Ultraviolet light-emitting CdII complexes: synthesis and property studies

Four ultraviolet light-emitting Cd^II complexes, [CdL₁(H₂O)]_n (1), [CdL₁(bpy)(H₂O)₂]_n (2), [CdL₂(H₂O)]_n (3), and [CdL₂(bpy)(H₂O)₂]_n (4), where L₁ = 3,3′-(4-phenyl-4H-1,2,4-triazole-3,5-diyl)dibenzoate, L₂ = 3,3′-(4-(4-fluorophenyl)-4H-1,2,4triazole-3,5-diyl)dibenzoate, and bpy = 2,2′-bipyridine, were hydrothermally synthesized and characterized by single-crystal X-ray diffraction, powder scattering spectra, and infrared spectra. 1–4 possess excellent thermal stability with decomposition temperature of ca. 340 °C. Their powder samples mainly give luminescent spectra at 350, 339, 351, and 339 nm, respectively, which should be attributed to the ligand-centered π*?→?π transfer transitions. Additionally, 1–4 have weak emission bands at 400–500 nm, which are tentatively attributed to the triplet ligand to ligand charge transfer transitions.     

Magnetic properties of biacetyldihydrazone complexes

Summary Magnetic susceptibilities of the biacetyldihydrazone (BdH) complexes [M(BdH)₃](NO₃)₂ (M = Co^II, Ni^II, Cu^II or Zn^II), [Fe(BdH)₃](NO₃)₃, [M(BdH)₃](Ni(dto)₂] (M = Co^II, Ni^II or Zn^II; dto = dithiooxalate), [(BdH)₂Cu(dto)Ni(dto)] and [Fe(BdH)₃]₂[Ni(dto)₂]₃ have been studied in the 4.2–295 K range. Zn^II complexes are diamagnetic, and complexes of Ni^II, Cu^II and Fe^III obey the Curie-Weiss law. The Co^II complexes behave anomalously and the results are interpreted in terms of a high spinlow spin equilibrium.     

Eu3+和Tb3+冠醚配合物的合成、荧光性质及与DNA作用研究

合成了含联萘骨架的酰胺型开链冠醚配体及稀土苦味酸盐配合物RE(pic)3L[L=N,N-乙基,苯基-N’,N’-二苯基-1,1’-联萘-2,2’-二(氧杂乙酰胺),RE=Eu3+,Tb3+],通过元素分析、IR、TG-DTA和摩尔电导率对配合物进行组成和结构推测。荧光光谱表明:Eu3+配合物的荧光强度远大于Tb3+配合物,说明配体L的三重态能级与Eu3+的激发态能级匹配较好。通过光谱法和粘度法研究了配合物与DNA的作用方式为插入作用,求出了Eu3+,Tb3+配合物与DNA的结合常数分别为4.072×104L.mol-1,8.780×103L.mol-1,证明配合物与DNA的作用大小是Eu3+(pic)3LTb3+(pic)3L.     

肼基硫代甲酸酯配合物的合成、晶体结构、光谱及三阶非线性光 学性质研究

报道三种有推拉电子基团的肼基硫代酸酯衍生物配体(HL^1^～^3)。此类配体与二价过渡金属离子配位时脱去一质子,形成D-M-D和A-M-A(D=给体,M=金属,A=受体)类型、含有共轭体系的中性配合物。本文集中研究了该类配体的镍、铜、钯、铂配合物的IR、磁化率、ESR谱,电子光谱和三阶非线性光学性质,通过光谱研究初步确定了它们均为平面正方形构型配合物,文中还报道了CuL2^1的晶体结构。晶体属P1空间群,a=0.7835(2),b=1.0530(2),c=1.1816(2)nm,α=100.61(3),β=92.38(3),γ=110.00(3)ⅲ,Z=1,最终的R因子为0.063。通过晶体结构测试,进一步确定铜配合物的结构为平面构型。     

Magnetic properties of bridged azido complexes

It was shown on the basis of the generalized angular overlap model that specific features of the electronic structure of the N₃ ^– anion in polynuclear complexes with the M(_1,1-N_{3 2}M magnetic fragment should result in strong ferromagnetism. The _1,3-N₃ coordination mode favors antiferromagnetic properties. The theoretical results agree with experimental magnetostructural correlations.     

4,4′-Bipyridyl complexes of iron: Magnetic,Mössbauer and other spectroscopic studies

Summary 4,4-Bipyridyl (4,4-bipy) complexes of ferrous salts of the Fe(4,4-bipy)_x(anion)_y type (where x or y=1 or 2) and of ferric salts of the Fe(4,4-bipy)_m(anion)_n type (where m=1 or 2 and n=3) have been synthesised. Elemental analyses, i.r. and electronic spectra, magnetic and Mössbauer studies have been performed to characterize the complexes. 4,4-Bipy and some anions are inferred to act as bridging ligands. The magnetic moments, electronic and Mössbauer spectra suggest that the complexes are of high spin type with distorted octahedral structures. The value of the isomer shift and quadrupole splitting are discussed in terms of bonding of the ligand and anions.     

二环己基18-冠-6异构体D与十五个稀土硝酸盐配合物的合成及其性质的研究

合成了二环己基18-冠-6-的异构体D与十五个稀土硝酸盐的配合物,系统研究了它们的FOURIER变换红外光谱的变化规律;测定了部分配合物的核磁共振氢谱和碳谱。结果均表明,在稀土系列内离子直径与冠醚穴大小的比例是否合适是影响配合稳定性的主要因素。文中还讨论了配合物中NO3[-]与稀土离子形成接触离子对对红外光谱及核磁共振谱的影响。在NO3[-]v6(B1)中观察到镧系"斜W"规律。基于红外光谱及核磁共振谱的结果,初步讨论了配合物的结构。     

Computational studies on G-quadruplex DNA-stabilizing property of novel Wittig-based Schiff-Base ligands and their copper(II) complexes

A series of mono imine (C=N) group that contained Wittig-based Schiff-Base ligands was optimized using the DFT-based computational method and Gaussian 09 program package. These optimized molecules were docked with Quadruplex DNA (PDB ID: 1KF1) and duplex DNA (PDB ID: 1BNA) using AutoDock Vina program along with the reference molecules. Schiff-Base ligands derived from fused aromatic rings contained amines and precursor aldehyde (PA-5 both Z and E isomers) showed lower binding energy for G-quadruplex DNA among all and N-5 category both Z and E isomer Schiff-Base ligands have shown high selectivity for G-quadruplex DNA over duplex DNA which is a very important phenomenon to develop the G-quadruplex DNA stabilizers. For a few Schiff-Base molecules like Ligand-6 (1-{[2-Hydroxy-5-(2-pyren-1-yl-vinyl)-benzylidene]-amino}-naphthalen-2-ol) of N-5 category both Z and E isomers with groove binding and end stacking modes, molecular dynamic calculations were carried out. The study revealed that Ligand-6 of N-5 category E isomer with groove binding mode has higher stabilizing effect on G-quadruplex DNA in spite of having the higher binding energy value. Among Schiff-Base copper(II) complexes, Complex-3 (E-(1-{[2-Hydroxy-5-(2-pyren-1-yl-vinyl)-benzylidene]-amino}-naphthalen-2-ol)Cu) is having high binding affinity for G-quadruplex DNA as compared to others.

     

Magnetic coupling in dinuclear Gd complexes

A spin density functional (SDFT) study of carboxylate-bridged and diazenido-bridged dinuclear gadolinium compounds is presented. Calculated magnetic coupling constants for the carboxylate-bridged structures are in good agreement with experimental data, confirming the ability of the broken symmetry approach used in this work to predict magnetic behavior in such compounds. The systematic trend wherein symmetrically bridged complexes are antiferromagnetically coupled and asymmetrically bridged are ferromagnetically coupled is reproduced by the SDFT calculations. The mechanism underlying magnetic coupling in closed- and open-shell dinuclear complexes is described using a perturbative molecular orbital model that focuses the influence of the 4f(7)-5d exchange interaction on molecular orbitals with significant 5d-orbital character for the complex [[[(Me(3)Si)(2)N](2)(thf)Gd](2)(N(2))]. Open-shell electronic configurations facilitate strong ferromagnetic coupling, whereas in closed-shell systems antiferromagnetic coupling is usually preferred.     

Synthesis, characterization and catalytic property of ruthenium-terpyridyl complexes

The known compound 4′-(carboxyphenyl)-2,2′:6,2″-terpyridine (LH) was prepared and complexed with RuCl₃.3H₂O. The resulting complex [Ru(LH)Cl₃] was then allowed to react separately with 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), triphenylphosphine (PPh₃) and 1,2-bis-(diphenylphosphino)ethane (dppe). The compositions of corresponding complexes [Ru(LH)bpyCl](BF₄) 1, [Ru(LH)phenCl](BF₄) 2, [Ru(LH)(PPh₃)(CH₃CN)₂] (BF₄)₂3 and [Ru(LH)(dppe)Cl](BF₄) 4 were assigned on the basis of their FAB-mass spectra, elemental analysis, spectroscopic (IR, NMR) data and X-ray diffraction measurements. The diamagnetic, cationic complexes displayed strong MLCT transitions in the visible region with significant shift in MLCT band energy corresponding to the strength of substituted ligands. The redox behaviour of the complexes was investigated using cyclic voltammetry measurements. Among all the complexes, 3 efficiently catalyzed the synthesis of propargylamine via three components coupling reaction.     

Magnetic coupling in EE and EO azido-bridged binuclear copper complexes: Synthesis,structure and magnetic studies

Four azide bridged dinuclear copper(II) complexes, [Cu₂(L^X)₂(N₃)₂](ClO₄)₂, with L^X = substituted N,N-bis[(3,5-dimethylpyrazole-1-yl)-methyl]benzylamine, [X = H (1), OMe (2), Me (3) and Cl (4)] have been synthesized, out of which complexes 1 and 2 have been characterized structurally. In Complex 1 the two bridging azide ligands have connected the two metal centers in an end-on (EO) fashion with aSP (asymmetric Square Pyramidal) geometry and showed an weak antiferromagnetic interaction (J = −3.34 cm⁻¹). On the contrary, in complex 2, the two metal centers have been connected in end-to-end (EE) fashion exhibiting moderately strong ferromagnetic interaction (J = +19.7 cm⁻¹). Cyclic voltammetric studies performed on all the four complexes show a reasonably good correlations when E_1/2 for Cu^IICu^II → Cu^IICu^III and Cu^IICu^III → Cu^IIICu^III oxidations are plotted against σ (substituent constants) with ρ = −0.182 (R² = 0.92) and −0.684 (R² = 0.99) respectively.     

Magnetic circular dichroism studies XXXII

CNDO calculations of the MCD spectra of 7- and 9-methyladenine have been carried out in two approximations. A minor modification of the CNDO/S method of Jaffé and coworkers shows an improvement over Jaffé's parameterization with respect to band separations and the signs of the MCDB terms, but is not applicable ton→ π* transitions.     

不对称四核环状Co3^IIM^II簇合物的磁化学

本文用一种新的方法对三个核环状化合物Co3Fe(mp)4(Hmp)(PBu3^n)3(1) Co4(mp)4(Hmp)(PMe2Ph)3(2)(H2mp=2-巯基苯酚)和Co4(mp)4(PBu3^n)3Cl(MeOH)(3)进行了1。5-300K温度范围的磁性质研究, 即在各向同性海森堡模型的基础上, 用全矩阵对角化方法求自旋态能量本征值, 从而得到化合物的磁化率, 然后用阻尼最小二乘法拟合变温磁化率, 得到磁交换常数。因避免了使用Kambe理论, 无须对化合物进行模型简化处理, 所以得到更多、更准确的磁交换信息。拟合结果显示三个化合物都呈较弱的磁偶合作用。对化合物1得到J1=-3.14cm^-^1, J2=-3.04cm^-^1, J3=2.92cm^-^1和J4=4.08cm^-^1, 对2得到J1=-3.07cm^-^1, J2=-3.19cm^-^1,J3=-0.33cm^-^1和J4=-1.91cm^-^1; 对3得到J1=-4.818cm^-^1,J2=-4.244cm^-^1, J3=-1.164cm^-^1和J4=-2.634cm^-^1, 其中J1和J2代表通过双重μ2-S桥, J3和J4分别代表通过单重和双重μ2-O桥进行的磁交换作用常数。     

Magnetic anisotropies in paramagnetic polynuclear metal complexes

The study of the magnetic properties of highly anisotropic paramagnetic molecules is an area of intense current research interest. Of these, single-molecule magnets (SMMs) and single-chain magnets (SCMs) showing non-equilibrium magnetization have remained a key topic over the past two decades. The slow magnetization reversals found in SMMs and SCMs are contingent on two requirements: a large ground-state spin forbidding direct quantum transitions of spin reversal, and a series of excited spin levels, due to the anisotropy of the system, which can act as steppingstones for the thermal relaxation of the spin orientations (the Orbach process). In this critical review, the latter requirement, i.e. the existence of magnetic anisotropies in paramagnetic species, is reviewed with the aim of providing clues towards the rational design of molecule-based magnets (100 references).     

链型四核配合物中的磁交换作用

本文用不可约张量法导出了链型BAAB四核体系的自旋Hamilton算符^H的矩阵元的一般表达式。用此式系统处理了M·Cu·Cu·M(其中M是氧化数为2的Zn, Cu, Ni,Co, Fe, Mn)即S2=S3/2,S1=S4=0,1/2,1,3/2,2,5/2的六个体系, 分别得出它们的能级和磁化率公式。我们又合成了七个链型BAAB四核配合物(CuLMX4)2, 其中L为双(N-氧化吡啶-2-甲醛)缩乙二胺(L＇)或双(N-氧化吡啶-2-甲醛)缩-1,2-丙二胺(L〃)。用CF-1型提拉样品磁强计测定了它们在4.2-300K范围内的变温磁化率, 然后用理论得出的公式对实验数据进行最小二乘法拟合, 得出磁交换常数J值和J＇值以及分裂因子g值, 所得J值说明了本文中的七个(CuLMX4)2型分子中, 中间两个Cu原子之间有弱的铁磁性交换作用, 而所得的J＇值则表明链端的M与相邻的Cu之间有弱的反铁磁性相互作用。最后用AGK理论对交换途径作了说明。     

Synthesis,crystal structure and two-photon property studies on a series of complexes derived from a novel Schiff base ligand

A new Schiff base ligand derived from S-benzyldithiocarbazate and 4-[N-hydroxy ethyl-N-(methyl)amino]benzaldehyde (HL, where H is a dissociable proton) and its Ni^II, Cu^II, Zn^II and Pd^II complexes were prepared and fully characterized. The structures of HL and Ni(L)₂ were determined by X-ray diffraction analysis, which revealed that the geometry of the Ni^II ion is square-planar with two equivalent Ni=N and Ni=S bonds, and that the two neighboring molecules in two layers have weak contact. The electronic spectra and solution fluorescence of the ligand and the complexes were studied, and the quantum yields of single-photon fluorescence for the compounds were determined. The compounds possess two-photon absorption (t.p.a.) character and the t.p.a. coefficient and t.p.a. cross-section were determined by the Z-scan technique. Especially, the Zn(L)₂complex and the HL ligand exhibit intensive two-photon fluorescence (t.p.f.) at 800 nm laser pulses in the femtosecond regime.     

Magnetic property of a triply bridged linear trinuclear nickel complex

A new linear trinuclear nickel(II) complex, [Ni₃L₂(OCn)₄] (HL = 2-[(3-dimethylamino-propylimino)-methyl]-phenol, OCn = cinnamate), with phenoxo bridge and a novel tridentate bridging mode (in a 2.21 fashion according to Harris notation), of the cinnamate ligand has been synthesized and characterized by IR spectroscopy, UV-Vis spectroscopy, X-ray crystallography and static magnetic measurements. The molecular structure shows that each nickel ion occupies octahedral coordinating geometry. Apart from the phenoxo bridges, the carboxylic group of cinnamic anion shows two types of bridging modes viz. 2.11 and 2.21. The magnetic data indicate that a moderate intramolecular ferromagnetic and a weak intermolecular antiferromagnetic interaction are present in the complex under study. Broken symmetry density functional theory has been used to estimate the sign and magnitude of the coupling constants to understand the magnetic exchange mechanisms of the present system. The relative abilities of different bridging groups to mediate magnetic exchange interactions between paramagnetic nickel centers have been investigated by DFT calculation with variable angles. The results show that a small change in phenoxo-bridging angle has a very strong impact on the magnetic properties.