Cyclic triureas--synthesis, crystal structures and properties

The synthesis of 24-membered macrocycles is described, in which rigid xanthene units (X) and/or diphenyl ether units (D) as flexible analogues are linked via urea groups. All four possible combinations (XXX, XXD, XDD, DDD) have been obtained with yields of 40-72% for the cyclisation step. In two cases, the respective cyclic hexamers (XXDXXD, XXXXXX) were also isolated. Two compounds have been characterised by a single crystal X-ray analysis of the free triurea (XXD, XDD) and one example (DDD) by its complex with tetrabutylammonium chloride. It shows the chloride anion in the centre of the macrocycle, held by six NH...Cl- hydrogen bonds. The interaction with various other anions has been studied by 1H NMR. Complexation constants for chloride, bromide and acetate have been measured for all trimers by UV spectrophotometry. Molecular dynamics simulations have been carried out to determine the conformation of the free receptors in chloroform and acetonitrile. They show that in chloroform, intramolecular hydrogen bonding occasionally facilitated by trans-->cis isomerisation of an amide bond dominates the conformation of the macrocycles while in acetonitrile (the solvent used for complexation measurements), the ligating urea NH protons are properly arranged for the complexation of anions, however, their strong solvation is counteractive to the complexation.     

Cyanocomplexes with one-dimensional structures: preparations,crystal structures and magnetic properties

The review surveys the preparation methods, crystallochemistry and magnetic properties of one-dimensional cyanocomplexes. Their preparation methods are mainly based on reactions in solutions containing suitable building blocks as precursors of the polymeric structure. The analysis of published data on crystal structures is given, as the knowledge of the crystal structure is essential for the study of magneto-structural correlation. Published data on magnetic properties are discussed along with the methods used for the study of magnetic properties.     

Synthesis, crystal structures, and photophysical properties of electron-accepting diethynylindenofluorenediones

A series of 6,12-bis[(trialkylsilyl)ethynyl]indeno[1,2-b]fluorene-5,11-diones has been synthesized. X-ray crystallographic analysis of these compounds reveals that triisopropylsilyl (TIPS) substitution on the alkyne terminus affords the largest number of intermolecular π-π interactions in the solid state. Conversely, use of trialkylsilyl groups smaller or larger than TIPS furnishes a variety of crystal-packing motifs that contain fewer π-π interactions. Electrochemical and photophysical data suggest that these molecules are excellent electron-accepting materials.     

Synthesis, crystal structures and DNA-binding properties of dinuclear complexes with macrocyclic ligands

Two symmetrical macrocyclic dinuclear complexes, [Cu₂L¹(ClO₄)₂(H₂O)₂][Cu₂L¹(H₂O)₂] (ClO₄)₂ (1) and [Cu₂L²(ClO₄)₂] (2), (where H₂L¹ and H₂L² are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-flurophenol, respectively), have been synthesized and characterized. The electronic and magnetic properties of the complexes were studied by cyclic voltammetry and magnetic susceptibility. There are strong antiferromagnetic couplings between the two copper(II) centers in both complexes. The strongly electron-withdrawing fluorine groups in H₂L² weaken the antiferromagnetic exchange, but make the metal centers more easily reduced than its analog H₂L¹. The interactions of the complexes with calf thymus DNA were studied by UV?CVis and CD spectroscopic techniques.     

Syntheses, crystal structures, and electrochemical properties of multi-ferrocenyl resorcinarenes

Tetraaryl and tetraferrocenyl resorcinarenes 1a-1c have been synthesized by the HCl-catalyzed condensation of resorcinol with aromatic aldehydes or ferrocenecarbaldehyde, which were fully alkylated with ethyl α-chloroacetate to give the activated ethyl resorcinarylacetates 2a-2c. Reaction of 2a-2c with hydrated hydrazine yielded the resorcinarene acylhydrazine derivatives 3a-3c, from which the multi-ferrocenyl functional groups were selectively and efficiently introduced on the upper rim, or on the lower rim, or both on the upper and lower rims of resorcinarenes 4a-4c and calixarenes 4d-4f based upon the condensation reactions of acylhydrazones with ferrocenecarboxaldehyde.     

Metal naphthalenedicarboxylates with diverse network architectures: Synthesis,crystal structures and properties

Reactions of 1,4-naphthalenedicarboxylic acid (1,4-H₂nda) and a bent dipyridyl co-ligand 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole (4bpt) with Co^II, Zn^II, or Cd^II acetate afford four coordination polymers, [Co(1,4-nda)(4bpt)(H₂O)]_n (1), {[Co(1,4-nda)₂(4bpt)(H₂O)₂][Co(4bpt)(H₂O)₄](H₂O)_1.5}_n (2), {[Zn(1,4-nda)₂(4bpt)(H₂O)₂][Zn(4bpt)(H₂O)₄](H₂O)_1.5}_n (3), and {[Cd₂(1,4-nda)₂(4bpt)₂(H₂O)₂](DMF)_1.5(H₂O)₃}_n (4). In the structure of the Co^II complex 1, the polycatenation of inclined 2-D (4,4) coordination layers leads to the formation of a 3-D supramolecular framework, whereas two types of 1-D polymeric chains are observed in another Co^II coordination species 2, which are interconnected via H-bonding to result in an unusual 3-D host–guest lattice. Notably, complexes 1 and 2 have been prepared under similar hydrothermal conditions and their structural discrepancy can only be ascribed to a subtle change of basicity for the reaction solution. The Zn^II complex 3 is isostructural to 2, and the Cd^II complex 4 displays a 2-fold parallel interpenetrating array of undulating (4,4) coordination layers. By using the conventional solvent evaporation method, two Pb^II naphthalenedicarboxylates [Pb(1,4-nda)(DMF)]_n (5) and {[Pb₂(2,6-nda)₂(DMF)₂](DMF)}_n (6) have also been prepared (2,6-nda = 2,6-naphthalenedicarboxylate). Complex 5 has a unique 5-connected 3-D coordination architecture, whereas 6 represents a 3-fold interpenetrating framework of 4-connected diamond topology. Their structural difference suggests the significant isomeric effect of the naphthalenedicarboxylate tectons on structural assemblies. Thermal stability of these crystalline materials has been investigated by thermogravimetric and differential thermal analysis (TG–DTA) technique and solid-state luminescent properties of the Zn^II, Cd^II, and Pb^II complexes have also been explored.     

Syntheses,crystal structures,and properties of two molecular double-supporting polyoxotungstates

Two molecular double-supporting polyoxotungstates [SiW₁₂O₄₀{M(phen)₂H₂O}₂] · nH₂O (phen = 1,10′-phenanthroline, M = Mn 1, n = 2; M = Co 2, n = 3) were synthesized hydrothermally and characterized by elemental analyses, IR, TG, and X-ray single-crystal diffraction. The variable-temperature magnetic susceptibilities were measured at 2–300 K. The double-supporting polyoxotungstate molecule consists of a Keggin-type dodecatungstosilicate anion and a pair of transition metal complex fragments which are covalently linked to opposite sides of the Keggin anion. The transition metal ion locates in the center of a distorted octahedron. Multiple H-bonding interactions are observed between the coordinated waters of the transition metal complex fragments and terminal oxygen atoms of Keggin units and also between the bridging oxygen atoms of Keggin units and the lattice waters, which creates one-dimensional chains or two-dimensional layers. Between the layers or chains there are weak CH···O hydrogen bonding interactions and van der Waals forces. The molecular double-supporting polyoxotungstosilicate begins to decompose at ca. 500 °C. The variable-temperature magnetic behavior of 1 shows weak antiferromagnetic characteristics with a small value of θ = −0.289 K.     

Lanthanoid-containing open Wells-Dawson silicotungstates: synthesis, crystal structures, and properties

Five novel lanthanoid-containing silicotungstates with polymeric crystal structures [Ln(2)(H(2)O)(7)Si(2)W(18)O(66)](n)(10n-) [Ln = Gd(III) (Gd-1 and Gd-2), Tb(III), Ho(III)] and [Dy(2)(H(2)O)(6.5)(C(2)H(4)O(2))(0.5)Si(2)W(18)O(66)](n)(10n-) were obtained from the one-step reaction of Na(10)[SiW(9)O(34)]·nH(2)O with Ln(NO(3))(3)·nH(2)O in a sodium acetate buffer. The compounds were characterized by single-crystal X-ray diffraction and a wide range of analytical methods, including FT-IR, UV/vis, and photoluminescence spectroscopy as well as electrochemistry and thermogravimetric analysis. This new polyoxotungstate series is the first example of lanthanoids embedded in the open Wells-Dawson silicotungstate anion [α-Si(2)W(18)O(66)](16-). The lanthanoid-containing Wells-Dawson-type polyoxoanions [Ln(2)(H(2)O)(7)Si(2)W(18)O(66)](10-) [Ln = Gd(III) (Gd-1 and Gd-2), Tb(III), Ho(III)] and [Dy(2)(H(2)O)(6.5)(C(2)H(4)O(2))(0.5)Si(2)W(18)O(66)](10-) are linked by Ln(3+) cations to form 3D architectures for Gd-1 or 2D frameworks for the isostructural compounds Tb-2, Dy-2, Ho-2, and Gd-2. The structure-directing influence of the lanthanoid cation on the local structure of the dimeric building blocks and on the crystal packing motifs is investigated in detail. The photoluminescence properties of Tb-2 and Dy-2 were investigated at room temperature, and Ho-2 exhibits an interesting photochromic behavior. The magnetic susceptibility of Gd-1 and Gd-2 was studied in the temperature range between 2 and 300 K for its effective magnetic moment.     

Pyrrole azocrown ethers—synthesis, crystal structures, and fluorescence properties

Pyrrole containing macrocycles with chromophoric and fluorescent residues were prepared. X-ray structures for compounds 1 and 4 were determined. The presented pyrrole azocrowns are lead(II) chemosensors, which can be used both in UV-vis and fluorescence spectroscopy.     

异金属膦酸铀的合成、晶体结构和荧光性质

构建异金属膦酸铀仍然具有挑战性。在本工作中,从苯磺酰甲基膦酸二乙酯(Et₂L)出发,成功合成了一系列同构的异金属膦酸铀化合物[UO₂Mn (L)₂(H₂O)₄],其中M=Mn (1)、Co (2)、Ni (3)、Zn (4)、Cd (5)。晶体结构研究表明,磺酰基团没有与金属离子配位,而膦酸基团完全去质子化,连接2个铀酰离子和1个过渡金属离子,形成了二维层状晶体结构。荧光研究表明,在Mn (Ⅱ)、Co (Ⅱ)和Ni (Ⅱ)离子存在时,铀酰离子的特征荧光发射被淬灭,而在Zn (Ⅱ)和Cd ((Ⅱ)离子存在时,显示出强的特征荧光发射。     

异金属膦酸铀的合成、晶体结构和荧光性质

构建异金属膦酸铀仍然具有挑战性。在本工作中,从苯磺酰甲基膦酸二乙酯(Et₂L)出发,成功合成了一系列同构的异金属膦酸铀化合物[UO₂M (L)₂(H₂O)₄],其中M=Mn (1)、Co (2)、Ni (3)、Zn (4)、Cd (5)。晶体结构研究表明,磺酰基团没有与金属离子配位,而膦酸基团完全去质子化,连接2个铀酰离子和1个过渡金属离子,形成了二维层状晶体结构。荧光研究表明,在Mn (Ⅱ)、Co (Ⅱ)和Ni (Ⅱ)离子存在时,铀酰离子的特征荧光发射被猝灭,而在Zn (Ⅱ)和Cd (Ⅱ)离子存在时,显示出强的特征荧光发射。     

Synthesis, crystal structures, and photophysical properties of triphenylamine-based multicyano derivatives

A new series of intramolecular charge transfer (ICT) molecules were synthesized by attaching various strong electron-withdrawing groups to a triphenylamine backbone. Relationships between chemical structures and optoelectronic properties of these compounds were investigated with X-ray diffraction, cyclic voltammetry, absorption spectroscopy, and density functional theory calculations. It is shown that the compounds exhibit intensive ICT interactions leading to substantial extension of their absorption spectral response, which may be potentially used for efficient solar cells.     

Novel coordination polymers with ferrocene-containing dicarboxylate ligand: Syntheses, crystal structures and properties

A new ferrocene-containing dicarboxylate ligand, L = 5-ferrocene-1,3-benzenedicarboxylic acid, has been prepared. Self-assembly of L, M(II) salts (M = Co and Zn) and chelating ligands dpa or phen (dpa = 2,2′-dipyridylamine and phen = 1,10-phen) gave rise to four new coordination polymers {[Co(L)(dpa)] · 2MeOH}_n (1), {[Zn(L)(dpa)] · 2MeOH}_n (2), {[Co(L)(phen)(H₂O)] · MeOH} (3), [Zn(L)(phen)(H₂O)] · MeOH (4). The isostructural complexes 1 and 2 possess 1D helical chain structures with 2₁ screw axes along the b-direction, and the right- and left-handed helical chains are alternate arrayed into 2D layer structures through hydrogen-bonding interactions; while isostructural complexes 3 and 4 are 1D linear chain structures with phen and ferrocene groups of L as pendants hanging on the different sides of the main chain. A structural comparison of complexes 1–4 demonstrated that the characteristics of subsidiary ligands and slight difference in coordination models of L play very important role in the construction of the complexes. In addition, the redox properties of complexes 1–4, as well as the magnetic properties of complexes 1 and 3 are also investigated.     

Syntheses, crystal structures and properties of six coordination compounds with flexible dps ligand

Six new compounds: [M(dps)(dca)₂]_∞ (1, M = Cd; 2, M = Fe), [Cu(dps)(dca)₂(CH₃OH)₂]_∞ (3), [M(dps)₂(SCN)₂(H₂O)₂]_∞ (4, M = Cd; 5, M = Fe), [Cu(dps)₄(SCN)₂]_∞ (6), (dps = 4,4′-dipyridyl sulfide, dca = dicyanamide) were synthesized, characterized by FT-IR, element analysis and TG. Their structures were determined by single crystal X-ray diffraction. According to the structure analysis, compounds 1 and 2 are three-dimensional microporous frameworks constructed by Cu-dps-Cu and Cu-dca-Cu bridges; compound 3 shows a zigzag chain constructed by a Cu-dps-Cu bridge; compounds 4 and 5 show double-stranded chains constructed by a Cu-(dps)₂-Cu bridge while thiocyanate anions act as terminal groups; compound 6 is a mononuclear compound. Moreover, compound 1 shows visible yellow luminescence under UV light irradiation and such phenomenon is mainly attributed to inter-ligand transitions.     

New cycloplatinated complexes with 2-arylimidazolines: Synthesis, crystal structures and photophysical properties

The synthesis, crystal structures and photophysical properties of a series of cycloplatinated complexes are presented. The complexes have the general formula (C^∧N)Pt(O^∧O), where O^∧O is acetylacetonate and C^∧N represents 2-arylimidazoline ligands. All of them are luminescent in CH₂Cl₂ solution at room temperature. Different aryl group on N-1 of the ligand has no significant effect on the emission properties of the platinum complexes. While introducing alkyl group on N-1 or electron-donating group on 2-aryl ring does result in a blue shift of emission maxima or even an increase in emission intensity.     

Synthesis,properties and crystal structures of nitrobenzoatocopper(II) complexes with pyrazinecarboxamide

The synthesis, spectral characterization and crystal structures of two nitrobenzoatocopper(II) complexes, namely [Cu(2-O₂Nbz)₂(pca)₂(H₂O)₂] (1) and [Cu(3,5-(O₂N)₂bz)₂(pca)₂(H₂O)₂] (2) (where 2-O₂Nbz = 2-nitrobenzoate, 3,5-(O₂N)₂bz = 3,5-dinitrobenzoate, pca = pyrazinecarboxamide), are reported. Complexes 1 and 2 consist of centrosymmetric molecules with the Cu(II) atom monodentately coordinated by a pair of anionic 2-nitrobenzoato (1) or 3,5-dinitrobenzoato (2) ligands and a pair of pyrazinecarboxamide ligands, forming a nearly tetragonal basal plane, and by a pair of water ligands that complete the tetragonal–bipyramidal coordination polyhedron. The molecules of both complexes are linked by N–H⋯O and O–H⋯O hydrogen bonds and lie in planes, which have different orientations depending on the space group. Similar experiments with 3-nitrobenzoic acid resulted in the isolation of the hydrolysis product [Cu(pyzCOO)₂] _n (3) (pyzCOO = pyrazinecarboxylate). The known crystal structure of complex 3 has been re-determined at low temperature with significantly higher precision. The crystal packing and C–H⋯O/C–H⋯N hydrogen bonds are discussed.     

Synthesis, crystal structures and magnetic properties of cyanide-bridged macrocyclic complexes

Three cyanide-bridged dodecanuclear macrocyclic wheel-like complexes [Cr(bpmb)(CN)₂]₆[Mn(5-Brsalpn)]₆·12H₂O (1), [Co(bpmb)(CN)₂]₆[Mn(5-Brsalpn)]₆·12H₂O (2) and [Co(bpmb)(CN)₂]₆[Mn(5-Clsalpn)]₆·24H₂O·8CH₃CN (3) [bpmb²⁻= 1,2-bis(pyridine-2-carboxamido)-4-methylbenzenate dianion; 5-Brsalpn²⁻ = N,N′-propylenebis(5-bromosalicylideneaminato) dianion; 5-Clsalpn²⁻ = N,N′-propylenebis(5-chlorosalicylideneaminato) dianion] have been synthesized and their crystal structures and magnetic properties have been investigated. The three compounds are structurally isomorphous and consist of alternating Mn(III)-Schiff base cations and [M(bpmb)(CN)₂]⁻ anions, generating cyanide-bridged nanosized dodecanuclear macrocyclic structures with an approximate diameter of 2 nm. The study of the magnetic properties of complex 1 reveals an antiferromagnetic interaction between the Cr(III) and Mn(III) ions through the cyanide bridges. A best-fit to the magnetic susceptibility of the complex leads to a magnetic coupling constant of J _CrMn = −2.65(6) cm⁻¹ on the basis of a one-dimensional alternating chain model with the Hamiltonian $ H = - J_{CrMn} \sum\limits_{i = 0}^N {S_i \cdot S_{i + 1} } $ H = - J_{CrMn} \sum\limits_{i = 0}^N {S_i \cdot S_{i + 1} } .     

氰根桥联大环配合物的合成、结构与磁性研究

合成了三个氰根桥联的十二核大环齿轮状配合物[Cr（bpmb）（CN）2]6-[Mn（5-Brsalpn）]6·12H2O（1）、[Co（bpmb）（CN）2]6[Mn（5-Brsalpn）]6·12H20（2）和[Co（bpmb）-（CN）2]6[Mn（5-Clsalpn）]6·24H20·8CH3CN（3）（bpmb^2-=1,2-bis（pyridine·2-carboxamido）-4-methylbenzenate）,表征了其晶体结构和磁性．三配合物是同晶型的,包含交替排列的锰（Ⅲ）-Schiff碱阳离子和[M（bpmb）（CN）2]-阴离子,阴阳离子单元用氰根离子连成十二核环状结构．分子环直径约2nm．配合物1呈反铁磁性,说明通过氰根桥铬（Ⅲ）．锰（Ⅲ）离子间存在反铁磁相互作用．基于一维交替链模型（哈密顿算符H=-JCrMnN∑i=0Si·Si＋1）导出的磁化率公式与实验数据进行拟和得到磁耦合参数JCrMn=-2．65（6）cm^-1．