Controllable Synthesis Of Self-assembled Porphyrin Nanostructures And Their Photo/Electrochemical Properties

Biochemical analysis plays an extremely important role in clinical testing,life sciences,and food analysis.Electrochemiluminescent(ECL)bioanalysis and photoelectrochemical(PEC)bioanalysis have the advantages of good selectivity,high sensitivity,and wide linear range of detection,which have attracted more and more attention.The application of ECL bioanalysis and PEC bioanalysis in the field of biochemical analysis for the determination of various biological substances has very practical significance.Porphyrin molecules have special photochemical and photophysical properties and have important applications in the field of analytical chemistry.They are ECL and PEC active substances.Porphyrin nanocrystals synthesized by supramolecular self-assembly have better photoelectrochemical activity than porphyrin derivatives,and have potential advantages in biosensing.In this thesis,a series of ECL and PEC bioanalysis systems for porphyrin-based assembly materials have been developed.Through the design and synthesis of porphyrin-based assembly materials with special photo-electrochemical activity,the formation process of porphyrin-based assembly structure and its photo-electrochemical mechanism are studied,and the photo-electrochemical analysis system is constructed and optimized by combining micro nano technology,spectroscopy characterization technology and chemical biology.The dissertation is mainly focused on the following four parts:1.Enhanced electrochemiluminescence of microemulsion-assisted assembled porphyrin-based nanomaterialsMicelles and microemulsions are used as chemical reactors because of their special interfacial properties.The presence of surfactants may affect the whole reaction process.In this work,under the assistance of microemulsion and Tetra-n-octylammonium bromide(TOAB),the nanostructure of Zn(II)mesotetraphenylporphine chloride(ZnTPP)is formed during microemulsion assisted nucleation and growth process.The X-ray powder diffraction(XRD),UV-Vis absorption spectrum and other characterization methods are used to infer the way of porphyrin molecular stacking and its aggregation form with surfactants.The as-prepared ZnTPP-TOAB nanostructures exhibits remarkably different morphologies,spectroscopies and electrochemical properties.The prepared ZnTPP-TOAB is used to modify the glassy carbon electrode(GCE),and the ECL properties of ZnTPP-TOAB/GCE are studied with oxygen working as a co-reactant.The enhanced ECL behavior of ZnTPP-TOAB is further studied by ECL emission spectroscopies and cyclic voltammetry,and the corresponding mechanism is proposed.2.Self-assembled meso-tetra(4-carboxyphenyl)porphine:Structural modulation using surfactants for enhanced photoelectrochemical propertiesThe morphology and size of porphyrin self-assembled materials prepared by microemulsion method are too different.In order to prepare homogenous porphyrin self-assembled structures,in this work,we synthesized three different aggregated nanostructures of meso-tetra(4-carboxyphenyl)porphine(TCPP)via self-assembly technique.The micro-environments of porphyrin self-assembly were modulated by using sodium dodecyl sulfate(SDS)and cetyltrimethyl ammonium bromide(CTAB)as“soft template”respectively,aqueous solution without surfactant as control.Due to the different driving forces of self-assembly,the as-prepared TCPP nanostructures exhibited remarkably different morphologies,electrochemical and PEC properties.Among them,the self-assembled TCPP using SDS(SA-TCPP/SDS)possessed enhanced PEC performance.In presence of dopamine,a significant photocurrent response can be feasibly obtained in aqueous media at 0.4 V(vs.Ag/Ag Cl).Moreover,the self-assembly process was also investigated using in situ UV-visible spectroscopy and the corresponding structure formation mechanisms were proposed.3.Enhanced electrochemiluminescence of one-dimensional surfactant-assisted self-assembled porphyrin hexagonal nanoprismsIn order to prepare structurally stable porphyrin self-assembled nanomaterials,in this work,we synthesized the one-dimensional nanostructure of zinc 5,10,15,20-tetra(4-pyridyl)-21H,23Hporphine(ZnTPyP)via a self-assembly technique.Using SDS as“soft template”,the self-assembled ZnTPyP(SA-ZnTPyP)had the morphology of hexagonal nanoprisms with a uniform size(diameter of 100 nm).The SA-ZnTPyP exhibited remarkably different spectral properties compared to those of the original ZnTPyP.The as-prepared Sa-ZnTPyP was used to modify glassy carbon electrodes(GCE),and the ECL behaviors of the SA-ZnTPyP/GCE were investigated.The hydrophilic carbon dots(C-dots)could efficiently prevent the dissolution of SA-ZnTPyP in DMF containing 0.1 mol L^-1 TBAP and,simultaneously,could accelerate electron transfer.Therefore,the enhanced ECL was realized by C-dots/SA-ZnTPyP/GCE by using H₂O₂ as co-reactant.This amplification of ECL was further studied by ECL spectroscopies and cyclic voltammetry,and the corresponding mechanism was proposed.4.Enhanced electrochemiluminescence of porphyrin-based metal-organic frameworks controlled via coordination modulationPrecise control over composition,morphology and size of porphyrin-based metal-organic frameworks is challenging but the extension of these hybrid materials will enable the creation of novel ECL emitters.The coordination of various entities are made from Zn²⁺ions and TCPP,modulated by both solvent and bathophenanthrolinedisulfonic acid disodium salt(BPS)as capping agent,resulting in limited crystal growth of Zn-TCPP in DMF/H₂O(V/V,1:1)and the formation of nanoscale TCPP-Zn-BPS.The role of BPS is also evaluated using Zn-TCPP and BPS-Zn-TCPP as control,prepared in the absence of BPS and different coordinating sequence of ligands,respectively.The newly obtained TCPP-Zn-BPS exhibits a variety of different morphologies,as well as,spectral,and optoelectronic properties.The ECL behavior of the TCPP-Zn-BPS is investigated by using H₂O₂ as co-reactant.The amplification of ECL is further studied by ECL spectroscopies and cyclic voltammetry,with the corresponding mechanism proposed.