Corannulene-mediated Peroxyoxalate Chemiluminescent Reaction And Its Applications

Corannulene and its derivatives are bowl-shaped polycyclic aromatic hydrocarbons which have aroused people’s great attention due to their unique structural and electronic properties.With the development of the preparation methods,they have been applied in the fields of fluorescence,electrochemistry,and so on.However,it has not been introduced to the chemiluminescence（CL）analytical method.In this thesis,corannulene-mediated peroxyoxalate chemiluminescence（PO-CL）system was established for the first time.The proposed PO-CL system consists of bis（2,4,6-trichlorophenyl）oxalate（TCPO）,hydrogen peroxide（H₂O₂）and corannulene or its derivatives.In the second chapter,we investigated the kinetic curve of the corannulene-mediated TCPO-H₂O₂ CL reaction.With the addition of corannulene into the TCPO-H₂O₂ CL reaction,a strong CL signal was observed.Besides,the CL spectrum was measured which was close to the fluorescent spectrum of corannulene indicating that the luminophore of the PO-CL system was the excited corannulene.So the mechanism of the corannulene-mediated PO-CL can be summarized as follows:when H₂O₂ is injected into the PO-CL system,the oxidation of TCPO produces chemical reactive intermediate C₂O₄ which transfers necessary excitation energy to corannulene.After accepting energy,the excited states of corannulene forms which returns to the ground state with light radiation.We investigated the influence of different enhancers on the proposed CL system including sodium citrate,imidazole,and Tris.The results showed that sodium citrate had the best enhancement effect and was used as the enhancer for subsequent researches.In this thesis,we compared the fluorescent properties and CL performance of ten compounds,including coronene,corannulene and its derivatives.The results indicated that the increased conjugated degree of the corannulene caused the red shift of the fluorescence emission spectra.The CL intensity of corannulene-mediated CL system is lower than that of the planar hydrocarbon（Coronene）.However,there is evidence that the CL performance of corannulene can be improved substantially by modifying different substituents.In chapter three,the quenching effect of gold nanoparticles（Au NPs）on the corannulene-mediated TCPO-H₂O₂ CL system was investigated.The well-dispersed Au NPs has quenching effect on corannulene-mediated TCPO-H₂O₂ CL system.The quenching effect decreases when the Au NPs are aggregated.The mechanism of the quenching effect of Au NPs was investigated.The experiment results showed that it was attributed to the interaction between TCPO and Au surface which may lead to the decrease of formation of chemical reactive intermediate C₂O₄ and the inhibition of the CL intensity.Based on tuning the quenching effect of Au NPs on this CL reaction,a turn-on sensing method for cysteine（Cys）was established.Cys can cause the aggregation of Au NPs through the communication with aspartic acid,leading to CL recovery.Under the optimal experimental conditions,the linear range for the CL sensing of Cys was from 0.075 to 0.75μM.As low as 0.064μM Cys could be detected by using the proposed CL sensing platform.The established method also showed good selectivity and reproducibility（RSD 2.52%）.In order to evaluate the universality of the Au NPs-based CL platform,the proposed method was applied to the detection of acetylcholinesterase（ACh E）and its inhibitor screening.ACh E can hydrolyze thioacetylcholine iodide（ATCI）and produce thiocholine which contains both sulfhydryl group and quaternary ammonium group.The produced thiocholine can lead to the aggregation of Au NPs and subsequent CL signal recovery.A good linear relationship was observed between the CL intensity and the concentration of ACh E in the range of 1-15 m U m L^-1.The LOD of ACh E was calculated to be 0.67 m U m L^-1based on the 3σrule.At last,the applicability of the proposed CL sensing for the screening of ACh E inhibitors was evaluated by using two classic ACh E inhibitors,neostigmine bromide and tacrine.The proposed method can easily be extended to the detection of kinds of analytes which may affect the disperse state of Au NPs.This method has great application potential in various fields including biochemistry,environmental analysis,pharmaceutical analysis,clinical diagnosis,and so on.