环芳类化合物分子轨道相互作用的研究

建立模型分子描述环芳类分子中二苯环、二乙炔的π轨道间的相互作用,应用多重散主射Ｘα自洽场方法对模型分子的电子结构进行计算,得到分子轨道通过空间相互作用的大小随二苯环、二乙炔间距离的增加呈指数下降,在环芳类经合物分子电子结构研究基础上,分析了分子轨道通过键的相互作用,表明,分子轨道通过空间相互作用与通过键相互作用相互抵消,采用过滤态方法计算环芳类化合物分子前线分子轨道电离能,与实验符合较好。     

β-环糊精对丁吡吗啉的包合作用

采用紫外光谱定量研究了β-环糊精(β-CD)对新型杀菌剂丁吡吗啉的包结行为, 结果表明, β-CD与丁吡吗啉形成包结比为1∶1的包结物, 其包结常数随温度升高而减小, 表明包结是一个放热过程; 包结反应热力学参数ΔH, ΔS和ΔG均为负值, 说明包结反应是焓变驱动的自发过程.相溶解度实验表明, β-CD能显著提高丁吡吗啉在水中的溶解度, 有助于该产品剂型的水基化, 且包合对其杀菌活性没有明显影响. 对固态包结物的IR和2D ROESY分析表征表明, 丁吡吗啉以其苯环端从β-CD的窄端进入其空腔, 叔丁基进入到β-CD的阔端, 而分子中的其它部分位于空腔的窄端外.     

发光金属配合物8-羟基喹啉镓(Gaq3)的

利用abinitioHF和密度泛函理论(DFT)B3LYP方法,对有机发光材料8-羟基喹啉镓(Gaq3)进行了几何结构优化,系统分析前线分子轨道特征和能级分布规律以探索其电子跃迁的机理.对3种Gaq3衍生物及其高聚物进行分子设计,分析它们的发光可能性及配体对光谱性质的影响.揭示Gaq3及其衍生物所形成的高分子体系的能带分布特征和规律.结果表明,电子在基态与激发态间的跃迁,主要是在配体8-羟基喹啉环内或环间的电荷转移,主要为π-π*跃迁.电子从含O的苯酚环转移至含N的吡啶环上,O为电子的给体,N为电子的受体.电荷转移的途径应有两种方式:一种是通过喹啉环上的C原子环内传递;另一种则是通过金属离子对配体8羟基喹啉的有效支撑,加强了环间相互作用,促进电子的转移.Gaq3衍生物的分子设计将有效提供合成发光材料的一个方向.     

烷基吡啶及氯化铝正负离子结构的密度泛函研究

采用量子化学密度泛函方法对N-烷基吡啶阳离子和阴离子AlCl4-,Al2Cl7-和Al3Cl10-进行了全优化计算,得到了阴阳离子的几何构型和净电荷分布.计算发现,吡啶环上的电子数符合4n 2规则,具有芳香性.吡啶阳离子的LUMO轨道主要由环上原子的2pz所贡献,是反键π分子轨道.AlCl4-,Al2Cl7-和Al3Cl10-的HOMO轨道主要由Cl原子的2px所贡献.推测吡啶阳离子的LUMO与阴离子的HOMO相互作用形成离子液体分子.     

新型[1+1]Schiff碱大环化合物的合成与表征

在硫酸催化作用下,采用前体二醛1,7-二(2’-甲酰苯基)-4-氮-1,7-二氧-4-(4’-对甲苯磺酸基)庚烷(1)和1,7-二(2’-甲酰苯基)-1,4,7三氧庚烷(2)与二胺化合物N,N’-(2-胺基苯基)-2,6-二甲酰亚胺吡啶(3)分别进行缩合,得到[1+1]Schiff碱大环化合物4和5,并用元素分析、1H NMR、IR和质谱等对大环化合物4和5进行表征.同时用X射线衍射方法测定了2个前体和2个Schiff碱大环的晶体结构.单晶X射线衍射结果表明,2个大环化合物分子中,分子内氢键作用导致整个分子呈现为一扭曲"8"字形构型,分子内一对苯环之间的π-π相互作用进一步稳定其分子的扭曲结构.其紫外研究结果显示,大环化合物4和5对镧(III)离子具有选择性识别作用.     

插销式分子器件——可利用酸碱调控的超分子准轮烷

含有吗啉的富π电子苯醚链化合物与缺π电子联吡啶环玢CPQT通过分子间的π-π堆积作用形成超分子准轮烷结构。研究发现,随着温度的变化,该准轮烷结构的相对运动速度加快,弱相互作用减弱;并进一步发现,随着酸和碱的依次加入,该准轮烷结构呈现"开"与"关"的"插销式"器件性能。     

环芳有机分子中分子轨道的通过空间相互作用

本文给出了描述环芳类化合物分子轨道通过空间相互作用的模型, 进一步采用离散变分X~α自洽场方法研究它们的电子结构, 并计算三类环芳有机分子轨道的通过空间相互作用, 计算结果表明环芳类有机分子的通过空间相互作用的大小随分子中苯环, 乙炔、乙烯间距离的增大而衰减, 本文的结果与定性分析是一致的。     

扩展苯基衍生物分子器件的电子输运的理论研究

通过结合杂化密度泛函和前线轨道理论与弹性散射格林函数方法研究了三种苯基衍生物分子器件的电子输运性质. 基于杂化密度泛函方法计算扩展分子电子结构的基础上, 计算了苯基衍生物三分子结的输运性质. 计算结果表明, 在低偏压下, 电流与电压呈线性变化; 分子结的电阻的对数与苯环的数目呈线性增加关系.     

发光金属配合物8-羟基喹啉镓(Gaq3 )的电子性质及其分子设计

利用ab initio HF 和密度泛函理论(DFT)B₃LYP方法,对有机发光材料8-羟基喹啉镓(Gaq₃)进行了几何结构优化,系统分析前线分子轨道特征和能级分布规律以探索其电子跃迁的机理.对3种Gaq₃衍生物及其高聚物进行分子设计,分析它们的发光可能性及配体对光谱性质的影响.揭示Gaq₃及其衍生物所形成的高分子体系的能带分布特征和规律.结果表明,电子在基态与激发态间的跃迁,主要是在配体8-羟基喹啉环内或环间的电荷转移,主要为π-π^*跃迁.电子从含O的苯酚环转移至含N的吡啶环上,O为电子的给体,N为电子的受体.电荷转移的途径应有两种方式:一种是通过喹啉环上的C原子环内传递;另一种则是通过金属离子对配体8羟基喹啉的有效支撑,加强了环间相互作用,促进电子的转移.Gaq₃衍生物的分子设计将有效提供合成发光材料的一个方向.     

支载型分子印迹聚合物膜的制备及其透过选择性研究

以2-氨基吡啶为模板,采用聚四氟乙烯微孔膜为支载膜,甲基丙烯酸为功能单体,偶氮二异丁腈为引发剂,紫外光引发聚合,制备出支载型分子印迹膜,并研究了分子印迹膜对2-氨基吡啶及其结构类似物的透过选择性,并对甲基丙烯酸与2-氨基吡啶之间的相互作用和膜的形貌进行了表征。结果表明,甲基丙烯酸对模板分子能够形成摩尔比为1∶2的配合物,分子印迹膜能够实现2-氨基吡啶与其类似物的分离。     

Rebek Imide Platforms as Model Systems for the Investigation of Weak Intermolecular Interactions

A Rebek imide receptor with an acetylene‐linked phenyl ring complexes 2,6‐di(isobutyramido)pyridine in (CDCl₂)₂ via triple H‐bonding and π–π‐stacking interactions, and the influence of para‐substituents on both rings was investigated by ¹H NMR binding titrations. When the phenyl ring was extended to biphenyl and the C(4)‐pyridine substituent varied, interaction energies increased in the order CH₃CH₂???phenyl<CH₃S???phenyl<phenyl???phenyl?N‐methylcarboxamide???phenyl, highlighting the energetic gain from π stacking on amide fragments. The predicted preference of amide–π stacking for an antiparallel alignment of the local dipoles could not be confirmed with the studied system. Different substituents were introduced in the para position of the phenyl ring and their interaction with bound 2,6‐di(isobutyramido)pyridine was investigated. Theoretical predictions that the mere introduction of a substituent has a stabilizing effect on π–π stacking, regardless of its electronic nature, were experimentally confirmed.     

The first example of a sigma(2)lambda(2)-dioxaphosphenium cation, stabilized by an intramolecular dative P(+) <-- S bond

[structure in text] The first example of a sigma(2)lambda(2)-dioxaphosphenium cation 5 bearing dioxathiophosphocin ring systems stabilized by an intramolecular dative P(+) <-- S bond and its reactivity with pyridine and cycloaddition reaction with 2,3-dimethylbutadiene are reported.     

The 1:1 complex of 4‐nitro­phenol and 4‐methyl­pyridine

4‐Nitro­phenol and 4‐methyl­pyridine form a 1:1 hydrogen‐bonded dimer, C₆H₅NO₃.C₆H₇N, with the mol­ecules linked by an O—H?N hydrogen bond [O?N 2.668 (2) Å]. The dihedral angle between the phenyl and pyridine ring is 57.8 (4)°. The dimers pack in a herring‐bone structure in the crystal lattice.     

Synthesis and Crystal Structure of Rctt-1-(2-benzoxazolyl)-2-(4-chlorophenyl)-4-phenyl-3-(4-pyridinyl)cyclobutane

1INTRODUCTIONThephotodimerizationof1,2-bisarylethenederivativesisaconvenientwayforsynthesizingtetraarylsubstitutedcyclobutane.Forthisreason,thephotochemistryofstilbeneandstyrylpyridinederivativeshasbeenextensivelystudied[1,2].UpontheirradiationwithUVlight(?=300～400nm),thesemonomersareconvertedtohead-to-tailphotodimersinpolarsolventwithperfectyields.Inrecentyears,ourgrouphasbeenstudyingthephotodimerizationreactionsofheteroarylethenescontainingbenzoxazolyl[3]andphenyloxazolyl[4]groups.Itw…     

N‐Benzylnicotinamide and N‐benzyl‐1,4‐dihydronicotinamide: useful models for NAD+ and NADH

3‐Aminocarbonyl‐1‐benzylpyridinium bromide (N‐benzylnicotinamide, BNA), C₁₃H₁₃N₂O⁺·Br⁻, (I), and 1‐benzyl‐1,4‐dihydropyridine‐3‐carboxamide (N‐benzyl‐1,4‐dihydronicotinamide, rBNA), C₁₃H₁₄N₂O, (II), are valuable model compounds used to study the enzymatic cofactors NAD(P)⁺ and NAD(P)H. BNA was crystallized successfully and its structure determined for the first time, while a low‐temperature high‐resolution structure of rBNA was obtained. Together, these structures provide the most detailed view of the reactive portions of NAD(P)⁺ and NAD(P)H. The amide group in BNA is rotated 8.4 (4)° out of the plane of the pyridine ring, while the two rings display a dihedral angle of 70.48 (17)°. In the rBNA structure, the dihydropyridine ring is essentially planar, indicating significant delocalization of the formal double bonds, and the amide group is coplanar with the ring [dihedral angle = 4.35 (9)°]. This rBNA conformation may lower the transition‐state energy of an ene reaction between a substrate double bond and the dihydropyridine ring. The transition state would involve one atom of the double bond binding to the carbon ortho to both the ring N atom and the amide substituent of the dihydropyridine ring, while the other end of the double bond accepts an H atom from the methylene group para to the N atom.     

Chemistry of the phenoxathiins and isosterically related heterocycles. XXXII . The synthesis of 2-azathianthrene and selected analogs

The synthesis of 2-azathianthrene ([1,4]benzodithiino[2,3-c]pyridine), the only remaining monoazathianthrene yet to be reported, is described. Attempts at the direct condensation of disubstituted pyridines with the dianion of 1,2-dimercaptobenzene were generally unsuccessful requiring that the alternative condensation of the dianion with disubstituted pyridine 1-oxides be employed. The title compound was characterized by physical means including ¹³C-nmr spectroscopy. One analog, 4-nitro-2-azathianthrene was also studied by X-ray crystallographic means; the molecule crystallized with two molecules in the asymmetric unit P2₁/n, a = 20.712(3), b = 7.8109(13), c = 13.720(2)Å, β = 107.880(11)°, Z = 8, the data refined to a final R = 0.051 for 3061 reflections. Dihedral angles between the planes of the phenyl rings were 135.00(13) and 132.52(13)° for the two independent molecules contained in the crystal. Close non? bonded S ?O intramolecular contacts were observed in both molecules between the sulfur and nitro-group oxygens. Both nitro groups are twisted out of the plane of the pyridine ring and are oriented at angles of 28.75 and 38.82° respectively.     

Synthesis,Structure and Raman Data of the New Binuclear Zirconium Complex [Ph4P]2[(ZrCl4Py)2O], with a Zr‐O‐Zr Bridge

The new Zirconium(IV) coordination compound [Ph₄P]₂[(ZrCl₄Py)₂O] (Ph = phenyl, Py = pyridine) was synthesized by dissolving ZrCl₄, [Ph₄P]Cl and a stoichiometric amount of NaOH/Na mixture in pyridine or pyridine/organic solvent mixtures. The title phase was obtained as colourless crystals. The crystal structure of [Ph₄P]₂[(ZrCl₄Py)₂O] was determined. It crystallizes monoclinic, P2₁/c, Z = 4, a = 13.412(2), b = 13.461(2), c = 16.442(3) Å, β = 102.72(1)°. The structure consists of isolated tetraphenylphosphonium cations and [(ZrCl₄Py)₂O]^2? complex anions. The centrosymmetric complex anion contains a linear Zr–O–Zr bridge. Each Zr atom is coordinated by one oxygen dianion, the N atom of one pyridine ring and four chloro ligands in a distorted octahedral geometry. The Raman spectrum of [Ph₄P]₂[(ZrCl₄Py)₂O] is also reported. Most of the observed frequencies can be assigned to vibrations of the tetraphenylphosphonium cations and the pyridine rings.     

The Structure of 3-Phenyl-4-(N-Carbamyl-1,4,2-Oxathiazolimin-3-yl)Sydnone,C11H7N5O4S·0.8 CH2Cl2

The title compound (M_r = 373) crystalizes in the othorhombic space group P bna with a = 10.410(2), b = 11.658(4), c = 23.108(3) Å, V = 2804.4 Å Z = 8. The single crystal intensity data were collected using MoK∞ radiation (λ = 0.7093Å) at room temperature. The crystal and molecular structure was solved with the final agreement index R = 0.039 for 1046 observed reflections. The bond lengths N(1)- C(7) and C(7)-C(8) of the title compound are slightly longer than those of 3-substituted sydnone derivatives. This may be attributed to the steric effect arising from the interaction of the phenyl ring and the 4-substituent with the neighboring atoms of sydnone ring. Both the title compound and 4-acetyl-3-(p-tolyl)sydnone have smaller dihedral angles between the sydnone ring and the plane of the sp² orbital of the double bond of the 4-substituent and both have shorter C(7)-C(9) bond lengths than those of other similar sydnone derivatives.     

A New Two-dimensional Zinc Coordination Polymer Constructed by 1,3-Bis(4-pyridyl)-propane and Terephthalate: Synthesis and Crystal Structure

A new zinc coordination polymer, [Zn2(bpp)(tpa)2H2O] 1 (bpp=1,3-bis(4-pyridyl)-propane and tpa=terephthalate) has been hydrothermally synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. X-ray crystal structure analysis reveals that complex 1 crystallizes in monoclinic, space group P2/c with a=18.348(2), b=10.9080(14), c=13.7924(18), β=98.156(2)°, V=2732.5(6)3 , Z=4, C29H24N2O9Zn2 , Mr=675.24, Z=4, F(000)=1376, Dc=1.641 mg/m3 , μ=1.815 mm-1 , the final R=0.0443 and wR=0.0769 for 2715 observed reflections (I>2σ(I)). The title complex exhibits a two-dimensional (4, 4) sheet structure which is further stacked through face-to-face π-π interactions between the monodentately coordinated pyridine ring of bpp ligand and the phenyl ring of terephthalate ligand to form a 3-dimensional supramolecular structure. Thermogravimetric analyses show that the host framework of the complex is thermally stable up to ca. 400 ℃.     

Two 1,4‐dihydropyridine derivatives with potential calcium‐channel antagonist activity

The title compounds, benzyl 4‐(3‐chloro‐2‐fluorophenyl)‐2‐methyl‐5‐oxo‐4,5,6,7‐tetrahydro‐1H‐cyclopenta[b]pyridine‐3‐carboxylate, C₂₃H₁₉ClFNO₃, (I), and 3‐pyridylmethyl 4‐[2‐fluoro‐3‐(trifluoromethyl)phenyl]‐2,6,6‐trimethyl‐5‐oxo‐1,4,5,6,7,8‐hexahydroquinoline‐3‐carboxylate, C₂₆H₂₄F₄N₂O₃, (II), belong to a class of 1,4‐dihydropyridines whose members sometimes display calcium modulatory properties. The 1,4‐dihydropyridine ring in each structure has a shallower than usual shallow‐boat conformation and is nearly planar in (I). In each structure, the halogen‐substituted benzene ring is oriented such that the halogen substituents are in a synperiplanar orientation with respect to the 1,4‐dihydropyridine ring plane. The oxocyclopentene ring in (I) is planar, while the oxocyclohexene ring in (II) has a half‐chair conformation, which is less commonly observed than the envelope conformation usually found in related compounds. In (I), the frequently observed intermolecular N—H...O hydrogen bond between the amine group and the carbonyl O atom of the oxocyclopentene ring of a neighbouring molecule links the molecules into extended chains; there are no other significant intermolecular interactions. By contrast, the amine group in (II) forms an N—H...N hydrogen bond with the pyridine ring N atom of a neighbouring molecule. Additional C—H...O interactions complete a two‐dimensional hydrogen‐bonded network. The halogen‐substituted benzene ring has a weak intramolecular π–π interaction with the pyridine ring. A stronger π–π interaction occurs between the 1,4‐dihydropyridine rings of centrosymmetrically related molecules.