Carbon nanotube "T Junctions": formation pathways and conductivity

Using tight-binding molecular dynamics we simulate the formation of single wall carbon nanotube T junctions via the fusing of two nanotubes. We propose energetically efficient pathways for this process in which all atoms maintain their sp(2) arrangements throughout. Recent experimental advances have greatly increased the plausibility of synthesizing T junctions as proposed in the simulations. We further report I-V characteristics of the formed junctions.     

Catalytic properties of binuclear rhodium(II) complexes in hydrogenation and isomerization of allylbenzene

Binuclear hexafluoroacetylacetonate complexes of Rh(II) with axial ligands (Py, H₂O) exhibit activity in hydrogenation and isomerization of allylbenzene, and the isomerization reaction also takes place in an atmosphere of Ar. The catalytic system [Rh₂(hfacac)₄(H₂O)₂]-Ph₃P is much more active than Rh(II) hexafluoroacetylacetonate complexes in transformation of allylbenzene. Treatment of the acetate complex [Rh₂(O₂CCH₂)₄] with sodium borohydride significantly increases its activity, probably due to the formation of [Rh₂(O₂CCH₃)₃]⁺ and [Rh₂(O₂CCH₂)₂]²⁺ complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1957–1961, September, 1989.     

Synthesis of Diels–Alder adducts of the quinolizidine alkaloids N-methylcytisine, (−)-leontidine,and (−)-thermopsine with N-phenylmaleimide

The Diels–Alder adducts of the quinolizidine alkaloids N-methylcytisine, (?)-leontidine, and (?)-thermopsine with N-phenylmaleimide have been synthesized. The structures and absolute configurations of the new asymmetric centers of the products were determined by NMR spectroscopy experiments, QC-calculations, and X-ray data.     

GC–MS Studies of Thiophenes in the Supercritical Fluid CO2 and Solvent Extracts of Tagetes patula L.

The intact plant parts and genetically modified hairy root clone #TpA6 of Tagetes patula were extracted with supercritical fluid CO₂ extraction (SFE) and a conventional solvent extraction. SFE optimization included the variation of fluid CO₂ pressure, dynamic time, and the addition of methanol modifier co-solvent. The four characteristic thiophene metabolites, 5-(3-buten-1-ynyl)-2,2′-bithienyl (BBT), 2,2′:5′,2″-terthiophene (α-T), 5-(4-acetoxy-1-butynyl)-2,2′-bithienyl (BBTOAc), and 5-(3,4-diacetoxy-1-butynyl)-2,2′-bithienyl [BBT(OAc)₂], were analysed by GC–MS. The proposed SFE method allowed the selective extraction of thiophenes in 60 min dynamic time with supercritical CO₂ without modifier co-solvent, at 30 MPa and 40 °C. The SFE and the reference solvent extraction yielded similar results. The SFE of intact roots and flowers yielded 717 ± 31.3 and 480 ± 26.6 μg g^?1 α-T, respectively, while the leaves did not contain considerable amounts of thiophenes. Remarkable amounts of BBT, BBTOAc, and BBT(OAc)₂ were characteristic of the SFE of hairy root cultures.     

Penta‐ and hexa‐m‐phenylcyclophosphites and their derivatives

New representatives of an original class of crown ethers—cyclopenta‐ and cyclohexaresorcinolamidophosphites—were synthesized using the molecular assemblage technique. Their thio and oxo derivatives were obtained, as well as the rhodium (I) complexes. A macrocycle containing both tri‐ and pentavalent phosphorus atoms was synthesized. ¹H and ³¹P NMR spectroscopy data suggested the higher conformational flexibility of phosphite macrocycles as compared to phosphate ones. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:129–137, 2000