Synthesis and structural studies of new Mannich base ligands and their metal complexes

The new Mannich bases bis(1,4-diphenylthiosemicarbazide methyl) phosphinic acid H₃L¹ and bis(1,4-diphenylsemicarbazide methyl) phosphinic acid H₃L² were synthesised from the condensation of phosphinic acid, formaldehyde with 1,4-diphenyl thiosemicarbazide and 1,4-diphenylsemicarbazide, respectively. Monomeric complexes of these ligands, of general formulae K₂[Cr^III(L ⁿ )Cl₂], K₃[Mn^II(L ⁿ )Cl₂] and K[M(L ⁿ )] (M = Co(II), Ni(II), Cu(II), Zn(II) or Hg(II); n = 1, 2), are reported. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometries for the Cr(III), Mn(II) complexes, square planar for Co(II), Ni(II) and Cu(II) complexes and tetrahedral for the Zn(II) and Hg(II) complexes.     

Synthesis of aluminium complexes bearing a piperazine-based ligand system

Aluminium complexes bearing the N,N-chelating ligand 1,4-bis(2-hydroxy-3,5-di-tert-butyl)piperazine (1) have been synthesised. Both monometallic and bimetallic aluminium methyl complexes (2 and 3, respectively) were prepared by treatment of 1 with the appropriate amount of AlMe₃. Complex 2 can be converted to 3 by addition of excess AlMe₃. Bimetallic aluminium-ethyl complex 4 was also prepared. Treatment of 1 with AlEt₂Cl afforded the monometallic chloride complex 5. Treatment of this latter complex with potassium alkoxides (KOR, R = Me, Et, ⁱPr, ^tBu) or AgOTf afforded the corresponding aluminium alkoxide complexes (6, R = Et; 7, R = Me; 8, R = ⁱPr; 9, R = ^tBu; 10, R = OTf) in good yields. Aluminium ethoxide complex 6 was also synthesised by treatment of 1 with AlEt₂OEt. All of these complexes were tested as potential catalysts in the ring-opening polymerisation of rac-lactide and caprolactone with limited success.     

Speciation analysis of aluminium and aluminium fluoride complexes by HPIC-UVVIS

The study presents a new analytical method for speciation analysis in fractionation of aluminium fluoride complexes and free Al³⁺ in soil samples. Aluminium speciation was studied in model solutions and soil extract samples by means of high performance ion chromatography (HPIC) with UV-VIS detection using post-column reaction with tiron for the separation and detection of aluminium fluoride complex and Al³⁺ forms during one analysis. The paper presents particular stages of the chromatographic process optimization involving selecting the appropriate eluent strength, type of elution or concentration and quantity of derivatization reagent. HPIC was performed on a bifunctional analytical column Dionex IonPac CS5A. The use of gradient elution and the eluents A: 1 M NH₄Cl and B: water acidified to pH of eluent phase, enabled full separation of fluoride aluminium forms as AlF₂⁺, AlF₃⁰, AlF₄⁻ (first signal), AlF²⁺ (second signal) and form Al³⁺ in a single analytical procedure. The proposed new method HPIC-UVVIS was applied successfully in the quantitative and qualitative analysis of soil samples.     

异双希夫碱配合物的合成与表征

邻苯二胺与5-氯-2-羟基二苯酮、2-羟基-1-萘醛作用合成了一种异双四齿希夫碱配体C30H21N2O2Cl(H2L)。在无水体系中该配体与金属醋酸盐作用合成了5种固体配合物[ML]·nH2O(M=Cu(Ⅱ),Zn(Ⅱ),Mn(Ⅱ),Co(Ⅱ),Ni(Ⅱ);n=0-1)。通过元素分析、IR、UV、TG-DTG及摩尔电导分析等手段对合成的配合物进行了表征。     

稀土与直链醚-乙酰丙酮Schiff碱新配合物合成、形成机理 与波谱

首次合成了直链醚Schiff碱,乙酰丙酮缩二甘醇二胺(ACACDA),并以分步法得到它与稀土元素的九种新配合物:[Ln(ACACDA)~2(NO~3)](NO~3)~2·4H~2O(Ln=La,Pr,Nd,Sm,Gd,Tb,Er,Yb,Y)。以紫外、红外光谱,特别是500MHz的NMR谱表征了配合物,通过其形成机理探讨,证明配合物中配体采取烯胺式构型形成稳定共轭结构。研究了Gd配合物的EPR谱,呈"U"谱特征,并出现"零场效应",据此讨论了配合物中晶体场强度及Gd^3^+周围的局部对称性。     

Synthesis and spectral characterization of homo-and hetero-dinuclear complexes with a new septadentate Schiff base ligand

Reaction between 3-formylsalicylic acid and bis-(2-aminophenyl)-disulphide yields a septadentate Schiff base with N₂SO₄ donor frame of which the inner compartment is N₂SO₂ and the outer is O₂O₂ type. It forms several complexes with inner copper centre and outer nontransition/transition metal ions. The complexes have been characterised by elemental analyses, spectral (IR, absorption, diffused reflectance), thermal and magnetic data. Dinuclear copper complexes exhibit subnormal magnetic moments (≈ 0.80 BM), showing magnetic exchange, and six-line solid-state ESR spectra at 77 K.     

Synthesis,characterization, and biological evaluation of new polyester containing Schiff base metal complexes

The production of new biocidal polyester Schiff base metal complexes [PESB–M(II)] via polycondensation reaction between chelated Schiff base diol and adipoyl chloride is reported. The resulting polyesters were characterized by physico-chemical and spectroscopic methods. The analytical data of all the synthesized polyesters were found to be in good agreement with 1:1 molar ratio of chelated Schiff base diol to adipoyl chloride. Thermogravimetric analyses of synthesized polyesters were studied by TG in nitrogen atmosphere up to 1073 K and results indicate that Cu(II) polyester complex exhibited better heat resistant properties than the other polyesters complexes. Magnetic moment and UV–visible spectra were examined to explain the structure of all the polyesters which reveled that Mn(II), Co(II), Ni(II) have octahedral geometry while Cu(II) possess a distorted octahedral geometry. These newly developed polyesters were also tested for their antibacterial activity against several bacteria and fungi. Among all the tested compounds PESB–Cu(II) possess the highest bactericidal and fungicidal activity.     

Synthesis and genotoxicity of Schiff base transition metal complexes

A new ONNO‐type azomethine ligand, 2,2′‐(ethane‐1,2‐diylidenedinitrilo)dibenzoic acid, (YLH₂) ( 1 ) has been prepared by the condensation of 2‐aminobenzoic acid and glyoxal. The coordination compounds [Ni(YL)] ( 2 ), [Co(YL)] ( 3 ), [Cu(YL)(H₂O)] ( 4 ), [Zn(YL)] ( 5 ), and [Cd(YL)] ( 6 ) of the YLH₂ ligand with five transition metal ions, Ni(II) Co(II), Cu(II), Zn(II), and Cd(II) have been prepared. The structures of these new azomethine compounds are proposed on the basis of the elemental analyses, proton nuclear magnetic resonance, infrared, ultraviolet–visible spectroscopy, and X‐ray powder diffraction patterns. Elemental analyses indicate a ligand metal ratio of 1:1 in the coordination compounds. X‐ray powder diffraction parameters for [Cu(YL)(H₂O)] and [Cd(YL)] compounds correspond to orthorhombic and monoclinic structures, respectively. The ligand acts as a tetradentate ligand bending through oxygen atoms of the hydroxyl groups of benzoic acid and nitrogen atoms of the azomethine groups. In addition, the ligand and its metal complexes have been studied for their possible genotoxic potential. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:119–130, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20665     

Synthesis, characterization and thermal analysis of some new transition metal complexes of a polydentate Schiff base

A new polydentate Schiff base (H3L) was synthesized from the condensation of 2,6-diformyl-4-methylphenol and S-methylhydrazine-carbodithionate. The 1:1 metal complexes were obtained from the interaction of H3L and the metal ions Cr(III), Co(II), Ni(II), Cu(II), Cd(II) and Hg(II). The complexes were characterized by elemental analysis and IR spectroscopy. Detailed studies of the thermal properties of the complexes were investigated by thermogravimetry techniques.     

直链醚-二甘肽型Schiff碱与稀土新配合物的合成、配 位作用与波谱

合成了稀土与四甘醇醛-二甘肽型Schiff碱(TAGLGL)形成的六种新配合物,在此配体中同时引入了C=N及HN—C＝O基团。经元素分析、光谱等表征,确定该类多核配合物组成为：[Ln3(TAGLGL)(NO3)7]·4H2O(Ln=La,Nd,Sm,Gd,Yb,Y)。以液体1^HNMR谱、固体高分辨^13CNMR等方法,并结合Gd(Ⅲ)配合物的EPR波谱着重探讨了配位作用,配位数和晶体场强等。     

Synthesis,characterization, and anticancer activity of some metal complexes with a new Schiff base ligand

A new Schiff base ligand, 2-((E)-((4-(((E)-benzylidene)amino)phenyl)imino)methyl)-naphthalene-1-ol, was prepared by the reflux condensation of p-phenylenediamine with 2-hydroxy-1-naphthaldehyde and benzaldehyde. Metal complexes were prepared by reacting the ligand with metal salts: VCl₃, CrCl₃·6H₂O, MnCl₂·3H₂O, FeCl₃·6H₂O, CoCl₃·6H₂O, NiCl₂·6H₂O, CuCl₂·2H₂O, and ZnCl₂. The ligand and its metallic complexes were characterized by various techniques such as elemental analysis, AAS, NMR, IR, UV–Vis, TGA, DTA, XRD and TEM. The data confirmed that the ligand coordinated with the metal ions in a bidentate nature, bonding through its azomethine nitrogen atom and phenolic oxygen atom; this gave an octahedral geometry. The XRD patterns of the complexes indicated that they were of various structures: the Mn(II), Co(III), and Cu(II) complexes were triclinic, the ligand and Ni(II) complex were orthorhombic, the V(III) and Zn(II) complexes were hexagonal, the Cu(II) complex was monoclinic, and the Fe(II) complex was cubic. TEM analysis confirmed that the complexes were nanoscale in nature. The antibacterial and antifungal activities of the ligand and its complexes against Salmonella enterica serovar typhi and Candida albicans were investigated by the hole plate diffusion method. It was observed that the Co(II) and Zn(II) complexes had intermediate antibacterial activities, while the V(III) complex had the highest activity against C. albicans fungi. The in vitro anticancer activities of the ligand and its metal complexes were tested towards PC-3, SKOV3, and HeLa tumour cell lines, where they exhibited higher antitumour activities against these selected human cell lines than clinically used drugs such as cisplatin, estramustine, and etoposide.     

Synthesis,characterization, and antibacterial activity of new rare-earth ion complexes with unsymmetrical Schiff base ligand

A new unsymmetrical Schiff base ligand (H₂LLi) was synthesized using L-lysine, salicylaldehyde, and 2-hydroxy-1-naphthaldehyde. Three rare-earth ion complexes of this ligand, [REE(H₂L)(NO₃)]NO₃ · 2H₂O (REE = La, Sm, Ho), have been prepared and characterized by elemental analyses, IR spectra, UV spectra, TG-DTG, and molar conductance. The antibacterial activity of the ligand and its complexes are also studied. The antibacterial experiments indicate that this ligand and its complexes possess antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis and the complexes have higher activity than that of the ligand. The article was submitted by the authors in English.     

Synthesis and characterization of polylactides with different branched architectures

Star‐shaped and comb‐like poly(L‐Lactide)s (PLA) are produced by employing multifunctional initiators, and hyperbranched structure is prepared using a cyclic co‐monomer with hydroxyl group. FTIR, size exclusion chromatography, and H‐NMR techniques are employed to characterize the synthesized polymers, validating the formation of desired structures with chain lengths above the critical length for entanglement. After characterization of the synthesized polymers, the effect of branching on PLA properties is investigated by comparing the crystallization and rheological behavior of branched PLAs to those of a linear commercial grade. Differential scanning calorimetry and optical microscopy observations reveal a remarkable improvement in PLA crystallization due to the nucleation role of branching points. Moreover, synthesized polylactides exhibit strain hardening behavior during elongational viscosity measurements by a sentmanat extension rheometer platform. Significant improvements in crystallization and elongational rheology behavior of the synthesized polymers support the achievement of branched polymer structures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 522–531     

Electrochemical and chemical synthesis of new luminescent schiff base complexes

Bis-chelate complexes of zinc, cadmium, lead, and mercury with o-N-tosylbenzylidene imines containing the C₇H₁₅ and C₁₈H₃₇ substituents at the C=N group nitrogen atom were prepared by the methods of electrochemical and chemical syntheses. The structure of the azomethines and their complexes was established by the methods of heteronuclear ¹H, ¹³C NMR spectroscopy (multidimensional and multinuclear COSY, HETCOR and HETCOR_LONG techniques). The complexes, as demonstrated by the X-ray analysis for the zinc chelate, have strongly distorted octahedral structure formed by the four azomethine nitrogen atoms and two oxygen atoms of the tosyl fragments. The coordination compounds show fluorescence in the blue part of the spectrum in high quantum yields for the zinc chelates.     

Lithium and aluminium complexes supported by chelating phosphaguanidinates

Diisopropylcarbodiimide, (i)PrN[double bond, length as m-dash]C[double bond, length as m-dash]N(i)Pr, inserts into the lithium-phosphorus bond of in situ prepared "Ph(2)PLi(THF)(n)" to afford the lithium salt, [Li(Ph(2)PC{N(i)Pr}(2))(THF)(n)](x)(2a); alternatively, this compound can be made by deprotonation of the neutral phosphaguanidine, Ph(2)PC{N(i)Pr}{NH(i)Pr}(1a) with (n)BuLi. Displacement of the THF solvate in 2a is readily achieved with TMEDA to afford Li(Ph(2)PC{N(i)Pr}(2))(TMEDA)(3a). X-Ray crystallographic analyses show that 2a exists as a dimer in the solid state with a folded ladder structure and an N,N' chelating phosphaguanidinate, while 3a is monomeric with N,P-coordination of the ligand to lithium. Compound 2a reacts via a transmetallation pathway with AlMe(2)Cl to afford the dimethylaluminium complex, Al(Ph(2)PC{N(i)Pr}(2))Me(2)(4a), which can also be prepared by protonation of a methyl group of AlMe(3) using 1a. The formation of a series of dialkylaluminium compounds has been investigated employing this latter pathway using both 1a and the N,N'-dicyclohexyl analogue, Ph(2)PC{NCy}{NHCy}(1b), affording Al(Ph(2)PC{NR}(2))Et(2)(5a,b), Al(Ph(2)PC{NR}(2))(i)Bu(2)(6a,b) and the diphenylaluminium compound Al(Ph(2)PC{N(i)Pr}(2))Ph(2)(7a). The oily nature of most of the dialkyl compounds and high sensitivity to oxygen and moisture lead to difficulty in manipulation and characterization; however, NMR spectroscopy indicated highly pure products (>95%) upon removal of the solvent. The molecular structures of the crystalline examples 4a and 7a are reported, showing monomeric aluminium species with symmetrically chelating phosphaguanidinate ligands. The series of aluminium compounds AlLCl(2){L=[EC{NiPr}(2)](-): A, E=Me; B, E=Me(2)N; C, E=(Me(3)Si)(2)N and D, E=Ph(2)P} were investigated using density functional theory. In the more simple cases A and B, the delocalized electron density of the metallacycle was represented by a combination of the HOMO and an orbital of lower energy (A, HOMO-5; B, HOMO-6). The HOMO-1 in B was pi-bonded across the Me(2)N-C bond suggesting delocalization of electron density into the metallacycle. In the more complex systems C and D, delocalization within the metallacycle was less extensive due to the (Me(3)Si)(2)N- and Ph(2)P-moieties. A number of occupied orbitals in D, however, display phosphorus 'lone-pair' characteristics, indicating that these species have the potential to behave as Lewis bases in the formation of poly(metallic) systems.     

新型Schiff碱双核配合物的合成及光谱特征

首次报道了新型Schiff碱双核配合物-双[N,N"-亚烃基-2,2'(苯亚甲基)二(3,4-二甲基吡咯-5醛缩亚胺)]合双锰及双铁配合物的合成方法及光谱特征。     

Development of a new analytical method for online simultaneous qualitative determination of aluminium (free aluminium ion, aluminium-fluoride complexes) by HPLC-FAAS

The paper presents a novel method for simultaneous online examination of inorganic forms of aluminium: AlF₂⁺, AlF^2+, and Al³⁺ by means of the high performance liquid chromatography hyphenated with a detection by the atomic absorption spectrometry with flame atomization (HPLC-FAAS) without post-column reaction. The application of optimization procedure conditions of chromatographic separation of inorganic forms of aluminium was achieved by the analytical column IonPac CS5A (Dionex) with guard column IonPac CG5A (Dionex) and an aqueous ammonium chloride mobile phase, at pH about 3 with gradient elution. The separation of Al forms with nominal charge of 1+, 2+, 3+ required a run time of less than 8 min during a single analysis. The proposed method has been successfully used for the examination of aluminium forms formation AlF_n⁽³⁻ⁿ⁾⁺ in environmental samples.     

Synthesis,spectral, electrochemical and catalytic studies of new Ru(III) tetradentate Schiff base complexes

The synthesis and characterization of several hexa‐coordinated ruthenium(III) Schiff base complexes of the type [RuX(EPh₃)(L)] (X = Cl or Br; E = P or As; L = dianion of the tetradentate Schiff base) are reported. IR, EPR, electronic spectra and cyclic voltammetric data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all of these complexes. The new complexes have been subjected to catalytic activity in the reaction of oxidation of alcohols in the presence of N‐methylmorpholine‐N‐oxide. Copyright © 2007 John Wiley & Sons, Ltd.     

Employing (half-)titanocene complexes as initiators for the synthesis of end-functionalized polylactides by coordination polymerization

Seven (half-)titanocene alkoxide complexes, [Cp₂TiCl(OEt)], [Cp₂TiCl(O-2-Bu)], [Cp₂TiCl(OCH₂CF₂CF₂H)], [CpTiCl₂(OEt)], [CpTiCl₂(O-(S)-2-Bu)], [CpTiCl₂(OCH₂CF₃)], and [Cp₂TiCl(OCH₂CF₃)], were synthesized and employed in lactide coordination polymerization. These organotitanium (IV) compounds proved to be very efficient initiators for the ring-opening polymerization of enantiomeric l -lactide and racemic mixture of rac-lactide, leading to end-functionalized polymers. Kinetic studies illustrated that these compounds produce well-defined polymers in a controlled manner. This was further demonstrated by synthesizing poly(l -lactide-b-hexyl isocyanate) diblock copolymer. The effect of the alkoxy end groups on the thermal behavior of the polymers was also studied by thermogravimetric analysis and differential scanning calorimetry. The polymers were characterized using size exclusion chromatography and proton nuclear magnetic resonance spectroscopy. The optical properties of the diblock copolymer were also investigated. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2192–2202