Synthesis And Fluoride Ion Sensing Properties Of Borane-containing Polyacetylene Derevatives

The design and synthesis of functional polyacetylenes and organoborane-containing conjugated π-systems have both been hot topic in the field of polymer science. On one hand, functional side groups can endow the substituted polyacetylenes with corresponding functionality due to their electronic interaction, steric effect, charge transfer or energy transfer. What’s more, versatile functionalities can be achieved by adjusting the interaction between the main chain and functional side groups. On the other hand, organoborane-containing conjugated π-systems display unique electronic and optical properties. These attractive materials find potential applications in emissive devices, nonlinear optical materials, charge-transport materials, and chemosensors, etc. It is expected that the incorporation of organoborane groups into polyacetylene can lead to novel functional materials with unique characteristics which are derived from actions of boryl moieties and conjugation main chain.According to the theory of Sonogashira Coupling, four objective monomers (la, lc,1A,1C) were designed and and sucessfully synthesized. They were polymerized to yield polyacetylene derivatives (2a,2c,2A,2C) with Rh+(nbd)[C6H5B-(C6H5)3] as catalysts. Two of them are triarylborane-containing polyacetylene derivatives (2a,2c), and the other two (2A,2C) are the same with the corresponding2a and2c except for having no triarylborane. All polymers have good solubility in common organic solvents except2C.2A and2C have better thermo-stability than the corresponding triarylborane-containing polyacetylene derivatives (2a,2c). The temperature of weight loss (Td) of2a and2c were approximately265℃, while2A and2C were340℃and390℃respectively.Fluoride sensing properties of the triarylborane-containing polyacetylene derivatives (2a,2c) were investigated by adding tetra-n-butylammonium salts of a series of anions to their THF solution with UV-vis absorption and emission measurements. The results revealed that the triarylborane-containing monomers showed the "turn off" response for F".2a containing fluorenyl moieties exhibited "turn on" fluorescence F-sensing ability. The addition of F’ changed the color of the biphenyl groups-containing2c from yellow to orange in THF, indicating that2c can be used as a colorimetric sensor.2a and2c could selectively detected F" while did not show any response for other anions such as Cl", Br-, and I-. However, the optical properties of2A and its monomer (1A) did not show any change while F-exists,1a,1c and 1A monomers possessed higher photoluminescence efficiency than their corresponding polymers. Their results indicated that different side group can endow the polymer with corresponding functionality.