1-烃基-2-(4-β-D-吡喃阿洛糖苷-苯基)-苯并咪唑类化合物的合成及其镇静活性的研究

以豆腐果苷为原料, 在冰醋酸催化下和邻苯二胺缩合生成中间体2-(4-β-D-吡喃阿洛糖苷-苯基)-苯并咪唑(2), 2与卤代烃在K₂CO₃作用下以乙醇为溶剂合成了一系列1-烃基-2-(4-β-D-吡喃阿洛糖苷-苯基)-苯并咪唑类化合物3a～3h. 新化合物2和3a～3h的结构经¹H NMR, IR和MS (HRMS)确认, 并对2和3a～3h进行了药理活性筛选. 结果表明, 部分化合物具有良好的镇静活性; 其中化合物2 (100 mg•kg^－1), 3f (100 mg•kg^－1)与豆腐果苷相比较具有更强的药理活性.     

CIRCULAR DICHROISM OF BIS(DIMETHYLGLYOXIMATO)COBALT(III) COMPLEXES CONTAINING OPTICALLY ACTIVE AMINES

Abstract

The preparations and circular dichroism (CD) spectra of a series of bis(dimethylglyoximato)cobalt(III) complexes, each containing two asymmetric unidentate amines in trans positions, are reported. Tentative spectral assignments are made for the d-d region on the basis of effective D_4h molecular symmetry. In all cases the rotational strengths observed for the aromatic amine complexes are larger than those observed for the alkyl amine complexes.     

A Local D4h Symmetric Dysprosium(III) Single-Molecule Magnet with an Energy Barrier Exceeding 2000 K**

Three six-coordinate Dy^III single-molecule magnets (SMMs) [Dy(O^tBu)₂(L)₄]⁺ with local D_4h symmetry are obtained by optimizing the equatorial ligands. One of the compounds with L=4-phenylpyridine shows an energy barrier (U_eff) of 2075(11) K, which is the third largest U_eff, and the first U_eff>2000 K for SMMs with axial-type symmetry so far. Ab initio analysis indicates that the exceptional uniaxial magnetic anisotropy is deeply related to the axially compressed octahedral geometry. This work provides a new insight into the local D_4h symmetry for high-performance SMMs.     

3-(4-β-D-吡喃阿洛糖苷-苯基)-4-芳基-5-芳基-1,2,4-噁二唑啉的合成及其镇静活性的研究

以豆腐果苷为原料, 与盐酸羟胺缩合反应生成4-β-D-吡喃阿洛糖苷-苯甲醛肟(2), 2与次氯酸叔丁酯发生取代反应生成4-β-D-吡喃阿洛糖苷-α-氯苯甲醛肟(3); 再将3与Schiff碱通过1,3-偶极环加成生成一系列3-(4-β-D-吡喃阿洛糖苷-苯基)-4-芳基-5-芳基-1,2,4-噁二唑啉(5a～5h). 3和 5a～5h共9个化合物均未见文献报道, 其结构经¹H NMR, IR和MS (HRMS)加以确认, 并对5a～5h进行了药理活性筛选. 结果表明, 部分化合物具有良好的镇静活性. 其中, 化合物5g (200, 100 mg•kg^－1)和5h (200, 100 mg•kg^－1)与豆腐果苷相比较具有更强的活性.     

Novel supramolecular columnar liquid crystals based on thiosemicarbazides

Novel liquid crystal materials based on 3,4-di-n-alkoxybenzoylthiosemicarbazides (3a–h, n = 5–10, 12, 14) were synthesised. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Compound 3a did not show mesomorphic properties; 3b shows a monotropic hexagonal columnar (Col_h) phase. Compounds 3c–h display an enantiotropic Col_h phase. The mesomorphic properties were found to be dependent on the length of alkoxy side chains. In N,N-dimethylformamide solution, all the compounds displayed a room temperature emission with λ_max at 361–332 nm. A thermogravimetric analysis also was performed.     

One-pot synthesis of novel 1,2,3-triazole-pyrimido[4,5-c]isoquinoline hybrids and evaluation of their antioxidant activity

A series of novel pyrimido[4,5-c]isoquinolines (3a–3h) and 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinolines (4a–4h) were synthesized in good to excellent yields in the one-pot method. The reaction of 6-amino-1,3-dimethyluracil with different 2-iodo benzoyl chlorides using Pd catalyst in dimethylformamide afforded corresponding pyrimido[4,5-c]isoquinolines (3a–3h). One-pot reaction of pyrimido[4,5-c]isoquinolines with propargyl bromide and benzyl azide in THF at room temperature furnished 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinoline (4a–4h). In vitro antioxidant activity examination revealed that compounds 4d and 4c found to exhibit potent antioxidant activity as compared to the standard drug Trolox with IC₅₀ values 6.02?±?0.6 and 12.18?±?0.9?µM, respectively.     

Bridged structures in multiply bonded silicon compounds: Disilyne,protonated disilyne and disilene

Ab initio SCF and electron correlation calculations are reported for the singlet ground state of the title compounds. These calculations confirm earlier findings that non-planar bridged Si₂H₂ is the most stable structure. For protonated disilyne (Si₂H³⁺) a bridged D_3h structure is the global mimimum. Two bridged structures of C_2v and C_2h symmetry are found in the case of disilene (Si₂H₄) which are only 14–17 kcal/mol above the D_2h structure.     

Control of Chromophore Symmetry by Positional Isomerism of Peripheral Substituents

The first example of the control of porphyrinoid chromophore symmetry based on the positional isomerism of peripheral substituents has been achieved by preparing tetraazaporphyrins (TAPs) with C_4h, D_2h, C_2v, and C_s symmetry due to the relative arrangement of peripheral tert‐butylamino and cyano groups as push and pull substituents, respectively. The four structural isomers were successfully isolated and characterized by ¹H NMR spectroscopy and X‐ray crystallography. The band morphology in the Q‐band region varies depending on the molecular symmetry due to the significant perturbation introduced into the chromophore by the push and pull substituents. The C_4h and C_2v isomers exhibit a single Q band, whereas the Q bands of the D_2h and C_s isomers show a marked splitting. The magnetic circular dichroism spectra indicate that the push–pull TAPs retain the properties of the 16‐membered 18π‐electron perimeter generally observed for porphyrinoids. Theoretical calculations have demonstrated that the perturbation introduced by the substituents lowers the D_4h symmetry of the parent TAP π‐conjugated system, and this results in significant spectral changes. A novel approach to the fine‐tuning of the spectral properties of porphyrinoids based on changes in the chromophore symmetry is described.     

Structural study of the 1:1 clathrate of an asymmetric calix[4]arene and acetone

The crystal and molecular structure of the 1:1 clathrate of the asymmetric calix[4]arene,1, and acetone has been determined by X-ray analysis. The crystal data are: tetragonal, space groupP4/n,a=b=12.574(6),c=12.572(6) Å,V=1988(2) ų,Z=2,D _x =1.111 g cm^–3,D _m =1.108 g cm^–3. Least-squares refinement based on 1131 observed reflections withF ₀>3(F ₀) and anisotropic temperature factors led toR=0.096. In spite of the molecular asymmetric calixarene1 the crystal structure has high symmetry, because a part of the host and guest molecules are in disordered states.     

Multiple bonds and re(4f) binding energies of some rhenium halides

Experimental results on the bombardment of some rhenium trihalides by argon ions in a photoelectron spectrometer have yielded lower-valency rhenium halides. The presence of the compounds have been made evident by the destabilization of the Re(4f) and the relative decrease in the halogen spectral line intensities. A theoretical approach to the energy of the Re(4f) states have been studied by the MS X-α method. The molecular model used in the calculations is made up of rhenium polyhalides in D_4h symmetry having the structure Re₂X (n = 2, 4, 6). A discussion is also presented on the formation of multiple bonds as a result of the overlap between the d_xy orbitals of rhenium.     

New cobalt(II) coordination polymer based on carboxyphenyl-tpy ligand: Photoluminescence,crystal structures and magnetic properties,without orbital contribution

One coordination polymer, [Co(3-ctpy)₂(H₂O)₂]_n*2nEtOH (1), was synthesized by a solvothermal method mixing the complex precursor cobalt(II) acetylacetonate (Co(acac)₂*2H₂O) with 4′-(4-carboxyphenyl)-3,2′:6′,3″-terpyridine (3-Hctpy). This paramagnetic complex has been isolated as a neutral, air and thermal stable solid and has been characterized by elemental analysis, FT-IR and single-crystal X-ray diffraction analysis. The thermal stability and photoluminescence properties were studied in the solid state. The magnetic behavior presents an interesting challenge since the Co(II) ion has a spin 3/2, which leads to multiple possibilities under the influence of an energy crystal field, from the identification of the ground state to possible transitions to excited states. The usual orbital contribution of the magnetic moment has been extinguished, due to an axially distorted octahedral environment for cobalt, changing the O_h symmetry (with ⁴T_1g ground state) to D_4h (with ⁴A_2g ground state). This decrease in symmetry is responsible for the quenching of the orbital contribution, as will be discussed in this article.     

High Nuclearity Bimetallic Rhodium–Palladium Carbonyl Cluster Complexes. Synthesis and Characterization of Rh6(CO)16[Pd(PBu t 3)]3 and Rh6(CO)16[Pd(PBu t 3)]4

The reaction of Rh₄(CO)₁₂ with Pd(PBu ^t ₃)₂ yielded the high nuclearity bimetallic hexarhodium-tripalladium cluster complex Rh₆(CO)₁₆[Pd(PBu ^t ₃)]₃, 10, in 11% yield. Compound 10 was converted to the hexarhodium-tetrapalladium cluster Rh₆(CO)₁₆[Pd(PBu ^t ₃)]₄, 11, in 62% yield by reaction with an additional quantity of Pd(PBu ^t ₃)₂. Both compounds were characterized crystallographically. Structurally, both compounds consist of an octahedral cluster of six rhodium atoms with sixteen carbonyl ligands analogous to that of the known compound Rh₆(CO)₁₆. Compound 10 also contains three Pd(PBu ^t ₃) groups that bridge three Rh–Rh bonds along edges of the Rh₆ octahedron to give an overall D₃ symmetry to the Rh₆Pd₃ cluster. Compound 11 contains four edge bridging Pd(PBu ^t ₃) groups distributed across the Rh₆ octahedron to give an overall D_2d symmetry to the Rh₆Pd₄ cluster. Each Rh–Pd connection in both compounds contains a bridging carbonyl ligand that helps to stabilize the bond between the Pd(PBu ^t ₃) groups and the Rh atoms. Both compounds can be regarded as Pd(PBu ^t ₃) adducts of Rh₆(CO)₁₆.     

The infrared spectra of SbF−6 isolated within alkali halides

The SbF^?₆ ion is found to lose its O_h symmetry when isolated within RbI and RbBr lattices. The most likely symmetry is D_2h. ν₃(F_1u) and ν₄(F_1u) each split into three infrared active components. Two components are observed in the infrared from the previously inactive ν₆ (F_2u under O_h) but no infrared absorption has been observed for those modes which were Raman active under O_h symmetry.     

Approximate symmetry-breaking in the independent particle model of monocyclic completely conjugated polyenes

We examine the singlet stability of symmetry adapted, restricted Hartree-Fock (RHF) solutions and the implied symmetry breaking for various planar, π-electron systems with conjugated double bonds as described by the semiempirical Pariser-Parr-Pople Hamiltonian. In particular, we explore the energy and charge- density waves (CDWs) in various real and hypothetical structures that result by a systematic deformation of the nuclear framework: we start with a highly symmetric cyclic polyene C _N H _N having a nondegenerate ground state (N = 2n = 4ν + 2, ν = 1, 2,...), whose sites form a regular N-gon (D _Nh point group), and proceed to structures with lower symmetry (D _6h , D _3h , D _2h point groups), or with only the planar symmetry of the conjugated π-electron system (C _1h ). The objective of this study is to explore the phenomenon that could be referred to as a breaking of an approximate symmetry or an implied symmetry breaking.     

HMO-elektronen-Struktur von Annulenen mit Bindungsalternanz

Zusammenfassung Für 4n- und (4n + 2)-Annulene mit Bindungsalternanz werden analytische Ausdrücke für die LCAO-Koeffizienten und die Elemente der Ladungs-/ Bindungsordnungsmatrix hergeleitet. Die auf die Umordnung des Orbital-schemas zurückgehende sprunghafte Änderung der Bindungsordnungen in 4n-Annulenen beim SymmetrieübergangD _(2n)h D _(4n)h wird diskutiert.

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HMO-Electron structure of annulenes with bond alternation

Analytical expressions for the LCAO-coefficients and the elements of the charge-bond order-matrix are derived for 4n and for (4n +2) annulenes with alternant bond lengths. Due to the reorganization of the orbital scheme there is a discontinuity in the bond orders of 4n -annulenes at the symmetry change fromD _(2n)h toD _(4n)h .

     

Angular parameters of the overlap integrals of f-orbitals

Angular parameters are calculated for these integrals for - and -types in the complexes MX₆ (O_h and D_3h symmetry), MX₈ (O_h, D_4d, D_2d, D_6h, C_2V, and D_3h), and MX₉ (D_3h). Examples are given of the use of the angular parameters in considering coordination compounds of the lanthanide elements: stabilization energy of the addend field and geometry of the compounds in the ground and excited states.     

Structures and aromaticity of the planar Al<Subscript>2</Subscript>P<Subscript>2</Subscript><Superscript><Emphasis Type="Italic">n</Emphasis>−</Superscript> (<Emphasis Type="Italic">n</Emphasis>=1–4) clusters

Clusters Al₂P₂ ⁿ⁻ (n = 1–4) were theoretically investigated using density functional theory (DFT) methods at the B3LYP/6-311+G* and B3PW91/6-311+G* levels of theory. The calculated results showed that the planar structure (D _2h symmetry) of Al₂P₂ ⁿ⁻ (n = 1–4) species was the global minimum. And the negative nucleus-independent chemical shift (NICS) value of Al₂P₂ ⁿ⁻ (n = 1–4) species indicated the existence of a ring current in the planar structure (D _2h symmetry). A detailed molecular orbital (MO) analysis revealed that the planar structures (D _2h symmetry) had π aromaticity, which further exhibited the strongly aromatic character for Al₂P₂ ⁿ⁻ (n = 1–4) species.     

Fuzzy Symmetry Characteristics of Propadine Molecule

The fuzzy symmetry characteristics for the internal-rotation of propadine were analyzed using the fuzzy symmetry theory for molecule and molecular orbital (MO). In the process of rotation, three different symmetry point groups D_2h, D_2d, and D₂ were considered. Using the D_4h point group, which is the minimal point group including all symmetry elements of D_2h, D_2d, and D₂, we can analyze the fuzzy symmetry for this process. The elements included in D_4h point group can be classified to four subsets: (i) G0—it includes all the elements in D₂ point group, also belongs to all the above three point groups of D_2h, D_2d, and D₂; (ii) G1—it includes the elements in D_2h point group, but not in D_2d point group; (iii) G2—it includes the elements in D_2d point group, but not in D_2h point group; (iv) G3—it includes the elements in D_4h point group, but not in D_2h or D_2d point group. On the basis of the above four subsets, we analyzed the membership functions and the regularity of variation in MOs for the internal-rotation of propadine.     

Air-Stable Hexagonal Bipyramidal Dysprosium(III) Single-Ion Magnets with Nearly Perfect D6h Local Symmetry

Eight-coordinated Dy^III centres with D_6h symmetry are expected to act as high-performance single-molecule magnets (SMMs) due to the simultaneous fulfilment of magnetic axiality and a high coordination number (a requisite for air stability). But the experimental realization is challenging due to the requirement of six coordinating atoms in the equatorial plane of the hexagonal bipyramid; this is usually too crowded for the central Dy^III ion. Here a hexaaza macrocyclic Schiff base ligand and finetuned axial alkoxide/phenol-type ligands are used to show that a family of hexagonal bipyramidal Dy^III complexes can be isolated. Among them, three complexes possess nearly perfect D_6h local symmetry. The highest effective magnetic reversal barrier is found at 1338(3) K and an open hysteresis temperature of 6 K at the field sweeping rate of 1.2 mT s⁻¹; this represents a new record for D_6h SMMs.     

Liquid crystalline guanidinium phenylalkoxybenzoates: towards room temperature liquid crystals via bending of the mesogenic core and the use of triflate counter ions

A series of guanidinium salts 1(C _n ) _m –4(C _n ) _m ?X bearing phenyl alkoxybenzoate cores have been synthesised and their mesomorphic properties have been investigated by polarising optical microscopy (POM), differential scanning calorimetry (DSC) and powder X-ray diffraction experiments (small-angle X-ray scattering and wide-angle X-ray scattering). While compounds 1(C₁₂)₁?X and 3(C₁₂)₁?X with one alkoxy chain showed smectic A (SmA) phases irrespective of the counter ion, compounds 1(C₁₂)₂?OTf and 3(C₁₂)₂?OTf with two alkoxy chains displayed SmA phases and the corresponding chlorides 1(C₁₂)₂?Cl and 3(C₁₂)₂?Cl displayed Col_h. Guanidinium salts 1(C _n )₃–4(C _n )₃?X with three alkoxy chains showed Col_h phases. Whereas the use of cyclic guanidinium head groups rather than acyclic ones had only a minor influence on the mesophase properties, melting points were significantly decreased by bent core units instead of linear core units. Replacement of chloride counterions by triflate lead to a further depression of the clearing points and shifted the mesophase towards room temperature.