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1.
Two new Schiff base macrocycles - a 4+4 condensation product and a meso-type 2+2 condensation product - were obtained in a reaction of trans-1,2-diaminocyclohexane and 2,6-diformylpyridine. Reduction of these compounds led to the corresponding 4+4 and 2+2 macrocyclic amines. The macrocycles were characterised by NMR spectroscopy and electrospray mass spectrometry. The symmetry and stereochemistry of these macrocycles, as well as of new 3+3 and 4+4 diastereomers identified in solution, has been established. X-Ray structures of the 2+2 and 4+4 Schiff base macrocycles confirm the configurations determined on the basis of spectroscopic investigations. The crystal structures reveal that the centres of the square-shaped 4+4 macrocycles form channels as a result of columnar stacking.  相似文献   

2.
Five-coordinate Schiff-base Zn complexes (1,2-cyclohexanediamino-N,N′-bis(salicylidene)) zinc-pyridine 1 and (1,2-cyclohexanediamino-N,N′-bis(3,5-di-tert-butylsalicylidene)) zinc-pyridine 2 were synthesized and the structures of 1 and 2 have been determined by single-crystal X-ray analysis. All Zn atoms are five-coordinate in both structures. Both complexes exhibit interesting structures based on intermolecular π–π stacking and hydrogen bond interactions. Complex 1 has a one-dimensional molecular chain structure via π–π stacking interaction, while complex 2 has an interesting lattice structure (with cavities with dimensions 10.9?×?6.9?Å) formed through intermolecular π–π stacking and hydrogen bond interactions. 1 and 2 are compared and characterized by MS, elemental analysis, IR, UV-Vis and Photoluminescence (PL). Fluorescence spectra show that the maximal emission wavelength of 1 and 2 are 454?nm, and 480?nm, respectively, upon radiation by UV light. Cyclic voltammetry performed on 1 and 2 indicate a dependence of the cathodic potentials upon conformational and electronic effects. Electronic spectral properties of 1 and 2 were studied by TD-DFT methods. The fluorescent emission of these complexes originates from ligand-centred π–π? transitions. The Zn (II) centres play a key role in enhancing the fluorescent emission of the ligands.  相似文献   

3.
合成并表征了配合物1,[Zn2(EBTC)(BPDO)(DMSO)(H2O)2]n,其中EBTC为1,1′-苯乙炔-3,3′,5,5′-四羧酸根,BPDO为4,4′-二吡啶基1,1′-二氧化物,DMSO为二甲亚砜。1沿着b轴的方向具有类似于三腿梯子状的链状结构,链与链之间通过氢键作用和π-π堆积作用形成了三维超分子结构。在室温条件下1表现出了荧光性质。  相似文献   

4.
The syntheses of tetra-tetrazole macrocycles, containing two bis-tetrazole units linked by a variety of alkyl-chain lengths from four to eight carbons, are described. The crystal structures of three of these derivatives are reported, and the molecular conformation in the solid state is compared to that of the previously reported tetra-tetrazole macrocycle and to other bis- and tris(tetrazole)benzene structures. The macrocycle conformation is influenced by the length of the alkyl-chain linker, the relative orientation of the tetrazole rings on the benzene ring and by intermolecular interactions. In the macrocycles based on 1,2-bis(tetrazole)benzene, the adjacent tetrazole rings on the benzene ring are prevented from becoming co-planar on intramolecular (steric) grounds. In the 1,3- and 1,4-bis(tetrazole)benzene derivatives, there is no such impediment, and a co-planar arrangement is observed where intra- and/or intermolecular stacking interactions exist. Deviations from co-planarity are associated with optimisation of intermolecular interactions between the tetrazole rings and adjacent alkyl chains. In the macrocycle based on 1,4-bis(tetrazole)benzene with four-carbon linkers, an intramolecular stacking interaction exists, which precludes the presence of any cavity. In the macrocycle based on 1,3-bis(tetrazole)benzene with six-carbon linkers, a cavity of 10.8×9.4 Å is observed for each molecule in the solid state, although the packing of adjacent molecules is such that there are no extended channels running through the crystal.  相似文献   

5.
Two novel discotic macrocycles, substituted cyclohexa‐m‐phenylene (CHP) and cyclo‐3,6‐trisphenanthrylene (CTP), and the linear oligomer 3,3′:6′,3′′‐terphenanthrene (TP) as a model substance have been synthesized by repetitive cross‐coupling reactions. To correlate the molecular design with the supramolecular architecture and the established macroscopic order, 2D wide‐angle X‐ray scattering experiments were performed on mechanically extruded filaments. At room temperature in their crystalline phases, all three compounds revealed columnar assemblies in which the macrocycles self‐organized by π‐stacking interactions. The degree of macroscopic order was found to depend upon the planarity and stiffness of the aromatic core. The flexible CHP ring showed a poor macroscopic order of the columnar structures and a low isotropization temperature, whereas the more‐planar, less‐flexible CTP self‐assembled into well‐defined superstructures. The larger π‐stacking area and the more‐pronounced intermolecular interactions for CTP led to the formation of a mesophase over a very large temperature range. The surprising columnar organization of the “open” TP system was explained by back‐folding of the molecule into a ringlike structure.  相似文献   

6.
Phase-selective photochemical reaction of 2-pyridone derivatives was examined. Irradiation of 1 in benzene mainly gave rearrangement products 2. However, intermolecular [4 + 4] photocycloaddition proceeded quantitatively in the solid state, affording photodimers 3. An effective pi-pi stacking and dipole-dipole interaction between two pyridone moieties might play important roles in an effective arrangement of 1 for photodimerization in their crystal structures. [reaction: see text]  相似文献   

7.
This study of 3‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)‐2H‐chromen‐2‐one, C17H10N2O3, 1 , and 3‐[5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazol‐2‐yl]‐2H‐chromen‐2‐one, C16H9N3O3, 2 , was performed on the assumption of the potential anticancer activity of the compounds. Three polymorphic structures for 1 and two polymorphic structures for 2 have been studied thoroughly. The strongest intermolecular interaction is stacking of the `head‐to‐head' type in all the studied crystals. The polymorphic structures of 1 differ with respect to the intermolecular interactions between stacked columns. Two of the polymorphs have a columnar or double columnar type of crystal organization, while the third polymorphic structure can be classified as columnar‐layered. The difference between the two structures of 2 is less pronounced. Both crystals can be considered as having very similar arrangements of neighbouring columns. The formation of polymorphic modifications is caused by a subtle balance of very weak intermolecular interactions and packing differences can be identified only using an analysis based on a study of the pairwise interaction energies.  相似文献   

8.
Four ferrocenyl macrocyclic derivatives 3 and 4 containing anthracene fluorophores have been synthesized. The fluorescent properties of these receptors have been studied in three organic solvents, both in the absence and presence of phenyl amino alcohols. All receptors exhibit sensitive fluorescence response to l- or d-phenylglycinol, a strong emission band is produced due to the intermolecular exciplex between host and guest. These special phenomena were not observed when other species were used as the guests; such highly selective fluorescent response indicates that these receptors can easily discriminate phenylglycinol from other similar species. Solvent comparative experiments also indicate that acetonitrile is the most appropriate solvent to detect this fluorescent change. The intramolecular energy transfer between excited anthracene and ferrocene, and π–π stacking interaction between the aromatic rings play critical roles in this special fluorescence enhancement. Model calculations at DFT level further suggest the possible interaction modes, structures and relatively steric position between the host and guest also influence the optical response.  相似文献   

9.
Two new fluorescent coordination polymers based on pamoic acid and different polydentate N-donor ligands, namely {[Cd(PA)(TPTZ)(H2O)](DMF)2}n ( 1 ) and [Cd(PA)(BIB)]n ( 2 ) [H2PA = pamoic acid, TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, BIB = 1,4-bis(1-imidazolyl)benzene], were synthesized and characterized. Complex 1 showed a 1D zigzag chain structure with intramolecular hydrogen bonds. The 2D supramolecular structure in 1 was formed through π–π stacking interactions and intermolecular hydrogen bonds. Complex 2 displayed a 2D network structure. Intramolecular hydrogen bonds and π–π stacking interactions were observed in 2 . By studying the fluorescence sensing performance of two coordination polymers, complex 1 exhibited high selectivity for tracking Al3+ ion and complex 2 could discriminately detect inorganic or aliphatic amines with high selectivity.  相似文献   

10.
Fully conjugated giant macrocyclic oligothiophenes with 60pi, 90pi,120pi, 150pi, and 180pi frames (1, 2, 3, 4 and 5) have been designed, and their butyl-substituted derivatives (1a, 2a, 3a, 4a, and 5a) have been synthesized using modified Sonogashira and McMurry coupling reactions as key steps. The 60-180pi systems 1-5 are circular with 1.8-6 nm inner cavities and 3.3-7.5 nm outside molecular diameters. Compound 1a containing ten 3,4-dibutyl-2,5-thienylene, eight ethynylene, and two vinylene units has been converted into macrocyclic oligo(3,4-dibutyl-2,5-thienylene-ethynylene) 6a using bromination/dehydrobromination procedure. Giant macrocycles 1a-6a exhibit a red shift of their absorption spectra and a fairly strong fluorescence with a large Stokes shift as compared to a linear conjugated counterpart having five thiophene rings. Compounds 1a-6a exhibit multistep reversible redox behaviors with fairly low first oxidation potentials, reflecting their cyclic conjugation. Furthermore, chemical oxidation of 1a-6a with FeCl3 shows drastic changes of spectroscopic properties due to intramolecular and intermolecular pi-pi interactions. Doping of 1a-3a with iodine forms semiconductor due to its pi-donor properties and pi-pi stacking ability. X-ray analysis of 1a confirmed a round, planar structure with nanoscale inner cavity, and revealed host ability for alkanes and unique packing structure. Interestingly, 2a and 3a self-aggregate in the solid state to form "molecular wires," which are about 200 nm thick and more than 1 mm long. The internal structures of fibrous aggregates have been investigated by optical microscope, scanning electron microscopy, atomic force microscopy, and X-ray diffraction analyses.  相似文献   

11.
Being a close analogue of amflutizole, methyl 4‐amino‐3‐phenylisothiazole‐5‐carboxylate (C11H10N2O2S) was assumed to be capable of forming polymorphic structures. Noncentrosymmetric and centrosymmetric polymorphs have been obtained by crystallization from a series of more volatile solvents and from denser tetrachloromethane, respectively. Identical conformations of the molecule are found in both structures. The two polymorphs differ mainly in the intermolecular interactions formed by the amino group and in the type of stacking interactions between the π‐systems. The most effective method for revealing packing motifs in structures with intermolecular interactions of different types (hydrogen bonding, stacking, dispersion, etc.) is to study the pairwise interaction energies using quantum chemical calculations. Molecules form a column as the primary basic structural motif due to stacking interactions in both polymorphic structures under study. The character of a column (straight or zigzag) is determined by the orientations of the stacked molecules (in a `head‐to‐head' or `head‐to‐tail' manner). Columns bound by intermolecular N—H…O and N—H…N hydrogen bonds form a double column as the main structural motif in the noncentrosymmetric structure. Double columns in the noncentrosymmetric structure and columns in the centrosymmetric structure interact strongly within the ab crystallographic plane, forming a layer as a secondary basic structural motif. The noncentrosymmetric structure has a lower density and a lower (by 0.59 kJ mol?1) lattice energy, calculated using periodic calculations, compared to the centrosymmetric structure.  相似文献   

12.
This paper summarizes our findings on the effects of protons and neutral salt ions on intermolecular interactions and the self-organization of nucleotide systems in aqueous media, both at monomer and polymer levels. To gain quantitative information about these processes, methods were developed to determine the thermodynamic parameters of monomer association from the data obtained by various experimental techniques (NMR , UV spectroscopy, and spin labeling) and to estimate the individual contributions of base stacking and H-bonding in ordered structures of polynucleotides and their complexes. The main results obtained using these methods are as follows. (i) A difference was discovered in the effects of positive and negative charges on the stacking interaction between ionized and neutral molecules of nucleic heterocycles. Protonation strongly decreases the heterocycle ability to form ordered stacks whereas deprotonation slightly affects stacking. (ii) Base–phosphate interaction, which has not yet really been investigated, was studied. This interaction, along with base stacking, governs nucleotide association in water media. It appears upon protonation of the base moiety and increases with decreasing ionic strength. (iii) Base stacking was found to become stronger under the action of salt anions stabilizing the water structure and it became weaker under the action of destabilizing salt anions, both in monomer and polymer systems, which is indicative of an indirect mechanism of the anionic effects. It is essential that small salt ion additives acting by such a “distance” mechanism can affect the formation of ordered structures in nucleotide systems as strong as the direct interaction of the bases with protons. (iv) The results obtained suggest that an increase in solvent entropy upon the self-organization of nucleotide systems in aqueous media may be an important factor promoting these processes. (v) As follows from our data, specific weakening or strengthening of intermolecular interactions by protons and salt ions at small, physiological-range changes in pH or solvent salt composition seems to be an effective regulatory mechanism for the functioning of nucleotide systems.  相似文献   

13.
A single‐chain magnet (SCM) was constructed from manganese(III) 5,10,15‐tris(pentafluorophenyl)corrole complex [MnIII(tpfc)] through supramolecular π–π stacking without bridging ligands. In the crystal structures, [Mn(tpfc)] molecules crystallized from different solvents, such as methanol, ethyl acetate, and ethanol, exhibit different molecular orientations and intermolecular π–π interaction or weak Mn ??? O interaction to form a supramolecular one‐dimensional motif or dimer. These three complexes show very different magnetic behaviors at low temperature. Methanol solvate 1 shows obvious frequency dependence of out‐of‐phase alternating‐current magnetic susceptibility below 2 K and a magnetization hysteresis loop with a coercive field of 400 Oe at 0.5 K. It is the first example of spin‐canted supramolecular single‐chain magnet due to weak π–π stacking interaction. By fitting the susceptibility data χMT (20–300 K) of 1 with the spin Hamiltonian expression ${\overrightarrow{H}}A single-chain magnet (SCM) was constructed from manganese(III) 5,10,15-tris(pentafluorophenyl)corrole complex [Mn(III) (tpfc)] through supramolecular π-π stacking without bridging ligands. In the crystal structures, [Mn(tpfc)] molecules crystallized from different solvents, such as methanol, ethyl acetate, and ethanol, exhibit different molecular orientations and intermolecular π-π interaction or weak Mn???O interaction to form a supramolecular one-dimensional motif or dimer. These three complexes show very different magnetic behaviors at low temperature. Methanol solvate 1 shows obvious frequency dependence of out-of-phase alternating-current magnetic susceptibility below 2?K and a magnetization hysteresis loop with a coercive field of 400?Oe at 0.5?K. It is the first example of spin-canted supramolecular single-chain magnet due to weak π-π stacking interaction. By fitting the susceptibility data χ(M) T (20-300?K) of 1 with the spin Hamiltonian expression H = -2J Σ(i=1)(n-1) S(Ai) S(Ai+1) + D Σ(i) S((iZ)(2)), the intrachain magnetic coupling parameter transmitted by π-π interaction of -0.31?cm(-1) and zero field splitting parameter D of -2.59?cm(-1) are obtained. Ethyl acetate solvate 2 behaves as an antiferromagnetic chain without ordering or slow magnetic relaxation down to 0.5?K. The magnetic susceptibility data χ(M) T (20-300?K) of 2 was fitted by assuming the spin Hamiltonian H = -2JΣ(i=1)(n-1) S(Ai) S(Ai+1), and the intrachain antiferromagnetic coupling constant of -0.07?cm(-1) is much weaker than that of 1. Ethanol solvate 3 with a dimer motif shows field-induced single-molecule magnet like behavior below 2.5?K. The exchange coupling constant J within the dimer propagated by π-π interaction is -0.14?cm(-1) by fitting the susceptibility data χ(M) T (20-300?K) with the spin Hamiltonian H = -2J S(A) S(B) + β(S((A)g(A)) + S((B)g(B)))H. The present studies open a new way to construct SCMs from anisotropic magnetic single-ion units through weak intermolecular interactions in the absence of bridging ligands.  相似文献   

14.
Liu W  Wang CF  Li YZ  Zuo JL  You XZ 《Inorganic chemistry》2006,45(25):10058-10065
Using the tricyano precursor, (Bu4N)[(Tp)Fe(CN)3] (Tp = Tris(pyrazolyl) hydroborate) (1), four new tetranuclear clusters, [(Tp)Fe(CN)3Cu(Tp)]2.2H2O (2), [(Tp)Fe(CN)3Cu(bpca)]2.4H2O (3) (bpca = bis(2-pyridylcarbonyl)amidate anion), [(Tp)Fe(CN)3Ni(tren)]2(ClO4)2.2H2O (4) (tren = tris(2-amino)ethylamine), and [(Tp)Fe(CN)3Ni(bipy)2]2[(Tp)Fe(CN)3]2.6H2O (5) (bipy = 2,2'-bipyridine), have been synthesized and structurally characterized. The four clusters possess similar square structures, where FeIII and MII (M = CuII or NiII) ions alternate at the rectangle corners. There exist intermolecular - stacking interactions through pyrazolyl groups of Tp- ligands in complexes 2 and 4, which lead to 1D chain structures. Complex 5 shows a 3D network structure through the coexistence of - stacking effects and hydrogen-bonding interactions. Magnetic studies show intramolecular ferromagnetic interactions in all four clusters. The exchange parameters are +11.91 and +1.38 cm(-1) for clusters 2 and 3, respectively, while uniaxial molecular anisotropy can be detected in complex 3 due to the distorted core in its molecular structure. Complex 4 has a ground state of S = 3 and shows SMM behavior with an effective energy barrier of U = 18.9 cm(-1). Unusual spin-glass-like dynamic relaxations are observed for complex 5.  相似文献   

15.
Three new bis-terdentate Schiff base [2 + 2] macrocycles (H(2)L(Et), H(2)L(Pr), and H(2)L(Bu)) have been prepared in high yields by 1:1 condensation of 2,2'-iminobisbenzaldehyde with 1,2-diaminoethane, 1,3-diaminopropane, and 1,4-diaminobutane, respectively. Metalation of these macrocycles yields the corresponding dicopper(II) acetate (1, 2, and 3) and tetrafluoroborate (4, 5, and 6) complexes. The structures of H(2)L(Et), H(2)L(Pr), H(2)L(Bu), [Cu(II)(2)L(i)(OAc)(2)]·solvents (where i is Et, Pr or Bu) and [Cu(II)(2)L(Pr)(DMF)(4)] (BF(4))(2)·0.5H(2)O are reported. Intramolecular hydrogen bonding is a feature of the metal-free macrocycles. The copper(II) centers in [Cu(II)(2)L(i)(OAc)(2)]·solvents are four coordinate, and the macrocycles have U-shaped (Et, Bu) or stepped (Pr) conformations. Complex 5 crystallizes with two dimethylformamide (DMF) molecules bound per five coordinate copper(II) center. Electrochemical studies revealed ligand based oxidations for all of the macrocycles and complexes. Complexes 1 and 2 undergo two quasi-reversible oxidations in DCM which are associated with the deposition of a visible film on the electrode after multiple scans in this oxidative region, suggestive of electropolymerization. Complexes 4-6, studied in MeCN, have Cu(II) → Cu(I) redox potentials at more positive potentials than for 1-3.  相似文献   

16.
A synergistically directed assembly approach to distinctive metal‐organic frameworks utilizing both donor‐acceptor (D‐A) interaction from aromatic systems and coordination interactions is presented. Based on such an approach, the coronene‐tpt (tpt = 2,4,6‐tri(4‐pyridyl)‐1,3,5‐triazine) stacks based coronene‐MOF‐1 — 4 have been successfully fabricated. Their structural discrepancies with coronene‐ absent control products, 1′ — 4′ , illustrate clearly the significance of coronene‐tpt based D‐A interactions in these architectures. All these coronene‐MOFs contain varied coronene‐tpt stacks as organic secondary building blocks (SBUs), which are closely interrelated with the coordination based framework structures. Moreover, porous coronene‐MOF‐1 and ‐2 exhibit high physicochemical stability and significant light hydrocarbons storage and separation performances.  相似文献   

17.
表面辅助激光解吸电离质谱(SALDI-MS)已经成为固态、液态样品分析的重要手段,并且分析对象逐渐由生物大分子扩展到小分子.然而,对小分子电离微观反应机理的研究仍处于起步阶段.本研究选择3种分子结构相似的稠环芳烃化合物芘、六苯并苯、红荧烯作为研究对象,考察了这3种化合物激光电离产物的差异,并研究了激光能量对六苯并苯产物离子分布的影响.结果表明,观察到芘、六苯并苯多聚体离子产物,还观测到了六苯并苯失去C2H2的碎片离子峰;而没有观测到明显的红荧烯聚合物离子产物,只观测到了大量失去C6H5的碎片离子峰.最后,对3种不同化合物的激光电离微观机理进行了分析.由于芘、六苯并苯具有平面大π键,分子间的π-π键相互作用是产生多聚体离子的主要原因;而红荧烯的空间位阻削弱了分子间相互作用,从而阻碍了多聚体离子的形成.  相似文献   

18.
Novel π‐conjugated topologies based on oligothiophenes and phenanthroline have been assembled by combining their outstanding electronic and structural benefits with the specific properties of the topological structure. Macrocycles and catenanes are prepared by using an optimized protocol of transition metal‐templated macrocyclization followed by efficient Pd‐catalyzed cross‐coupling reaction steps. By using this method, [2]catenanes comprising two interlocked π‐conjugated macrocycles with different ring sizes have been synthesized. The structures of the [2]catenanes and corresponding macrocycles are confirmed by detailed 1H NMR spectroscopy and high resolution mass spectrometry. Single crystal X‐ray structural analysis of the quaterthiophene–diyne macrocycle affords important insight into the packing features and intermolecular interaction of the new systems. The fully conjugated interlocked [2]catenanes are fully characterized by spectroscopic and electrochemical measurements.  相似文献   

19.
Encapsulation of coronene inside single‐walled carbon nanotubes (SWNTs) was studied under various conditions. Under high vacuum, two main types of molecular encapsulation were observed by using transmission electron microscopy: coronene dimers and molecular stacking columns perpendicular or tilted (45–60°) with regard to the axis of the SWNTs. A relatively small number of short nanoribbons or polymerized coronene molecular chains were observed. However, experiments performed under an argon atmosphere (0.17 MPa) revealed reactions between the coronene molecules and the formation of hydrogen‐terminated graphene nanoribbons. It was also observed that the morphology of the encapsulated products depend on the diameter of the SWNTs. The experimental results are explained by using density functional theory calculations through the energies of the coronene molecules inside the SWNTs, which depend on the orientation of the molecules and the diameter of the tubes.  相似文献   

20.
通过芳香二胺单体1和二酸酰氯单体2的一步环化反应合成了酰胺键上的氢原子被2,4-二甲氧基苄基部分取代的一系列新型的芳香酰胺八聚体大环化合物3, 这些带有不同R基团环状八聚体的结构得到了核磁、高分辨质谱和MALDI-TOF的确认.  相似文献   

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