Folding of aromatic polyamides into a rare intrachain β-sheet type structure and further reinforcement of the secondary structure through host–guest interactions

Abstract

We report the design, synthesis, and folding of aromatic polyamides into an intrachain β-sheet-like structure. Additionally, the effect of a guest molecule in stabilizing the β-sheet structure has also been demonstrated here.

Comparison of Thermoresponsive Behavior between Polyproline and Periodically Grafted Polyproline toward Hofmeister Ions: An Explanation of Its Conformational Origin

“…Hence, the observed hysteresis is primarily controlled by kinetics and the kinetics of recovering the native PPII conformation was extremely slow. In contrast to PLP 50 , the temperature-induced conformational change for PLP 46 -TEG was remarkably different. Figure 5 (bottom panel) shows that the PLP 46 -TEG shows characteristic PPII conformation of polyproline at room temperature.…”

“…Nevertheless, PLP 46 -TEG exhibits excellent thermoresponsive behavior in the presence of inorganic salts such as Na 2 SO 4 , NaCl, and so forth. Therefore, we compare the thermoresponsive behavior of PLP 46 -TEG with the native polyproline (PLP 50 ) of similar chain length (in a salt solution) by measuring the transmittance at 600 nm wavelength using a simple UV−vis spectrophotometer. As shown in Figure 2A,B,D,E, depending on the employed salt solution, the transmittance decreases sharply beyond a critical temperature.…”

“…The detailed synthetic procedure for the monomer is provided in the Supporting Information File (Scheme S1). The post-polymerization modifications of the propargyloxy-functionalized polyproline were carried out using TEG-N 3 via azide-yne click chemistry. − The purity of the NCA monomer is crucial for the preparation of homopolypeptide with a controlled structure and low polydispersity indices (Đ). In this regard, a highly crystalline propargyloxy NCA monomer (2) obtained after the recrystallization (mp = 60–62 °C) of the crude NCA monomer ensures the purity of the monomer used for ROP purposes.…”