Catalytic hydrolysis of p‐nitrophenyl picolinate by copper(II) and zinc(II) complexes of N‐(2‐deoxy‐β‐D‐glucopyranosyl‐2‐salicylaldimino)

D‐glucosamine Schiff base N‐(2‐deoxy‐β‐D‐glucopyranosyl‐2‐salicylaldimino) and its Cu(II) and Zn(II) complexes were synthesized and characterized. The hydrolysis of p‐nitrophenyl picolinate (PNPP) catalyzed by ligand and complexes was investigated kinetically by observing the rates of the release of p‐nitrophenol in the aqueous buffers at 25°C and different pHs. The scheme for reaction acting mode involving a ternary complex composed of ligand, metal ion, and substrate was established and the reaction mechanisms were discussed by metal–hydroxyl and Lewis acid mechanisms. The experimental results indicated that the complexes, especially the Cu(II) complex, efficiently catalyzed the hydrolysis of PNPP. The catalytic reactivity of the Zn(II) complex was much smaller than the Cu(II) complex. The rate constant k_N showing the catalytic reactivity of the Cu(II) complex was determined to be 0.299 s^?1 (at pH 8.02) in the buffer. The pK_a of hydroxyl group of the ternary complex was determined to be 7.86 for the Cu(II) complex. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 345–350, 2002     

3‐(2‐(2‐Oxo‐2H‐chromene‐3‐carbonyl)hydrazono)‐N‐(pyridin‐2‐yl)butanamide Complexes: Synthesis,Characterization, DFT,Biological, and Ion‐flotation studies

Schiff base complexes of Cu(II), Ni(II), Cd(II), and Zn(II) with 3‐(2‐(2‐oxo‐2H ‐chromene‐3‐carbonyl)hydrazono)‐N ‐(pyridin‐2‐yl)butanamide (H₂L) were produced. The synthesized compounds were deduced by elemental analysis, molar conductance, magnetic susceptibility, and spectroscopic techniques. The geometry of the prepared complexes was estimated by applying DFT method. Also, Cu(II) and Zn(II) were separated using a simple, quick, and low‐cost quantitative flotation technique preceding to their determinations using atomic absorption spectrophotometric (AAS). Additionally, the biological activities (antimicrobial, antioxidant, and cytotoxic) of isolated compounds were carried out.     

Capillary electrophoretic separation and computational modeling of inclusion complexes of β‐cyclodextrin and 18‐crown‐6 ether with primaquine and quinocide

The antimalarial drug primaquine (PQ) and its contaminant, the positional isomer quinocide (QC) have been successfully separated using capillary electrophoresis with either β‐cyclodextrin (β‐CD) or 18‐crown‐6 ether (18C6) as chiral mobile phase additive. The interactions of the drugs with cyclodextrins and 18C6 were studied by the semiempirical method (Parametric Model 3) PM3. Theoretical calculations for the inclusion complexes of PQ and QC with α‐CD, β‐CD and 18C6 were performed. Data from the theoretical calculations are correlated and discussed with respect to the electrophoretic migration behavior. More stable complexes are predicted for the PQ–β‐CD and PQ–18C6 complexes. The coelution of PQ and QC when α‐CD was used as buffer additive can be explained by their comparable stabilities of the inclusion complex formed, while significant differences in the complexation stabilities of the drugs with β‐CD is responsible for their separation. The stronger hydrogen bonding in PQ–18C6 system is responsible for the separation between PQ and QC when 18C6 was used as chiral mobile phase additive. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation and characterization of poly(ethylene oxide)‐loaded hydroxypropyl‐β‐cyclodextrin nanofibers

Hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) is a modified β‐cyclodextrin (β‐CD) derivative, which is toxicologically harmless to mammals and other animals. HP‐β‐CD is electrospun from an aqueous solution by blending with a non‐toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). Aqueous solutions containing different HP‐β‐CD/PEO blends (50:50–80:20) with variable concentrations (4 wt%–12 wt%) were used. Scanning electron microscope was used to investigate the morphology of the fibers, and Fourier transform infrared spectroscopy analysis confirmed the presence of HP‐β‐CD in the fiber. Uniform nanofibers with an average diameter of 264, 244, and 236 nm were obtained from 8 wt% solution of 50:50, 60:40, and 70:30 HP‐β‐CD/PEO, respectively. The average diameter of the fiber was decreased with increasing of HP‐β‐CD/PEO ratio. However, a higher proportion of HP‐β‐CD in the spinning solution increased beads in the fibers. The polymer concentration had no significant effect on the fiber diameter. The most uniform fibers with the narrowest diameter distribution were obtained from the 8 wt% of 50:50 solution. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorescence Sensing and Selective Binding of a Novel 4,4′‐Sulfonyldianiline‐Bridged Bis(β‐cyclodextrin) for Bile Salts

A novel 4,4′‐sulfonyldianiline‐bridged bis(β‐cyclodextrin (CD)) 2 was synthesized, and its complex stability constants (K_s) for the 1 : 1 inclusion complexation with bile salts, i.e., cholate (CA), deoxycholate (DCA), glycocholate (GCA), and taurocholate (TCA) have been determined in phosphate buffer (pH 7.2) at 25° by fluorescence spectroscopy. The result indicated that 2 can act as efficient fluorescent sensor and display remarkable fluorescence enhancement upon addition of optically inert bile salts. Structures of the inclusion complexes between bile salts and 2 were elucidated by 2D‐NMR experiments, indicating that the anionic tail group and the D ring of bile salts penetrate into one CD cavity of 2 from the wide opening deeply, while the phenyl moiety of the CD linker is partially self‐included in the other CD cavity to form a host–linker–guest binding mode. As compared with native β‐CD 1 upon complexation with bile salts, bis(β‐CD) 2 enhances the binding ability and molecular selectivity. Typically, 2 gives the highest K_s value of 26200 M ^?1 for the complexation with CA, which may be ascribed to the simultaneous contributions of hydrophobic, H‐bond, and electrostatic interactions. These phenomena are discussed from the viewpoints of multiple recognition and induce‐fit interactions between host and guest.     

Synthesis,spectral and antibacterial activity of Co(II), Ni(II) and Zn(II) complexes with 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H‐naphthalen‐1‐ylidene)‐hydrazide

A bioactive Schiff base HL i.e. 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H ‐naphthalen‐1‐ylidene)‐hydrazide was synthesized by reacting equimolar amount of salicylic acid hydrazide and 1‐tetralone. Co(II), Ni(II) and Zn(II) complexes of ligand HL was synthesized in 1:1 and 1:2 molar ratio of metal to ligand. The structure of the synthesized ligand and metal complexes was established by elemental analysis, molar conductance, magnetic susceptibility measurements, electronic, IR and EPR spectral techniques. For determining the thermal stability the TGA has been done. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6–31 + g(d,p) basis set. Spectral data reveal that ligand behave uninegative tridentate in ML complexes and uninegative bidentate in ML₂ complexes. On the basis of characterization octahedral geometry has been assigned for Co(II) and Ni(II) complexes, while tetrahedral for Zn(II) complexes. Antibacterial activity of the synthesized compounds were evaluated against Staphylococcus aureus , Bacillus subtilis, Escherichia coli , Xanthomonas campestris and Pseudomonas aeruginosa and the results revealed that metal complexes show enhanced activity in comparison to free ligand.     

Synthesis and Self‐Organization of Zinc β‐(Dialkoxyphosphoryl)porphyrins in the Solid State and in Solution

The first synthesis and self‐organization of zinc β‐phosphorylporphyrins in the solid state and in solution are reported. β‐Dialkoxyphosphoryl‐5,10,15,20‐tetraphenylporphyrins and their Zn^II complexes have been synthesized in good yields by using Pd‐ and Cu‐mediated carbon–phosphorous bond‐forming reactions. The Cu‐mediated reaction allowed to prepare the mono‐β‐(dialkoxyphosphoryl)porphyrins 1 Zn – 3 Zn starting from the β‐bromo‐substituted zinc porphyrinate ZnTPPBr (TPP=tetraphenylporphyrin) and dialkyl phosphites HP(O)(OR)₂ (R=Et, iPr, nBu). The derivatives 1 Zn – 3 Zn were obtained in good yields by using one to three equivalents of CuI. When the reaction was carried out in the presence of catalytic amounts of palladium complexes in toluene, the desired zinc derivative 1 Zn was obtained in up to 72 % yield. The use of a Pd‐catalyzed C? P bond‐forming reaction was further extended to the synthesis of β‐poly(dialkoxyphosphoryl)porphyrins. An unprecedented one‐pot sequence involving consecutive reduction and phosphorylation of H₂TPPBr₄ led to the formation of a mixture of the 2,12‐ and 2,13‐bis(dialkoxy)phosphorylporphyrins 5 H₂ and 6 H₂ in 81 % total yield. According to the X‐ray diffraction studies, 1 Zn and 3 Zn are partially overlapped cofacial dimers formed through the coordination of two Zn centers by two phosphoryl groups belonging to the adjacent molecules. The equilibrium between the monomeric and the dimeric species exists in solutions of 1 Zn and 3 Zn in weakly polar solvents according to spectroscopic data (UV/Vis absorption and NMR spectroscopy). The ratio of each form is dependent on the concentration, temperature, and traces of water or methanol. These features demonstrated that zinc β‐phosphorylporphyrins can be regarded as new model compounds for the weakly coupled chlorophyll pair in the photosynthesis process.     

Investigation of Mixed Chiral Selectors of Different Metal Ion-L-Alanine Complex and β-Cyclodextrin on the Chiral Separation of Dansyl Amino Acids with Capillary Electrophoresis

Chiral separation of dausyl amino acids by capillary electrophoresis using mixed selectors of Mn(ll)-L-alanine complex and β-cyclodextrin (β-CD) was studied. Resolution was considerably superior to that obtained by using either Mn (Ⅱ)-L-alanine complex or β-CD alone. The effects of separation parameters, such as pH value of buffer solution, capillary temperature, the concentration of Mn (Ⅱ)-L-alanine complex, the types of CD and ligand on the migration times and resolutions were investigated. Six different transition metal complexes,Cu(Ⅱ), Zn(Ⅱ), Co(Ⅱ), Ni(Ⅱ), Hg(Ⅱ) and Cd(Ⅱ)-L-alanine complexes have been employed and compared with Mn(Ⅱ)complex. Differences in retention and selectivity were found.The substitution of Cu(Ⅱ), Zn(Ⅱ), Co(Ⅱ) and Ni(Ⅱ) for Mn(Ⅱ) resulted in a better chiral resolution while Hg(Ⅱ) and Cd(Ⅱ) showed poorer resolution abilities. The chiral separation mechanism was also discussed briefly.     

Layer‐by‐layer Assembled Multilayers of Graphene/Mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin for Detection of Dopamine

Graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin multilayer films composed of graphene sheet (GS) and mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH₂‐β‐CD) were fabricated easily by two steps. First, negatively charged graphene oxide (GO) and positively charged mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (NH₂‐β‐CD) were layer‐by‐layer (LBL) self‐assembled on glassy carbon electrode (GCE) modified with a layer of poly(diallyldimethylammonium chloride) (PDDA). Then graphene/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GS/NH₂‐β‐CD) multilayer films were built up by electrochemical reduction of graphene oxide/mono‐(6‐amino‐6‐deoxy)‐β‐cyclodextrin (GO/NH₂‐β‐CD). Combining the high surface area of GS and the active recognition sites on β‐cyclodextrin (β‐CD), the GS/NH₂‐β‐CD multilayer films show excellent electrochemical sensing performance for the detection of DA with an extraordinary broad linear range from 2.53 to 980.05 µmol·L^?1. This study offers a simple route to the controllable formation of graphene‐based electrochemical sensor for the detection of DA.     

Novel 13,14‐dimethyl‐5,8‐dioxa‐2,11,13,14‐tetraaza‐1,12‐diphosphabicyclo [10.1.1] tetradecane 1,12‐dioxide ligand and its Ni(II), Co(II), and Cu(II) complexes: Synthesis,characterization, antimicrobial,DNA cleavage,and computational studies

A novel diazadiphosphetidine ligand derived from the reaction of 2,4‐dichloro‐1,3‐dimethyl‐1,3,2,4‐diazadiphosphetidine‐2,4‐dioxide and 2,2′‐(ethane‐1,2‐diylbis[oxy])bis(ethan‐1‐amine) and its Ni(II), Cu(II), and Co(II) complexes have been synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility, and conductivity methods, and screened for antimicrobial, DNA binding, and cleavage properties. Spectroscopic analysis and elemental analyses indicate the formula [M(H₂L)Cl₂] for the Cu(II), Co(II), Ni(II), and Zn(II) complexes and octahedral geometry for all the complexes. The non‐electrolytic nature of the complexes in dimethyl sulfoxide (DMSO) was confirmed by their molar conductance values, which are in the range 12.32–6.73 Ω^?1 cm² mol^?1. Computational studies have been carried out at the density functional theory (DFT)‐B3LYP/6‐31G(d) level of theory on the structural and spectroscopic properties of diazadiphosphetidine H₂L and its binuclear Cu(II), Co(II), Ni(II), and Zn(II) complexes. Six tautomers and geometrical isomers of the diazadiphosphetidine ligand were confirmed using semiempirical AM1 and DFT method from DMOL³ calculations. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA by agarose gel electrophoresis in the presence and absence of an oxidant (H₂O₂) and a free‐radical scavenger (DMSO), indicated no activity for the ligand and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H₂O₂.     

Tetrakis(diethyl‐phosphonat)‐, Tetrakis(ethyl‐phenylphosphinat)‐ und Tetrakis(diphenylphosphin‐oxid)‐substituierte Phthalocyanine

Tetrakis(diethyl phosphonate), Tetrakis(ethyl phenylphosphinate)‐, and Tetrakis(diphenylphosphine oxide)‐Substituted Phthalocyanines The title compounds 7, 9 , and 11 are obtained by tetramerization of diethyl (3,4‐dicyanophenyl)phosphonate ( 5 ), ethyl (3,4‐dicyanophenyl)phenylphosphinate ( 8 ), and 4‐(diphenylphosphinyl)benzene‐1,2‐dicarbonitrile ( 10 ). The ³¹P‐NMR spectra of the phthalocyanines 7, 9 , and 11 and of their metal complexes present five to eight signals confirming the formation of four constitutional isomers with the expected C_4h, D_2h, C_2v, and C_s symmetry. In the FAB‐MS of the Zn, Cu, and Ni complexes of 7 and 9 , the peaks of dimeric phthalocyanines are observed. By gel‐permeation chromatography, the monomeric complex [Ni( 7 )] and a dimer [Ni( 7 )]₂ can be separated. These dimers differ from the known phthalocyanine dimers, i.e., possibly the P(O)(OEt)₂ and P(O)(Ph)(OEt) substituents in 7 and 9 are involved in complexation. The free phosphonic acid complex [Zn( 12 )] and [Cu( 12 )] are H₂O‐soluble. In the FAB‐MS of [Zn( 12 )], only the peaks of the dimer are present; the ESI‐MS confirms the existence of the dimer and the metal‐free dimer. In the UV/VIS spectrum of [Zn( 12 )], the hypsochromic shift characteristic for the known type of dimers from 660–700 nm to 620–640 nm is observed. As in the FAB‐MS of [Zn( 12 )], the free phosphinic acid complex [Zn( 13 )] shows only the monomer, an ESI‐MS cannot be obtained for solubility problems. The UV/VIS spectrum of [Zn( 13 )] demonstrates the existence of the monomer as well as of the dimer.     

Synthesis,spectroscopic properties,density functional theory calculations and nonlinear optical properties of novel complexes of 5‐hydroxy‐4,7‐dimethyl‐6‐(phenylazo)coumarin with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions

5‐Hydroxy‐4,7‐dimethyl‐6‐(phenylazo)coumarin (L) has been synthesized and its novel complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions have also been prepared and identified using various analytical tools. The complexes are octahedral binding via one/two oxygen, nitrogen atoms for 1:1 and 1:2 complexes and two/three coordinated water molecules. All the prepared solid complexes behave as neutral in dimethylformamide. The optimized structures of the studied complexes were theoretically investigated at the B3LYP/6‐311G** level. Molecular stability and bond strengths were investigated by applying natural bond orbital analysis. The geometries of the studied complexes are non‐planar as indicated from the values of dihedral angles. The global properties of hardness, global softness and electronegativity were computed. The calculated small energy gap between highest occupied and lowest unoccupied molecular orbital energies shows that charge transfer occurs within the complexes. The obtained total static dipole moment, mean polarizability, anisotropy of polarizability and mean first‐order hyperpolarizability (<β>) were compared with those of urea as a reference material. The results for <β> showed that the complexes are excellent candidates as nonlinear optical materials. The three‐dimensional plots of the molecular electrostatic potential for some selected complexes were investigated.     

Synthesis of Polypyrrole Microtubes with Actinomorphic Morphology in the Presence of a β‐Cyclodextrin Derivative‐Methyl Orange Inclusion Complex

Summary: Polypyrrole (PPy) microtubes with an actinomorphic morphology are synthesized by a chemical method in the presence of an inclusion complex (IC) of mono [6‐deoxy‐6‐(2‐butenedinitrile‐2,3‐dimercapto sodium salt)]‐β‐cyclodextrin (6‐mnt‐β‐CD) with methyl orange (MO) as a dopant in aqueous solution. The morphologies of the obtained PPy were studied using transmission electron microscopy (TEM). It was found that the IC of 6‐mnt‐β‐CD with MO significantly affects the morphology of the resulting PPy.

The morphology of polypyrrole synthesized in the presence of 6‐mnt‐β‐CD/MO, determined by TEM.     

Ultrasensitive and Signal‐on Electrochemiluminescence Aptasensor Using the Multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin Complexes

An ultrasensitive and signal‐on electrochemiluminescence (ECL) aptasensor to detect target protein (thrombin or lysozyme) was developed using the host‐guest recognition between a metallocyclodextrin complex and single‐stranded DNA (ss‐DNA). The aptasensor uses both the photoactive properties of the metallocyclodextrins named multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin complexes and their specific recognition with ss‐DNA, which amplified the ECL signal without luminophore labeling. After investigating the ECL performance of different multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin (multi‐Ru‐β‐CD) complexes, tris‐tris(bipyridine)‐ruthenium(II)‐β‐cyclodextrin (tris(bpyRu)‐β‐CD) was selected as a suitable host molecule to construct an atasensor. First, double‐stranded DNA (ds‐DNA) formed by hybridization of the aptamer and its target DNA was attached to a glassy carbon electrode via coupling interaction, which showed low ECL intensity with 2‐(dibutylamino) ethanol (DBAE) as coreactant, because of the weak recognition between ds‐DNA and tris(bpyRu)‐β‐CD. Upon addition of the corresponding protein, the ECL intensity increased when target ss‐DNA was released because of the higher stability of the aptamer‐protein complex than the aptamer‐DNA one. A linear relationship was observed in the range of 0.01 pmol/L to 100 pmol/L between ECL intensity and the logarithm of thrombin concentrations with a limited detection of 8.5 fmol/L (S/N=3). Meanwhile, the measured concentration of lysozyme was from 0.05 pmol/L to 500 pmol/L and the detection limit was 33 fmol/L (S/N=3). The investigations of proteins in human serum samples were also performed to demonstrate the validity of detection in real clinical samples. The simplicity, high sensitivity and specificity of this aptasensor show great promise for practical applications in protein monitoring and disease diagnosis.     

β‐Cyclodextrin‐Functionalized Gold Nanoparticles/Poly(L‐cysteine) Modified Glassy Carbon Electrode for Sensitive Determination of Metronidazole

A simple electrochemical method was developed to determine metronidazole based on β‐cyclodextrin‐functionalized gold nanoparticles/poly(L ‐cysteine) modified glassy carbon electrode (β‐CD‐GNPs/poly(L ‐cys)/GCE). The electropolymerized film of poly(L ‐cys) provides a stable matrix for the fabrication of a sensing interface. β‐CD‐GNPs can form inclusion complexes with metronidazole and act as a modifier with catalytic function. The modified electrode exhibited excellent electrocatalytic activity towards metronidazole. The reaction of metronidazole at the modified electrode was an irreversible process controlled by diffusion. Under optimum experimental conditions, the logarithm of catalytic currents shows a good linear relationship with that of the metronidazole concentration in the range of 0.1–600 µmol/L with a low detection limit of 14 nmol/L. In addition, the modified electrode exhibited satisfactory stability, sensitivity and reproducibility, and could be applied to the determination of metronidazole in an injection solution.     

Synthesis,characterization, anti‐inflammatory and analgesic activity of transition metal complexes of 3‐[1‐(2‐hydroxyphenyl) ethylideamino]‐2‐phenyl‐3,4‐dihydroquinazolin‐4(3H)‐one

A new quinazolinone derivative, 3‐[1‐(2‐hydroxyphenyl)ethylideamino]‐2‐phenyl‐3,4‐dihydroquinazolin‐4(3H)‐one ( LH ) was synthesized by the condensation of 2‐hydroxyacetophenone‐2‐aminobenzoylhydrazone and benzaldehyde. The cyclization to form 1,2‐dihydroquinazolinone was confirmed by IR, 1D and 2D HETCOR studies. Coordination compounds of Co(II), Ni(II), Cu(II) and Zn(II) of LH were synthesized and characterized using various physico‐chemical studies like stoichiometric, conductivity, magnetic moment measurements and spectral techniques such as IR, NMR, UV‐vis and EPR spectroscopy. The elemental analysis and thermal studies suggested a general stoichiometry [M(HEPDQ)Cl] for all the complexes. A four‐coordinate geometry was assigned to all the complexes. The complexes along with the parent ligand were screened for their anti‐inflammatory activity, using carrageenan‐induced rat paw edema, and for their analgesic activity by Eddy's hot plate method. The activity of the ligand was enhanced on complexation with metal ions. This enhanced activity was attributed to the increased lipophilic nature of the complexes. Notable anti‐inflammatory activity was observed for Ni(II), Cu(II) and Zn(II) complexes. The analgesic activity of the ligand was greater than the standard at 60 min. and at a 10 mg kg⁻¹ dose, whereas the activity of Ni(II) and Cu(II) complexes at 10 mg kg⁻¹ dose was comparable with the standard used. Copyright © 2011 John Wiley & Sons, Ltd.     

Some divalent metal(II) complexes of novel potentially tetradentate Schiff base N,N′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde: Synthesis,spectroscopic characterization and bioactivities

A novel tetradentate dianionic Schiff base ligand, N ,N ′‐bis(2‐carboxyphenylimine)‐2,5‐thiophenedicarboxaldhyde (H₂L) and some first row d‐transition metal chelates (Co(II), Cu(II), Ni(II) and Zn(II)) were synthesized and characterized using various physicochemical and spectroscopic methods. The spectroscopic data suggested that the parent Schiff base ligand coordinates through both deprotonated carboxylic oxygen and imine nitrogen atoms. The free Schiff base and its metal chelates were screened for their antimicrobial activities for various pathogenic bacteria and fungi using the agar well diffusion method. The antibacterial and antifungal activities of all the newly synthesized compounds are significant compared to the standard drugs ciprofloxacin and nystatin. The antioxidant activities of the compounds were determined by reduction of 1,1‐diphenyl‐2‐picrylhydrazyl and compared with that of vitamin C as a standard. DNA binding ability of the novel Schiff base and its complexes was investigated using absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and thermal denaturation. The obtained results clearly demonstrate that the binding affinity with calf thymus DNA follows the order: Cu(II) complex > Ni(II) complex > Zn(II) complex > Co(II) complex >H₂L. Furthermore, the DNA cleavage activity of the newly synthesized ligand and its metal complexes was investigated using supercoiled plasmid DNA (pUC18) gel electrophoresis.     

β-环糊精与有机胺之间包合作用的理论与实验研究

通过实验和理论计算方法研究了β-环糊精(CD)与乙二胺1及它的三个类似物: 二乙烯三胺2、三乙胺3和乙二胺四乙酸4之间的包合作用. 利用旋光法确定了β-CD与客体分子形成1:1型主–客体包合物, 在298.2 K下测定了包合物在水中的稳定常数(K). 采用半经验PM3方法考察了β-CD与短链脂肪胺1~7、环状脂肪胺8~11以及芳香胺12~13的分子间结合能力, 报道了β-CD与这些客体分子间的包合络合过程并讨论了这些包合体系之间的包合差异性. 变形能和水合能对包合体系的相互作用能的贡献均相当小. β-CD包合物的稳定性取决于主、客体分子之间的尺寸匹配. 对于β-CD与客体1~4形成的包合物而言, 旋光法测定的包合物的K值的顺序与PM3计算得到的包合物络合能绝对值的排序有很好的一致性.     

Cyclodextrins in Polymer Modification: Diels–Alder Addition of Cyclopentadiene/Methylated‐β‐Cyclodextrin Complex on Unsaturated Polyester and Formation of a New Type of Polypseudorotaxane

Summary: Cyclopentadiene ( 1 ) was incorporated as a guest into the cavity of randomly methylated‐β‐cyclodextrin (me‐β‐CD) as a host, yielding the stable, water compatible cyclopentadiene/me‐β‐CD complex ( 1a ). We successfully attempted to use the synthesised complex in a Diels–Alder addition with a water‐soluble unsaturated polyester ( 2 ) derived from poly(ethylene glycol) and maleic anhydride. The reaction yielded a new type of polypseudorotaxane ( 3 ). Examination of the polypseudorotaxane ( 3 ) and a model inclusion complex of the starting unsaturated polyester with me‐β‐CD ( 2a ) showed that cyclodextrins are threaded onto the main chain in both cases. The cyclohexene moiety formed after the Diels–Alder addition does not act as a stopper, a dethreading process being evidenced and discussed.

The polypseudorotaxane synthesized here.     

Transition Metal Complexes of N‐(4,6‐Dimethoxypyrimidin‐2‐Ylcarbamothioyl)Benzamide: Design,Synthesis and Herbicidal Activity

Transition metal (Cu(II), Zn(II), Co(II)) complexes of N‐(4,6‐dimethoxypyrimidin‐2‐ylcarbamothioyl)benzamide were prepared. The structures of all the newly synthesized complexes were identified by elemental analyses, IR, ¹H NMR, XPS, MS and TG. Their herbicidal activities were evaluated against a variety of weeds. The preliminary results showed that the target complexes had moderate biological activities against both broad leaf weeds and monocotyledon plants. More importantly, the complexes exhibited some improved herbicidal activities over their non‐complexed counterparts. The present work provides a novel class of transition metal‐based derivatives with potent herbicidal activities for further optimization.