Synthesis Of Chiral PEDOTs Bearing Chiral Moieties In Side Chains And Its Application In Chiral Recognition Field

Chirality(handedness)is ubiquitous in nature at the molecular level.Many essential biochemicals such as the natural amino acids and simple sugars are chirality and,significantly,exist in only one enantiomeric(mirror)form.Helical chirality is common in important biopolymers such as proteins,nucleic acids and DNA.Although enantiomers show the same physical properties(such as solubility,melting point,boiling point etc.),they can display different influence on living organisms,such as pharmacological activity,metabolic rate,metabolic processes,and toxicity.Therefore,it is very necessary to selective recognize enantiomer drugs in pharmaceutical industry as well as in clinic.On the one hand,to date,the dominant approaches for chiral recognition are chromatographic methods,spectroscopic techniques and sensor methods.Even if the chromatographic methods and spectroscopic techniques are fairly efficient,they are usually time consuming,require costly equipment and need sophisticated and extensive analysis procedures.However,electrochemical strategies offer some advantages over the other techniques such as low cost,simple equipment,on-line measurement and high sensitivity.Thus,the combination of the electrochemical chiral recognition approach and chiral electrodes can be potentially utilized to fabricate a chiral electrochemical sensor.On the other hand,chiral conducting polymers(CPs)that possess chirality and present chiral recognition opportunities when used as chiral electrode materials.They could,for example,find applications in electrochemical chiral sensing.Among the chiral CPs,chiral poly(3,4-ethylenedioxythiophene)(PEDOT),emerging as a “superstar” material,has attracted tremendous attention in the field of electrochemical sensor due to its unique structure and electronic properties.Despite the fact that chiral PEDOTs has been already synthesized in 2004,immense challenges have been encountered for their chiral recognition application.Furthermore,the field of using chiral PEDOTs for enantiomer recognition is still in its early days.The chiral selective electrodes for enantiomers discrimination and its mechanism still remain unexplored.Hence,understanding the mechanism of chiral recognition,and then pursuing the more efficient chiral electrode materials to develop the application of chiral PEDOT is valuable and fascinating.In this work,the chiral moieties were grafted into the side chain of PEDOT.As chiral electrodes,chiral PEDOTs were employed to successfully recognize enantiomers.In addition,the electrochemical behavior,structural characterization,thermal stability,morphology and circular dichroism of corresponding chiral polymers were investigated in detail.1.Two novel EDOT derivatives were synthesized by incorporated a pendant(R)-/(S)-2-phenylpropionic acids.Corresponding polymers((R)-PEDTM-PP and(S)-PEDTM-PP)were obtained by electropolymerization.As chiral electrodes,(R)-PEDTM-PP and(S)-PEDTM-PP modified glassy carbon electrodes(GCEs)were employed to successfully recognize 3,4-dihydroxyphenylalanine(DOPA)enantiomers by electrochemical technologies.2.Two single chiral EDTC monomers((R)-/(S)-EDTC)were obtained.The chirality of EDTC was introduced by bringing in a chiral source.The corresponding polymers were employed as excellent chiral recognition materials for fabricating chiral sensors and then discriminate 3,4-dihydroxyphenylalanine(DOPA)enantiomers rapidly.These results clearly indicate that a clear chiral discrepancy was observed:(R)-PEDTC/GCE showed a higher peak current response towards L-DOPA;(S)-PEDTC/GCE showed a higher peak current response towards D-DOPA.Importantly,the mechanism of the stereospecificity of the interaction between the DOPA enantiomers and chiral polymers was discussed specifically.3.Design and synthesis water-soluble chiral EDOT((R)-/(S)-EDTM),which extend its application in the field of electrochemical chiral recognition.A series of performances of corresponding polymers were characterized in some detail using different strategies.Finally,(R)-PEDTM/GCE and(S)-PEDTM/GCE were successfully employed to recognize DOPA and tryptophane(Trp)enantiomers.These results clearly indicated that(R)-PEDTM/GCE showed a higher peak current response towards L form enantiomer;while the contrary phenomenon occurred on(S)-PEDTC/GCE.In addition,we established a new model of the action in enantioselectivity.