Chiral Polyurea from Tartaric Acid Derived and Lysine Backbone: A Synthetic and Computational Study
GC Unay and E Yildirim and A Akdag, CHEMISTRYSELECT, 5, 13358-13369 (2020).
In recent years, the studies on artificial helical polymers have become an attractive field due to their impressive optical activity and functions. They have numerous potential applications in many areas such as chiral recognition, enantioselective crystallization, enantioselective release, asymmetric catalysis, and 3D displays.Two new urea containing polymers were synthesized in this study. P-1 synthesis was accomplished, starting from tartaric acid. Tartaric acid was successfully converted to diamine 4. The diamine was treated with a p-phenylene diisocyanate to get helical structures at the macroscopic level, as evidenced by SEM images. This was shown to be the case through interchain H-bonding between urea groups and microphase separation between the segments due to hydrophobicity difference along the chain. Limited conformational space in P-1 also assisted the helical structure formation. P-2 was synthesized by treating L-lysine with p-phenylene diisocyanate. Due to the ample conformational space and intersegmental mixing due to hydrogen bond between urea and L-lysine segments, P-2 was shown not to be in a helical conformation. Molecular dynamics simulations and first principle studies were used to explain observed structural behaviour for these polymers.
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