共查询到20条相似文献,搜索用时 203 毫秒
1.
由三价轻稀土、钇(Ⅲ)和铈(Ⅳ)的硝酸盐分别与2,3,11,12-四苯基-1,4,7,10,13,16-六氧-2,11-十八环二烯反应,合成了相应的六种固体络合物,並进行了元素分析,IR、NMR、TG、DTA、电导及溶解度等性质的研究。 相似文献
2.
The luminescent properties of divalent europium complexes with crown ether, azacrown ether, N-pivot-azacrown ether, and cryptand in methanol or water have been systematically investigated under UV irradiation. These divalent europium complexes show greatly enhanced emission from 417 nm to 488 nm in the visible blue region in comparison with that of the methanol solution of EuCl 2. The aqueous solution of EuCl 2 is non-luminescent. This obvious distinction in luminescent properties between the macrocyclic ligand-coordinated divalent europium and uncoordinated divalent europium is attributed to the “insulation effect” of Eu 2+ ion from the solvent molecules of CH 3OH and H 2O by the macrocyclic crown ether or cryptand encapsulation to divalent europium. Moreover, these macrocyclic ligands provide an additional restriction to the electronic charge expansion of the excited Eu 2+. This also contributes to the enhancement of the Eu 2+ luminescence. Among all the investigated macrocyclic ligands, 15-crown-5 (15C5) affords the largest enhancement to the Eu 2+ emission. The intensity of the Eu 2+–15C5 complex is 690 times that of the EuCl 2 methanol solution with the same Eu 2+ concentration. This special emission enhancement effect is related to the particular complex composition of 1:3 (Eu 2+:15C5) and corresponding configuration of Eu 2+–15C5 complex in methanol. Concerning the mechanism, the luminescence enhancement of divalent europium by complexation with these macrocyclic crown ether or cryptand ligands is found to be initiated from the decrease in non-radiative rate constant rather than from the increase in radiative one. The divalent europium complexes of methacrylate polymeric polyether derivatives such as 15C5-, 18-crown-6- (18C6), and cryptand [2.2.1]- or [2.2.2]-containing polymer and copolymer have also been prepared. Their luminescent properties in solid state have been studied to aim for practical application. As a similar situation to the simple polyether complexes, the divalent europium complex with 15C5-containing polymer or copolymer shows the largest luminescent enhancement effect. Its emission intensity reaches about 20% that of the commercial inorganic luminescence product CaWO4:Pb (NBS 1026). In addition, the doping effect of several divalent ions, namely Mg, Sr, Ba and Zn in polymeric complexes, has also been investigated according to the luminescence concentration quenching mechanism in solid state luminescence materials. The emission intensity of 15C5-containing polymer europium(II) complex is raised to twice stronger by doping of Zn2+ ion. 相似文献
3.
1-substituted-5-benzoylamino-4-pyrazolecarboxamides(2)were prepared by the reaction of 1-substituted pyrazolo[3, 4-d]-oxazinone(1)with amines in benzene.The compound 2 was refluxed with excess LiAlH 4 in a mixture of THF and ether, one of the two carbamoyl groups in the molecule 2 was reduced selectively.As the results, 1-substituted-5-benzylamino-4-pyrazolecarboxamides (3) were obtained.Compounds 3reacted with Cl 2PPh-X, or P(NET 2)3, producing the title compounds(4).The conditions of the reactions were studied. 相似文献
4.
From the culture medium of Verticillium inlertexlum three metabolitcs have been isolated, namely the hexaketidcs sorbicillin (1) and 2'3'-dihydrosorbicillin (2), and the dimeric hexaketide bisvertinoquinol (3). 1 has previously been isolated from Penicillium chrysogenum and also synthesised. Hydrogenation of 1 yielded tetrahydrosorbicillin (8), 2'5'-dihydrosorbicillin (9) and 2',3'-dihydrosorbicillin (2). 2 was also obtained by a BF 3-catalysed condensation of 2,4-dimethyl-resorcinol (5) with (4R *, 5S *)-4,5-dibromo-hexanoic acid (6), followed by debromination with zinc and acetic acid. The structure of the dimeric hexaketide 3 (without absolute configuration) was obtained by X-ray structure analysis. It may be considered to be a Diels-Alder adduct of the quinols 11 and 12, the latter being related to 1 and 2, respectively, by simple hydroxylation at C(5). The 1H and 13C NMR signals of 3 and its mono-methyl ether 10 are interpreted and compared with the corresponding properties of 1, 2, vertinolide (4), 3-methoxy-2-methyl-2-cyclohexenone (14), and 2-[(E,E)-2,4-hexadienoyl)]-cyclohexanone (13). The latter was prepared by acylation of the lithium enolate of cyclohexanone with sorbyl chloride. From the spectra of the hexaketides from V. intertextum several patterns have been extracted which are characteristic for some common and some distinguishing substructures in these natural products. 相似文献
5.
我们曾用自己设计的半微量相平衡方法研究了La(NO 3) 3•4H 2O-B15C5-CH 3CN三元体系在25℃时的溶解度,发现同生成它的母液处于平衡状态时的固态络合物的组成为La(NO 3) 3•B15C5•4H 2O,在一般条件下的相对稳定形式为La(NO 3) 3B15C5•2H 2O。说明了Cassol和King等人所得无水络合物La(NO 3) 3•B15C5是由于后处理条件不当所引起的。 相似文献
6.
本文合成了一种金属冠醚卟啉化合物并提出了一种基于该化合物的阴离子识别机制,为阴离子的可视化识别提供了一种简便的思路。 相似文献
7.
用X射线单晶衍射方法测定了PrCl 3·C 10H 20O 5和SmCl 13·C 10H 20O 5的晶体结构。二者均属单斜晶系,P2 1/c空间群。a=8.167(2)[8.129(7)],b=14.225(3)[14.176(7)],c=14.208(4)[14.117(5)]Å,β=104.78(2)[104.62(5)]°,Z=4。稀土离子的一侧与三个氯,另一侧与五个冠醚氧键合,形成不规则的八配位多面体。Ln-O平均键长为2.606[2.566]Å,Lu-Cl为2.714[2.666]Å,都比配位数高的相应键长短。 相似文献
8.
After anaerobic incubation of abrusin 2'-O-beta-D-apioside (1) with a human fecal suspension, five metabolites were isolated and identified as abrusin (2), 1-(2',6'-dihydroxy-3',4'-dimethoxyphenyl)-3-(4'-hydroxyphenyl)propan-1- one (5), 5,6-dimethoxybenzene-1,3-diol (6), 3-(4'-hydroxyphenyl)propionic acid (7) and 3-phenylpropionic acid (8). However, methyl ether derivatives of abrusin (4'-O-methylabrusin and 4'-O-, 5-O-dimethylabrusin) resisted degradation under the same conditions. 相似文献
9.
The reaction of trans-[Mo(N 2) 2(PPh 2Me) 4] with the tripodal phosphine tris(2-diphenylphosphinoethyl)phosphine, PP 3, in benzene has been studied. The product was recrystallized from a mixture of benzene and petroleum ether to give [Mo(PP 3) 2]·C 5H 10, whose crystal structure shows a distorted octahedral “MoP 6” coordination with both phosphines acting as tridentate ligands. 相似文献
10.
Treatment of 2,4,6-triisopropylbenzaldehyde with tris(trimethylsilyl)silylmagnesium bromide (2) gives 2,4,6-triisopropylphenyl-tris(trimethylsilyl)silyl-methanol (3) in approximately 70% yield and E-3,4-bis(2,4,6-triisopropylphenyl)-1,1,2,2-tetrakis(trimethylsilyl)-1,2-disilacyclobutane (5) (15%). 5 is the [2 + 2] head-to-head cyclodimer of the transient 1,1-bis(trimethylsilyl)-2-(2,4,6-triisopropylphenyl)silene (4), formed by trimethylsilanolate elimination according to a Peterson mechanism from the magnesium alkoxide, derived from the alcohol 3. Deprotonation of 3 with McLi at low temperature in ether produces a complex mixture of products, the main constituents being the silene dimer 5 (10%) and bis(trimethylsilyl)-2,4,6-triisopropylbenzyl-trimethylsiloxysilane (10) (60%), which is formed by readdition of the eliminated lithiumtrimethylsilanolate at the Si=C bond of 4. The deprotonation of 3 with McMgBr or PhMgBr (activated by LiBr) in THF at room temperature results in the formation of the polysilane (Me 3Si) 3SiSi(SiMe 3) 2CH 2(2,4,6-C 6H 2iPr 3) (13). Its generation indicates that there exists an equilibrium between the magnesium alkoxide derived from the alcohol 3 on one side, and the magnesium silanide 2 and 2,4,6-triisopropylbenzaldehyde on the other side. Possible pathways of the formation of the compounds mentioned, as well as of further by-products, are discussed. The 1,2-disilacyclobutane 5 is characterized by an X-ray crystal structure analysis. 相似文献
11.
Poly(ether ether ketone)(PEEK)was synthesized via polycondensation of hydroquinone with 4,4′-difluorobenzophenone at 320℃for 5 h.Thermal and thermo-oxidative degradation of PEEK was studied over a wide range of temperatures.In an inert medium,decomposition of the polymer occurred in one stage,with the formation of a coke residue accounting for approximately 50%of the original polymer mass.In air,the mass loss curve exhibited two distinct stages.The first stage involved breakdown of the main polymer chain,the speed of which indicated a radical chain failure mechanism.In the second stage,the rate of mass loss clearly decreased,indicating a transition from the radical chain failure mechanism to simple combustion reactions(wherein the polymer combusted completely).To further investigate the nature of the processes occurring during the pyrolysis of PEEK,the investigations were carried out using gas chromatograph under isothermal conditions.It was concluded that during thermal degradation,the decomposition of the polymer starts with the rupture of ketone and ether bonds and proceeds to destruction of the benzene ring at higher temperatures,which is accompanied by the formation of H2O and CH4.Above 500℃,the polymer degradation further involved thermohydrolysis.The thermo-oxidation of PEEK,which was accompanied mainly by the formation ofH2,was noticeable beginning at 325℃.The total yield of the latter indicated oxidation of fragments of the benzene ring. 相似文献
12.
On treatment with Pd(PPh 3) 4 allyl vinyl ether (1) undergoes a Pd(0) catalysed 1,3 oxygen to carbon allyl shift to afford -allyl ketone (2). In the presence of both Pd(PPh 3) 4 and base the allyl vinyl ether undergoes a Pd(0) catalysed tandem 1,3 allyl shift and intramolecular Heck arylation to give the spiro indane (3). Mechanistic investigations suggest that the 1,3-allyl shift proceeds via a π-allyl palladium intermediate. 相似文献
13.
The first representative of a new class of TcN complexes with thiacrown ethers have been prepared by ligand exchange reaction of NBu 4[TcNCl 4] with 1,4,8,11-tetrathiacyclotetradecane (14S4), 1,5,9,13-tetrathiacyclohexadecane (16S4), 1,5,9,13-tetrathiacyclohexadecane-3,11-diole (16S4-(OH) 2) and 1,4,7,10,13,16-hexathiacyclooctadecane (18S6). The crystal structure of [TcNCl(14S4)]TcNCl 4 1) consists of couples of independent cations with the metal in the oxidation state + 5 and hexavalent TcNCl 4− anions. In the complex cation the metal is six-coordinated in a rather distorted octahedral geometry, being directly bound to four sulphur atoms from the macrocyclic ligand in the equatorial plane and to the nitrido atom and to one chlorine atom in the axial positions. The strong trans influence of the nitrido ligand causes an extreme lengthening of the Tc---Cl bond distance to 2.718 Å. The octahedral molecular structure of [TcNCl(18S6)]TcNCl 4 (3) is comparable with that of 1, but only four sulphur atoms of the thiacrown ether form the equatorial plane, two sulphur atoms remain non-coordinated, and the nitrido and Cl − ligands are in axial positions. The most interesting feature in the structure of [TcNCl(16S4-(OH) 2)]Cl (5) is the observation of an exceptionally long Tc---N distance of 1.95 Å. 相似文献
14.
The ligands 4,7-diaza-2,3,8,9-dibenzo-15-crown-5 (L1), 4,10-diaza-2,3,11,12-dibenzo-18-crown-6 (L2), 4,10-diaza-2,3,11,12-di(4′- tert-butylbenzo)-18-crown-6 (L3) and N, N-di(methylenecarboxyethoxy) 4,10-diaza-2,3,11,12-dibenzo-18-crown-6 (L4) have been prepared. Partition coefficients and acid dissociation constants for these four diazadibenzocrown ether compounds were determined in water-chloroform. Their effectiveness was assessed in solvent extraction of Pb 2+ from aqueous solutions into toluene. Ligands L3 and L4 provide high selectivity for Pb 2+ over Cd 2+ and Zn 2+ in transport across plasticized cellulose triacetate membranes. 相似文献
15.
The photoinduced energy transfer (ET) from naphthalene (N) to Tb 3+ has been studied in the complexes of Tb 3+ ion with 2,3-naphtho-17-crown-5 ether(I), 2,3-naphtho-20-crown-6 ether(II), 1,8-naphtho-21-crown-6 ether(III) and 1,5-naphtho-22-crown-6 ether(IV), respectively, using nitrate (NO 3−) ion as the counter anion in EtOH glass at 77 K. The ligands are so designed that the Tb 3+ ion can be complexed with a predetermined orientation with respect to the naphthalene molecular plane. In systems I and II, the Tb 3+ ion is along the Z-axis; in system III, it is along the Y-axis and in IV, it is along the X-axis, where Z- and Y- are the molecular in-plane long and short axes of the naphthalene molecular plane respectively and X- is the out-of plane axis perpendicular to the naphthalene molecular plane. Present studies indicate that the efficiency of energy transfer (ET) and the quenching of naphthalene phosphorescence show a strong dependence on the orientation of the acceptor metal ion (Tb 3+) with respect to the π-plane of the donor naphthalene moiety. The ET studies suggest that an exchange mechanism involving the lowest (ππ *) triplet state of N and the 5D 4 state of Tb 3+ ion is predominantly operating. Our observation further indicates that for a given orientation in a complex the emission intensity of the various transitions ( 5D 4 → 7F J, J=2–6) for Tb 3+, vis-a-vis ET efficiency varies considerably with Δ J values (=0, +1 and +2). 相似文献
16.
Treatment of Mn(CO) 5SiTol p2H (2) with an excess of LiAlH 4, NaBH 4, or NaBH 3(CN) in THF at room temperature gave hydrosilane H---SiTol p2H in high yield together with Mn 2(CO) 10. No reduction of CO ligands was observed. On the other hand, treatment of 2 with an excess of Red-Al (=Na[(CH 3OCH 2CH 2O) 2AlH 2]) in toluene and subsequent addition of aqueous acidic solution afforded alkylsilanols (CH 3)SiTol p2(OH) and (C 2H 5)SiTol p2(OH). Treatment of the reaction mixture of 2 and Red-Al with LiAlH 4 in diethyl ether instead of hydrolysis gave alkylhydrosilanes (CH 3)SiTol p2H and (C 2H 5)SiTol p2H. The methyl and ethyl groups on silicon originate from the CO ligands in 2. These products clearly demonstrate that not only the Si---C coupling, but also C---C coupling occurs efficiently in this reaction. 相似文献
17.
近年来,随着对高分子材料功能化研究的深入,合成了许多具有特殊性能的聚芳醚酮.聚芳醚酮是一类综合性能优异的半结晶性特种工程塑料,在分子链中引入氟官能团可降低聚合物的介电常数.然而,不对称强极性氟的引入增加了聚合物分子的极性,不利于进一步降低介电常数,且在高温加工时容易放出氟化氢.因此,无氟、低氟的低介电高分子材料将会有很好的发展前景. 相似文献
18.
Treatment of octafluorotoluene (2) with approximately one-molar equivalents of the oximates R 1R 2C = NO~ M + (R 1 = R 2=Me;R 1 = R 2 = Ph; R 1 = Me, R 2 = Ph;M = Na) (6a-c) in diethyl ether gives 4-(R 1R 2C = NO)C 6F 4CF 3 (7a-c) as the only isolated products. Corresponding reaction of 3,5-dichlorotrifluoropyridine (3) with the oximates 6a-c affords 4-and 2-(R 1R 2C = NO)C5F 2C12N (8a-c) and (9a-c), respectively (4-/2ratios at −35 °C: 65:35; 30:70; 12:88) ; the lithium oximates (R 1 = R 2 =Ph ; R 1 = Me, R 2 = Ph; M = Li) (6d) and (6e) give comparable results. With 3-chlorotetrafluoropyridine (4), treatment with sodium oximate 6c gives 4-(PhCMe = NO)-3-ClC 5F 3N (10) and 2-(PhCMe = NO)-5ClC 5F 3N (11) (ratio 44:56 at −35 °C). Such competition between S NAr attack of these alkali-metal oximates at the C-4 and C-2 positions of chlorofluoropyridines 3 and 4 can be rationalized by invoking chelation of an alkali-metal cation with ring nitrogen in the transition state leading to formation of an orthio-quinonoidal σ-complex. Exclusive initial attack at the C-4 ring site appears to occur in the reaction of tetrafluoropyrimidine (5) with oximates 6a and 6c to afford 4-(MeC = NO)C 4F 3N 2 (12a) and 4-(PhCMe=NO)C 4F 3NN 2 (12b), respectively; Some further attack on product 12b by oximate 6c at the C-6 site takes place to give the disubstituted derivative 4,6-(PhCMe=NO) 2C 4F 2N 2 (13). 相似文献
19.
Photodecomposition of 10 different molybdenum and tungsten mixed carbonyl complexes, [M(CO) 3(B)(A)]I 2 where B= o-phenanthroline or bipyridyl, A=3-(2-propynyl)thio-4,5-diphenyl-4H-1,2,4-triazole (TRZA) or S-propynyl-2-thio benz-imidazole (BIMDA) and 2(2-propynyl-thio(5-phenyl)-1,3,4-oxadiazole (OXA). M(CO) 3(TRZA)I 2, [M(CO) 2(PPh 3) X(TRZA)I Y]I Z where M=Mo, X, Y and Z=1 and M=W, X and Z=2, Y=0, have been performed at 365 nm in oxygen saturated chloroform at 25 °C. The absorbance spectrum of these complexes have been recorded with the time of irradiation in order to examine the kinetics of photodecay. The apparent rate constant (Kd) for the first-order reaction have been calculated and found to be (3.32–4.79)×10−5 s−1. The primary quantum yields (Φ) has also been calculated and were in the range (8.33–12.1)×10−4. The mechanism of the photodecomposition has been suggested according to the kinetic, and photoproduct analysis data, and is similar to reaction of photo-oxidative degradation of polluted molecules in the water. 相似文献
20.
1-苯基-3-甲基-4-苯甲酰基吡唑酮-5(HPMBP)对五十多种元素的萃取行为、作用机理以及固态配合物的组成与性质已有较全面的研究,但对四位为己酰基的相应化合物有关报道不多,它与稀土元素的萃取机理以及固态配合物的制备尚未见报道。本文考察了HPMCP对稀土元素La、Nd、Gd、Lu、Y的萃取机理,并用斜率法求出了配合物的组成,确定了萃取平衡反应,计算了萃取平衡常数、合成了它们的固态配合物,并对其组成以及热谱、红外光谱、核磁共振谱等进行了研究。 相似文献
|