Study On Luminescent Properties Of Porphyrins And Their Composites

Porphyrins are widely present in life and tissues closely related to energy transfer.They play exceedingly important role in the activities of living organisms such as oxygen transfer,respiration,photosynthesis,energy transmission and transfer,which are known as"Life pigment".Due to its excellent optical properties,it was universally used in photovoltaic,artificial photosynthesis,photocatalysis and enzyme systems.However,we need to overcome scientific problems of porphyrin such as poor stability,easy aggregation,and weak Q-band absorption.Here we mainly synthesized porphyrin compounds and their composites to study their electrochemical luminescence and fluorescence properties.By combining porphyrin with other materials,the composite material has the comprehensive properties of both and becomes a new type of material.The composite material maintains the excellent properties of each item,while making up for the deficiency of porphyrin.The research can be divided into the following three parts:?1?In order to solve the problem that porphyrins are easy to accumulate in water,we introduced ion-conducting hydrogel.With the characteristics of the three-dimensional network structure,high water content,insolubility in water and adhesion of the hydrogel,porphyrins?5,10,15,20-tetra?4-carboxyphenyl?porphyrin,TCPP?were encapsulated in an acrylamide ion conductive hydrogel by hydrogen bonding.After coating with hydrogel,the good optical properties of protoporphyrin were maintained,while the?-?accumulation of the porphyrin was prevented.Finally the porphyrin can emit light in a solid form.Compared with the original porphyrin,the fluorescence quantum yield increased to 3.93%.The ECL performance of porphyrin hydrogel and protoporphyrin was further compared.The signal of porphyrin hydrogel was about 4 times that of protoporphyrin.?2?In this part of the work,a TCPP/C₃N₅ self-assembled nanosheet was synthesized by using the relatively narrow band gap and electron-rich characteristic of C₃N₅,which has a good lamellar structure.The assembly material was water-soluble,which solved the problem of poor water solubility of TCPP.It was further explored that the cathode ECL of this material when K₂S₂O₈ was used as a co-reactant.The ECL could be excited at a lower potential.Besides,under the action of the co-reactant K₂S₂O₈ and C₃N₅,more TCPP^*was generated,which enhanced the ECL signal of porphyrin.?3?In this part of the work,the properties of red fluorescence with porphyrins were been used.TCPP and rhodamine 6G?Rhodamine 6G?were been encapsulated into MIL-101?Al?-NH₂ to detected fluoride ions.MIL-101?Al?-NH₂ emits blue fluorescence,Rhodamine 6G emits green fluorescence,and TCPP emits red fluorescence.Therefore,under the excitation of 350 nm,the composite material emited fluorescence at 450,550and 650 nm,achieving the effect of single excitation and multiple emission.The ratio-type fluorescence sensor was been constructed using this material,and the composite material showed a significant fluorescence on response to fluoride ions.