869308-34-9Relevant academic research and scientific papers
The self-assembly of amphiphilic oligothiophenes:Hydrogen bonding and poly(glutamate) complexation
Brustolin, Fiorella,Surin, Mathieu,Lemaur, Vincent,Romanazzi, Giuseppe,Sun, Qianyao,Cornil, Jerome,Lazzaroni, Roberto,Sommerdijk, Nico A. J. M.,Leclere, Philippe,Meijer
, p. 1703 - 1715 (2007)
The self-organization behavior of an amphiphilic sexithiophene bearing amide functionalities is studied and compared to that of a derivative bearing an ester group at the same position. The introduction of hydrogen-bond interactions in assemblies of these Π-conjugated oligomers is found to affect the molecular organization both in protic media and in thin deposits on mica. The amphiphilic 2,2′;5′,2″;5″,2?;5?, 2″″;5″″,2′″″-sexithiophene-5, 5′″″-dicarboxylic acid bis[(4,7,10,13,16-pentaoxaheptadecyl) amide] forms assemblies in n-butanol and water and partially aggregates in toluene. Spectroscopy reveals that the presence of a hydrogen-bonding moiety increases the thermal stability of the assemblies in n-butanol and even more in water solution. On mica surfaces, the formation of rod-like one-dimensional nano-structures is observed after deposition from toluene solutions. In addition, transmission electron microscopy in combination with selected area electron diffraction shows that in water plate-like structures are formed built from parallel oriented stacks, with a Π-Π distance of 3.5 A. Comparison of these data to molecular modeling and quantum chemistry calculations is used to better understand the influence of the amide group on the stacking of these compounds. The introduction of these H-bonding interactions leads to denser and more stable stacks. Furthermore, we show that a derivative of the amide compound, bearing terminal ammonium groups, forms a complex with chiral polyanions in aqueous media such that the sexithiophene segments are stacked in a meta-stable helical fashion with preferred handedness. We observed that poly(glutamate) and DNA generate a chiral sexithiophene assembly. In time the induced chirality disappears, which is explained by the meta-stability of the kinetically formed adduct. This constitutes one step forward towards the controlled formation of functional multi-component systems in aqueous solution.
Design, synthesis and biological evaluation of bivalent ligands against A 1-D 1 receptor heteromers
Shen, Jian,Zhang, Lei,Song, Wan-Ling,Meng, Tao,Wang, Xin,Chen, Lin,Feng, Lin-Yin,Xu, Ye-Chun,Shen, Jing-Kang
, p. 441 - 452 (2013/08/25)
Aim:To design and synthesize bivalent ligands for adenosine A 1-dopamine D 1 receptor heteromers (A 1-D 1 R), and evaluate their pharmacological activities.Methods:Bivalent ligands and their corresponding A 1 R monovalent ligands were designed and synthesized. The affinities of the bivalent ligands for A 1 R and D 1 R in rat brain membrane preparation were examined using radiolabeled binding assays. To demonstrate the formation of A 1-D 1 R, fluorescence resonance energy transfer (FRET) was conducted in HEK293 cells transfected with D 1-CFP and A 1-YFP. Molecular modeling was used to analyze the possible mode of protein-protein and protein-ligand interactions.Results:Two bivalent ligands for A 1 R and D 1 R (20a, 20b), as well as the corresponding A 1 R monovalent ligands (21a, 21b) were synthesized. In radiolabeled binding assays, the bivalent ligands showed affinities for A 1 R 10-100 times higher than those of the corresponding monovalent ligands. In FRET experiments, the bivalent ligands significantly increased the heterodimerization of A1R and D 1 R compared with the corresponding monovalent ligands. A heterodimer model with the interface of helixes 3, 4, 5 of A1R and helixes 1, 6, 7 from D 1 R was established with molecular modeling. The distance between the two ligand binding sites in the heterodimer model was approximately 48.4 ?, which was shorter than the length of the bivalent ligands.Conclusion:This study demonstrates the existence of A 1-D 1 R in situ and a simultaneous interaction of bivalent ligands with both the receptors.
