Titanocene complexes of the N-methyl and N-phenyl-1,3-thiazoline-2-thione-4,5-dithiolates and 4,5-diselenolate ligands

Cp₂Ti(dithiolene) and Cp₂Ti(diselenolene) complexes containing the N-methyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (Me-thiazdt), the N-phenyl-1,3-thiazoline-2-thione-4,5-dithiolate ligand (Ph-thiazdt) and the N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate ligand (Me-thiazds) have been synthesized. Three approaches have been developed in order to generate the dithiolene or the diselenolene ligands which were reacted with Cp₂TiCl₂ to form the corresponding heteroleptic complexes. Their X-ray crystal structures, UV-Vis absorption spectra as well as their redox properties, determined by cyclic voltammetry have been investigated and discussed. Variable-temperature ¹H NMR experiments have been performed in order to determine the activation energies of the chelate ring inversion.     

Identifying similarities and differences between analogous bisdithiolene and bisdiselenolene complexes: A computational study

Due to ligand non‐innocence and reversible one‐electron‐transfer processes dithiolene complexes have been intensively studied both experimentally and computationally. While the substitution of the ligating sulfur atoms by selenium provides a means to delicately tune the behavior of dithiolene compounds, diselenolene complexes have not been as thoroughly examined. Yet, the search for such ligands has been ongoing since the 1970s. Thus, we have looked at several metal‐bisdiselenolene complexes and have compared key properties of these complexes with their bisdithiolene analogues to determine the effect of substituting the chalcogen atom. The results herein show that substitution of the sulfur atoms by selenium within these complexes only subtly changes the thermodynamics and kinetic reactivity of bisdithiolene complexes while not significantly affecting the geometries of the complexes. The significance being that the relatively minor structural changes that occur upon redox is a key feature of dithiolene complexes. Due to ligand non‐innocence and reversible one‐electron‐transfer processes dithiolene complexes have been intensively studied, however, diselenolene complexes have not. First‐principles calculations show that substitution of the sulfur atoms by selenium within the investigated complexes does offer the ability to subtly tune the thermodynamics and kinetic reactivity of bisdithiolene complexes, while not significantly affecting the geometries of the complexes. © 2015 Wiley Periodicals, Inc.     

Synthesis and fluorescence property of terbium complex with novel schiff-base macromolecular ligand

Novel schiff-base macromolecular ligand was synthesized by copolymerizing schiff-base monomer, methyl methacrylate and ethyl acrylate. New polymeric materials based on terbium complex with this macromolecular ligand were prepared. The fluorescence properties of the terbium-complex polymer were investigated experimentally. The new polymeric materials developed herein exhibit the characteristic fluorescence properties of the terbium(III) ion, making them applicable in a wide range of new technologies.     

A New Tetranuclear Copper(Ⅰ) Complex of Dithiolate Ligand Fused with TTF Moiety

Dithiolatemetalcomplexeshavegeneratedgreatinterestforalongtimeduetoitsuniqueelectronicandmagneticpropertieshave.Recently,anewsystemofdithiolateligands,combinedwiththeTTFmoiety,hasreceivedmuchattentionl.Underhilletal.havereportedonthestrUcturesofadianionicmercurycomplex[Nme412[Hg(C1oH1oS8)8],andlateronaplanarneutralnickelcomplex[Ni(C,,H,,S,),]"'.Strongdrr-pninteractionbetweenthecentralmetalionandtheconjugatedligands,andtherichredoxbehaviorsofthesecomplexesimplyagoodpotentialinitSapplicati…     

Synthesis,characterization, and antioxidant activity of a new Gd(III) complex

A new gadolinium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in molar ratio of 1:3 to ligand. The structure of the complex was determined by elemental analysis, FT-IR, and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Gd(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygens. The newly synthesized gadolinium(III) complex of 5-aminoorotic acid (GdAOA) showed antioxidant properties. The antioxidant activity of both HAOA and GdAOA was related with their electron donor properties.     

Synthesis and properties of palladium diselenolenes: X-ray crystal structures of [Pd[SeC(R(1))=C(R(2))Se](PBu(3))(2)] [R(1), R(2) = (CH(2))(n), n = 4, 5, 6

The reaction between [Pd(2)(dba)(3)] (dba = dibenzylideneacetone), tributylphosphine, and a bis(cycloalkeno)-1,4-diselenin leads to either a mononuclear diselenolene [Pd[SeC(R(1))=C(R(2))Se](PBu(3))(2)] or a dinuclear diselenolene [Pd(2)[SeC(R(1))=C(R(2))Se](2)(PBu(3))(2)] [R(1), R(2) = (CH(2))(n), n = 4, 5, 6] depending on the stoichiometry employed. Treatment of the dinuclear diselenolenes with 1,2-bis(diphenylphosphino)ethane (dppe) provides a high-yielding route to the mononuclear species [Pd[SeC(R(1))=C(R(2))Se](dppe)]. All new compounds have been characterized by standard spectroscopic and analytical techniques, in particular by multinuclear NMR spectroscopy; the structure of each of the mononuclear tributylphosphine complexes has been determined by X-ray crystallography. Computational studies show that the observed asymmetry of the diselenolenes in the solid state is a result primarily of intramolecular repulsive interactions between the ligands.     

Structural, electronic, and acid/base properties of [Ru(bpy)2(bpy(OH)2)]2+ (bpy = 2,2'-bipyridine, bpy(OH)2 = 4,4'-dihydroxy-2,2'-bipyridine)

We have synthesized the complex [Ru(bpy)(2)(bpy(OH)(2))](2+) (bpy =2,2'-bipyridine, bpy(OH)(2) = 4,4'-dihydroxy-2,2'-bipyridine). Experimental results coupled with computational studies were utilized to investigate the structural and electronic properties of the complex, with particular attention paid toward the effects of deprotonation on these properties. The most distinguishing feature observed in the X-ray structural data is a shortening of the CO bond lengths in the modified ligand upon deprotonation. Similar results are also observed in the computational studies as the CO bond becomes double bond in character after deprotonating the complex. Electrochemically, the hydroxy-modified bipyridyl ligand plays a significant role in the redox properties of the complex. When protonated, the bpy(OH)(2) ligand undergoes irreversible reduction processes; however, when deprotonated, reduction of the substituted ligand is no longer observed, and several new irreversible oxidation processes associated with the modified ligand arise. pH studies indicate [Ru(bpy)(2)(bpy(OH)(2))](2+) has two distinct deprotonations at pK(a1) = 2.7 and pK(a2) = 5.8. The protonated [Ru(bpy)(2)(bpy(OH)(2))](2+) complex has a characteristic UV/Visible absorption spectrum similar to the well-studied complex [Ru(bpy)(3)](2+) with bands arising from Metal-to-Ligand Charge Transfer (MLCT) transitions. When the complex is deprotonated, the absorption spectrum is altered significantly and becomes heavily solvent dependent. Computational methods indicate that the deprotonated bpy(O(-))(2) ligand mixes heavily with the metal d orbitals leading to a new absorption manifold. The transitions in the complex have been assigned as mixed Metal-Ligand to Ligand Charge Transfer (MLLCT).     

Pyrimidoquinazolinophenanthroline Opens Next Chapter in Design of Bridging Ligands for Artificial Photosynthesis**

The synthesis and detailed characterization of a new Ru polypyridine complex containing a heteroditopic bridging ligand with previously unexplored metal-metal distances is presented. Due to the twisted geometry of the novel ligand, the resultant division of the ligand in two distinct subunits leads to steady state as well as excited state properties of the corresponding mononuclear Ru(II) polypyridine complex resembling those of prototype [Ru(bpy)₃]²⁺ (bpy=2,2'-bipyridine). The localization of the initially optically excited and the nature of the long-lived excited states on the Ru-facing ligand spheres is evaluated by resonance Raman and fs-TA spectroscopy, respectively, and supported by DFT and TDDFT calculations. Coordination of a second metal (Zn or Rh) to the available bis-pyrimidyl-like coordination sphere strongly influences the frontier orbitals, apparent by, for example, luminescence quenching. Thus, the new bridging ligand motif offers electronic properties, which can be adjusted by the nature of the second metal center. Using the heterodinuclear Ru−Rh complex, visible light-driven reduction of NAD⁺ to NADH was achieved, highlighting the potential of this system for photocatalytic applications.     

新型含氮三齿钯(II)配合物的合成及其催化性能研究

以白屈氨酸为原料, 经酯化、还原、溴化、胺化等反应合成了4位带活性基团的新型含氮(NN'N)三齿配体, 配体进一步与氯化钯反应制得了Pd(II)的配合物, 并用红外、核磁、元素分析等手段进行了表征. 考察了这种钳形配合物的催化性能, 结果表明该配合物对卤代苯与乙烯基化合物的Heck芳基化反应具有较高的催化活性.     

Tetrapodal amidoxime ligands I. Coordination isomerism due to self-complementary dimerization of a pyramidal cobalt(III) coordination module

A bis-μ-amidoximato-bridged cobalt(III) dimer obtained with a new tetrapodal ligand possesses interesting structural parameters as a consequence of intramolecular hydrogen bonding intentionally built into the complex. Its synthesis and properties are described. The new ligand type combines attributes of two previously described ligand classes: It binds a metal ion in a tetrapodal pentadentate fashion and forms a pseudomacrocycle through hydrogen bonds, characteristic of chelating oxime ligands. Coordination isomerism, which is a consequence of dimer formation, has been analyzed by means of X-ray crystallography and carbon-13 nuclear magnetic resonance spectroscopy.     

99mTc标记COI配合物的制备及其用作心室显像剂的初步研究

通过改变异腈配体的结构和配合物的中心核,以期获得标记方法简单、放化纯度高以及生物性能优良的新型心室显像剂.以环辛胺为原料,通过甲酰胺化和脱水两步反应制得配体环辛基异腈(COI),并以氯化亚锡为还原剂和二硫代肼基甲酸甲酯为供氮体,通过配体交换反应得到放化纯度大于95%的^99mTcN-COI标记物.以氯化亚锡为还原剂直接标记制得放化纯度大于95%的^99mTc-COI配合物.两种标记物在室温下放置6h以上,其放化纯度无明显变化.在正常昆明小鼠体内进行的生物分布实验研究结果显示,^99mTcN-COI和^99mTc-COI在心脑中有一定摄取,但肝、肺及血等本底摄取相对较高.二者在血液中都有很高的浓集,且滞留也很好,其中^99mTc-COI配合物在静脉注射后60min时的血/心、血/肝和血/肺摄取比分别为6.67,1.54和2.07,有望成为一种新型的制备方法简单的心室显像剂.     

具有近红外三阶非线性光学性质的咪唑邻菲罗啉钌配合物的合成及其与DNA作用特性

以邻菲罗啉双酮和N,N-二(4-丁氧基苯基)氨基苯甲醛为原料,设计合成了光功能配体(L)及其钌配合物1,运用现代分析测试手段进行了表征。 利用开/闭孔Z扫描技术测试了目标化合物的三阶非线性光学性质。 结果表明,在近红外范围内钌配合物具有比配体更大的三阶非线性系数和双光子吸收截面。 通过UV-Vis吸收光谱、荧光光谱、圆二色光谱和粘度实验,研究了配合物与小牛胸腺DNA结合特性。 结果表明,配合物通过插入模式与DNA结合。 因此,该新型钌配合物可以作为非线性光学材料应用于生物显影。     

Synthesis,characterization, thermal decomposition studies and dyeing properties of some novel transition metal complexes of an azo derivative formed from 2-aminothiophene

An azo derivative was synthesized by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with 2-naphthol and this new ligand formed a series of metal complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) salts. These complexes were characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-Visible, IR and ¹H NMR spectral data. Analytical data revealed that all the complexes exhibited 1: 1 metal-ligand ratio. Spectral studies showed that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated to the metal ion in a tridentate fashion. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry was proposed for each complex. The ligand and its cobalt(II) complex were subjected to X-ray diffraction study. The thermal behaviour of the ligand and its copper(II) complex was examined by thermogravimetry. The ligand and its copper(II) and nickel(II) complexes were applied to silk fabric and their fastness properties were evaluated.     

Microwave Assisted Synthesis of a New Triplet Iridium(III) Pyrazine Complex

A new cyclometalated iridium(III) complex Ir(DPP)₃ (DPP=2,3-diphenylpyrazine) was pre-pared by reaction of DPP with iridium trichloride hydrate under microwave irradiation. The structure of the complex was confirmed by elemental analysis, ¹H NMR, and mass spec-troscopy. The UV-Vis absorption and photoluminescent properties of the complex were investigated. The complex shows strong ¹MLCT (singlet metal to ligand charge-transfer) and ³MLCT (triplet metal to ligand charge-transfer) absorption at 382 and 504 nm, respec-tively. The complex also shows strong photoluminescence at 573 nm at room temperature.These results suggest the complex to be a promising phosphorescent material.     

CpNi(diselenolene)] neutral radical complexes: electron paramagnetic resonance and density functional theory investigations

77Se-enriched CpNi(bds) (bds = 1,2-benzenediselenolate), has been synthesized and its g tensor and 77Se hyperfine tensors have been obtained from its frozen solution electron paramagnetic resonance (EPR) spectrum. These parameters are consistent with those calculated by density functional theory (DFT); it is shown that 10% of the spin is localized on each selenium and that the direction associated to the maximum 77Se couplings is aligned along the gmin direction, perpendicular to the Ni(bds) plane. EPR measurements and DFT calculations are also carried out on the 77Se enriched complex CpNi(dsit) as well on the two dithiolene analogues CpNi(bdt) and CpNi(dmit). The optimized structures of the isolated CpNi(bds) and CpNi(bdt) complexes have been used to generate the idealized dimers (bds)NiCp...CpNi(bds) and (bdt)NiCp...CpNi(bdt) characterized by Cp...Cp overlap. The exchange parameters J calculated at the DFT level for these systems are in reasonable accord with the experimental values. The influence of the geometry of the dimer on its magnetic properties is assessed by calculating the variation of J as a function of the relative orientation of the two Ni(diselenolene) or Ni(dithiolene) planes.     

Selectivity and sensitivity of metal determination by co-ordination compounds

Quantum chemical structure calculations for metal co-ordination compounds with various organic ligands allow choice of generalized parameters of chelate electronic structures, to form a basis for systematization and prediction of analytical properties. The extent of the co-ordinative saturation of a metal is measured as the sum of the covalent bonding energies of the two-centre metal interactions with the ligand atoms. The concept of "valence state of the ligand" is considered and characterized by the energy sum of the covalent components of two-centre interactions in the ligand. It is shown that the ligand structure can be correlated with the complex stability and this provides a new mechanism for assessing the influence of substituents in ligands. The calculated data make it possible to predict compound stability in solutions and synergic action, and therefore such analytical properties as sensitivity and selectivity. For the azo dyes as an example, it is shown that quantum chemical calculations can explain many of the experimental data on the use of azo dyes in photometry, and suggest directions of search for new analytical reagents.     

A new fullerene complexation ligand: N-pyridylfulleropyrrolidine

The subject of this paper is a new fullerene building block design with the potential for defined geometry and good electronic communication. The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with metalloporphyrins is reported. X-ray structural and molecular modeling studies, (1)H NMR, UV-vis spectroscopy, electrochemistry studies, and fluorescence quenching data support the formation of a strong complex between the new ligand and the metal center of ZnTPP. On the basis of computational studies, the highest occupied molecular orbital (HOMO) of this ligand is significantly different from a model compound with insulating carbons between the pyridine and the fullerene. The N-pyridinium fulleropyrrolidine salts of the new ligand and model compound were also prepared and their spectral and electrochemical properties are reported.     

A new photoluminescent silica aerogel based on N-hydroxysuccinimide–Tb(III) complex

The paper describes the preparation of a new photoluminescent silica aerogel by embedding a new Tb(III) complex in a silica matrix by using N-hydroxysuccinimide as ligand. The Tb(III) complex prepared at a metal to ligand ratio of 1:3 (mol%) exhibits strong photoluminescence as a result of specific radiative transitions within the Tb(III) cation with the most intense peak located at 543 nm due to ⁵D₄ → ⁷F₅ transition. The synthesized complex was doped in the silica matrix through a catalyzed sol–gel process. After ageing in ethanol, the alcogel was dried under supercritical regime by exchanging the ethanol with liquid carbon dioxide followed by supercritical evaporation. The leaching of the free complex from the alcogel during ageing and solvent exchange phases was found to be minimal most likely due to the interactions between chemical groups of complex with those specific to silica matrix. The obtained regular shaped monolithic aerogel preserved the remarkable photoluminescent properties and also improved the thermal stability of the free complex. Both, the free complex and doped aerogel were characterized through thermal analysis, FT-IR, powder X-ray diffraction, Scanning electron microscopy and fluorescence spectroscopy. For comparison purposes, an undoped silica aerogel was also prepared and investigated through FT-IR, BET analysis and powder X-ray diffraction. The excellent photoluminescent properties might recommend the prepared aerogel for applications in optoelectronic devices where photonic conversion materials are required.     

Bridging Ligand Length Controls AT Selectivity and Enantioselectivity of Binuclear Ruthenium Threading Intercalators

The slow dissociation of DNA threading intercalators makes them interesting as model compounds in the search for new DNA targeting drugs, as there appears to be a correlation between slow dissociation and biological activity. Thus, it would be of great value to understand the mechanisms controlling threading intercalation, and for this purpose we have investigated how the length of the bridging ligand of binuclear ruthenium threading intercalators affects their DNA binding properties. We have synthesised a new binuclear ruthenium threading intercalator with slower dissociation kinetics from ct‐DNA than has ever been observed for any ruthenium complex with any type of DNA, a property that we attribute to the increased distance between the ruthenium centres of the new complex. By comparison with previously studied ruthenium complexes, we further conclude that elongation of the bridging ligand reduces the sensitivity of the threading interaction to DNA flexibility, resulting in a decreased AT selectivity for the new complex. We also find that the length of the bridging ligand affects the enantioselectivity with increasing preference for the ΔΔ enantiomer as the bridging ligand becomes longer.     

Synthesis,molecular structure,and spectral properties of new metal chelates based on organic autocomplexes and charge transfer therein

A number of new chelate compounds based on 3d-transition metals and autocomplexes of the dinitroquinoline series were synthesized. The crystalline structure of the new complexes was determined by X-ray analysis, and their spectral properties were studied. The complexes have a conformation which gives rise to two modes of contact intramolecular charge transfer: intraligand, which is intrinsic to the initial ligand molecules, and interligand (as in binary charge-transfer complexes). The latter involves the corresponding pairs of donor and acceptor fragments of the initial ligand molecules, which appear spatially close as a result of complex formation.