| Quinazolinones are widely found natural product frameworks and drug fragments,which have remarkable optical activity and excellent biological effects and play an important role in medicine,biology,pesticides and other fields.Quinazolinones have super-strong fluorescence properties and are used in dyes,pigments,ion detection,bioimaging,electroluminescent devices,etc.Therefore,quinazolinones have a wide application prospect.So quinazolinone has a wide application prospect in the field of optoelectronics.At present,few studies have been done on the structure-property relationship,structure modification and efficient luminescence of 2-aryl quinazolinone skeleton itself.In order to systematically understand the influence of substituents on the skeleton properties of quinazolinone,A variety of D-A fluorescent molecules based on2-aryl quinazolinone were designed and synthesized in this paper.The main work of this paper is divided into four parts:(1)In the second chapter,2-phenylquinazolinone was used as the receptor and electron-donating N,N-dimethylamino was introduced as the donor to enhance intramolecular charge transfer.In solution,2-phenyl-para-substituted enhanced the luminescence,and 6-substituted caused more significant red shift.In solid state,The2-phenyl-para-substituted product emits white light in the solid state.As for the double substituted molecule,its red-shift is significant and largest,and the fluorescence lifetime is the longest.All compounds are responsive to protons and fluorescence is reversible.(2)On the basis of the previous chapter,the stronger electron-donating group triphenylamine was introduced into the 6-position of 2-aryl quinazolinone,and the ortho-,meto-and para-pyridine replaces 2-aryl,and is introduced to enhance the electron-deficiency of the receptor.All the compounds display solvatochromism,the fluorescence emission peak show a red shift,the Stokes shift increases,and the fluorescence quantum yield is nearly 100%.All compounds can be used as highly selective fluorine ion probe.The o-pyridine products also have the properties of copper ion recognition and mechanochromic property.(3)In chapter 4,N in pyridine is replaced by nitro group on the basis of chapter 3,in order to explore the influence of strong electron withdrawing group on luminescence.Ortho-nitro of the 2-phenyl improved solubility to some extent,the meta-nitro group enhanced the luminescence,and the para-nitro group caused significant red shift and fluorescence quenching.The ortho nitro group hinders the response of the molecule to F~-.(4)Based on the previous work,in the fifth chapter,intramolecular charge transfer was further enhanced by changing the 2-phenyl group into the aromatic heterocycle with larger conjugated system,such as quinoline and thiazole.The two synthesized molecules show nearly 100%quantum yield in solution,high solid quantum yield and large Stokes shift of more than 200.Meanwhile,they have the properties of solvatochromism,mechanochromismand,selective copper ion recognition,which proves that they are new Multi-responsive organic small molecule fluorescence materials.The results show that the introduction of different donors into the 6-position of2-phenylquinazolinone and the introduction of aromatic/heterocyclic groups with different substituents into 2-position by structural modification is one of the effective methods to obtain this kind of multi-functional D-A type quinazolinone organic photoelectric materials.In addition,the problem of poor molecular solubility of quinazolinone can be solved by introducing heteroatom into the ortho position of2-aryl to break intermolecular hydrogen bonds. |
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