258330-87-9Relevant academic research and scientific papers
Synthesis and chiroptical properties of chiral azoaromatic dendrimers with a C3-symmetrical core
Angiolini, Luigi,Benelli, Tiziana,Giorgini, Loris
experimental part, p. 99 - 109 (2010/09/06)
New chiral azoaromatic dendrimeric systems have been synthesized starting from 1,3,5-benzenetricarbonyl trichloride as the core molecule. The simultaneous presence of the (S)-3-hydroxy pyrrolidinyl ring as the optically active moiety and the azobenzene donor-acceptor conjugated system as the photochromic group with permanent dipole moment, makes these systems potentially interesting as materials for advanced applications in nanotechnologies. All the compounds obtained have been characterized with particular attention to the effects induced by changing the electron-with-drawing group in the chromophoric moiety and to their optical activity. A strong nonlinear enhancement of chiroptical properties related to the number of chiral units linked to the symmetrical core is observed in these derivatives, which indicates the presence of conformationally chiral substructures.
Mechanism of Site-Directed Protein Cross-Linking. Protein-Directed Selectivity in Reactions of Hemoglobin with Aryl Trimesates
Kluger, Ronald,de Stefano, Vittorio
, p. 214 - 219 (2007/10/03)
Site-directed cross-linking of hemoglobin has become an efficient way to produce a structurally defined altered protein with desirable functional properties. The reagent trimesoyl tris(3,5-dibromosalicylate) (1) introduces a bis amide cross-link derived from the ∈-amino groups of the side chains of the two β-Lys-82 residues in human hemoglobin. The basis of its specificity was investigated using a set of analogues of 1 (2-12). There are marked differences in the reaction patterns of these compounds with amino groups in hemoglobin compared to reactions with n-propylamine. The compounds that effectively modify the protein contain a carboxyl group ortho to the phenolic oxygen of the ester, while materials with meta or para carboxyl groups give little or no reaction. In contrast, the reactions with n-propylamine are slowest with the ortho carboxyl materials. Addition of the unreactive compound 5 to a solution containing hemoglobin reduces the ability of 1 to modify the protein, showing that the unreactive compound binds but does not react. On the basis of these observations and the known reaction patterns of salicylates, it is clear that the environment in the protein controls the reaction, regardless of the inherent reactivity of the reagent. We propose that the carboxyl group positions the reagent critically within the protein. Only the ortho arrangement permits transfer of the acyl function to the nucleophile.
