2,2′-联吡啶同自旋双自由基的量子化学研究

采用量子化学ab initio方法,讨论了2,2′-联吡啶同自旋双自由基体系构象变化对铁磁耦合的影响.结果表明,在各种构象下,体系的磁性耦合符合自旋极化规则;对于·CH2,·NH2+两种自由基磁性耦合性质是相同的,只影响到体系磁性耦合的强度,这一结论为有机磁性材料的分子设计提供了有益的信息.     

邻、间、对-二甲氧基亚甲基苯及衍生物双自由基体系的自旋耦 合规律

采用量子化学abinitio法对具有甲氧基的碳、氧双自由基邻、间、对二甲氧基亚甲基苯及衍生物体系基态自旋耦合规律进行研究,得到非平面共轭体系中自由基之间磁性耦合的拓朴规则:共轭体系中,两个自由基之间以偶数个碳原子耦合,则有效交换积分J~i~j<0,体系具有低自旋基态;两个自由基之间以奇数个碳原子耦合,则J~i~j>0,体系具有高自旋基态。自由基性质对自旋耦合的影响较大,正离子自由基间磁性耦合能力较强,这些结论为有机磁性材料的分子设计与实验合成提供了理论依据。     

以喹啉为耦合单元双自由基体系的理论研究

设计用4种自由基自旋中心连接在耦合单元喹啉的不同位置上的双自由基体系,用AM1-CI方法计算的结果表明:双自由基连接的位置不同对体系耦合作用的影响符合双自由基之间磁性耦合的拓扑规则,即共轭体系中,两个自由基之间以偶数个C(或N)原子耦合,体系具有低自旋基态,表现反铁磁耦合;两个自由基之间以奇数个C(或N)原子耦合,体系具有高自旋基态,表现铁磁耦合.当双自由基连接在喹啉的相邻奇数个C或N原子位置时,体系具有高自旋基态,表现铁磁耦合.     

对嘧啶的邻、间、对位双自由基体系的自旋耦合规律的研究

采用量子化学abinitio法和密度泛函方法对不同取代位置的嘧啶自旋耦合规律进行研究 .两种方法比较 ,用UHF方法计算导致自旋污染严重 ,而用UB3LYP方法计算 ,自旋污染则减少了许多 .计算结果得到了双自由基之间磁性耦合的拓扑规则 :共轭体系中 ,两个自由基之间以偶数个碳 (或氮 )原子耦合 ,则有效交换积分Jij<0 ,体系具有低自旋基态 ,表现为反铁磁耦合 ;两个自由基之间以奇数个碳 (或氮 )原子耦合 ,则有效交换积分Jij>0 ,体系具有高自旋基态 ,表现为铁磁耦合 .自由基性质和铁磁耦合单元的不同位置对自旋耦合的影响较大 ,这些结论为有机磁性材料的分子设计与实验合成提供了理论依据 .     

双卡宾、双氮宾体系基态自旋的从头算研究

采用量子化学从头算UHF方法, 对平面型双卡宾及双氮宾体系的基态自旋情况进行研究。结合前面的分析结果, 进一步探讨了多自由基体系基态自旋的耦合规律, 为有机磁性体的分子设计提供了可靠的理论依据。     

双自由基间苯体系铁磁分子设计

采用量子化学从头算UHF方法对不同组成的双自由基及其异构体进行了系统比较,进而对系列双自由基体系的基态自旋耦合规律进行了研究,并讨论了具有空间位阻的顺反异构现象对双自由基自旋耦合的影响。对以双自由基为基础的有机铁磁体的合成具有指导意义。     

铁磁性高分子——聚丁二炔衍生物的合成与磁性研究

本文报道了三种类型丁二炔的合成:R_1-C≡C-C≡C-R_2,a:R_1=R_2=自由基;b:R_1≠R_2 R_1或R_2为自由基;c:R_1=R_1≠自由基.利用热聚合方法制得三种类型的聚丁二炔,并对它们的磁行为进行了研究,对聚丁二炔衍生物的磁性来源进行了讨论,证明了聚丁二炔衍生物中单独全共轭链自旋体系和单独的自由基侧链自旋体系均不产生铁磁性,其磁性来源于聚丁二炔衍生物中氮氧自由基和共轭主链的共同作用.     

构象对同位乙烯双自由基体系基态自旋多重度及其稳定性影响的理论研究

用DFT,CASSCF和QCISD(T)方法6-31G^*基组计算了构象对同位二取代乙烯双自由基体系基态自旋多重度及其稳定性的影响.结果表明,用DFT或CASSCF方法计算的单、三重态的能量差随自由基与乙烯间的二面角增加成不规则变化;用QCISD(T)方法计算的单、三重态的能量差随二面角的增加而逐渐降低,并呈规律性变化,说明QCISD(T)方法用于计算分子的磁性是可信的.对于同位二取代乙烯双自由基体系,无论双自由基旋转,还是单自由基旋转,高自旋基态稳定性随自由基与乙烯间二面角的增加而降低,只是降低的幅度不同,当二面角接近90°时,同位乙烯由具有平面或近似平面构象时强的铁磁耦合单元变成接近垂直平面构象时弱的反铁磁耦合单元或弱的铁磁耦合单元.     

一个包含Cu（Ⅱ）和氮氧自由基自旋支链的新颖杂自旋一维链状化合物的结构和磁性研究

本文合成了一个含Cu（Ⅱ）离子和氮氧自由基自旋支链的新颖杂自旋-维链状化合物{[Cu（tcph）（H20）4][cu（tcph）（NIT3Py）2]·2H2O}n（1）（tcph=四氯令K苯二甲酸,NIT3Py=2．（3’-吡啶基）-4,4,5,5-四甲基咪唑啉-3-氧化-1-氧基自由基）．对其结构分析表明,该配合物是一个由四氯邻苯二甲酸连接Cu（Ⅱ）离子构成的一维链状化合物,其中自由基作为自旋支链与水分子分别交替与链上的Cu（Ⅱ）离子进行配位．磁性研究中我们采用了计入自旋态布居的一维链近似模型对其磁性数据进行了合理的拟合,得到以下耦合参数：Jcu2-Rad=22．4cm^-1和J′cul-cu2=-2．4cm^-1,表明分子内Cu2与NIT3Py自由基问存在铁磁相互作用,而由四氯邻苯二甲酸连接的Cu1和Cu2间存在反铁磁作用．     

有机双自由基体系的磁性偶合规律

采用量子化学从头算UHF方法对系列有机双自由基体系的基态自旋耦合规律进行研究, 进一步证实了自由基之间在共轭体系中出现铁磁性耦合的拓扑规则,统一了关于自由基耦合规律的几种解释, 为有机磁性材料的实验合成提供了理论指导。     

π–π Stacking,hydrogen bonding and anti-ferromagnetic coupling mechanism on a mononuclear Cu(II) complex

Weak anti-ferromagnetic coupling is observed in a mononuclear copper(II) complex, [Cu(Pid)(OSO₃)(H₂O)]?·?(H₂O) (Pid?=?2,2′-(1,10-phenanthrolin-2-ylimino)diethanol). The Cu(II) complex is a distorted square pyramid. Analysis of the crystal structure indicates that there are two types of magnetic coupling pathways, where one pathway involves π–π stacking between adjacent complexes and the second one involves the O–H?···?O hydrogen bonds between adjacent complexes. The variable-temperature magnetic susceptibilities show that there is a weak anti-ferromagnetic coupling between adjacent Cu(II) ions with Curie–Weiss constant θ?=??13.71?K?=??9.93?cm^?1. Theoretical calculations reveal that the π–π stacking resulted in anti-ferromagnetic coupling with 2J?=??6.30?cm^?1, and the O–H?···?O hydrogen-bonding pathway led to a weaker anti-ferromagnetic interaction with 2J?=??3.38?cm^?1. The theoretical calculations also indicate that anti-ferromagnetic coupling sign from the π–π stacking accords with the McConnell I spin-polarization mechanism.     

A new tetranuclear copper(II) complex containing decameric water clusters bridged by–OH–and pyridine-2,4, 6-tricarboxylate: synthesis and magnetic characterization

Using pyridine-2,4,6-tricarboxylic acid (H₃ptc) and 2,2-bipyridine (2,2-bipy), a tetranuclear copper(II) compound [Cu₄(2,2-bipy)₄(ptc)₂(H₂O)₂(OH)₂] · 12H₂O (1) has been isolated under hydrothermal conditions. Variable temperature magnetic susceptibility of 1 from 2–300 K indicates anti-ferromagnetic interactions. The magnetic exchange coupling constants of J = ?159.4 and J′ = ?18.66 cm^?1 for 1 can be obtained through fit of the magnetic data, corresponding to two kinds of bridges, hydroxyl anions (OH^?) and pyridine carboxylate oxygen of ptc^3?. Moreover, decameric water clusters can also be observed, which are located between these tetranuclear copper(II) entities, forming a series of intricate O-H ··· O hydrogen bonds and stabilizing the resulting three-dimensional (3-D) hydrogen-bonded framework structure.     

Synthesis,structure, and character of two rare earth carboxylic acid complexes

Two rare earth carboxylic acid complexes, [Sm(MeBA)₃(2,2′-bipy)]₂·2(2,2′-bipy) (MeBA = 3-methylbenzoic acid; 2,2′-bipy = 2,2′-bipyridine) (1) and [Pr(MeBA)₃(H₂O)₂]_n?n(4,4′-bipy) (4,4′-bipy = 4,4′-bipyridine) (2), have been synthesized under hydrothermal conditions and structurally determined by single-crystal X-ray diffraction. Compound 1 is a dimer and further assembles into an infinite chain, two-dimensional net and three-dimensional supramolecular structure via weak π–π and C–H···π interactions. Some 2,2′-bipy coordinates with Sm and some exist by non-covalent C–H···π interactions. Compound 2 is a 1D infinite chain structure, with adjacent 1D chains connected into a 2D layer structure by O–H···N hydrogen bonds. The two complexes were characterized by elemental analyses, IR, photoluminescence, and TGA. In order to illustrate subtle structural characteristics of intermolecular interactions and magnetic sensitivity of the complex, 2D-IR correlation spectra (2D-IR COS) under magnetic perturbation for 1 were performed.     

Intermolecular Interaction and Magnetic Coupling Mechanism of a Mononuclear Nickel(II) Complex

The mononuclear complex [Ni(HOphen)(OSO₃)(H₂O)₃] · 5H₂O (HOphen = 1, 10‐phenanthrolin‐2‐ol) was prepared and its single structure was determined by X‐ray crystallography. In this complex, the Ni^II ion has a distorted octahedral arrangement. Crystal structure analysis shows that two kinds of π–π stacking interactions and C–H ··· O short contact intermolecular interactions exist among the adjacent complexes. Fitting to the variable‐temperature magnetic susceptibility data gave the magnetic coupling constant, 2J = –0.98 cm^–1. Theoretical calculations, based on density functional theory (DFT) coupling with the broken‐symmetry approach (BS), revealed that the π–π stacking magnetic coupling pathways resulted in weak ferromagnetic interactions with 2J = 4.86 cm^–1 and 2J = 4.16 cm^–1, respectively, for the adjacent Ni^II ions with separations of 8.568(19) Å and 8.749(32) Å, respectively; whereas the magnetic coupling pathway of the C–H ··· O short contact intermolecular interaction led to a weak antiferromagnetic interaction with 2J = –17.62 cm^–1 for the adjacent Ni^II ions with a separation of 10.291(26) Å. The ferromagnetic coupling sign can be explained by the McConnell I spin‐polarization mechanism.     

A New Polynuclear Copper‐Complex‐Substituted Tungstoarsenate(V)

A new polynuclear copper‐complex‐substituted dimeric tungstoarsenate(V), H₂[{Cu(2,2′‐bpy)}₈(H₂O)₂(AsW₉O₃₄)₂] · 12H₂O ( 1 ) (2,2′‐bpy = 2,2′‐bipydine), was synthesized hydrothermally and its structure was determined by single‐crystal X‐ray diffraction. The title compound has Ci symmetry and consists of two trilacunary Keggin anions [α‐AsW₉O₃₄]^9– supported by eight copper complex cations. The compound was also characterized by IR and fluorescence spectroscopy, TG analysis, and magnetic measurements. The emission spectrum of the compound in solid‐state exhibits a redshift relative to those of Na₈[A‐HAsW₉O₃₄] · 11H₂O and the free ligand 2,2′‐bpy. Magnetic measurements of the compound indicate competing ferro‐ and antiferromagnetic intramolecular coupling among the Cu^II atoms in the cluster anion.     

Synthesis,structure, and activity of (PhCH2NH2)2CuCl2 for oxidative coupling of 2‐naphthylamine

(PhCH₂NH₂)₂CuCl₂ ( 2 ), an effective oxidation reagent for oxidative coupling of 2‐naphthylamine ( 1 ) to form 2,2′‐diamino‐1,1′‐binaphthyl ( 4 ), is studied. Oxidative coupling of 2‐naphthylamine ( 1 ) is carried out at room temperature in methanol by (PhCH₂NH₂)₂CuCl₂ ( 2 ), which is prepared from CuCl₂·2H₂O and benzylamine in methanol, to give a novel copper complex, [{1,1′‐(C₁₀H₆)₂‐2,2′‐(NH₂)₂}₂CuCl]Cl·CH₃OH·3H₂O ( 3 ), in good yield. Treatment of 3 with aqueous HCl (37%), followed by addition of NH₃·H₂O (25%), gives 2,2′‐diamino‐1,1′‐binaphthyl ( 4 ) in a moderate yield (total yield from 1 : > 70%). Both 2 and 3 have been characterized by various techniques, such as infrared spectroscopy, elemental analyses and X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd.     

A 3D supramolecular dimeric assembly based on thiacalix[4]arene by halogen bonding and carbonyl bonding and its dynamic NMR study of conformational preferences

The dimeric assembly of 5,11,17,23-tetrabromo-25,26,27,28-tetrahydroxy thiacalix[4]arene (2) was constructed with several interesting noncovalent interactions such as halogen bonding, sulfur···sulfur (S···S), C=O···π, and hydrogen bonding which were also supported by DFT calculations. In addition, we studied the conformational preferences of 2 using variable temperature NMR experiments. The results revealed that the compound exists in various conformations in a solution state and in a partial cone conformation in a solid state.     

Proton magnetic resonance spectra of thenyl derivatives—II. Chloromethylthiophenes and some dithienylmethanes

PMR spectra of thirty-eight chloromethylthiophene and seven dithienylmethane derivatives were observed at 60 or 40 MHz. The chemical shifts of methylene protons were 4·63 to 5·25 ppm for monosubstituted 2-chloromethylthiophenes and 4·37 to 4·56 ppm for monosubstituted 3-chloromethylthiophenes, respectively, with reference to TMS. Those for 2,2′ -dithienylmethanes, which have one substituent in each ring, were 4·12 to 4·34 ppm. These shifs are useful for determination of the positions of the methylene groups in the related compounds. The long-range coupling constants observed for methylene proton signals are also useful for the determination of the positions of substituents.     

Construction of a magnetic chiral coordination polymer based on a semi-rigid carboxylic acid

A 2-D chiral entangled coordination polymer, {Mn₃(2,2′-bpy)₂(3-cpta)₂·H₂O}_n (1) (3-H₃cpta=3-(3′-carboxyphenoxy)phthalic acid, 2,2′-bpy=2,2′-bipyridine), has been synthesized via the solvothermal method. X-ray diffraction analysis reveals that 1 consists of one right-handed helical chain and one wavelike 2-D plane, which are connected with each other through hydrogen bonds and π···π interactions to generate a 3-D supra-molecule. Thermal gravimetric analysis shows that 1 possesses good thermal stability. Temperature dependent magnetic susceptibilities have also been measured from 1.8 to 300 K, which shows 1 to be anti-ferromagnetic.     

一个得到1,1'-联-2-萘胺的合成新方法

以2-萘胺为原料,在甲醇溶液中与1.5eq的CuCl2·2H2O反应,氧化偶合得到1,1'-联-2-萘胺(1)与CuCl2的络合物沉淀。沉淀依次经沸水和氨水处理,得到产率56%的1。