LOW MOLECULAR WEIGHT O-CARBOXYMETHYLATED CHITOSANS DERIVED FROM IRRADIATED CHITOSAN AND THEIR ANTIBACTERIAL ACTIVITY

INTRODUCTIONChitin is the second most naturally abundant biopolymer and is found in a variety of organisms, including fungalcell walls, the exoskeleton of crustaceans, skeletal tissue of mollusks and the integument of insects.When treated with alkali, chitin can be deactylated and turned into chitosan, which is a linear binaryheteropolysaccharide composed of (1-4) linked 2-acetamido-2-deoxy-β-D-glucopyranose and 2-amino-2-deoxy-β-D-glucopyranose residues. Chitosan has a wide variety of …     

An Improved Synthesis of Tn Antigen

Tn (GalNAc(1?O-Ser/Thr) 6 is a human tumor-associated carbohydrate antigen1. Protein conjugates of Tn antigen have a role for the active specific immunotherapy of cancer. The total synthesis of Tn antigen has been reported2 by glycosidating between 3,4,6-tri-O-acetyl-2-azido-2-deoxy-(-D-galactopyranosyl chloride and L-serine derivative, then removing the protecting groups. In this route, the key intermediate 3,4,6-tri-O-acetyl-2-azido-2-deoxy-(-D-galactopyranosyl chloride was afforded by …     

Synthesis ofα-D-GlcpNAc-（1→2）-[α-D-ManpNAc-（1→3）-]α-L-Rhap-（1→2）-α-L-Rhap-（1→3）-α-L-Rhap,the repeating unit of O10 antigen from Acinetobacter baumannii

An efficient synthesis ofα-D-GlcpNAc-（1→2）-[α-D-ManpNAc-（1→3）-]α-L-Rhap-（1→2）-α-L-Rhap-（1→3）-α-L-Rhap（1）, the repeating unit of the O10 antigen from Acinetobacter baumannii was achieved via sequential assembly of the building blocks,p- methoxylphenyl 2,4-di-O-benzoyl-α-L-rhamnopyranoside（2）;2-O-allyloxycarbonyl-3,4-di-O-bcnzoyl-α-L-rhamnopyranosyl tri- chloroacetimidate（3）;4-methoxylphenyl 3-O-allyloxycarbonyl-4-O-benzoyl-α-L-rhanmopyranoside（4）;2-azido-3-O-benzoyl-2- deoxy-4,6-O-isopropylidene-α-D-mannopyranosyl trichloroacetirnidatc（5）;2-azido-3,4,6-tri-O-benzoyl-2-deoxy-α,β-D-glucopyr- ano syl trichloroacetimidatc（6）.The total yield of 1 from 4 was 4.7%.     

2－脱氧－烟酰胺基－β－D－氨基葡萄糖的合成和表征

A new nicotinic acid derivative,2-deoxy-2-nicotinoylamido-β-D-glucopyranose, was synthesized with β-configuration exclusively. The structure and properties of the product were characterized by ^1H NMR, PT-IR, MS, DSC and polarimeter. The details of ^1H NMR spectrum and the mass spectrum proved that there are a great amount of hydrogen bonds in the product.     

Synthesis of A Novel Fulleroaziridine Carrying 4-Deoxy-4＇-demethylepipodophyllotoxin

A novel fulleroaziridine 2 with a closed 6,6-ring junction was synthesized from [60]fullerene and 4-azido-4-deoxy- 4‘-demethylepipodophyllotoxin 1 in 1, 2-dichlorobenzene at 110℃ for 45 h, in a yield of 39.3 % based on consumed C60. The structure of the product was characterized by NMR and MS.     

Synthesis,Crystal Structure and DNA-binding Properties of a New Copper（Ⅱ） Schiff Base Complex

A new asymmetric bidentate copper(Ⅱ) complex,CuL 2(HL=2-((E)-(4-bromophenylimino)methyl)-6-bromo-4-chlorophenol),has been synthesized and characterized by elemental analyses and single-crystal X-ray diffraction.The complex crystallizes in the monoclinic space group P2 1 /c with a=11.218(3),b=9.355(3),c=13.449(4),β=108.722(4)°,V=1336.8(6)3,Z=2,Dc=2.008 g/cm 3,μ(MoKα)=7.024 mm-1,F(000)=806,S=0.999,the final R=0.0342 and wR=0.0641for2611observed reflections (I>2σ(I)).The central copper(Ⅱ) is four-coordinate and bonds to two nitrogen and two oxygen atoms from two Schiff base ligands.The complex is linked into a two-dimensional supramolecular structure by weak intermolecular interactions.In addition,DNA-binding properties of the metal complex were investigated using spectrometric titrations and viscosity measurements.The results show that the complex binds with calf-thymus DNA(CT-DNA),presumably via a partial intercalative mode.The intrinsic binding constant of the Cu(Ⅱ) complex with DNA is 7.335×10 3 M-1.     

Comparative studies on molecular induced aggregation of hepta-imidazoliumyl-β-cyclodextrin towards anionic surfactants

A β-cyclodextrin derivative bearing seven cationic arms and its singly charged analogue, i.e., per-6-deoxy-6-(1-methylimidazol-3-ium-3-yl)-β-cyclodextrin(3) and mono-6-deoxy-6-(1-methylimidazol-3-ium-3-yl)-β-cyclodextrin(4) were synthesized and fully characterized. Their induced aggregation behaviours towards two anionic surfactant, that is, sodium dodecyl sulfonate(SDS) and dioctyl sodium sulfosuccinate(Aerosol OT, AOT), were investigated by UV–vis, NMR, Zeta-potential, dynamic light scattering(DLS), and transmission electron microscopy. The results revealed that host 3 can induce the molecular aggregation of anionic surfactant at concentration far lower than its original CAC, leading to the larger diameter, the narrower size distribution and the higher thermal stability of the induced aggregate towards the anionic surfactant possessing more hydrophobic tails.     

PHYTOECDYSONES FROM THE ROOTS OF TINOSPORA CAPILLIPES

In addition to 2-deoxycrustecdysone(1),we isolated and identi-fied two new natural moulting hormones-2-deoxy-3-epicrustecdysone(2)and2-deoxycrustecdysone-3-O-β-D-glucopyranoside(3)from the roots of Tino-spora capillipes,it is the first time to get ecdysteroids from this genus.     

Insight into the formation mechanism of levoglucosenone in phosphoric acid-catalyzed fast pyrolysis of cellulose

The catalytic fast pyrolysis of cellulose impregnated with phosphoric acid (H_3PO_4) offers a promising method for the selective production of levoglucosenone (LGO),a valuable anhydrosugar product.However,the fundamental mechanism for selective LGO formation is unclear.Herein,quantum chemistry calculations and catalytic fast pyrolysis experiments were performed to reveal the formation mechanism of LGO in H3_PO_4-catalyzed cellulose pyrolysis.H_3PO_4 significantly decreased the energy barriers of the pyrolytic reactions and altered the competitiveness of the LGO formation pathways,promoting LGO formation.Through different pathways in the non-catalytic and H3P04-catalyzed conditions,LGO is mainly produced from the primary decomposition of glucose units of cellulose and secondary conversion of levoglucosan.The major catalytic formation pathways of LGO comprise similar reactions,with dehydration at the 3-OH+2-H site as the rate-determining step.Importantly,secondary conversion of 1,4;3,6-dianhydro-α-D-glucopyranose is not feasible for LGO formation,in contrast to previous reports.In addition,a high degree of polymerization is beneficial for the selectivity of LGO formation in the catalytic process,because the glycosidic bond is important for the formation of the bicyclic structure (1,5-and1,6-acetal rings).     

Study on disulfur-backboned nucleic acids:Part Ⅳ.Efficient synthesis of 3',5'-dithio-2'-deoxyguanosine

<正>An efficient and novel method for synthesizing 3′,5′-dithio-2′-deoxyguanosine was described.In this method normal guanosine was used as the starting material.A very efficient procedure was used to synthesize 2-O-tosylguanosine 1,which used 0.1 eq.DBTO instead of 2 eq.1 was treated with LTBH to give 9-(2-deoxy-β-D-threo-pentofuranosyl)guanine 2.2 could be easily turned to the target compound.     

Syntheses and Crystal Structures of Two Two-dimensional Coordination Polymers with 2,3-Dimethylpyrazine-1,4-dioxide and Thiocyanate as Mixed Bridge Ligands

Two two-dimensional coordination polymers,[Cd(μ1,3-SCN-)2(μ1,6-L)]n 1 and [Co(μ1,3-SCN-)2(μ1,6-L)]n 2,have been synthesized with 2,3-dimethylpyrazine-1,4-dioxide (L) and thiocyanate as mixed bridging ligands,and their crystal structures were determined by X-ray crystallography.Both crystals belong to monoclinic system,space group C2/c.The other crystal parameters are as follows:for complex 1:a = 9.732(3),b = 14.658(5),c = 8.811(3) (A),β =102.935(4)°,Z = 4,V = 1225.1(7)(A)3,CsHsCdN4O2S2,Mr = 368.71,Dc.-- 1.999 g/cm3,F(000) =720 andμ = 2.117 mm-1;for complex 2:a = 9.528(7),b = 14.563(11),c = 8.415(6) (A),β =102.195(9)°,V= 1141.3(14) (A)3,Z = 4,C8H8CoN4O2S2,Mr = 315.23,Dc = 1.835 g/cm3,F(000) =636 andμ = 1.863 mm-1.The two complexes show similar two-dimensional sheet structures.Along the c axis one-dimensional chains are constructed by the coordination of Cd(Ⅱ) (or Co(Ⅱ))ions with μ1,6-L bridging ligand,and the μ1,3-SCN- bridging ligands make the chains connect to each other,resulting in the formation of a two-dimensional sheet on the ac plane.     

A new polyhydroxysteroidal glycoside from the starfish Anthenea chinensis

A new polyhydroxysteroidal glycoside,(20R,24R)-16-O-(4-O-methyl-2-acetamido-2-deoxy-β-D-galactopyranosyl)-24-ethyl- 5α-cholest-8(14)-en-3β,6β,7β,16α-tetrol(anthenoside A,1),was isolated from the starfish Anthenea chinensis.Its structure was elucidated by extensive spectral analysis and chemical evidences.1 exhibited significant cytotoxicity against human tumor K-562, BEL-7402 and U87MG cells.     

Synthesis of di-and tetrasaccharide containing 6-deoxytalose from the O-antigenic polysaccharide of B. pseudomallei strain 304b

Synthesis of the disaccharide β-D-Glup-(1→3)-6-deoxy-α-L-Talp Ⅱ,and its dimer Ⅲ from the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b,were achieved through assembly of suitably synthesized building blocks,4-methoxylphenyl 6-deoxy-2,4-di-O-benzoyl-α-L-talopyranoside (7),3-O-allyl-2,4,6-tri-O-benzoyl-α,β-D-glucopyranosyl trichloroacetimidate (8) and 2,3,4,6-tetra-O-benzoyi-α,β-D-glucopyranosyl trichloroacetimidate (Ⅱ).The total yield of Ⅲ from 4-methoxyiphenyl 2,3-O-isopropylidene-α-L-rhamnopyranoside (1) was 18%.     

Synthesis,Structure and Properties of a New Terbium(Ⅲ) Complex Tb_2(C_(15)H_(11)O_3)_6(phen)_2

A new terbium(Ⅲ) complex Tb_2(C_(15)H_(11)O_3)_6(phen)_2 has been synthesized with 2-(4-methylbenzoyl)benzoic acid and 1,10-phenanthroline as ligands.Crystal data for the complex are as follows:monoclinic,space group P2_1/n,a=15.0786(6),b=13.5762(5),c=22.9683(9) A,β=104.130(4)°,V=4559.6(3) A~3,D_c=1.540_g/cm~3,Z=2,μ(MoKα)=1.615 mm~(-1),F(000)=2136,the final R=0.0528 and wR=0.0740.The Tb(Ⅲ) ion is coordinated by eight atoms to give a distorted square antiprism coordination geometry.The complex shows four fluorescence emission bands arising from the transitions of Tb~(3+5)D_4→~7F_6(490 nm),~5D_4→~7F_5(546 nm),~5D_4→~7F_4(588 nm) and ~5D_4→~7F_3(622 nm).The complex is an antiferromagnet in the range of 300～2 K.Also reported in the paper is the thermal stability property of the title complex.     

Two Carboxylato-bridged Binuclear Cobalt(Ⅱ) Complexes Pillared Coligands: Synthesis,Structures and Magnetic Properties

By adopting mixed-ligand strategy, two Co(Ⅱ) coordination polymers, [Co(phda)(itmb)(H_2O)_2]_n(1) and [Co(phda)(Hpytz)]_n(2)(H_2phda = 1,2-phenylenediacetate, itmb = 1-(imidazo-1-ly)-4-(1,2,4-triazol-1-yl methyl) benzene and Hpytz = 3,5-di(4-pyridyl)-1,2,4-triazolate), were hydrothermally synthesized and then characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis(TGA), powder X-ray diffraction(PXRD) and single-crystal X-ray diffraction. The single-crystal X-ray diffraction reveals that two complexes feature carboxylato-bridged binuclear subunits extended further by the nitrogen-rich coligands to form different structures. Complex 1 containing phda-bridged binuclear cobalt is developed by itmb coligand to 1D double-stranded chain, whereas complex 2 exhibits 2D open bilayers, which result from the ribbon-like carboxylate chains pillared Hpytz coligands. In addition, the magnetic susceptibilities of both compounds were measured over the temperature range of 3～300 K, and the data were analyzed well using Mag Saki software. The best fitting parameters were κ = 0.98, λ =-100 cm~(-1), ? = 588 cm~(-1) and J = 0.6 cm~(-1) for complex 1 and κ = 0.86, λ =-110 cm~(-1), ? = 756.8 cm~(-1) and J =-1.25 cm~(-1) for complex 2. The results indicate the existence of weaker ferromagnetic interaction for complex 1 and antiferromagnetic interaction for complex 2 between the metal centers in the dinuclear metal units.     

Synthesis and Fluorescent and Magnetic Properties of a New Europium Complex Eu(C_(20)H_(14)O_3N)_3(2,2'-bipy)(H_2O)·H_2O

A new europium(Ⅲ) complex Eu(C_(20)H_(14)O_3N)_3(2,2?-bipy)(H_2O)·H_2O has been synthesized with2-diphenylanine carbonyl benzoic acid and 2,2?-bipyridine as ligands.Crystal data for the complex are as follows:triclinic,space group ■,a=11.3334(5),b=16.0883(7),c=17.0116(8)?,α=70.411(4)o,β=82.435(4)o,γ=85.095(4)o,V=2894.0(2)?~3,D_c=1.484 g/cm~3,Z=2,μ=1.15 mm~(-1),F(000)=1320 and the final R=0.0447 and w R=0.0578.The Eu(Ⅲ) ion is coordinated by nine atoms to give a monocapped square antiprism coordination geometry.The complex shows two intense fluorescence emission bands arising from the transitions of Eu~(3+):~5D_0→~7F_1 (592 nm) and ~5D_0→~7F_2 (616 nm),respectively.Also reported is the magnetic property of the complex.The complex exhibits antiferromagnetism in the temperature range of 300～2 K.     

Synthesis,Crystal Structure and Luminescent Properties of a Mn（Ⅱ） Complex Constructed from 2,2＇-Bibenzimidazole

A new complex associated with Mn ion,[Mn(Hbibm)(SO4)]·0.5H2O(1,Hbibm= 2,2'-bibenzimidazole),was prepared under solvothermal conditions,and characterized by single-crystal X-ray diffraction,elemental analysis and IR spectra.The complex belongs to the triclinic system,space group P1 with a=8.9250(5),b=12.8022(8),c=13.3505(8),α=66.614(2),β= 72.567(2),γ=80.627(2)°,V=1334.1(1)3,Z=1,Dc=1.565 g/cm3,S=0.996,μ=0.628 mm-1,F(000)=644,R=0.0447 and wR=0.0586 for 5155 observed reflections(Ⅰ > 2σ(Ⅰ)).Complex 1 is a mononuclear Mn(II) complex.The π-π interactions and interchain hydrogen-bonding interactions further extend the mononuclear for 1,generating a 3D supramolecular architecture.Complex 1 shows strong blue fluorescent emissions in the solid state upon 395 nm photo-excitation at room temperature.     

Synthesis and Crystal Structure of 2,4-Diiodo-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol-copper(Ⅱ)

2,4-Diiodo-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol-copper(Ⅱ) has been designed and synthesized.The structure was determined by UV,IR and single-crystal X-ray study.The title complex crystallizes in the triclinic system,space group P1 with a=6.6090(13),b=10.377(2),c=12.550(3),α=113.29(3),β=93.84(3),γ=98.31(3)°,V=774.9(3)3,Dc=2.215g/cm3,C26H30CuO4N4I4,Mr=1033.68,F(000)=487,μ=4.726 mm-1,Z=1,the final R=0.0563 and wR=0.1475 for 2101 observed reflections(I2σ(I)).The central copper(Ⅱ) is four-coordinated by two nitrogen atoms and two oxygen atoms from two 3,5-diiodosalicylaldehyde-2-morpholinoethylamine Schiff bases.The complex is linked into a column by π-π stacking interaction.The complex was assayed for antibacterial activities against three Gram positive bacterial strains(B.subtilis,S.aureus and S.faecalis) and three Gram negative bacterial strains(E.coli,P.aeruginosa and E.cloacae) by MTT method.Fortunately,the title complex shows potent antibacterial activity against these six bacterial strains.     

Synthesis of Substituted 3H-Indole-modified β-Cyclodextrin

Substituted 3H-indole modified β-cyclodextrin (β-CD) was prepared by the reaction of 6-deoxy-6-[(2-aminoethyl)amino]-β-CD (CDen) with 2-[(p-amino)phenyl]-3, 3-dimethyl-5-car-boxyl-3H-indole (substituted 3H-indole) in the presence of dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBt). The product has been characterized by means of elementalanalysis, MS and ^1H NMR.     

Synthesis and Crystal Structure of a Novel Binuclear Copper(Ⅱ)Complex,[Cu(paba)C1]

A novel binuclear Cu(Ⅱ)complex[Cu(paba)C1](pabaH=2-(2-pyridylmethylimine)benzenesulfonic acid)has been synthesized and characterized by elemental analysis,IR andsingle-crystal X-ray diffraction.The crystal of the title complex crystallizes in a monoclinie system,space group P21/n,with a=6.8165(7),b=15.3073(16),c=12.3795(13)(A),β=95.0160(10)°,V=1286.8(2)(A)3,Mr=360.26,Dc=1.860 g/cm3,μ=2.074 mm-1,F(000)=724,Z=4,the final R=0.0252 and wR=0.0675 for 2395 observed reflections with I＞2σ(I).The title complex is centrosymmetric and a pair of chlorides act as μ2-bridges to link two Cu(Ⅱ)ions forming a binuclear complex.Every Cu(Ⅱ)ion is five-coordinated by pyridyl N,imine N and sulfonate O atoms of the tridentate paba ligand as well as two bridging Cl-,constructing the distorted square-pyramidal geometry.In the structure extensive hydrogen bonds and weak π-π stacking stabilize the solid structures,through which the complex builds its 3-dimensional supramolecular structure.