Preparation Of Fluorescent Conjugated Polymers With Protonated Amino Groups And The Application In Detecting Aldehydes

Aldehydes are widely used in our daily life,and may cause great harm to human health.Many methods have been developed for detecting them.For selectively sensing of aldehydes using small molecules,primary amino groups are commonly used as receptors,based on the reaction between primary amino group and aldehyde group to form the Schiff base.The fluorescence of small molecules changed based on the photo-induced electron transfer or intramolecular charge transfer mechanism.However,to the best of our knowledge,there is no literature that employed fluorescent conjugated polymers for detecting aldehydes.Here,we report the synthesis of fluorescent conjugated polymers with protonated amino groups and the application in detecting aldehydes,especially GA.System 1:The PPE-NBoc was obtained via the Sonogashira coupling polymerization,and the protecting groups were then removed by treating PPE-NBoc with trifluoroacetic acid to yield poly[p-?phenyleneethynylene?]with protonated primary amino pedant groups?PPE-NH₃⁺?.The fluorescence of the conjugated polyelectrolyte PPE-NH₃⁺in aqueous solution changed upon aldehydes.GA displayed the strongest quenching of fluourescence of PPE-NH₃⁺,and the detection limit was 0.49?M.GA,as a dialdehyde,could react with amino groups on different polymer chains simultaneously,and thus might result in more efficient chain aggregation and quenching.Finally,this sensory system was also demonstrated to be very effective in detecting GA in real water samples.System 2:Focusing on the detection of aldehyde vapors,four different fibrous membranes,i.e.,PPE-NH₃⁺/PVA,PPE-NH₃⁺/PAN,PPV/PVA and PPV/PEI/PVA were prepared by electrospinning technique.Only the PPE-NH₃⁺/PVA fibrous membrane showed a great response to aldehydes vapors.The results indicated that a synergistic effect between the matrix polymer and the conjugated polymer of the PPE-NH₃⁺/PVA fibrous membrane would be the key to detection of aldehyde vapors.Very likely,the PPE-NH₃⁺was enriched on the surface of the fibers,therefore the probability of reaction with aldehyde increased.System 3:Two different polyelectrolytes P1-NH₃⁺and P2-NH₃⁺were prepared by Sonogashira coupling followed by deprotection.The polyelectrolyte P2-NH₃⁺was sonicated in sodium hydroxide solution to prepare PPE-NH₂COO^-nanoparticles.These nanoparticles contain both amino and carboxyl groups,and in the form of carboxylates they can be dispersed in water stably.