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1.
Conformational properties of 2,2′‐bithiazole and 4,4′‐dimethyl‐2,2′‐ bithiazole have been studied by using AM1 and PM3 semiemperical methods and ab initio HF/6‐311+G* and B3LYP/6‐311+G* calculations. All methods agree that the planar s‐trans conformation is the global minimum and the perpendicular conformation is the transition state. Additional local minima were found using the Hartree–Fock (HF) and B3LYP levels for 2,2′‐bithiazole while for 4,4′‐dimethyl derivative the minima was located only at the MP2//B3LYP level. The barrier heights for rotation are 1.72, 7.69, and 7.88 kcal/mol at the PM3, HF, and B3LYP levels, respectively, and methyl substitution did not affect appreciably this value. Fourier expansion terms and bond orders were used to explain the origins of the rotational barrier in terms of π conjugation, electrostatic interaction, and steric effects, which represent the main factors in the shape of the rotational barrier. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 79: 367–377, 2000  相似文献   

2.
The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5′‐dmbpy)2]ClO4·H2O (where 5,5′‐dmbpy is 5,5′‐dimethyl‐2,2′‐bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate–5,5′‐dmbpy–KClO4 system. Within the complex cation, the NiII atom is hexacoordinated by two chelating 5,5′‐dmbpy ligands and one chelating ac ligand. The mean Ni—N and Ni—O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen‐bonded centrosymmetric dimers, which are further connected by π–π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single‐ion anisotropy, D, which arises from the reduced local symmetry of the cis‐NiO2N4 chromophore. The fitting of the variable‐temperature magnetic data (2–300 K) gives giso = 2.134 and D/hc = 3.13 cm−1.  相似文献   

3.
A novel coordination polymer, [Ag4ppdc)(H2bpdc)(Hbpdc)2] (bpdc = 2,2′‐bipyridyl‐3,3′‐dicarboxylate), was hydrothermally synthesized at 403 K and structurally characterized by single crystal X‐ray diffraction analysis. The compound crystalizes in the monoclinic space group C2/c with a=1.9516(4) nm, b=1.9503(4) nm. c=1.2566(3) nm, and β=112.48(3)°. In the two‐dimensional crystal structure, AgI center is coordinated, in a scarce coordination environment, double‐capped tetrahedron, by one bpdc ligand to form N‐Ag‐N chelate bond via two pyridyl N atoms, and other two bpdc ligands to form two O‐Ag‐O chelate bonds, respectively, via two carboxyl O atoms. The bpdc ligands are present in one non‐protonated form, bpdc, and two protonated forms, Hbpdc and H2bpdc, which all act as μ3‐ligand in a hexadentate fashion (N, N′; O, O′; O, O′) to coordinate with three Ag centers, respectively, through the three chelate bonds. This coordinated fashion of bpdc ligand is first found in the title compound. W‐Us‐NIR reflectance spectroscopy study revealed insulator nature for the crystal with an optical energy gap of 3.1 eV.  相似文献   

4.
The reaction of NiCl2, K2C2O4·H2O and 2,2′‐bipyridine (bpy) in water–ethanol solution at 281 K yields light‐purple needles of the new pentahydrate of bis(2,2′‐bipyridine)oxalatonickel(II), [Ni(C2O4)(C10H8N2)2]·5H2O or [Ni(ox)(bpy)2]·5H2O, while at room temperature, deep‐pink prisms of the previously reported tetrahydrate [Ni(ox)(bpy)2]·4H2O [Román, Luque, Guzmán‐Miralles & Beitia (1995), Polyhedron, 14 , 2863–2869] were gathered. The asymmetric unit in the crystal structure of the new pentahydrate incorporates the discrete molecular complex [Ni(ox)(bpy)2] and five solvent water molecules. Within the complex molecule, all three ligands are bonded as chelates. The complex molecules are involved in an extended system of hydrogen bonds with the solvent water molecules. Additionally, π–π interactions also contribute to the stabilization of the extended structure. The dehydration of the pentahydrate starts at 323 K and proceeds in at least two steps as determined by thermal analysis.  相似文献   

5.
A highly sensitive reversed‐phase liquid chromatographic (HPLC) method was investigated to analyze a range of positron emission tomography (PET) radiopharmaceuticals using electrogenerated chemiluminescence (ECL) detection. ECL is based on the reaction of PET molecules with tris(2,2′‐bipyridyl)ruthenium(III) [Ru(bpy)33+], which is generated through the on‐line electro‐oxidation of Ru(bpy)32+. In 21 different radiopharmaceuticals studied, 18 compounds could be detected with detection limits (signal‐to‐noise ratio = 3) of 0.12–72 ng/mL per 20 μL injection. Sufficient reproducibility and linearity were obtained for the quantitative determination of PET molecules in pharmaceutical fluid. This method could be successfully applied to quality control tests of PET radiopharmaceuticals with ultra‐high specific radioactivity. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

6.
A lithium(I) coordination polymer has been formed from LiClO4 and the 2,2′‐bipyrimidine (bpym) ligand in which each square pyramidal lithium(I) atom is coordinated in the basal plane by four nitrogen donor atoms derived from two bpym ligands and one water molecule at the apical position. These are connected into a layer structure via hydrogen‐bonding interactions involving the perchlorate anions. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

7.
The molecular structures of trichlorido(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)gallium(III), [GaCl3(C15H11N3)], and tribromido(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)gallium(III), [GaBr3(C15H11N3)], are isostructural, with the GaIII atom displaying an octahedral geometry. It is shown that the Ga—N distances in the two complexes are the same within experimental error, in contrast to expected bond lengthening in the bromide complex due to the lower Lewis acidity of GaBr3. Thus, masking of the Lewis acidity trends in the solid state is observed not only for complexes of group 13 metal halides with monodentate ligands but for complexes with the polydentate 2,2′:6′,2′′‐terpyridine donor as well.  相似文献   

8.
The ternary Cu(II) complex with 2,2′‐bipyridyl (bipy) and L‐methioninate (L‐Met) has been synthesized and characterized by elemental analysis, molar conductivity, UV‐Vis spectra, IR spectra and pH‐potentiometric titration methods. The structure of the complex [Cu(L‐Met) (bipy) (H2O)]ClO4 · 3/8H2O was characterized by the X‐ray diffraction analysis. It crystallizes in the triclinic system, space group P1 with four molecules in a unit cell of dimensions, a = 0.7656(2) nm, b = 1.3142(3) nm, c = 2.0596(4) nm, α = 97.70(3)°, β = 97.96(3)°, γ = 94.33(3)°, V= 2.0244(8) nm3, R1, = 0.0441 and wR2 = 0.0678. The crystal contains four crystllographically independent [Cu(L‐Met) (bipy) (H2O)]+ complexes (Cu1—Cu4), having a distorted square‐pyramidal geometry with the same coordinated atoms around each copper center. The base plane is occupied by two nitrogen atoms of one bipy, the amino nitrogen atom and one carboxylate oxygen atom from each independent L‐Met moiety, and one water oxygen at an axial position. Cu1 and Cu3 are essentially enantiomers of Cu2 and Cu4. The four molecules are packed with each other by intermolecular hydrogen‐bonding and aromatic‐ring stacking interactions.  相似文献   

9.
Two noble metal complexes involving ancillary chloride ligands and chelating 2,2′‐bipyridylamine (Hdpa) or its deprotonated derivative (dpa), namely [bis(pyridin‐2‐yl‐κN)amine]tetrachloridoplatinum(IV), [PtCl4(C10H9N3)], and [bis(pyridin‐2‐yl‐κN)aminido]dichloridogold(III), [AuCl2(C10H8N3)], are presented and structurally characterized. The metal atom in the former has a slightly distorted octahedral coordination environment, formed by four chloride ligands and two pyridyl N atoms of Hdpa, while the metal atom in the latter has a slightly distorted square‐planar coordination environment, formed by two chloride ligands and two pyridyl N atoms of dpa. The difference in conjugation between the pyridine rings in normal and deprotonated 2,2′‐dipyridylamine is discussed on the basis of the structural features of these complexes. The influence of weak interactions on the supramolecular structures of the complexes, providing one‐dimensional chains of [PtCl4(C10H9N3)] and dimers of [AuCl2(C10H8N3)], are discussed.  相似文献   

10.
Novel 4,4′‐dichloro‐2,2′‐[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L) and its complexes [CuL] and {[CoL(THF)]2(OAc)2Co} have been synthesized and characterized by elemental analyses, IR, 1H‐NMR and X‐ray crystallography. [CuL] forms a mononuclear structure which may be stabilized by the intermolecular contacts between copper atom (Cu) and oxygen atom (O3) to form a head‐to‐tail dimer. In {[CoL(THF)]2(OAc)2Co}, two acetates coordinate to three cobalt ions through Co? O? C? O? Co bridges and four µ‐phenoxo oxygen atoms from two [CoL(THF)] units also coordinate to cobalt ions. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

11.
A classical model of “molecular machine,” which acts as an ON–OFF switch for 2,2′‐bipyridyl‐3,3′‐15‐crown‐5 ( L ), has been theoretically studied. It is highly important to understand the mechanism of this switch. The alkali‐metal cations (Na+ and K+) and W(CO)4 fragment are introduced to coordinate with the different active sites of L , respectively. The density functional theory (DFT) method is used for understanding the stereochemical structural natures and thermodynamic properties of all the target molecules at B3LYP/6‐31G(d) and SDD (Stuttgart–Dresden) level, together with the corresponding effective core potential (ECP) for tungsten (W). The fully optimized geometries have been performed with real frequencies, which indicate the minima states. The nucleophilicity of L has been investigated by the Fukui functions. The natural bond orbital analysis is used to study the intermolecular charge‐transfer interactions and explore the origin of the internal forces of the molecular switch. In addition, the binding energies, enthalpies, Gibbs free energies, and the cation exchange energies have been studied for L , W(CO)4 L , and their corresponding complexes. The properties of the complexes displayed by in presence or absence of the W(CO)4 fragment are also analyzed. The calculated results of allosterism displayed by L are in a good agreement with the experimental results. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011  相似文献   

12.
Four metal‐organic frameworks (MOFs), {[Mn3.5L(OH)(HCOO)4(DMF)] · H2O} ( 1 ), {[In2.5L2O(OH)1.5(H2O)2] · DMF · CH3CN · 2H2O} ( 2 ), {[Pb4L3O(DMA)] · CH3CN} ( 3 ), and {[LaL(NO3)(DMF)2] · 2H2O} ( 4 ) were synthesized by utilizing the ligand 2,2′,6,6′‐tetramethoxy‐4,4′‐biphenyldicarboxylic acid (H2L) via solvothermal methods. All MOFs were characterized by single‐crystal X‐ray diffraction, powder X‐ray diffraction, thermogravimetric analysis, and infrared spectroscopy. In 1 , the Mn2+ ions are interconnected by formic groups in situ produced via DMF decomposition to form a rare 2D macrocyclic plane, which is further linked by L2– to construct the final 3D network. In 2 , 1D zip‐like infinite chain is formed and then interconnected to build the 3D framework. In 3 , a [Pb64‐O)2(O2C)10(DMA)2] cluster with a centrosymmetric [Pb64‐O)2]8+ octahedral core is formed in the 3D structure. In 4 , the La3+ ions are connected with each other through carboxylate groups of L2– to generate 1D zigzag chain, which is further linked by L2– to construct a 3D network with sra topology. Solid photoluminescence properties of 3 and 4 were also investigated.  相似文献   

13.
The condensation reaction of 1,1′‐diacetylferrocene with thiocarbohydrazide and carbohydrazide to form bis‐(1,1′‐disubstituted ferrocenyl)thiocarbohydrazone and bis‐(1,1′‐disubstituted ferrocenyl)carbohydrazone has been studied. The compounds obtained have been further used as ligands for their ligand and antimicrobial properties with cobalt(II), copper(II), nickel(II) and zinc(II) metal ions. The compounds synthesized have been characterized by physical, spectral and analytical methods and have been screened for antibacterial activity against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar well‐diffusion method. All the compounds synthesized have shown good affinity as antibacterial and antifungal agents, which increased in most of the cases on complexation with the metal ions. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

14.
4,4′‐Bipyridine‐1,1′‐diium (H2bipy) acetylenedicarboxylate, C10H12N22+·C4O42−, (1), is a new member of a family of related structures with similar unit‐cell parameters. The structures in this family reported previously [Chen et al. (2012). CrystEngComm, 14 , 6400–6403] are (H2bipy)[Cu(ox)2] (ox is oxalate), (2), (H2bipy)[NaH(ox)2], (3), and (H2bipy)[H2(ox)2], (4). Compound (1) has a one‐dimensional structure, in which H2bipy2+ cations and acetylenedicarboxylate (ADC2−) anions are linked through a typical supramolecular synthon, i.e.R22(7), and form linear `–cation–anion–' ribbons. Through an array of nonclassical C—H...O hydrogen bonds, adjacent ribbons interact to give two‐dimensional sheets. These sheets stack to form a layered structure viaπ–π interactions between the H2bipy2+ cations of neighbouring layers. The supramolecular isostructurality of compounds (1)–(4) is ascribed to the synergistic effect of multiple interactions in these structures. The balanced strong and weak intermolecular interactions stabilizing this structure type include strong charge‐assisted N—H...O hydrogen bonds, C—H...O contacts and π–π interactions.  相似文献   

15.
4′‐Substituted derivatives of 2,2′:6′,2′′‐terpyridine with N‐containing heteroaromatic substituents, such as pyridyl groups, might be able to coordinate metal centres through the extra N‐donor atom, in addition to the chelating terpyridine N atoms. The incorporation of these peripheral N‐donor sites would also allow for the diversification of the types of noncovalent interactions present, such as hydrogen bonding and π–π stacking. The title compound, C24H16N4, consists of a 2,2′:6′,2′′‐terpyridine nucleus (tpy), with a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus deviates slightly from planarity, with interplanar angles between the lateral and central py rings in the range 2.24 (7)–7.90 (7)°, while the isq group is rotated significantly [by 46.57 (6)°] out of this planar scheme, associated with a short Htpy…Hisq contact of 2.32 Å. There are no strong noncovalent interactions in the structure, the main ones being of the π–π and C—H…π types, giving rise to columnar arrays along [001], further linked by C—H…N hydrogen bonds into a three‐dimensional supramolecular structure. An Atoms In Molecules (AIM) analysis of the noncovalent interactions provided illuminating results, and while confirming the bonding character for all those interactions unquestionable from a geometrical point of view, it also provided answers for some cases where geometric parameters are not informative, in particular, the short Htpy…Hisq contact of 2.32 Å to which AIM ascribed an attractive character.  相似文献   

16.
Syntheses and Structures of Bis(4,4′‐t‐butyl‐2,2′‐bipyridine) Ruthenium(II) Complexes with functional Derivatives of Tetramethyl‐bibenzimidazole [(tbbpy)2RuCl2] reacts with dinitro‐tetramethylbibenzimidazole ( A ) in DMF to form the complex [(tbbpy)2Ru( A )](PF6)2 ( 1a ) (tbbpy: bis(4,4′‐t‐butyl)‐2,2′bipyridine). Exchange of the two PF6? anions by a mixture of tetrafluor‐terephthalat/tetrafluor‐terephthalic acid results in the formation of 1b in which an extended hydrogen‐bonded network is formed. According to the 1H NMR spectra and X‐ray analyses of both 1a and 1b , the two nitro groups of the bibenzimidazole ligand are situated at the periphery of the complex in cis position to each other. Reduction of the nitro groups in 1a with SnCl2/HCl results in the corresponding diamino complex 2 which is a useful starting product for further functionalization reactions. Substitution of the two amino groups in 2 by bromide or iodide via Sandmeyer reaction results in the crystalline complexes [(tbbpy)2Ru( C )](PF6)2 and [(tbbpy)2Ru( D )](PF6)2 ( C : dibromo‐tetrabibenzimidazole, D : diiodo‐tetrabibenzimidazole). Furthermore, 2 readily reacts with 4‐t‐butyl‐salicylaldehyde or pyridine‐2‐carbaldehyde under formation of the corresponding Schiff base RuII complexes 5 and 6 . 1H NMR spectra show that the substituents (NH2, Br, I, azomethines) in 2 ‐ 6 are also situated in peripheral positions, cis to each other. The solid state structure of both 2 , and 3 , determined by X‐ray analyses confirm this structure. In addition, the X‐ray diffraction analyses of single crystals of the complexes [(tri‐t‐butyl‐terpy)(Cl)Ru( A )] ( 7 ) and [( A )PtCl2] ( 8 ) display also that the nitro groups in these complexes are in a cis‐arrangement.  相似文献   

17.
The photoluminescence characteristics of the [Cd(bipy)3][PF6]2 complex are reported. A moderately large quantum yield (φ) of 1.07 × 10?2 is exhibited in acetonitrile solution at 298 K. Crystallography shows the dication to have a distorted octahedral geometry and the crystal structure to be stabilized by C? H···π and C? H···F interactions. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

18.
The syntheses, characterizations and in vitro cytotoxities of seven soluble silver (I) compounds (1–7) with 2,2′‐bipyridine (bpy), 5,5′‐dimethyl‐2,2′‐bipyridine (dmbpy) and 1, 10‐phenanthroline (phen) are described. Two of the complexes, [Ag(dmbpy)(NO3)] (1) and [Ag(dmbpy)]ClO4(2), have been structurally established by single‐crystal X‐ray diffraction, which reveals the silver(I) atom in compound 1 is in a Y‐shape coordination geometry with two N atoms (av. Ag? N = 227.8 pm) from a chelate dmbpy ligand and an O atom (Ag? O=221.8(4) pm) from a monodentate nitrate. The Ag(I) atom in compound 2 is three‐coordinated by three N atoms, two of which are from a chelate dmbpy, and one from an acetonitrile ligand. The seven compounds showed strong cytotoxities in vitro to both normal and carcinoma cells.  相似文献   

19.
New aromatic dicarboxylic acids having kink and crank structures, 2,2′-bis(p-carboxyphenoxy) biphenyl and 2,2′-bis(p-carboxyphenoxy)-1,1′-binaphthyl, were synthesized by the reaction of p-fluorobenzonitrile with biphenyl-2,2′-diol and 2,2′-dihydroxy-1,1′-binaphthyl, respectively, followed by hydrolysis. Biphenyl-2,2′-diyl-and 1,1′-binaphthyl-2,2′-diyl-containing aromatic polyamides having inherent viscosities of 0.58–1.46 dL/g and 0.63–1.30 dL/g, respectively, were obtained by the low-temperature solution polycondensation of the corresponding diacid chlorides with aromatic diamines. These polymers were readily soluble in a variety of organic solvents including N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide, m-cresol, and pyridine. Transparent, pale yellow, and flexible films of these polymers could be cast from the DMAc or NMP solutions. These aromatic polyamides containing biphenyl and binaphthyl units had glass transition temperatures in the range of 210–272 and 260–315°C, respectively. They began to lose weight around 380°C, with 10% weight loss being recorded at about 450°C in air. © 1993 John Wiley & Sons, Inc.  相似文献   

20.
New aromatic diamines having kink and crank structures, 2,2′-bis(p-aminophenoxy)biphenyl and 2,2′-bis(p-aminophenoxy)-1,1′-binaphthyl, were synthesized by the reaction of p-fluoronitrobenzene with biphenyl-2,2′-diol and 2,2′-dihydroxy-1,1′-binaphthyl, respectively, followed by catalytic reduction. Biphenyl-2,2′-diyl- and 1,1′-binaphthyl-2,2′-diyl-containing aromatic polyamides having inherent viscosities of 0.44–1.18 and 0.26–0.88 dL/g, respectively, were obtained either by the direct polycondensation or low-temperature solution polycondensation of the diamines with aromatic dicarboxylic acids (or diacid chlorides). These polymers were readily soluble in a variety of organic solvents including N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide, m-cresol, and pyridine. Transparent, pale yellow, and flexible films of these polymers could be cast from the DMAc or NMP solutions. These aromatic polyamides containing biphenyl and binaphthyl units had glass transition temperatures in the range of 215–255 and 266–303°C, respectively. They began to lose weight at ca. 380°C, with 10% weight loss being recorded at about 470°C in air. © 1993 John Wiley & Sons, Inc.  相似文献   

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