Synthesis Of Optically Active Poly(N-Propargylsulfamides) With Helical Conformation And Their Application In Functional Materials

Artificial helical polymers not only show unique electronic, magnetic and optical properties but also possess significant potential applications originated in their molecular recognition ability, catalytic ability for asymmetric synthesis, and optical resolution ability.A novel chiral N-propargylsulfamide monomer (la) and its enantiomer (1b) were synthesized and polymerized with (nbd)Rh⁺B^-(C₆H₅)₄ as a catalyst providing poly(1) (poly(1a) and poly(1b)) in high yields (≥99%). Poly(1) could take stable helices in less polar solvents (chloroform and THF), demonstrated by strong CD signals and UV-vis absorption peaks at about 415 nm and the large specific rotations; but in more polar solvents including DMF and DMSO, poly(1) failed to form helix. Quantitative evaluation with anisotropy factor showed that the helical screw sense had a relatively high thermal stability. These results together with the IR spectra measured in solvents showed that hydrogen bonding between the neighboring sulfamide groups is one of the main driving forces for poly(1) to adopt stable helices.In addition, copolymerization of monomer la and monomer 2 was conducted, the solubility of poly(1) was improved drastically. However, the copolymerization had adverse effects on the formation of stable helices in the Copolymers. Copolymerization of monomer la and monomer 1b was conducted, and the result showed that the copolymerization obeyed the "majority rules"; Copolymerization of monomer la and monomer 3 was conducted, and the result showed that the copolymerization obeyed the "sergeants-and-soldiers principle"; Copolymerization of monomer la and monomer 4 was conducted, and the result showed that the copolymerization could not obey the "sergeants-and-soldiers principle".The influence of solvent on the geometrical and secondary structure of poly(N-propargyl-(1R)-camphor-10-sulfamide) (poly(1)) was investigated. ¹H NMR spectra of poly(1) measured in varied solvent and at varied temperature showed that solvent influenced the mobility of the polymer's main chain. Poly(1) adopted stable helices or disordered states in different solvents. Poly(1) could take helical conformation in toluene. Further characterization showed that hydrogen bond could form between the neighboring sulfamide groups. In mixed solvent comprising toluene and methanol, poly(1) underwent aggregation rather than taking helix when the content of methanol exceeded 40 vol %. In another binary solvent comprising DMSO and chloroform, poly(1) changed gradually from helical to disordered conformation with increasing the content of DMSOA macroporous molecularly imprinted monolith is successfully fabricated by polymerization of styrene (St) and divinyl benzene (DVB), using heliacal copolymer as a template and organic spheres as porogen. The parameters of polymerization were optimized. The optimization condition is as follow: polymerization temperature: 43℃; ratio of St and DVB is 50:50 (w/w). SEM observation showed that the monolith has well-defined 3D ordered macroporous structure and large internal surface. Enantiomer-selective adsorption experiment showed that the monolith can predominantly adsorb the enantiomer of the corresponding monomer of the print macromolecular. This result suggested that, via the interaction between the guest (template) and the host (crosslinked polymer), the monolith may has chiral cavities which have a shape similar to the template polymer.