Multimode Interference Couplers with Different Background Refractive Index *

A novel structure of MMI coupler with different background refractive index has been designed. With stronger optical confinement in multimode waveguides, more guided modes are excited to improve imaging quality. Two-dimensional finite difference beam propagation method (2-D FDBPM) was used to simulate this new structure and had proven that its imaging quality, in terms of power uniformity and excess loss, is much better than conventional structure. This structure can be applied in SOI rib waveguides by deep etching method.

IL-2基因的突变及其与肠毒素融合基因的克隆和表达

由金黄色葡萄球菌分泌到胞外的单亚基蛋白中有肠毒素A和B。近年来两种毒素在肿瘤治疗研究方面取得了很大进展。白介素-2作为靶向分子，在抗肿瘤的药物中很有应用前景。本文分别对肠毒素A、肠毒素B和白介素-2进行了克隆和表达，并将白介素-2（125Ala）分别与肠毒素A227AI。肠毒素B进行了融合表达。从筛选到的天然金黄色葡萄球菌STSw的基因组中，通过PCR方法扩增出seb基因，同时突变了该基因两端几个稀有密码子。并将其克隆到7ZTS载体上进行表达，表达量占细胞总蛋白的33.5％。以seam基因为模板，通过重叠PCR将其227位天冬氨酸突变为丙氨酸，以降低其毒性。该突变基因重组到7ZTS载体中，并在JM109（DE3）中表达，表达量占细胞总蛋白的51.5％。通过重叠PCR法，对人的IL-2基因进行定点突变。共突变60个碱基，涉及51个氨基酸，其中第125位的半肤氨酸被突变为丙氨酸。该基因在大肠杆菌中表达量占总蛋白的30％。分别对上述三个工程菌的表达条件进行了探索。先制备出融合基因，再对融合基因进行表达，得到两种融合蛋白。它们是以6个甘氨酸和1个苏氨酸为链，将IL一2（125Ala）与肠毒素A227（Ala）、B分别连接起来，即IL-2（125Ala）-SEA227（Ala）和IL-2（125Ala）-SEB二者在大肠杆菌中表达量分别占总蛋白的10％和12％。以上实验结果为将几种蛋白开发成抗肿瘤靶向药物奠定了坚实基础。

Chiral ligand 2-(2 '-piperidinyl)pyridine: synthesis, resolution and application in asymmetric diethylzinc addition to aldehydes

Chiral ligand 2-(2'-piperidinyl)pyridine 1 has been synthesized in good overall yield by sequential benzylation, hydrogenation and debenzylation of 2,2'-bipyridine. Its enantiomerically pure enantiomers have been obtained by resolution of 2-(1-benzyl-2-piperidinyl)pyridine 2 with D-tartaric acid (or L-tartaric acid) followed by debenzylation. The absolute configuration was determined by X-ray analysis of the (S)-2 D-tartrate. It was demonstrated that I can be used as an effective enantioselective catalyst in the addition of diethylzinc to aldehydes.

Supramolecular isomerism in zinc hydroxide coordination polymers with pyridine-2,4-dicarboxylic acid: Two polymorphs with centrosymmetric two-dimensional and acentric three-dimensional coordination networks

Reactions of Zn(BF4)(2) and pyridine-2,4-dicarboxylic acid (2,4-pydcH(2)) in the presence of 1,2-bis( 4-pyridyl) ethylene or 1,3-bis(4-pyridyl) propane under hydro(solvo) thermal conditions yielded two polymorphic metal-organic coordination polymers formulated as Zn-2(OH)(2)(2,4-pydc) (1 and 2). Polymorph 1 features a two-dimensional (2-D) layer-like structure that is constructed by 2,4-pydc ligands bridging between the Zn-OH-Zn double-chain units. Each single Zn-OH-Zn chain is composed of mu(2)-OH groups connecting trigonal bipyramidal and tetrahedral Zn centers. Polymorph 2 is a 3-D coordination polymer containing 2-D Zn-OH-Zn sheets that consist of mu(2)- and mu(3)-OH groups and trigonal bipyramidal Zn centers. The sheets are pillared by 2,4-pydc ligands to form an acentric structural architecture. 1 and 2 are rare examples that the two polymorphs exhibit a centrosymmetric 2-D coordination network and an acentric 3-D coordination network, respectively. The different structures lead to differences in photoluminescent properties and thermal stabilities for 1 and 2.

Synthesis, characterization and crystal structure of a new layered heterometallic coordination polymer {[(CuL) Sr-2(H2O)center dot Sr-2(H2O)(7)]center dot 2H(2)O center dot 0.5CH(3)OH}(n)

A copper-strontium heterometallic coordination polymer was synthesized and characterized by elemental analysis and IR spectra. The crystal structure was determined by single-crystal X-ray diffraction analyses. The title complex is a 2 D coordination polymer with the chemical formula [[(CuL)(2)Sr (H2O) center dot Sr-2 ((HO)-O-2)(7)]center dot 2H(2)O center dot 0.5CH(3)OH](n), where H4L = N-(2-hydroxybenzamido)-N'-(3-carboxylsalicylidene) ethylenediamine. Its structural unit is comprised of two adjacent units, which polymerized with each other to form a new layered heterometallic coordination polymer.

Novel two-dimensional sodium molybdenum phosphates containing {M(enMe)(2)}(2+) bridging groups (M = Ni, Cu; enMe=1,2-diaminopropane)

Two novel organic-inorganic hybrid compounds, (H(2)enMe)(4)(H3O)[Ni(enMe)(2)].[Na3Mo12O52P8(OH)(10)].5H(2)O (1) and (H(2)enMe)(4)(H3O)[Cu(enMe)(2)].[Na3Mo12O52P8(OH)(10)].5H(2)O (2) (enMe = 1,2-diaminopropane), have been hydrothermally synthesized and characterized by elemental analyses, IR, EPR, XPS, UV-Vis spectra and TG analyses. Single crystal X-ray diffraction shows that 1 and 2 are isostructural compounds. Both the compounds exhibit an unusual two-dimensional (2-D) window-like network consisting of one-dimensional (1-D) chains of sodium molybdenum phosphate anions connected by transition metal coordination complexes cations. Compound 1 and 2 represent the first 2-D molybdenum phosphate skeleton pillared by transition metal complex fragments.

Synthesis and crystal structure of bis (tert-butyl-cyclopentadienyl)erbium ethoxide, (t-BuCp)(2)ErOEt

The formation of ( t-BuCp)(2)ErOEt was discussed. Its single-crystal structure was determined by X-ray diffraction. The crystal is monoclinic, P2(1)/c space group, a = 1.0191(2), b = 1.6203(5), c = 1.2118(3) nm, beta = 102. 960( 10)degrees, V = 1.9500 (nm(3)), Z = 2, D-c = 1.566 mg . m(-3), R = 0.0450, R-w = 0.1363. The complex is monomeric and solvent-free in the solid state. The erbium ion is coordinated by two tert-butyl-cyclopentadienyl rings and one oxygen atom of ethoxy group to form a seven-coordinated complex.

Hydrothermal synthesis and structure of [Ni(en)(2)V6O14](n)

A new complex [Ni (en)(2)V6O14](n) was hydrothermally synthesized and characterized by 2-dimensional vanadium oxide framework pillared by Ni(en)(2)group. Single crystal X-ray analysis indicates that this compound crystallizes in monoclinic system, space group P2(1)/c with a=0. 892 17(18) nm, b = 1. 711 1(3) nm, c=0. 662 73(13) nm, beta=111. 58(3)degrees, V=0.940 8(3) nm(3), Z=2, D-c=2.501 g/cm(3), R=0. 042 3, omegaR=0. 060 9, S=1. 006.

Novel hydrogen-bonded three-dimensional networks encapsulating one-dimensional covalent chains: [M(4,4 '-bipy)(H2O)4](4-abs)2 center dot nH(2)O (4,4 '-bipy=4,4 '-Bipyridine; 4-abs=4-aminobenzenesulfonate) (M=Co, n=1; M=Mn, n=2)

Two novel compounds, [Co(4,4'-bipy)(H2O)(4)](4-abS)(2).H2O (1) and [Mn(4,4'-bipy)(H2O)(4)](4-abs)(2).2H(2)O (2) (4,4'-bipy = 4,4'-bipyridine; 4-abs = 4-aminobenzenesulfonate), have been synthesized in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses, UV-vis and IR spectra, and TG analysis. X-ray structural analysis revealed that 1 and 2 both possess unusual hydrogen-bonded three-dimensional (3-D) networks encapsulating one-dimensional (1-D) covalently bonded infinite [M(4,4'-bipy)(H2O)(4)](2+) (M = Co, Mn) chains. The 4-abs anions in 1 form 1-D zigzag chains through hydrogen bonds. These chains are further extended through crystallization water molecules into 3-D hydrogen-bonded networks with 1-D channels, in which the [Co(4,4'-bipy)(H2O)(4)](2+) linear covalently bonded chains are located. Crystal data for 1: C22H30CoN4O11S2, monoclinic P2(1), a = 11.380(2) Angstrom, b = 8.0274(16) Angstrom, c = 15.670(3) Angstrom, alpha = gamma = 90degrees, beta = 92.82(3)degrees, Z = 2. Compound 2 contains interesting two-dimensional (2-D) honeycomb-like networks formed by 4-abs anions and lattice water molecules via hydrogen bonding, which are extended through other crystallization water molecules into three dimensions with 1-D hexagonal channels. The [Mn(4,4'-bipy)(H2O)(4)](2+) linear covalent chains exist in these channels. Crystal data for 2: C22H32WN4O12S2, monoclinic P2(1)/c, a = 15.0833(14) Angstrom, b = 8.2887(4) Angstrom, c = 23.2228(15) Angstrom, alpha = gamma = 90degrees, beta = 95.186(3)degrees, Z = 4.

Hydrothermal synthesis and structural characterization of a novel P-V-O layered compound [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)8]

A new compound [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)(8)] has been hydrothermally synthesized. Single crystal X-ray analysis indicates that this compound crystallizes in a monoclinic system, space group P2(1)/n with a=1.438 5(3) nm, b=1.012 2(2) nm, c=1.832 5(4) nm, beta=90.21degrees, V=2.668 2 (9) nm(3), Z = 2, D-c = 2.112 g/cm(3), R = 0.055, wR = 0.149 7, S = 1.037. The structure of [H(2)en](2)[H3O](6)[Co(H2O)(2)(VO)(8)(OH)(4)(PO4)(8)] is characterized by P-V-O layers constructed by [(VO)4 (OH)(2)(PO4)(4)](6-) non-symmetric units. The P-V-O layers are pillared by [Co(H2O)(2)](2+) group, resulting in the channels within which the protonated diaminoethane and H3O+ are located.

Interactions of thiamine monophosphate (TMP) with one- and two-dimensional polymeric halogenomercurate anions. Crystal structures of (TMP)(Hg2Br5)center dot 0.5H(2)O and (TMP)(2)(Hg3I8)

An investigation into the interactions between thiamine monophosphate (TMP) and anions has resulted in the preparation and X-ray characterization of the compounds (TMP)(Hg2Br5).0.5H(2)O (1) and (TMP)(2)(Hg3I8) (2). In each compound the TMP molecule exists as a monovalent cation in the usual F conformation. The halogenomercurate anions occur in two-dimensional (2-D) network in 1 or one-dimensional (1-D) chain in 2. In both 1 and 2, the structures consist of alternating cationic sheets of the hydrogen-bonded TMP molecules and anionic sheets of the polymeric halogenomercurate anions. The TMP molecule binds to the polymeric anions through the characteristic 'anion bridge I', C(2)-H..X...pyrimidinium (X = Br in 1 and 1 in 2), and electrostatic interactions between electropositive S(1) and halogen atoms. The 'anion bridge II' of the type N(4'1)-H...X...thiazolium (X = phosphate group) plays a role in stabilizing the molecular conformation. The biological implication of the host-guest-like complexation between TMP and polymeric anions is discussed.

Crystal Structure of [PrAl(CF3COO)(2)(CF3CHOO)(C2H5)(2)(C4H8O)(2)](2)

[PrAl (CF3COO)(2) (CF3CHOO) (C2H5)(2) (C4H8O)(2)](2) M-r = 1420. 56, monoclinic, P2(1)/n, a = 10. 651 (6) , b = 24. 276(9), c = 11. 110(5) Angstrom, beta = 107. 650 (4)degrees , V = 2737. 4(1) Angstrom (3) , Z = 2, D-c = 3. 45 g/cm(3) , F(000) = 2816 , T = 233K, MoK alpha radiation (lambda= 0. 71069 Angstrom), mu(MoK alpha) = 38. 017 cm(-1) , R = 0. 048 for 2847 observed reflections (I greater than or equal to 3 sigma(I)). It is isostructural with [LnAl (CF3COO)(2) (CF3CHOO) -R-2 (C4H8O)(2)](2) (Ln = Ho, R = Et; Ln = Ndt Y, R = Bu-1). Pr3+ is coordinated by eight oxygen atoms from five bridging ligands and two THF forming a distorted bicap-prism.

Crystal structure and mechanism of (Z)-1-[2-(phenyl-bromide-chloride)vinyl]-1-cyclohexanol

The crystal structure and mechanism of the title molecule are described. This crystal is orthorhombic, belonging to space group PC21/B with a=1,002 1(2) nm, b=1.483 0(3) nm, c=2.173 6(4) nm, V=3.230 39(2) nm(3), Z=2, D-c=1.80 g/cm(3), R=0.069 3. The structure was solved by direct method. The tin atom of the title compound exists in two distorted-trigonal-bipyramidal geometry, defined by two carbon, one bromide, one chloride and one oxygen atoms leading to a five-membered chelate ring. In the structure, the five-membered ring containing the intermolecular O-->Sn has a half chair conformation.

Synthesis and structure of 1:1 complex of ethylphenyltin dichloride with N-4-methoxyphenyl-2-hydroxynaphthylideneimine

A novel organotin complex, EtPhSnCl(2) . 2HOC(10)H(6)CH = NC6H1OCH3 was synthesized, and its crystal structure was determined by X-ray diffraction method. The crystal is triclinic, belonging to space group, with unit cell parameters a = 1.150 8(5) nm, b = 1. 153 1(5) gm, c = 1. 004 6 (3) nm, alpha = 94. 15 (3)degrees, beta = 115.47 (3)degrees, r = 85. 94 (4)degrees, V = 1199 7(1) nm(3), Z=2, D-c=1.68 g/cm(3), mu=13. 20 cm(-1), F(000)=618 for 4 131 reflections tions. R=0. 047, R(w)=0. 047. The ligand coordinates to tin atom via phenolic oxygen atom. The complex has a distored trigonal bipyramidal structure, the phenolic oxygen atom of the ligand and one of two chlorine atoms occupy the axial position. The distance between noncoodinated nitrogen atom with phenolic oxygen atom is 0. 257 4 nm, which indicates that the intramolecular hydrogen bond of Schiff base ligand is retained in the complex.