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991.
IntroductionHighspinmoleculeshaveattractedmuchinterest,becausetheycanbeservedasthebuildingblockformagneticmaterials[1-2].ItissuggestedbyFukutome[3]andDoughertyetal.[4]thatthehighspinmoleculescanbedividedintotwocomponents:thespin-containing(SC)fragmen… 相似文献
992.
Two copper (Ⅱ) a-methacrylate complexes with benzimidazole, Cu [CH_2=C( CH_3)-COO]_2(C_7H_6N_2)_2(1) and Cu_2 [CH_2=C(CH_3)-COO]_4(C_7H_6N_2)_2 (2), have been prepared and characterized by elemental analyses, IR and electronic reflectance spectroscopies. The single crystal X-ray diffraction study of the two complexes shows that complex 1 has a square planar configuration, while complex 2 has a binuclear cage structure. The crystal structural analyses show that both complexes 1 and 2 are monoclinic, with space group P2_1/c, a=0.924 16(8) nm, b=1.233 02(13) nm, c =0.989 1(3) nm, β=91.912(13)°, D_c=1.386 g/cm~3, Z=2, R=0.033 9 for the former; and a=0.905 7(2) nm, b=2.252 1(5) nm, c=1.623 5(4) nm, β=90.11(2)°, D_c =1.411 g/cm~3 , Z=4, R=0.056 8, Cu-Cu=0.266 21 nm for the latter. Different structural types of complexes 1 and 2 were produced simultaneously in the reaction of copper (Ⅱ) α-methacrylate with benzimidazole in methanol solution. The forming mechanism of the complexes has been summarized. 相似文献
993.
新型金属-双二硫杂戊烯(M-BDT)配合物的合成、表征及X射线的指标化 总被引:2,自引:0,他引:2
合成了4个新型NiBDT配位化合物,BDT为具有9个S原子的杂戊烯.元素分析、IR谱、UV谱确定这4个新配合物的化学式分别为[(CH3)4N]2[Ni(C5S9)2](1),[(C2H5)4N]2·[Ni(C5S9)2](2),[(C4H9)4N]2[Ni(C5S9)2](3),[(C6H5)(CH3)3N]2[Ni(C5S9)2](4).采用Ito法对配合物1的X射线粉末图进行了指标化,确定该晶体属单斜晶系,简单晶格,晶胞参数:a=0.680nm,b=0.714nm,c=2.302nm,γ=111.4°,Z=2. 相似文献
994.
995.
Almazán-Almazán MC Paredes JI Pérez-Mendoza M Domingo-García M López-Garzón FJ Martínez-Alonso A Tascón JM 《Journal of colloid and interface science》2005,287(1):57-66
Poly(ethylene terephthalate) was exposed to oxygen and carbon dioxide plasmas for different periods of time. The surface-modified samples were characterized by infrared spectroscopy, atomic force microscopy, and inverse gas-solid chromatography. The main difference between both types of plasma was connected to the time scale of degradation, which was much faster when using oxygen plasma. Aggregate globular features were produced by different treatments due to chain scission and further recombination of evolved products. Oxygenated functionalities were introduced in significant amounts after long exposure times to the oxygen plasma. As a consequence, the specific component of the surface free energy was clearly observed to increase after these long treatments. 相似文献
996.
Miskoski S Soltermann AT Molina PG Günther G Zanocco AL García NA 《Photochemistry and photobiology》2005,81(2):325-332
Thyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photooxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5-diiodothyronine,3,3',5-triiodothyronine and 3,3',5,5'-tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3-iodotyrosine and 3,5-diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1Deltag)]-mediated and superoxide ion-mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 10(8)-10(9) M-1 s-1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type-II (O2(1Deltag) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, k(r), and the quotient between reactive and overall rate constants (k(r)/k(t) values, in the range of 0.7-0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem-crossing deactivation route within the encounter complex with the concomitant reduction of effective photooxidation. 相似文献
997.
Campos JM Sánchez-Martín RM Cruz-López O Conejo-García A Gallo MA Espinosa A 《Magnetic resonance in chemistry : MRC》2005,43(12):1066-1071
1H and 13C NMR spectroscopic data of both the quinolinium ring and the spacers for 32 symmetrical bisquinolinium compounds were assigned by a combination of one- and two-dimensional experiments (DEPT, HMBC, HMQC). The compounds have electron-releasing groups at position 4 of the quinolinium ring, with several arylalkyl linkers such as the 3,3'-, 4,4'-bis(methylene)biphenyl and 4,4'-bis(methylene)bibenzyl moieties. 相似文献
998.
de la Torre MC García I Sierra MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(12):3659-3667
(R)-(+)-Sclareolide 1 has been used as a starting material to develop a diversity oriented methodology to access hispanane 28 a, and hispanane-like derivatives 27 b-27 e. This methodology is based on the intramolecular Friedel-Crafts acylation of the corresponding 12-desoxylabdanoic-like acids 27, for the construction of the cycloheptane ring which is characteristic of the hispananes. Acids 27 are obtained from alcohols 20, available by addition of the lithium or magnesium reagents to amide 12 (followed by Luche reduction), or to aldehyde 21. This sequence has resulted in the preparation of hispanane framework 27 a. The versatility of this methodology therefore allows a structural diversity oriented synthesis, since it allows the access to a wide variety of hispanane-like derivatives. 相似文献
999.
Jiménez-González L Alvarez-Corral M Muñoz-Dorado M Rodríguez-García I 《Chemical communications (Cambridge, England)》2005,(21):2689-2691
A new strategy for the diastereoselective and convergent synthesis of pterocarpans which is able to control the relative stereochemistry of the molecule through allylation of aromatic aldehydes with cyclic allylsiloxanes is described. 相似文献
1000.