三氮唑类席夫碱的合成及其荧光性能

近年来,Schiff碱因其结构的多样化以及具有光、电、磁等物理材料性能[1-3]的配位化学性能[4-5]等引起人们的关注,同时一些特殊结构的Schiff碱的合成和性质研究具有更为重要的理论意义和应用价值.     

Synthesis and mesogenic properties of binuclear copper(II) complexes derived from salicylaldimine Schiff bases

The synthesis and mesomorphic (liquid crystal) properties of new binuclear dihalocopper(II) complexes derived from N- and ring-substituted salicylaldimine Schiff bases are reported, together with the mesomorphic properties of their monomeric precursor complexes. With just N-substituents both the dichlorodicopper(II) binuclear complexes and their mononuclear analogues are waxy solids with melting points that increase with their N-chain length. However, with both N- and ring-substituents in the 4-positions, the mononuclear and binuclear complexes are each liquid crystalline or mesogenic, except in case of the mononuclear complexes where the N-substituent is straight chain alkyl. The other mononuclear complexes exhibit a variety of liquid crystal phases: smectic A, C, and E (SA, SC, and SE, respectively). The liquid crystal phase SA is observed in the binuclears with shorter chain N-substituents p-R-O-C6H4- and shorter chain ring-substituents. The chain lengths were increased until the phase behavior expanded to a further form SC in the case of an N-substituent p-C14H29O-C6H4- and a -OC12H25 ring substituent. This points the way toward achieving multiphase behavior with these binuclear systems. The Cu-Br analogues of the binuclear complexes behave similarly but with significant qualitative differences, specifically lower mesophase stability and higher melting temperatures. The structures of the nonmesogenic binuclears ([Cu(N-dodecylSal)X]2, X=Cl, Br) were determined with the aid of X-ray crystallography. These are prototypes for the structures of the binuclear complexes and especially for the shape of the central Cu2O2 X2 core in the binuclears: distorted planar coordination about the copper with distortion toward tetrahedral measured by a characteristic twist angle tau (0 degrees planar; 90 degrees tetrahedral). The binuclear complexes also show magnetic coupling which can be used to estimate the geometry. For [Cu(N-dodecylSal)X]2 tau>36 degrees, which corresponds to weaker coupling than observed in the mesogenic binuclears where a stronger magnetic coupling indicates a geometry closer to planar (tau=25 degrees). The mesophases were characterized by differential scanning calorimetry (DSC) analysis and optical polarized microscopy.     

Synthesis and characterization of some nickel(II) Schiff bases complexes

Summary The reaction of nickel(II) salts with 2-picolyl- and 2,6-lutidyl-phenylketone benzoylhydrazone and theirp-nitro- andp-methoxy-derivatives were carried out and the compounds characterized on the basis of analytical and spectral data.     

Synthesis,structure, and properties of new phosphorus Schiff bases

A series of new Schiff bases has been synthesized on the basis of (2-aminophenyl)triphenyl-phosphonium chloride and substituted salicylaldehydes. The structure of the prepared compounds has been established by means of IR, UV, and ¹H NMR spectroscopy, as well as DFT B3LYP/6-31G(d,p) quantum-chemical simulation. The possible tautomerism and certain properties of the azomethines, including complex formation, have been studied.     

两种溴代水杨醛基单双Schiff碱衍生物的合成及变色发光性能研究

以3,5-二溴-2-羟基苯甲醛和1,2-二氨基乙烷、3-氨基苯甲酸为原料,合成了两种化合物N,N'-双3,5-二溴-2-羟基苯甲醛缩1,2-二氨基乙烷(DBSE)和N-3,5-二溴-2-羟基苯甲醛缩3-氨基苯甲酸(DBSA)。利用核磁共振氢谱、质谱、红外光谱和元素分析对目标化合物的结构进行了表征,通过紫外-可见吸收光谱、荧光光谱测定了其发光性能,另外通过TG-DTG测定了其热稳定性能。结果表明:目标化合物DBSE为蓝绿光发射,DBSA为紫色光发射;目标化合物的热分解温度均达260℃以上,具有良好的热稳定性;在254 nm紫外光照射不同时间下、不同的温度下、不同的极性溶剂中、不同浓度的Co2+离子滴定的情况中,目标化合物均表现出了一定的变色发光性能,整体来看DBSE的光致变色性能优于DBSA,而热致变色性能DBSA优于DBSE。     

两种含硫Schiff碱及其配合物的合成与光谱性质

合成了2-氨基噻唑缩5-溴水杨醛(HBrsatz)和2-乙酰噻吩缩4-羟基苯甲酰腙(Hetphz)两种含硫Schiff碱及其配合物[Cu(Brsatz)2](Ⅰ)和[Cd(H2O)(Hetphz)(phen)](NO3)2(Ⅱ),通过元素分析、红外光谱和紫外光谱对它们的结构进行了表征,并研究了它们在DMF溶液中的发光性质,结果表明HBrsatz和Hetphz及配合物Ⅱ具有较强的荧光发射.     

Rhenium(V) complexes with Schiff bases: Synthesis and reaction mechanisms

Summary Some isomers of the ReOX₂LPPh₃ complexes [X = Cl or Br and L =N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N'-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate] have been synthesized and characterized. Two different mechanisms for reaction of thetrans-ReOX₃(PPh₃)₂ complexes (X = Cl or Br) with the Schiff bases are supported by qualitative studies on such parameters as the Schiff base ligand form, concentration of free triphenylphosphine ligand, reaction solvent and temperature.     

Synthesis,crystal structure and fluorescence properties of two dinuclear zinc(II) complexes incorporating tridentate (NNO) Schiff bases

Reactions of hydrated zinc(II) trifluoroacetate and sodium azide with two tridentate Schiff bases HL¹ (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-chlorophenol) and HL² (2-((E)-(2-(dimethylamino)ethylimino)methyl)-4-bromophenol) under the same reaction conditions yielded two dinuclear isostructural zinc(II) complexes, [Zn(L¹)(N₃)]₂ (1) and [Zn(L²)(N₃)]₂ (2), respectively. The complexes were characterized systematically by elemental analysis, UV–Vis, FT-IR, and ¹H NMR spectroscopic methods. Single-crystal X-ray diffraction studies reveal that each of the dinuclear complexes consists of two crystallographically independent zinc(II) ions connected by double bridging phenoxides. All zinc(II) ions in 1 and 2 are surrounded by similar donor sets and display distorted square–pyramidal coordination geometries. The ligands and complexes reveal intraligand ¹(π → π*) flourescence. The enhancement of the fluorescence intensities for the complexes compared to the ligands indicates their potential to serve as photoactive materials.     

Synthesis,crystal structures,and catalytic properties of two oxidovanadium(V) complexes with tridentate Schiff bases

Two new oxidovanadium(V) complexes, [VO₂L¹] (I) and [VO₂L²] (II), where L¹ and L² are the deprotonated forms of 4-methyl-2-[(2-morpholin-4-ylethylimino)methyl]phenol (HL¹) and 2-[(2-isopropylaminoethylimino) methyl]-4-trifluoromethoxyphenol (HL²), respectively, have been prepared and characterized by physico chemical methods and single crystal X-ray diffraction (CIF files CCDC nos. 1443671 (I), 1443672 (II)). The V atom in each complex is coordinated by the phenolate oxygen, imino nitrogen and amino nitrogen of the Schiff base ligand, and two oxo groups, forming trigonal-bipyramidal geometry. The oxidation of olefins with the complexes as catalyst was evaluated, which indicated that both complexes showed effective catalytic efficiency in oxidation of several aliphatic and aromatic substrates by using tert-butyl hydrogen peroxide as oxidant.     

Synthesis,characterization and electrochemical studies of ruthenium(III) heterocyclic Schiff bases

A series of hexacoordinated Ru^III–PPh₃ complexes of general formula [RuCl(PPh₃)L] (L = tetradentate Schiff bases derived from the condensation of 2-furaldehyde or thiophene-2-carboxyaldehyde with alkyl and aryl diamines have been synthesized. The complexes were characterized by elemental analyses, spectroscopic and cyclic voltammetric studies. All of the complexes were paramagnetic. Coordination of the Schiff base appears to occur through the two nitrogen and two heterocyclic oxygen/sulphur atoms.     

Synthesis,characterization and biological properties of novel ON donor bidentate Schiff bases and their copper(II) complexes

Four novel ON donor Schiff bases (E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol (HL₁),(E)-3-((4-(4-biphenyloxy)phenyliminomethyl)benzene-1,2-diol (HL₂), (E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol (HL₃), (E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol (HL₄) and their copper(II) complexes bis((E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₁)₂) bis((E)-3-((4-(4-biphenyloxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₂)₂), bis((E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₃)₂), bis((E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L₄)₂) have been synthesized and characterized by spectroscopic (FTIR, NMR, UV–visible) and elemental analysis. The crystal structures of HL₁, HL₂, HL_3, and HL₄ have been determined, which reveal intramolecular N-H?O (HL₁, HL₂, HL_3, and HL₄) hydrogen bonds in the solid state. Keto-amine and enol-imine tautomerism is exhibited by the Schiff bases in solid and solution states. The Schiff bases and their copper(II) complexes have been screened for their biological activities. In antimicrobial assays (antibacterial and antifungal), HL₄ showed promising results against all strains through dual inhibition property while the rest of the compounds showed activity against selective strains. On the other hand, in cytotoxic, DPPH, and inhibition of hydroxyl (OH) free radical-induced DNA damage assays, the results were found significantly correlated with each other, i.e. the ligands HL₁ and HL₂ showed moderate activity while their complexes Cu(L₁)₂ and Cu(L₂)₂ exhibited prominent increase in activity. As the results of these assays are supporting each other, it represents the strong positive correlation and antioxidant nature of investigated compounds.     

Synthesis and spectroscopic properties of Schiff bases derived from 3-hydroxy-4-pyridinecarboxaldehyde

A series of six new Schiff bases has been prepared by reacting aniline and 4-R-substituted anilines (R=CH₃, OCH₃, Br, Cl, NO₂) with 3-hydroxy-4-pyridinecarboxaldehyde. The ¹H, ¹³C, ¹⁵N and ¹⁷O NMR data of these compounds are used to discuss the tautomerism. ¹⁵N NMR and ¹⁷O NMR chemical shifts established the tautomer existing in solution as the hydroxy/imino. ¹³C CPMAS NMR confirms that the same tautomer is found in the solid state. The stabilities of the tautomeric forms have been approached using density functional calculations (B3LYP/6-31G**) in the gas phase. In all cases the neutral hydroxy/imino with E configuration is more stable than the oxo/enamino form (by ∼22 kJ mol⁻¹) and significantly more stable than the betaine (by ∼75 kJ mol⁻¹).     

Synthesis and crystal structures of cobalt(III) and zinc(II) complexes with Schiff bases

Two new cobalt(III) and zinc(II) complexes, [Co(L¹)₂ (H₂O)] · ClO₄ (I) and [Ni(L²)₂ (H₂O)₂] · 2ClO₄ (II), where L¹ is the deprotonated form of 5-methoxy-2-[(2-morpholin-4-ylethylimino)methyl]phenol, and L² is the zwitterionic form of 2-[(2-isopropylaminoethylimino)methyl]-5-methoxyphenol, were synthesized and structurally characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. The crystal of I is monoclinic: space group P2₁/c, a = 11.1512(4), b = 28.2424(11), c = 10.9655(4) Å, β = 95.746(2)°, V = 3436.1(2) ų, Z = 4. The crystal of II is triclinic: space group P2₁/c, a = 8.1441(2), b = 10.4531(3), c = 10.8849(3) Å, α = 84.0240(10)°, β = 76.9800(10)°, γ = 74.2280(10)°, V = 867.92(4) ų, Z = 1. Complex I consists of a mononuclear cobalt(III) complex cation and a perchlorate anion. Complex II consists of a crystallographic centrosymmetric mononuclear nickel(II) complex cation and two perchlorate anions. Each metal atom in the complexes is in an octahedral coordination.     

Synthesis and spectroscopic studies of new Schiff bases

Five novel Schiff bases have been prepared from o-formylphenoxyacetic acid and a series of aminothiazoles to form a number of potentially biologically active compounds. The structures of these Schiff bases have been characterized using IR and (1)H-and (13)C-NMR spectroscopy.     

Synthesis, crystal structures, and magnetic properties of tetranuclear nickel(II) and copper(II) complexes with tridentate Schiff bases

Two cubane-type tetranuclear nickel(II) and copper(II) complexes, [Ni₄(L¹)₄(CH₃OH)₄] (1) and [Cu₄(L²)₄]·H₂O (2), where L¹ and L² are the dianionic forms of the tridentate Schiff bases 4-nitro-2-[(2-hydroxyethylimino)methyl]phenol (H₂L¹) and 5-methoxy-2-[(2-hydroxyethylimino)methyl]phenol (H₂L²), respectively, have been synthesized and characterized by physicochemical methods and single-crystal X-ray diffraction. The magnetic properties of the complexes show the presence of ferromagnetic interactions for complex 1 and antiferromagnetic interactions for complex 2, mediated by hydroxyl bridges.     

Synthesis and X-ray crystal structures of two cobalt(III) complexes with Schiff bases

Two new mononuclear cobalt(III) complexes, [Co(MP)₂(N₃)] (I) and [Co(BP)₂]NO₃ · 2H₂O (II), where MP is 2-methoxy-6-[(2-morpholin-4-ylethylimino)methyl]phenolate and BP is 4-bromo-2-[(2-methylaminoethylimino)methyl]phenolate, were prepared and structurally characterized by physicochemical methods and single crystal X-ray diffraction. Both complexes crystallize in the monoclinic space group P2₁/c. For I: a = 10.3526(18), b = 25.371(4), c = 11.3585(19) Å, β = 101.529(8)°, V = 2923.1(8) ų, Z = 4; for II: a = 9.801(2), b = 27.183(3), c = 10.846(2) Å, β = 114.269(2)°, V = 2634.2(8) ų, Z = 4. An X-ray structural analysis indicates that in both complexes the Co atoms adopt octahedral coordination. The hindrance effects of the Schiff bases can influence the coordination of the secondary ligands such as azide.     

Hafnium(IV) complexes with Schiff bases

Summary Hafnium(IV) complexes have been prepared by the reactions of hafnium(IV) isopropoxide isopropanol with Schiff bases [bis(salicylaldehyde)hydrazine] (Sal-AH₂), (bis(o-hydroxyacetophenone)hydrazine] (Acp-AH₂), [bis(resacetophenone)hydrazine] (Res-AH₂), [bis(salicylaldehyde)ethylenediimine) (SaleneH₂), [bis(o-hydroxyacetophenone)ethylenediimine] (AcpeneH₂) and [bis(salicylaldehyde)o-phenylenediimine] (SalpheneH₂) (derived from salicylaldehyde,o-hydroxyacetophenone, resacetophenone and diamines) in appropriate molar ratios using benzene as solvent. The complexes [Hf(OPr-i)₂(SB)] and [Hf(SB)₂] (where SB^2– represents the dianion of the Schiff base) are reported. The complexes of Sal-A, Acp-A and Res-A are 5-and 6-coordinate while those of salene, acpene and salphene are 6-and 8-coordinate. The Schiff bases draw on Sal-A, Acp-A and Res-A are tridentate and salene, acpene and salphene are tetradentate. The mode of bonding through nitrogen and oxygen and the stereochemistry of the complexes are discussed in relation to the elemental analyses and spectra (electronic, infrared and nuclear magnetic resonance).     

Synthesis,characterization and antibacterial properties of Schiff bases and Schiff base metal complexes derived from 2,3-diamino- pyridine

New copper(II), zinc(II) and nickel(II) Schiff base complexes derived from 2,3-diaminopyridine (DAPY) and selected aldehydes, namely salicylaldehyde (SalH), 4-hydroxybenzaldehyde (4-OHBenz) and 4-nitrobenzaldehyde (4-NO₂Benz), and one mixed Schiff base, DAPY-{4-OHBenz}{SalH} were prepared and characterized by a combination of elemental analyses, i.r. and n.m.r. spectra, and magnetic susceptibility measurements. The Schiff bases and some of the metal complexes display antibacterial properties.     

Synthesis,structural and spectroscopic properties of asymmetric Schiff bases derived from 2,3-diaminopyridine

Two Schiff base derivatives, 4-(2-amino-3-pyridyliminomethyl)phenol (I) and 3-(2-amino-3-pyridyliminomethyl)nitrobenzene (II), were synthesised and characterised by spectroscopy. The structure of I was determined by single crystal X-ray diffraction studies. The asymmetric Schiff base derived from 2,3-diaminopyridine selectively recognise transition and heavy metal cations, and some anion. Ligands I and II form stable complexes with Cu²⁺, Zn²⁺, Pb²⁺, Al³⁺ whereas ligand I also binds F~ ions. The stoichiometry for the host: cation is 1: 1 and 2: 1. The addition of F~ ion in CH₃CN to ligand I causes a colour change of the solution from colourless to yellow. The binding behaviour of ligand I towards several ions was investigated using density functional theory calculations.