二维镉配位聚合物的合成、结构及性质

以4,4-二（4-羟乙基苯并咪唑基苯基）丙烷（L₁）,4,4-二（4-羟乙基咪唑基苯基）丙烷（L₂）为原料,通过水热法得到2个二维结构的配位聚合物{[Cd（L₁）（bdc）H₂O]·2DMA}_n（1）,[Cd（L₂）（bdc）H₂O]_n（2）（H₂bdc=对苯二甲酸,DMA=N,N-二甲基乙酰胺）,通过X-射线单晶洐射、热重以及红外光谱对其进行了表征。结果显示晶体1为单斜晶系,P2/c空间群。晶体2为单斜晶系,C2/c空间群。配合物2为2D→2D穿插结构。热重分析表明配合物1和2分别在343和325℃时分解。     

含共轭三烯吡啶配体的配位聚合物的合成、结构及荧光性质

将1,6-双（4-吡啶基）-1,3,5-己三烯（bphte）和镉盐分别与2种羧酸配体（2,5-二呋喃二甲酸（2,5-H₂FDC）及1,3,5-均苯三甲酸（1,3,5-H₃BTC））进行溶剂热反应,得到2个配位聚合物：[Cd （2,5-FDC）（bphte）（H₂O）]_n （1）和[Cd （1,3,5-HBTC）（bphte）]_n （2）。对配合物1和2分别进行了元素分析、红外光谱、单晶X射线衍射、粉末X射线衍射和热重分析表征。配位聚合物1具有spl拓扑结构的三维互穿超分子框架,而配合物2是由bphte配体交叉连接一维链[Cd₂（1,3,5-HBTC）₂]_n形成的三维结构。配合物1和2在固态时表现出不同的荧光性质。配合物2遇到水溶液中Fe³⁺会发生荧光猝灭,因此以其作为荧光探针对水溶液中Fe³⁺进行了选择性荧光检测,它对Fe³⁺的检测限可达到0.013 μmol·L^-1。这种荧光猝灭过程可归因于Fe³⁺离子的吸收带与配合物2的激发带之间存在部分重叠。     

两个新型锌的配位聚合物的合成与晶体结构

本文以Zn(NO3)2.6H2O分别与1,3,5-均苯三甲酸(1,3,5-H3BTC)和2,5-噻吩二羧酸(2,5-H2TDC)通过水热/溶剂热反应合成了2个锌的配位聚合物[Zn3(OH)(BTC)2(C4N2H11)(H2O)]n(1)(C4N2H11=质子化的哌嗪)和[Zn(2,5-TDC)(i-PrOH)]n(2)。并对配位聚合物1和2进行了元素分析、FTIR和X-射线单晶结构解析等表征。X-射线单晶结构解析表明配位聚合物1和2的晶体均属于正交晶系,空间群分别为Pbca和P212121。化合物1中含有Zn3O结构单元,Zn3O结构单元通过BTC的连接构成1个层状结构,层状结构再通过堆积形成1个三维结构。化合物2中含有无机的Zn-O链。无机Zn-O链通过TDC配体与相邻的6个无机Zn-O链相连形成三维开放式的框架结构。     

Two 1D Ladderlike Heterometallic Zinc(II) Coordination Polymers: Syntheses,Crystal Structures,and Fluorescence Properties

Two coordination polymers [Zn₂(ipt)₂(CuL)₂(H₂O)] ( 1 ) and [Zn₂(ipt)₂(NiL)₂(H₂O)] ( 2 ) (ML, H₂L = 2,3‐dioxo‐5,6,14,15‐dibenzo‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐dien; H₂ipt = isophthalic acid) were synthesized by solvothermal methods and characterized by single‐crystal X‐ray diffraction. Complexes 1 and 2 exhibit ladderlike chains, consisting of Zn₄Cu₄ and Zn₄Ni₄ units, respectively, which are connected via oxamide and isophthalate. These chains are further interlinked by hydrogen bonds resulting in a 2D supramolecular architecture. The fluorescence properties of compounds 1 and 2 are also discussed.     

对苯二甲酸及双酚A衍生物构筑的二维镉配位聚合物的合成、结构及性质(英文)

以4,4-二(4-羟乙基苯并咪唑基苯基)丙烷(L1),4,4-二(4-羟乙基咪唑基苯基)丙烷(L2)为原料,通过水热法得到2个二维结构的配位聚合物{[Cd(L1)(bdc)H2O]·2DMA}n(1),[Cd(L2)(bdc)H2O]n(2)(H2bdc=对苯二甲酸,DMA=N,N-二甲基乙酰胺),通过X-射线单晶洐射、热重以及红外光谱对其进行了表征。结果显示晶体1为单斜晶系,P2/c空间群。晶体2为单斜晶系,C2/c空间群。配合物2为2D→2D穿插结构。热重分析表明配合物1和2分别在343和325℃时分解。     

Stable and Oriented Liquid Crystal Droplets Stabilized by Imidazolium Ionic Liquids

Liquid crystals represent a fascinating intermediate state of matter, with dynamic yet organized molecular features and untapped opportunities in sensing. Several works report the use of liquid crystal droplets formed by microfluidics and stabilized by surfactants such as sodium dodecyl sulfate (SDS). In this work, we explore, for the first time, the potential of surface-active ionic liquids of the imidazolium family as surfactants to generate in high yield, stable and oriented liquid crystal droplets. Our results show that [C₁₂MIM][Cl], in particular, yields stable, uniform and monodisperse droplets (diameter 74 ± 6 µm; PDI = 8%) with the liquid crystal in a radial configuration, even when compared with the standard SDS surfactant. These findings reveal an additional application for ionic liquids in the field of soft matter.     

Remarkable Energy Barrier for Magnetization Reversal in 3D and 2D Dysprosium-Chloranilate-Based Coordination Polymers

Herein, two coordination polymers (CPs) [{Dy(Cl₂An)_1.5(CH₃OH)} ⋅ 4.5 H₂O]_n ( 1 ) and [Dy(Cl₂An)_1.5(DMF)₂]_n ( 2 ), in which Cl₂An is chloranilate (2,5-dihydroxy-1,4-benzoquinone dianion), exhibiting field-induced single-molecule magnet behavior with moderate barrier of magnetization reversal are reported. Detailed structural and topological analysis disclosed that 1 has a 3D network, whereas 2 has a 2D layered-type structure. In both CPs, magnetic measurements showed weak antiferromagnetic exchange interaction between the dysprosium centers and field-induced slow magnetic relaxation with barriers of 175(9)K and 145(7)K for 1 and 2 , respectively. Notably, the energy barriers of magnetization reversal of 1 and 2 are remarkable for metal–chloranilate-based 3D ( 1 ) and 2D ( 2 ) CPs. The temperature and field dependence of relaxation time indicate the presence of multiple relaxation pathways, such as direct, quantum tunneling of magnetization, Raman, and Orbach processes, in both CPs. Ab initio theoretical calculations reinforced the experimentally observed higher energy barrier in 1 as compared with 2 due to the presence of large transverse anisotropy in the ground state in the latter. The average transition magnetic moment between the computed low-lying spin–orbit states also rationalized the relaxation as Orbach and Raman processes through the first excited state. BS-DFT calculations were carried out for both CPs to provide more insight into the exchange interaction.     

A Robust Microfluidic Device for the Synthesis and Crystal Growth of Organometallic Polymers with Highly Organized Structures

A simple and robust microfluidic device was developed to synthesize organometallic polymers with highly organized structures. The device is compatible with organic solvents. Reactants are loaded into pairs of reservoirs connected by a 15 cm long microchannel prefilled with solvents, thus allowing long‐term counter diffusion for self‐assembly of organometallic polymers. The process can be monitored, and the resulting crystalline polymers are harvested without damage. The device was used to synthesize three insoluble silver acetylides as single crystals of X‐ray diffraction quality. Importantly, for the first time, the single‐crystal structure of silver phenylacetylide was determined. The reported approach may have wide applications, such as crystallization of membrane proteins, synthesis and crystal growth of organic, inorganic, and polymeric coordination compounds, whose single crystals cannot be obtained using traditional methods.     

系列Ag-Ln配位聚合物的合成、结构及发光性能

采用水热合成法,以吡嗪-2-羧酸(2-Hpzc)、3,5-吡啶二羧酸(3,5-H_2PDA)和草酸(H_2ox)为配体,合成9种Ag-Ln配位聚合物:{[LnAg(2-pzc)_2(ox)]·H_2O}_n(Ln=Pr(1),Nd(2),Sm(3),Eu(4)),[LnAg(3,5-PDA)(ox)(H_2O)]_n(Ln=Pr(5),Nd(6)),[LnAg(3,5-PDA)(3,5-HPDA)(ox)_(0.5)(H_2O)_2]_n(Ln=Sm(7),Dy(8),Ho(9))。配位聚合物1～4是同构的,由2-pzc~-和ox~(2-)连接,而配位聚合物5～9是以3,5-PDA~(2-)和ox~(2-)为桥联配体,均呈现3D网状结构。光物理性能研究表明配位聚合物均表现出Ln(Ⅲ)的特征发射,这可归因于Ag-配体部分(d-block)的敏化作用。另外,在晶体场和Ag(1)离子4d轨道的共同作用下,Ln(Ⅲ)离子的4f轨道被调谐,使部分能级发生明显的位移,表现为相应NIR发射带的位移,在其UV-Vis-NIR吸收光谱中可以得到佐证。     

Flexibility Control of Two-Dimensional Coordination Polymers by Crystal Morphology: Water Adsorption and Thermal Expansion

Layer flexibility in two-dimensional coordination polymers (2D-CPs) contributes to several functional materials as it results in anisotropic structural response to external stimuli. Chemical modification is a common technique for modifying layer structures. This study demonstrates that crystal morphology of a cyanide-bridged 2D-CP of type [Mn(salen)]₂[ReN(CN)₄] ( 1 ) consisting of flexible undulating layers significantly impacts the layer configuration and assembly. Nanoplates of 1 showed an in-plane contraction of layers with a longer interlayer distance compared to the micrometer-sized rod-type particles. These effects by crystal morphology on the structure of the 2D-CP impacted the structural flexibility, resulting in dual-functional changes: the enhancement of the sensitivity of structural transformation to water adsorption and modification of anisotropic thermal expansion of 1 . Moreover, the nanoplates incorporated new adsorption sites within the layers, resulting in the uptake of an additional water molecule compared to the micrometer-sized rods.     

Flexo-Ionic Effect of Ionic Liquid Crystal Elastomers

The first study of the flexo-ionic effect, i.e., mechanical deformation-induced electric signal, of the recently discovered ionic liquid crystal elastomers (iLCEs) is reported. The measured flexo-ionic coefficients were found to strongly depend on the director alignment of the iLCE films and can be over 200 µC/m. This value is orders of magnitude higher than the flexo-electric coefficient found in insulating liquid crystals and is comparable to the well-developed ionic polymers (iEAPs). The shortest response times, i.e., the largest bandwidth of the flexo-ionic responses, is achieved in planar alignment, when the director is uniformly parallel to the substrates. These results render high potential for iLCE-based devices for applications in sensors and wearable micropower generators.     

两种铜配位聚合物的晶体结构和量子化学计算

在水热条件下以4-硝基邻苯二甲酸（4-H₂nph）/2,2''-联吡啶-4,4''-二甲酸（H₂bda）为主要配体,3-（2-吡啶基）吡唑（HL）/1,4-双（咪唑基-1-基）丁烷（bib）为辅助配体制备了2种新的金属有机配位聚合物[Cu₄（4-nph）（L）₆]_n （1）和{[Cu₂（bda）₂（bib）₂（H₂O）₄]·4H₂O}_n （2）。通过元素分析、红外光谱、热重X射线单晶衍射和X射线粉末衍射对它们进行了表征。结果表明,配合物1属于单斜晶系,C2/c空间群。晶胞参数：a=1.956 16（8） nm,b=1.290 68（8） nm,c=2.160 34（12） nm,β=97.073（2）°,V=5.412 9（5） nm³,Z=4。配合物2属于三斜晶系,P1空间群。晶胞参数：a=0.962 22（15） nm,b=1.102 90（17） nm,c=1.404 3（2） nm,α=72.752（4）°,β=79.271（4）°,γ=67.065 （3）°,V=1.306 6（4） nm³,Z=1。在配合物1中,羧基配体4-nph^2-通过单齿模式桥联金属中心,形成一维结构。在配合物2中,柔性bib配体连接金属中心形成具有26元环的双核结构。此外,还用Gaussian16程序PBE0/LANL2DZ方法从配合物1的晶体结构中提取“分子片段”进行了量子化学计算。计算结果表明配位原子与铜（Ⅱ）离子之间存在着共价作用。     

Water-Induced Breaking of the Coulombic Ordering in a Room-Temperature Ionic Liquid Metal Complex

Control of ion arrangements in ionic liquids represents a major challenge owing to the presence of the predominant coulombic interactions between cationic and anionic ion species that forms the coulombic ordering. Here, water-induced ion rearrangement in a room-temperature ionic liquid (RT-IL) metal complex, (1-ethyl-3-methylimidazolium)₂[MnN(CN)₄], is demonstrated through coordinative interactions between anions. Solidification occurred, which was associated with the formation of a “separated” structure consisting of cation columns and anionic cyanide-bridged one-dimensional coordination polymers. The energy diagram is in accord with the resultant RT-IL incorporating mononuclear [MnN(CN)₄]²⁻ molecules being a kinetic phase stabilized by inter-ion repulsions of the anionic divalent metal complex moieties. Water acts to decrease the coulombic interactions, including repulsion, giving rise to breaking of the coulombic ordering arising from coordination bond formation in the IL phase.