Polymerization of Bulky of Oxirane Monomers Leading to Polyethers Exhibiting Intramolecular Charge Transfer Interactions

Abstract

Three novel oxirane monomers, 2‐methoxycarbonyl‐3‐(3,4‐dibenzyloxyphenyl)oxirane (MDBPO), 2‐benzyloxycarbonyl‐3‐(3,4‐dibenzyloxyphenyl)oxirane (BDBPO), and 2‐t‐butyloxycarbonyl‐3‐(3,4‐dibenzyloxyphenyl)oxirane (TBDBPO) are prepared and polymerized using BF3‐OEt2 in CH2Cl2 to yield polyethers. The monomers smoothly lead to polymers under the cationic conditions in spite of the monomers' rather bulky structures. The obtained polymers exhibit characteristic UV spectra with intramolecular charge transfer (ICT) bands through hetero π‐stacked structure formed between the side‐chain carbonyl group and the phenyl group directly connects to the main chain. The relative intensity of the ICT bands is the strongest for poly(TBDBPO) having bulky t‐butyl ester group. This spectral feature is considered to have connection with rigidity of polymer chain. Poly(TBDBPO) having the bulkiest side‐chain group is considered to possess the most rigid chain conformation that can account for its strongest ICT interactions that may occur between the carbonyl group and the phenyl group directly attached to the main chain. The proposed rigid chain conformation of poly(TBDBPO) is supported by the fact that the polymer does not show clear Tg while the other two polymers do.

Enzymatic Synthesis and Antimicrobial Activity of Oligomer Analogues of Medicinal Biopolymers from Comfrey and Other Species of the Boraginaceae Family

“…TBDBPO did not polymerize under various conditions. These results might have been caused by the presence of bulky substituents in MDBPO, DBBPO, and TBDBPO, compared with MDMPO [38].…”

“…We have recently reported the synthesis and cationic polymerization of 2-methoxycarbonyl-3-(3,4-dimethoxyphenyl)oxirane (MDMPO) (Figure 3(3)) [37] 6)) [38]. The molecular masses of the obtained polymers poly(MDBPO) and poly(DBBPO) (M n = 810-2755 Da and 970-2840 Da, respectively) were markedly lower than those of poly(MDMPO)-M n 3800-12 800 Da (vs polystyrene standards).…”