Study of the properties of luminescent poly[1-(2-propynyl)-3-methylimidazolium bromide] oligomers prepared using a Mo(CO)6/phenol catalyst

Abstract

Luminescent poly[1-(2-propynyl)-3-methylimidazolium bromide] oligomers (degree of polymerization = 4), having a conjugated polyacetylene type backbone and imidazolium as pendant group, have successfully been synthesized with 55% yield by polymerizing 1-(2-propynyl)-3-methylimidazolium bromide ionic liquid using Mo(CO)₆/phenol as catalyst (89 : 1 : 89) at 120 °C. ¹H NMR, ¹³C NMR, FTIR, ESI-MS, and UV-Vis studies have confirmed its formation. It has shown a strong increase in fluorescence intensity compared to the monomer which is unusual for monosubstituted polyacetylenes. Further addition of sodium acetate has enhanced its fluorescence properties considerably. Thermal stability and solution conductivity of it have decreased, while its hygroscopic property has increased with respect to its monomer.