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1.
2.
Aqueous dispersions of single-wall and multiwall carbon nanotubes with designed amphiphilic polycations 总被引:1,自引:0,他引:1
Sinani VA Gheith MK Yaroslavov AA Rakhnyanskaya AA Sun K Mamedov AA Wicksted JP Kotov NA 《Journal of the American Chemical Society》2005,127(10):3463-3472
Poor solubility of single-walled and multiwalled carbon nanotubes (NTs) in water and organic solvents presents a considerable challenge for their purification and applications. Macromolecules can be convenient solubilizing agents for NTs and a structural element of composite materials for them. Several block copolymers with different chemical functionalities of the side groups were tested for the preparation of aqueous NT dispersions. Poly(N-cetyl-4-vinylpyridinium bromide-co-N-ethyl-4-vinylpyridinium bromide-co-4-vinylpyridine) was found to form exceptionally stable NT dispersions. It is suggested that the efficiency of macromolecular dispersion agents for NT solubilization correlates with the topological and electronic similarity of polymer-NT and NT-NT interactions in the nanotube bundles. Raman spectroscopy and atomic force and transmission electron microcopies data indicate that the polycations are wrapped around NTs forming a uniform coating 1.0-1.5 nm thick. The ability to wind around the NT originates in the hydrophobic attraction of the polymer backbone to the graphene surface and topological matching. Tetraalkylammonium functional groups in the side chains of the macromolecule create a cloud of positive charge around NTs, which makes them hydrophilic. The prepared dispersions could facilitate the processing of the nanotubes into composites with high nanotube loading for electronic materials and sensing. Positive charge on their surface is particularly important for biological and biomedical applications because it strengthens interactions with negatively charged cell membranes. A high degree of spontaneous bundle separation afforded by the polymer coating can also be beneficial for NT sorting. 相似文献
3.
Saira Shahzadi Moazzam H. Bhatti Khadija Shahid Saqib Ali Saadia R. Tariq Mohammad Mazhar Khalid M. Khan 《Monatshefte für Chemie / Chemical Monthly》2002,133(8):1089-1096
Summary. Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized
by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). 119Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of
the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin.
Received September 20, 2001. Accepted (revised) December 6, 2001 相似文献
4.
Tahir AA Molloy KC Mazhar M Kociok-Köhn G Hamid M Dastgir S 《Inorganic chemistry》2005,44(25):9207-9212
Ba(dmae)2 (dmaeH=N,N-dimethylaminoethanol, C4H11NO) reacts with Co(acac)2 (acac=2,4-pentanedionate) to produce the trinuclear coordination complex [Ba2Co(acac)4(dmae)3(dmaeH)] in an 85% yield. Spectroscopic and single-crystal X-ray diffraction experiments indicate that the complex possesses a structure in which two barium atoms and a cobalt atom are bridged by acac and dmae groups. The barium centers are eight and nine coordinate with BaO7N and BaO7N2 coordination spheres while the cobalt is a more regular CoO5N octahedron. This 2:1 heterobimetallic molecular complex was investigated as precursor for the deposition of thin film by AACVD. The film was characterized by SEM and XRD. TGA shows that the complex starts thermal decomposition upon heating in nitrogen atmosphere at 105 degrees C to produce barium cobalt oxide material of a Ba2CoO3 composition with an orthorhombic structure. The synthetic approach detailed here represents a unique route to the formation of a heterobimetallic barium cobalt coordination complex. 相似文献
5.
S. Shahzadi K. Shahid S. Ali M. Mazhar K. M. Khan 《Journal of the Iranian Chemical Society》2005,2(4):277-288
A brief account is given of the synthesis, structural chemistry and the antibacterial, antifungal and cytotoxic effects of organotin complexes of 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid. The unimolar and bimolar substitution products have been characterized by elemental analysis and spectral studies, including IR, 1H NMR, 13C NMR, 119Sn NMR, and mass spectra. The data support the binding of the oxygen atom to the tin atom in [R2Sn(OOCR’)2] and [R3Sn(OOCR’)] (R = Me, Bu, and Ph, R’ = 2-[(2,4-dichloroanilinocarbonyl)]benzoic acid). Based on these studies, with a coordination number of four, a distorted tetrahedral geometry has been proposed for the resulting derivatives in solution. The free ligand (R’/COOH) and its respective tin complexes were tested in vitro against a number of microorganisms to assess their biocidal properties and to correlate them with the structures of the derivatives. 相似文献
6.
Twelve new germanium substituted diphenyltin dipropionates with the general formula (R1GeCHR2‐CHR3COO)2SnPh2 where R1 = N(CH2CH2O)3, (C6H5)3 and (CH3C6H4)3, R2 = H, CH3, C6H5, p‐CH3C6H4, p‐CH3OC6H4, p‐ClC6H4, and R3 = H, CH3 have been synthesized by the reaction of diphenyltin oxide with a germanium substituted propionic acid. All the compounds were characterized by elemental analysis, IR, multi‐nuclear (1H, 13C, 119Sn) NMR and Mössbauer spectroscopies as well as mass spectrometry. The in vitro antibacterial activity of selected compounds is also reported. 相似文献
7.
Muhammad Ali Ehsan Muhammad Adil Mansoor Muhammad Mazhar Asif Ali Tahir Mazhar Hamid K. G. Upul Wijayantha 《应用有机金属化学》2012,26(9):493-498
A single molecular heterobimetallic complex, [Co2Ti(μ3‐O)(TFA)6(THF)3] (1) [TFA = trifluoroacetate, THF = tetrahydrofuran], was synthesized, structurally and spectroscopically characterized and implemented as a single‐source precursor for the preparation of CoTiO3–CoO composite thin films by aerosol‐assisted chemical vapour deposition (AACVD). The precursor complex was prepared by interaction of Co(OAc)2.4H2O [OAc = (CH3COO?)] with Ti(iso‐propoxide)4 in the presence of trifluoroacetic acid in THF, and was analysed by melting point, CHN, FT‐IR, single‐crystal X‐ray diffraction and thermogravimetric analysis. The precursor complex thermally decomposed at 480 °C to give a residual mass corresponding to a CoTiO3–CoO composite material. Good‐quality crystalline CoTiO3–CoO composite thin films deposited at 500 °C by AACVD and characterized through powder X‐ray diffraction and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy show that the crystallites have a rose‐flower‐like morphology with an average petal size in the range of 2–6 µm. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
8.
9.
Ornithine methyl ester reacts with aromatic aldehydes to generate bis-Schiff bases, which depending on the structure of the aromatic aldehyde, further undergo an intramolecular cycloaddition through the transient formation of a reactive 1,3-dipole. 相似文献
10.
Mazhar Ul-Islam Waleed Ahmad Khattak Minkyung Kang Sang Min Kim Taous Khan Joong Kon Park 《Cellulose (London, England)》2013,20(1):253-263
Physicochemical properties of materials can be amended by altering their physical structure through different processing conditions. The present study was conducted to investigate the post-synthesis structural variations and physico-mechanical properties of bacterial cellulose (BC) sheets prepared using different drying methods. Wet BC sheets of the same origin were freeze dried (BC-FD), dried at room temperature (25 °C) (BC-DRT), and dried at elevated temperature (50 °C) (BC-DHT). FE-SEM micrographs revealed that BC-DRT and BC-DHT had a more tightly packed and compact structure than the loosely held fibrils of BC-FD. XRD analysis revealed the relative crystallinity of the BC sample to be 64.60, 59.16, and 47.20 % for BC-DHT, BC-DRT and BC-FD, respectively. The water holding capacity (WHC) of the BC-FD was higher than that of the other two samples. Four consecutive drying and rewetting cycles demonstrated that the WHC of all samples decreased with each cycle. The WHC of BC-DRT and BC-DHT was reduced to almost 0 after the first drying cycle, but the BC-FD samples were able to regain some of their WHC. The tensile strength and elongation modulus were in the order of BC-DHT > BC-DRT > BC-FD. Overall, the results of this study revealed that the post-synthetic processing conditions had a strong effect on the structure and physico-mechanical properties of BC. 相似文献