Dynamically Stable Helices of Poly(N-propargylamides) with Bulky Aliphatic Groups

Abstract

N-Propargylamides with bulky pendent groups [HCtCCH2NHCOR, 9: R ) CH2C(CH3)3, 10: R ) C(CH3)3, 11: R ) C(CH3)2CH2CH2CH3, 12: R ) CH(CH2CH3)2, 13: R ) CH(CH2CH2CH3)2] were polymerized with a rhodium catalyst, (nbd)Rh + B -(C6H5)4 (nbd ) 2,5-norbornadiene), to obtain the polymers in 80-92% yields. Poly(11) and poly(12) possessed moderate molecular weights (Mn g 10 000) and were totally soluble in a few solvents including chloroform. On the other hand, the Mn values of poly( 9), poly-(10), and poly(13) were no more than 5000, and these polymers were not completely soluble in any solvents. The conformational transition behavior of these polymers was examined by temperature-variable UVvis spectroscopy in chloroform solution, which revealed that poly(10)-poly(13) could form dynamically stable helical conformation even at 60 °C. By copolymerizations of monomers 9 and 10 with monomer 4, HCtCCH2NHCO(CH2)4H, the solubility of the polymers was effectively improved and almost all the copolymers totally dissolved in chloroform, while the molecular weights of the copolymers increased up to 18 600-45 000. Moreover, the helix contents of poly(4 0.63-co-90.37) and poly (40.40-co-100.60) were the highest among the two series of (co)polymers, respectively. It is concluded that the copolymerization of 9 and 10 with 4 effectively decreased the steric repulsion between the crowded side chains, which probably allowed the copolymers to take helical conformation efficiently.

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.…”

“…1). This method had been widely used to determine the cis contents of poly(N -propargylamide)s [23] and poly(N -propargylurea)s [26]. The solubility of the four polymers, poly(1), poly(2), poly(3) and poly(4), was examined in six organic solvents: toluene, CH 2 Cl 2 , CHCl 3 , THF (tetrahydrofuran), DMF (N ,N -dimethylformamide) and DMSO (dimethyl sulfoxide).…”

“…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.…”

Synthesis and Properties of Helical Poly(macromonomer) Consisting of Polyacetylene Main Chain and Poly(methyl methacrylate) Side Chains

“…[24][25][26][27][28][29] However, the cis olefinic proton signal was not observed in the 1 H NMR spectrum of poly(M-PMMA), probably because of the low mobility of the polyacetylene main chain. 50 The GPC traces of M-PMMA and poly(M-PMMA) (Run 4, Table I) are illustrated in Figure 2.…”

“…[1][2][3][4][5] There are several classes of wellordered synthetic helical polymers including poly-(alkyl methacrylates), [6][7][8][9] polychloral, 10,11 polyisocyanides, [12][13][14][15] polyisocyanates, [16][17][18][19] and polysilanes. [20][21][22][23] Besides, some helical polyacetylenes have been synthesized by Rh-catalyzed polymerization of acetylenic monomers having chiral side groups such as chiral carboxylic acids, [24][25][26][27][28][29] alcohols, [30][31][32][33] amino acids, [34][35][36][37][38][39][40] sugars [41][42][43] and terpenes 44 as the helical sources. Recently, our laboratory reported that (S)-1-methylpropargyl alcohol served as a powerful helical source for substituted polyacetylenes.…”