标题：Morphology and chirality controlled self-assembled nanostructures of porphyrin-pentapeptide conjugate: effect of the peptide secondary conformation
作者：Quanbo Wang;Yanli Chen;Pan Ma
作者机构：[Wang, Q] Department of Chemistry, Shandong University, Jinan 250100, China;[ Chen, Y] Department of Chemistry, University of Jinan, Jinan 250022, Chi 更多
通讯作者地址：[Zhang, XM]Shandong Univ, Dept Chem, Jinan 250100, Peoples R China.
来源：Journal of Materials Chemistry: An Interdisciplinary Journal dealing with Synthesis, Structures, Properties and Applications of Materials, Particulary Those Associated with Advanced Technology
摘要：An optically active porphyrin-pentapeptide conjugate 1, actually a porphyrinato zinc complex covalently linked with a glycinyl-alanyl-glycinyl-alanyl-glycine (GAGAG) peptide chain, was designed and synthesized. The self-assembly properties of this novel porphyrin-pentapeptide conjugate in THF/n-hexane and THF/water were comparatively investigated by electronic absorption, circular dichroism (CD), IR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) technique. Associated with the different secondary conformation of the pentapeptide chain covalently linked to the porphyrin ring in different solvent systems, self-assembly of conjugate 1 leads to the formation of nanofibers with right-handed helical arrangement and nanotubes with left-handed helical arrangement in a stack of porphyrin chromophores according to the CD spectroscopic result in apolar THF/n-hexane(l : 3) and polar THF/water (1 : 3) system depending on the cooperation between intramolecular or intermolecular hydrogen bonding interaction with chiral discrimination between pentapeptide chains and porphyrin-porphyrin interactions in the direction parallel to the tetrapyrrole ring of neighboring conjugate molecules. IR spectroscopic result clearly reveals the α-helix and β-sheet secondary conformation, respectively, employed by the pentapeptide chain attached at the porphyrin core in the nanostructures formed in THF/n-hexane (1 : 3) and THF/ water (1 : 3). The X-ray diffraction (XRD) result confirms that in the nanotubes, a dimeric supramolecular bilayer structure was formed through an intermolecular hydrogen bonding interaction between two conjugate molecules which, as the building block, self-assembles into the target nanostructures. These results clearly reveal the effect of a secondary conformation of pentapeptide chain in the conjugate molecule on the packing mode of porphyrin chromophore, supramolecular chirality, and morphology of the sel