Synthesis and Properties of Poly(phenylene ethynylene)s with Pendant Hexafluoro-2-propanol Groups

Abstract

Several poly(phenylene ethynylene)s with pendant hexafluoro-2-propanol (HFIP) groups have been synthesized and characterized in terms of their solution and thin-film optical properties. The incorporation of strongly hydrogen-bond-donating HFIP groups into conjugated polymers is shown to greatly enhance their fluorescence response upon exposure to the vapors of several hydrogen-bondaccepting analytes such as pyridine and 2,4-dichloropyrimidine. The enhanced sensitivity of these conjugated polymer-based chemosensors is the result of stronger analyte/polymer binding interactions and more facile photoinduced charge-transfer reactions with hydrogen-bonded analytes.

Optical chemosensors and reagents to detect explosives

“…5) and tested their emission behaviour in the presence of electron deficient molecules. 26 Polymers 8 and 9 contain pendant hexafluoro-2-propanol groups, therefore displaying a strong hydrogen-bonding donating character. The exposure of polymers 7-9 to the vapours of 2,4-DNT brought about a moderate quenching of the emission intensities (between 16% and 28%).…”

Lewis acid–base interactions enhance explosives sensing in silacycle polymers

“…Adsorption is facilitated by hydrophobic π–π interactions. To further improve detection, other functionalities were employed to increase analyte binding [ 6 ]. The high sensitivity of detection has led to application of conjugated organic polymers in a commercial instrument for the detection of landmines by ICX Technologies.…”

Detection of Explosive Vapors: The Roles of Exciton and Molecular Diffusion in Real‐Time Sensing

“…These recent results are at odds to the early work on explosive sensing using conjugated polymers, in which it was proposed that long exciton diffusion lengths resulted in high sensitivity. Those reports used poly(phenyleneethynylene)‐based (PPE) explosive vapor sensory materials, that contained pentiptycene moieties along the polymer backbone to increase the film porosity and reduce inter‐polymer interactions . Given the unique structure of these PPEs, it is possible that they could interact differently to the materials used in the more recently reported studies on amorphous fluorescent films.…”

“…These recent resultsa re at odds to the early work on explosive sensing using conjugatedp olymers, in which it wasp roposed that long exciton diffusion lengthsr esulted in high sensitivity.T hoser eports used poly(phenyleneethynylene)-based (PPE) explosive vapor sensory materials, [1,3,8,[11][12][13][14][15][16][17] that contained pentiptycene moieties along the polymer backbone to increaset he film porosity and reducei nter-polymer interactions. [8,14,[18][19][20] Given the unique structure of these PPEs, it is possible that they could interact differently to the materials used in the more recently reported studies on amorphousf luorescent films. However, we note that the exposure of thin (2 nm or 20 nm) pentiptycene-PPE films to saturated vapors of explosive analytes did not lead to instantaneous quenching of the film luminescence, suggesting that the exciton diffusion lengths in such films might not be as large as first thought.…”