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211.
The synthesis of [2]rotaxanes, each comprising a viologen core threaded through a cucurbit[8]uril (Q8, Figure 1) macrocycle and stoppered by tetraphenylmethane groups, and their binding to second guests as inclusion complexes in organic and aqueous media are described. Stoppering was observed to have little effect on binding. Chemical modification of the threaded guest was used to control solubility and binding characteristics, thus demonstrating a novel approach to making artificial receptors with readily modifiable properties. 相似文献
212.
Maravanji S. Balakrishna P. Chandrasekaran Ramalingam Venkateswaran 《Journal of organometallic chemistry》2007,692(13):2642-2648
Cyclodiphosphazanes having donor functionalities such as cis-[tBuNP(OR)]2 (R = C6H4OMe-o (2); R = CH2CH2OMe (3); R = CH2CH2SMe (4); R = CH2CH2NMe2 (5)) were obtained in good yield by reacting cis-[tBuNPCl]2 (1) with corresponding nucleophiles. The reactions of 2-5 with [RuCl2(η6-cymene)]2, [MCl(COD)]2 (M = Rh, Ir), [PdCl2(PEt3)]2 and [MCl2(COD)] (M=Pd, Pt) result in the formation of exclusively monocoordinated mononuclear complexes of the type cis-[{tBuNP(OR)}2MLn-κP] irrespective of the reaction stoichiometry and the reaction conditions. In contrast, 2-5 react with [RhCl(CO)2]2, [PdCl(η3-C3H5)]2, CuX (X=Cl, Br, I) to give homobinuclear complexes. Interestingly, CuX produces both mono and binuclear complexes depending on the stoichiometry of the reactants and the reaction conditions. The mononuclear complexes on treatment with appropriate metal reagents furnish heterometallic complexes. 相似文献
213.
T. Ramalingam M. S. R. Murty Y. V. D. Nageswar P. B. Sattur 《Journal of heterocyclic chemistry》1990,27(4):981-982
The reaction of 3 -amino-1,2,4-triazolo[4,3-a]quinoline ( II ) with diethyl ethoxymethylenemalonate and ethyl acetoacetate/ethyl trifluoroacetoacetate afforded 10-carboethoxy-9-oxo-9H-pyrimido[1′,2′:1,5][1,2,4]triazolo-[4,3-a]quinoline ( III ) and 11-methyl/trifluoromethyl-9-oxo-9H-pyrimido[1′,2′:1,5][1,2,4]triazolo[4,3-a]quinoline ( IV/V ) respectively. 2-Chloropyridine-3-carboxylic acid chloride reacted with II to yield 5-oxo-5H-pyrido-[3″,2″:5′,6′]pyrimido[1′,2′:1,5][1,2,4]triazolo[4,3-a]quinoline ( VII ), a new ring system. 相似文献
214.
Anwar Iqbal Usman Saidu Farook Adam Srimala Sreekantan Noorfatimah Yahaya Mohammad Norazmi Ahmad Rajabathar Jothi Ramalingam Lee D. Wilson 《Molecules (Basel, Switzerland)》2021,26(9)
In this work, mesoporous TiO2-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO2. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O2●−. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS). 相似文献
215.
Babu PD Periandy S Mohan S Ramalingam S Jayaprakash BG 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(1):168-178
The FT-Raman and FT-IR spectra for benzenesulfonic acid methyl ester (BSAME) have been recorded in the region 4000-100 cm(-1) and compared with the harmonic vibrational frequencies calculated using DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) method by employing 6-311G (d, p) basis set with appropriate scale factors. IR intensities and Raman activities are also calculated by DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) methods. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for sulfonic acid and some substituted sulfonic acids. The experimental geometrical parameters show satisfactory agreement with the theoretical prediction from DFT. The scaled vibrational frequencies at LSDA/B3LYP/6-311G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra. Some of the vibrational frequencies of the sulfonic acid are effected upon profusely with the methyl substitution in comparison to benzene sulfonamide and these differences are interpreted. 相似文献
216.
The 1,3-dipolar cycloaddition reaction of tryarylideneacetyacetone derivatives with N-metalated azomethine ylides in the presence of titanocene dichloride and triethylamine has been investigated. This two-step synthetic sequence is very efficient and yielded the highly substituted pyrrolidines in good yields. The structure and stereochemistry of one of the products has been established by single-crystal x-ray structure and spectroscopic techniques. 相似文献
217.
Summary Phenylisocyanation and bromination of some twenty lanthanide -diketonates: Ln(acac)3, Ln(bzac)3 and Ln(dbzm)3 where Ln=PrIII, NdIII, SmIII, GdIII, DyIII and YIII and Ce(acac)4, Ce(bzac)4 and Ce(dbzm)4 have been investigated. While phenylisocyanation gives the expected 3-substituted phenylamido product, bromination, for the first time, has been observed to yield a substituted product with flipping of one (or two) six-membered diketone ring to give a five-membered ring in which the entering bromine electrophile is bonded to the metal and a carbon atom. The other diketone rings, although -substituted, remain intact with respect to metal coordination. The substituted complexes have been characterised by i.r., u.v. and n.m.r. spectroscopy. 相似文献
218.
Mahadevan D Periandy S Ramalingam S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):575-581
The FT-IR and FT-Raman spectra of 3-Bromo phenol (3-BP) molecule have been recorded using Bruker IFS 66V spectrometer in the range of 4000-100 cm(-1). The molecular geometry and vibrational frequencies in the ground state are calculated by using the ab initio Hartree-fock (HF) and DFT (B3LYP) methods with 6-31G (d, p) and 6-311G (d, p) basis sets. The computed values of frequencies are scaled using a suitable scale factor to yield good coherence with the observed values. Making use of the recorded data, the complete vibrational assignments are made and analysis of the observed fundamental bands of molecule is carried out. The geometries and normal modes of vibrations obtained from ab initio HF and B3LYP calculations are in good agreement with the experimentally observed data. The differences between the observed and scaled wave number values of most of the fundamentals are very small in DFT than HF. The inductive effect of halogen atom in the molecule has also been investigated. 相似文献
219.
A newly developed π-allylpalladium with a (-)-β-pinene framework and an isobutyl side chain catalyzed the enantioselective allylation of imines in good yields and enantioselectivities (20 examples, up to 98% ee). An efficient enantioselective synthesis of the (R)-α-propyl piperonylamine part of DMP 777, a human leukocyte elastase inhibitor and (R)-pipecolic acid have been achieved as a useful application of this methodology. 相似文献