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

Abstract

This article reports for the first time about a novel category of mono-substituted acetylene monomers (1-4, M1-M4) (C≡CCH 2 NHCSNHR, R for M1 = CH 2 CH 3 ; M2 = (CH 2 ) 3 CH 3 ; M3 = (CH 2 ) 5 CH 3 ; M4 = C 6 H 5 ). The four monomers were identified by FT-IR, 1 H-NMR, 13 C-NMR spectroscopy and elementary analysis. In the presence of a rhodium catalyst ((nbd)Rh + B − (C 6 H 5 ) 4 (nbd = 2,5-norbornadiene)), M1-M4 underwent polymerization and provided the expected poly(N-propargylthiourea)s in a moderate to high yield (58-92%) and with a high cis content ( 91%) in the polymer backbones. The substituents had a big influence on the solubility of poly(N-propargylthioureas). Among the four polymers, polymer 4 (poly(4)) showed good solubility and relatively higher number-average molecular weight (up to 12 000). This polymer was further characterized by FT-IR and UV-Vis spectroscopy. TGA analysis demonstrated that the polymer remained stable up to 175 • C. Poly(4) exhibited considerable adsorption ability toward to Fe 3+ ions. The novel substituted polyacetylenes are also expected to exhibit some unique properties, such as inhibition of bacteria, chiral recognition, metal extraction and metal detection, derived from a combination of conjugated polymer backbones and highly functional thiourea groups in the side-chains.

Novel optically active helical poly(N-propargylthiourea)s: synthesis, characterization and complexing ability toward Fe(iii) ions

“…It seems that the thiourea groups are not favorable for the monomers to form polymers with high molecular weight. 11 As we expected, poly(1) and poly (2) showed high specific rotations compared with those of the corresponding monomers (Table 1), reflecting that both of them were optically active. However, poly(3) and monomer 3 did not show optical activity because they are short of chiral carbon atom in their chemical structure.…”

“…Referring to the earlier studies, 11,14 polymerizations were carried out with (nbd)Rh + B À (C 6 H 5 ) 4 as a catalyst in a dry dimethyl formamide (DMF) under N 2 atmosphere, [monomer] 0 ¼ 0.5 M, [catalyst] ¼ 5 mM. After polymerization, the resulting solution was put into vacuum oven for 24 h at 30 C to evaporate the solvent.…”

“…poly(N-propargylamide)s, 8 poly(N-propargylsulfamide)s, 9 and poly(Npropargylurea)s. 10 In our previous study, a series of achiral thiourea moieties were successfully introduced in polyacetylene backbones as side chains. 11 Regretfully, the resulting polymers could not form helical conformation under the examined conditions. Based on the earlier poly(N-propargylthiourea)s without helices, two novel chiral poly(N-propargylthiourea)s (poly(1) and poly (2)) and an achiral poly(N-propargylthiourea) (poly(3)) were further designed and synthesized for the first time in this study.…”