Efficient Construction of Oligocholate Foldamers via “Click” Chemistry and Their Tolerance of Structural Heterogeneity
摘要:
The 1,3-dipolar cycloaddition between an alkynyl-terminated cholate trimer and an azido-functionalized cholate hexamer readily afforded the nonamer and dodecamer derivatives; whereas amide coupling employed in previous oligocholate synthesis failed beyond the octamer. Unlike typical oligocholate foldamers with exclusively head-to-tall arrangement of the repeat units, the newly synthesized "clicked" oligocholates contained head-to-head arrangement and flexible tethers in the sequence. Despite large structural perturbations, the clicked oligocholates folded similarly as the parent foldamers, demonstrating the robustness of the solvophobically driven folding mechanism.
Dispersion of large single-walled carbon nanotube (SWCNT) bundles into individual nanotubes or small bundles and thus strengthening of the nanotube/matrix interfacial interaction are prerequisites for taking full advantage of the remarkable multifunctional properties of SWCNTs in various carbon nanotube-based composites. Noncovalent functionalization of SWCNTs is an attractive option to simultaneously achieve these conditions. Toward this end, three reactive amino-containing pyrene derivatives (AmPys) with various spacer chain lengths were synthesized. One with the longest spacer length (12 methylene units, AmPy-12) shows the highest functionalization efficiency for SWCNTs in terms of dispersibility. Systematic characterization on a SWCNT/AmPy-12 hybrid suggests that ca. 10 wt% of AmPy-12 is strongly adsorbed on SWCNTs through π–π interactions, making them steadily dispersed into individual ones and/or small bundles without noticeable change in their electronic structure. AmPy-12-functionalized SWCNTs were then used for the preparation of epoxy composites. Since the SWCNT/epoxy interface was well engineered at a molecular level by application of AmPy-12, which interacts noncovalently with SWCNT but bonds chemically to the epoxy matrix, the composite with only 0.3 wt% SWCNTs displays an increase of 54% and 27% in tensile strength and Young's modulus, respectively, over neat resin. A low electrical percolation threshold of 0.1 wt% SWCNTs and improved thermal properties were also observed.
Pyrene‐Functionalised Copper Complexes as Potential Dual‐Modality Imaging Agents
作者:Jason P. Holland、Victoria Fisher、Jennie A. Hickin、Josephine M. Peach
DOI:10.1002/ejic.200900823
日期:2010.1
-copper complexes are reported. In contrast to previously reported bis(thiosemicarbazonato)Cu 2+ complexes which are nonfluorescent, the pyrene group remains highly fluorescent. The compounds have been characterised by using a wide range of techniques including reverse-phase HPLC, cyclic voltammetry, NMR, electronic absorption (UV/ Vis), infrared and fluorescence emission spectroscopy. Spectroelectrochemistry
Self-Assembled Single-Walled Carbon Nanotube:Zinc–Porphyrin Hybrids through Ammonium Ion–Crown Ether Interaction: Construction and Electron Transfer
作者:Francis D'Souza、Raghu Chitta、Atula S. D. Sandanayaka、Navaneetha K. Subbaiyan、Lawrence D'Souza、Yasuyuki Araki、Osamu Ito
DOI:10.1002/chem.200700583
日期:2007.10.5
An ammoniumion-crownetherinteraction has been successfully used to construct porphyrin-single-walled carbonnanotube (SWNT) donor-acceptor hybrids. The [18]crown-6 to alkyl ammonium ion binding strategy resulted in porphyrin-SWNT nanohybrids that are stable and soluble in DMF. The porphyrin-SWNT hybrids were characterized by spectroscopic, TEM, and electrochemical techniques. Both steady-state and
Efficient Construction of Oligocholate Foldamers via “Click” Chemistry and Their Tolerance of Structural Heterogeneity
作者:Xingang Pan、Yan Zhao
DOI:10.1021/ol802364c
日期:2009.1.1
The 1,3-dipolar cycloaddition between an alkynyl-terminated cholate trimer and an azido-functionalized cholate hexamer readily afforded the nonamer and dodecamer derivatives; whereas amide coupling employed in previous oligocholate synthesis failed beyond the octamer. Unlike typical oligocholate foldamers with exclusively head-to-tall arrangement of the repeat units, the newly synthesized "clicked" oligocholates contained head-to-head arrangement and flexible tethers in the sequence. Despite large structural perturbations, the clicked oligocholates folded similarly as the parent foldamers, demonstrating the robustness of the solvophobically driven folding mechanism.
Turn-on fluorescence of ruthenium pyrene complexes in response to bovine serum albumin
作者:Saša Opačak、Margareta Pernar Kovač、Anamaria Brozovic、Ivo Piantanida、Srećko I. Kirin
DOI:10.1039/d3dt02289g
日期:——
Two novel pyrene triphenylphosphine ruthenium conjugates act as fluorescent turn-on beacons for serum albumin, being non-fluorescent in aqueous media but exhibiting strong emissionuponbinding to BSA. The selective cytotoxicity of the compounds against tumour cells is enhanced upon irradiation by UV-light, paving the way for application in photodynamic therapy under two-photon excitation.