Chiral Conversion and Memory of TPPS J-aggregates in Complex Micelles: PEG-b-PDMAEMA/TPPS

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• 作者：Lizhi Zhao ; Rui Xiang ; Rujiang Ma ; Xin Wang ; Yingli An ; Linqi Shi
• 刊名：Langmuir
• 出版年：2011
• 出版时间：September 20, 2011
• 年：2011
• 卷：27
• 期：18
• 页码：11554-11559
• 全文大小：906K
• 年卷期：v.27,no.18(September 20, 2011)
• ISSN：1520-5827

文摘

In the presence of tryptophan (Trp), complex micelles were prepared by 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) and poly(ethylene glycol)-block-poly(2-(dimethylamino)ethyl methylacrylate) (PEG-b-PDMAEMA) in aqueous solutions at pH 1.8. Different mixing sequences led to different morphologies. Spheres and nanorods of small size were obtained in sequence I (P/Trp+TPPS) where TPPS was added into the mixed solution of PEG-b-PDMAEMA and Trp. More nanorods of larger length were achieved in sequence II (TPPS/Trp+P) where the copolymer was added as the last component. Two types of supramolecular chirality of TPPS aggregates caused by mixing sequences were investigated. In (P/Trp+TPPS), the circular dichroism (CD) signal of H-band was in line with the chirality of Trp while that of J-band exhibited an opposite signal (Chirality I). In (TPPS/Trp+P), chiral signals at both H- and J-bands followed that of Trp (Chirality II). The conversion between the two types of chirality can be accomplished by modulating the molar ratio of the repeating units on block PDMAEMA to TPPS, or a cycle of pH 1.8鈥?.5鈥?.8 processing on the micelle solution. In addition, the supramolecular chirality can be memorized via strong electrostatic interaction with achiral copolymer even after removal of the chiral template, but only Chirality II can be cyclically 鈥渟witched-off-on鈥?