98273-17-7Relevant academic research and scientific papers
Molecular spoked wheels: Synthesis and self-assembly studies on rigid nanoscale 2D objects
Aggarwal, A. Vikas,Jester, Stefan-S.,Taheri, Sara Mehdizadeh,Foerster, Stephan,Hoeger, Sigurd
, p. 4480 - 4495 (2013/05/23)
We present the efficient synthesis of a new molecular spoked-wheel structure (MSW-3). Two derivatives with diameters of approximately 4 nm have been prepared. By highlighting the importance of pseudo-high-dilution conditions during cyclization, we were able to access the compounds on a several hundred milligram scale. In addition to the standard characterization (NMR spectroscopy, MS), we describe a detailed investigation of the optical properties of the fluorescent MSWs by comparison with appropriate model chromophores. Furthermore, a comprehensive study of the structure in solution by means of light- and X-ray scattering experiments has been conducted. Scanning tunneling microscopy (STM) revealed the two-dimensional organization of the molecules on highly oriented pyrolytic graphite and emphasized the spoked-wheel structure. The diameter of these molecules measured by small-angle X-ray scattering is in very good agreement with that obtained from STM and matches the results of molecular modeling. This confirms the rigidifying effect of the spokes, which results in highly shape-persistent nanometer-sized oblate organic compounds. Copyright
Synthesis of sterically hindered polychlorinated biphenyl derivatives
Joshi,Vyas,Duffel,Parkin,Lehmler
, p. 1045 - 1054 (2011/06/20)
A series of sterically hindered (methoxylated) polychlorinated biphenyl derivatives were synthesized using the Suzuki and the Ullmann coupling reactions. The Suzuki coupling with Pd(dba)2-dicyclohexylphosphino-2,6- dimethoxybiphenyl (DPDB) gave better yields (65-98%) compared to the classic Ullmann coupling reaction (20-38%). Despite the reactive catalyst system, no significant coupling with aromatic chlorine substituents was observed. Crystal structure analysis of four PCB derivatives revealed solid state dihedral angles ranging from 69.7 to 81.0, which indicates that these highly ortho-substituted PCB derivatives have some conformational flexibility. Georg Thieme Verlag Stuttgart.
Regioselective iodination of chlorinated aromatic compounds using silver salts
Joshi, Sudhir N.,Vyas, Sandhya M.,Wu, Huimin,Duffel, Michael W.,Parkin, Sean,Lehmler, Hans-Joachim
experimental part, p. 7461 - 7469 (2011/10/10)
The iodination of chlorinated aromatic compounds using Ag 2SO4/I2, AgSbF6/I2, AgBF4/I2, and AgPF6/I2 offers access to iodoarenes that are valuable intermediates in organic synthesis. Specifically, iodination of phenols, anisoles, and anilines with a 3,5-dichloro substitution pattern preferentially yielded the ortho, para, and para iodinated product, respectively. In the case of chlorobenzene and 3-chlorotoluene, AgSbF6/I2, AgBF4/I2, and AgPF 6/I2, but not Ag2SO4/I2, selectively introduced the iodine in para position to the chlorine substituent.
2,2',3,3',6,6'-Hexachlorobiphenyl hydroxylation by active site mutants of cytochrome P450 2B1 and 2B11
Waller, Stephen C.,He, You Ai,Harlow, Greg R.,He, You Qun,Mash, Eugene A.,Halpert, James R.
, p. 690 - 699 (2007/10/03)
The structural basis of species differences in cytochrome P450 2B- mediated hydroxylation of 2,2',3,3',6,6'-hexachlorobiphenyl (236HCB) was evaluated by using 14 site-directed mutants of cytochrome P450 2B1 and three point mutants of 2B11 expressed in Escherichia coli. To facilitate metabolite identification, seven possible products, including three hydroxylated and four dihydroxylated hexachlorobiphenyls, were synthesized by direct functionalization of precursors and Ullmann and crossed Ullmann reactions. HPLC and GCfMS analysis and comparison with authentic standards revealed that 2B1, 2B11, and all their mutants produced 4,5-dihydroxy-236HCB and 5-hydroxy- 236HCB, while 2B11 L363V and 2B1 I114V mutants also catalyzed hydroxylation at the 4-position. The amount of products formed by 2B1 mutants I114V, F206L, L209A, T302S, V363A, V363L, V367A, I477A, I477L, G478S, I480A, and I480L was smaller than that of the wild type. I477V exhibited unaltered 236HCB metabolism, and I480V produced twice as much dihydroxy product as the wild type. For 2B11, substitution of Val-114 or Asp-290 with Ile decreased the product yields. Replacement of Leu-363 with Val dramatically altered the profile of 236HCB metabolites. In addition to an increase in the overall level of hydroxylation, the mutant mainly catalyzed hydroxylation at the 4- position. Incubation of P450 2B1 with 5-hydroxy-236HCB produced 4,5- dihydroxy-236HCB, which indicates that 4,5-dihydroxy-236HCB may be formed by a direct hydroxylation of 5-hydroxy-236HCB. The findings from this study demonstrate the importance of residues 114, 206, 209, 302, 363, 367, 477, 478, and 480 in 2B1 and 114, 290, and 363 in 2B11 for 236HCB metabolism.
