90 research outputs found
Synthesis and characterisation of nanostructured BiFeO3 for photodecolourisation of azo dyes using visible light
No full textIn this work, effort is being made to synthesize a narrow band gap ferroelectric perovskite nanostructure semiconductor that is BiFeO3 (BFO). The BFO nanopowders were synthesized at 650ºC using a self-combustion method with glycine as the fuel. The effect of the different fuel concentrations, annealing temperatures and the duration of annealing are all demonstrated to influence the phase and crystallography of the synthesized nanoparticles. The author has demonstrated that the self-combustion process can be used to produce high purity BFO nanopowders which exhibit good absorption in the visible-light regime as determined by the UV-Vis-NIR spectroscopy with a measured optical band gap of 2.22 eV. Cont/d
Non-linear optical properties of the inorganic cluster[(η-C<SUB>5</SUB>H<SUB>5</SUB>)CoFe<SUB>2</SUB>SSe(CO)<SUB>6</SUB>]
No full textNon-linear refraction and absorption have been studied in a mixed-metal, mixed chalcogenide cluster. The cluster displays optical limiting significantly superior to that displayed by C60
Varying structural motifs in oxyanions (NO<SUB>3</SUB><SUP>−</SUP>, CO<SUB>3</SUB><SUP>2−</SUP>) and phenoxyacetate (PhOAc<SUP>−</SUP>) bridged coordination polymers derived from alkoxo-bridged dicopper building blocks with {Cu<SUB>2</SUB>O<SUB>2</SUB>} core
No full textThe oxyanions (NO3−, CO32−) and phenoxyacetate (PhOAc−) bridged three 1D-coordination polymeric chains, {[Cu2(μ-hep)2(μ-NO3)]2}n (1), {[Cu2(μ-hep)2(H2O)2]·2H2O(μ-CO3)}n (3) and {[Cu2(μ-hep)2(μ-PhOAc−)]2}n (2) (hep-H = 2-(2-hydroxyethyl)pyridine) have been synthesized. In 1-3 the alkoxide bridged dicopper building units, [Cu(μ-hep)]2 with Cu2O2 core, are linked via the respective anions. Detailed structural analysis reveals that in 1 or 2, two units of NO3− (1) or PhOAc− (2), respectively, bind with the four copper ions in two adjacent alkoxide bridged dimeric units in head-to-head and tail-to-tail fashion and the same binding mode continues along the polymeric chain. This in effect yields a 12-membered metallacyclic ring in between two dimeric core units. However, in 3 only one CO32− group bridges the two copper centres associated with the two neighbouring alkoxide bridged dimeric units in head-to-tail mode which in turn forms a zig-zag polymeric chain. Two coordinated and two lattice water molecules from two adjacent polymeric layers in the structure of 3 form water tetramers. Furthermore, the interaction of water tetramer with the uncoordinated -C=O group of the bridging CO32− develops an additional zig-zag chain which is being trapped between the two outer zig-zag coordination polymeric chains in 3. The polymeric chains in 1-3 further develop a 2D-network pattern via an extensive non-covalent hydrogen bonding as well as C-H···π and π···π interactions
Reversible single-crystal to single-crystal transformations in a Hg(II) derivative. 1D-polymeric chain ⇋ 2D-networking as a function of temperature
No full textReactions of HgX2 (X = Cl-, Br-, l-) with the ligand hep-H (hep-H = 2-(2-hydroxyethyl)pyridine) in methanol at 298 K result in 1D-polymeric chains of [(X)Hg(μ-X)2(hep-H)]∞, 1-3, respectively, where hep-H binds to the Hg(II) ions in a monodentate fashion exclusively with the pyridine nitrogen donor and the suitably ortho-positioned -(CH2)2OH group of hep-H remains pendant. The packing diagrams of 1-3 exhibit extensive intramolecular and intermolecular hydrogen bonding interactions leading to hydrogen bonded 2D network arrangement in each case. Though the single crystal of either 2 (X = Br) or 3 (X = I) loses crystallinity upon heating, the single crystal of 1 selectively transforms to a 2D-polymeric network, 4 on heating at 383 K for 1.5 h. The polymeric 4 consists of central dimeric [Hg(μ3-Cl)(hep-H)Cl]2 units, which are covalently linked with the upper and lower layers of [-(μ-Cl)2-Hg-(μ-Cl)2-Hg(μ-Cl)2-]n. The packing diagram of 4 reveals the presence of O-H-Cl and C-H-Cl hydrogen bonding interactions which in effect yields hydrogen bonded 3D-network. Remarkably, the single crystals of 4 convert back to the single crystals of parent 1 on standing at 298 K for three days
Characterization of a species-specific repetitive DNA from a highly endangered wild animal, Rhinoceros unicornis, and assessment of genetic polymorphism by microsatellite associated sequence amplification (MASA)
No full textWe have cloned and sequenced a 906 bp EcoRI repeat DNA fraction from Rhinoceros unicornis genome. The contig pSS(R)2 is AT rich with 340 A (37.53%), 187 C (20.64%), 173 G (19.09%) and 206 T (22.74%). The sequence contains MALT box, NF-E1, Poly-A signal, lariat consensus sequences, TATA box, translational initiation sequences and several stop codons. Translation of the contig showed seven different types of protein motifs, among which, EGF-like domain cysteine pattern signatures and Bowman-Birk serine protease inhibitor family signatures were prominent. The presence of eukaryotic transcriptional elements, protein signatures and analysis of subset sequences in the 5' region from 1 to 165 nt indicating coding potential (test code value=0.97) suggest possible regulatory and/or functional role(s) of these sequences in the rhino genome. Translation of the complementary strand from 906 to 706 nt and 190 to 2 nt showed proteins of more than 7 kDa rich in non-polar residues. This suggests that pSS(R)2 is either a part of, or adjacent to, a functional gene. The contig contains mostly non-consecutive simple repeat units from 2 to 17 nt with varying frequencies, of which four base motifs were found to be predominant. Zoo-blot hybridization revealed that pSS(R)2 sequences are unique to R. unicornis genome because they do not cross-hybridize, even with the genomic DNA of South African black rhino Diceros bicornis. Southern blot analysis of R. unicornis genomic DNA with pSS(R)2 and other synthetic oligo probes revealed a high level of genetic homogeneity, which was also substantiated by microsatellite associated sequence amplification (MASA). Owing to its uniqueness, the pSS(R)2 probe has a potential application in the area of conservation biology for unequivocal identification of horn or other body tissues of R. unicornis. The evolutionary aspect of this repeat fraction in the context of comparative genome analysis is discussed
Spectroscopic study of the structures of [M<SUB>2</SUB>(η-C<SUB>5</SUB>H<SUB>5</SUB>)<SUB>2</SUB>(CO)<SUB>n</SUB>(CNR)<SUB>4-n</SUB>] complexes (n= 1 or 2; M = Fe or Ru) in solution. The structure of cis-[(η-C<SUB>5</SUB>H<SUB>5</SUB>)(OC)Fe(μ-CO)(μ-CNPr<SUP>i</SUP>)Fe(CNPr<SUP>i</SUP>)(η-C<SUB>5</SUB>H<SUB>5</SUB>)] in the solid state
No full textVarious [M2(η-C5H5)2(CO)n(CNR)4-n] complexes have been prepared [n= 2, M = Fe, R = Ph, p-ClC6H4CH2, PhCH2, p-MeC6H4CH2, p-MeOC6H4CH2, D(+)-Ph(Me) CH, Me, Et, Prn, Bun, Prl, C6H11, or But; M = Ru, R = Pri; n= 1, M = Fe, R = Me, Et, or Pri]. In solution, they exist as rapidly interconverting equilibrium mixtures of isomers; where n= 2, the RNC ligands are less likely to adopt bridged as opposed to terminal co-ordination as R is varied along the above series. The isomer distribution is a consequence of electron-withdrawing R favouring μ-CNR co-ordination and, less importantly, the more bulky R favouring terminal CNR. Where n= 1, only one predominant isomer is observed in solution. The crystal and molecular structure of cis-[Fe2(η-C5H5)2(COt)-(CNRt)(COμ)(CNRμ)](R = Pri) has been determined by an X-ray diffraction study. It has been solved by the heavy-atom method from photographic data and refined by full-matrix least squares to R= 0.103 for 807 non-zero unique reflections. Crystals are monoclinic with space group P21/c(no. 14), Z= 4, a=13.881 ± 0.015, b= 10.755 ± 0.010, c= 15.262 ± 0.015 Å, and β= 112.5 ± 0.1°
Synthesis, structure, and reactivity of mixed-metal clusters bearing eta(1)-acetylide groups, (eta(5)-C5H5)MFe2(mu(3)-E)(2)(CO)(6)(eta(1)-CCPh) (M = Mo or W and E = Se or Te)
No full textReaction of Fe-3(CO)(9)(mu(3)-E)(2) (E = Se, Te) with (eta(5)-C5H5)M(CO)(3)(C=CPh) (M = Mo, W); in the presence of trimethylamine-N-oxide (TMNO), in acetonitrile solvent at 60 C yields the novel mixed-metal clusters (eta(5)-C5H5)MFe2(mu(3)=E)(2)(CO)(6)(eta(1)-CCPh) (1, E = Se, M =Mo; 2, E = Se, M = W; 3, E = To, M = Mo; 4, E = Te, M = W) bearing eta(1)-acetylide groups. The reaction of 1 or 3 with dicobalt octacarbonyl at room temperature gives the mixed-metal clusters (eta(5)-C5H5)MoFe2Co2(mu(3)-E)(2)(CO)(9)(mu-CCPh) (5, 6). Structures of 1 and 6 have been established crystallographically
Synthesis, Structure, and Reactivity of Mixed-Metal Clusters Bearing η<sup>1</sup>-Acetylide Groups, (η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)MFe<sub>2</sub>(μ<sub>3</sub>-E)<sub>2</sub>(CO)<sub>6</sub>(η<sup>1</sup>-CCPh) (M = Mo or W and E = Se or Te)
No full textReaction of Fe3(CO)9(μ3-E)2 (E = Se, Te) with (η5-C5H5)M(CO)3(C⋮CPh) (M = Mo, W), in
the presence of trimethylamine-N-oxide (TMNO), in acetonitrile solvent at 60 °C yields the
novel mixed-metal clusters (η5-C5H5)MFe2(μ3-E)2(CO)6(η1-CCPh) (1, E = Se, M = Mo; 2, E =
Se, M = W; 3, E = Te, M = Mo; 4, E = Te, M = W) bearing η1-acetylide groups. The reaction
of 1 or 3 with dicobalt octacarbonyl at room temperature gives the mixed-metal clusters
(η5-C5H5)MoFe2Co2(μ3-E)2(CO)9(μ-CCPh) (5, 6). Structures of 1 and 6 have been established
crystallographically
Synthesis, Structure, and Reactivity of Mixed-Metal Clusters Bearing η<sup>1</sup>-Acetylide Groups, (η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>)MFe<sub>2</sub>(μ<sub>3</sub>-E)<sub>2</sub>(CO)<sub>6</sub>(η<sup>1</sup>-CCPh) (M = Mo or W and E = Se or Te)
No full textReaction of Fe3(CO)9(μ3-E)2 (E = Se, Te) with (η5-C5H5)M(CO)3(C⋮CPh) (M = Mo, W), in
the presence of trimethylamine-N-oxide (TMNO), in acetonitrile solvent at 60 °C yields the
novel mixed-metal clusters (η5-C5H5)MFe2(μ3-E)2(CO)6(η1-CCPh) (1, E = Se, M = Mo; 2, E =
Se, M = W; 3, E = Te, M = Mo; 4, E = Te, M = W) bearing η1-acetylide groups. The reaction
of 1 or 3 with dicobalt octacarbonyl at room temperature gives the mixed-metal clusters
(η5-C5H5)MoFe2Co2(μ3-E)2(CO)9(μ-CCPh) (5, 6). Structures of 1 and 6 have been established
crystallographically
Characterization of a species-specific repetitive DNA from a highly endangered wild animal, Rhinoceros unicornis, and assessment of genetic polymorphism by microsatellite associated sequence amplification (MASA
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