Synthesis of optically active poly(N‐propargylsulfamides) with helical conformation

Abstract

A novel chiral N‐propargylsulfamide monomer (1a) 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 circular dichroism 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 1a 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. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 500–508, 2007

A Novel Type of Mono-Substituted Polyacetylene: Synthesis and Characterization of Poly(N-Propargylthiourea)s

“…The results with respect to UV-Vis absorption spectra are similar to some mono-substituted polyacetylenes studied by us earlier, e.g., poly(N -propargylsulfamide)s [34] and poly(N -propargylurea)s [26]. However, under the investigated conditions, the present poly(N -propargylthiourea)s failed to form helical conformations, which were frequently observed in mono-substituted polyacetylenes [23][24][25]35]. The lacking of ordered helical conformations in the currently studied poly(N -propargylthiourea)s is assumed to be originated in the two -N-H groups of poly(4) in the pendant chains.…”

“…In appearance, poly(4) itself (Fig. 6a) appeared pale yellowish, similar to the other substituted polyacetylenes synthesized in our earlier studies [25,36,37]. The color of the metal complexes gradually became deeper with increasing amounts of Fe 3+ ions.…”

“…Acetylene-based polymers, as typical conjugated polymers, have been extensively investigated by the groups of Masuda [18], Tang [19], Yashima [20], Percec [21] and Aoki [22]. In our earlier studies, a series of mono-substituted polyacetylenes bearing various functional pendent groups have been synthesized, including poly(N -propargylamide)s [23,24], poly(Npropargylsulfamide)s [25] and poly(N -propargylurea) [26]. Taking into consideration of the versatile functional thiourea groups and interesting properties of conjugated polyacetylenes, we expect to design and prepare a novel type of substituted polyacetylenes containing pendent thiourea moieties in the side-chains.…”

Influence of Solvent on the Secondary Structure of Helical Poly(N-propargyl-(1R)-camphor-10-sulfamide)

“…Our previous investigations 16 showed that poly(N-propargylsulfamides), one of the substituted polyacetylenes could take helical conformation. However, the effect of solvent composition on the secondary structure of this new class of helical polymer has not been studied.…”

“…16 The main procedures are as follows. 1R-(À)-10-camphorsulfonyl chloride (5 g, 20 mmol), pyridine (3.2 mL, 40 mmol) and propargylamine (2.8 mL, 40 mmol) were added into diethyl ether (ca.…”