Synthesis Of Novel Naphthalimide Derivatives And Their Fluorescence Enhancement To Eosin

A series of novel fluorescent naphthalimide derivatives were synthesized with 2,4,6-trichloro-1,3,5-triazine(CNC),aliphatic diamine,1,8-naphthalimide andβ-naphthol as primary raw materials.Thermostability,UV/Vis absorption and fluorescent performances of the obtained products had been investigated.Furthermore,the synthesized compounds were used for constructing energy transfer systems with eosin and their fluorescence enhancement to eosin was studied.The contents were as follows:1,Synthesis and characterization of compounds with one,two and three 1,8-naphthalimide fluorophores:Through controlling reaction conditions,one,two or three chlorine atoms in 2,4,6-trichloro-1,3,5-triazine(CNC) were substituted by 4-amino-ethylamino-N-n-butyl-1,8-naphthalimide(EBNP) to get compounds with one, two and three 1,8-naphthalimide fluorophores CBNT,BCBNT and TCBNT.The reaction conditions were optimized,and the structures of the products were characterized by elementary analysis,FTIR,¹H-NMR and MS.2,Synthesis and characterization of compound with one 1,8- naphthalimide fluorophore and two naphthalene fluorophores:Three chlorine atoms in one equivalent 2,4,6-trichloro-1,3,5-triazine(CNC) were substituted by two equivalent 2-naphthol and one equivalent 4-amino-ethylamino-N-n-butyl-1,8-naphthalimide to achieve compound with one 1,8- naphthalimide fluorophore and two naphthalene fluorophores NCBNT.The reaction conditions were optimized,and the structure of the product was characterized by elementary analysis,FTIR,¹H-NMR and MS.3,Synthesis and characterization of compound containing four 1,8-naphthalimide fluorophores:The compound containing four 1,8-naphthalimide fluorophores G1.0(EBNP)4 was synthesized by the reaction of BCBNT and 1,2-ethylenediamine.The structure of the product was characterized by elementary analysis,FTIR,¹H-NMR and MS.and MS. 4,Investigation of the thermostability of the fluorescent molecules:The thermostability of CBNT,BCBNT,TCBNT,NCBNT and G1.0(EBNP)₄ were investigated.TGA analysis of the products showed that all of them had good thermostability.5,Study on UV/Vis absorption and emission spectra of the fluorescent molecules:The UV/Vis absorption and fluorescent emission spectra of CBNT,BCBNT, TCBNT,NCBNT and G1.0(EBNP)4 were tested.The order of the absorption abilities of their DMF solutions with the same concentration is G1.0(EBNP)4 >TCBNT > BCBNT > NCBNT > CBNT.The fluorescent intensity of products in DMF solution increased at first,then decreased when the concentration rose,and at the concentration of 5×10^-5 mol/L,CBNT,BCBNT,NCBNT got their maximum fluorescent intensity,and at the concentration of 2.0×10^-5 mol/L,TCBNT got the maximum fluorescent intensitywhile,and at the concentration of 2.5×10^-5 mol/L,G1.0(EBNP)4 got the maximum fluorescent intensity,the rank of fluorescent intensity was TCBNT>BCBNT>G1.0(EBNP)4>NCBNT>CBNT at the concentration of 2.0×10^-5 mol/L.6,Study on the fluorescence enhaneement to eosin by the products:The energy transfer systems of CBNT/eosin,NCBNT/eosin,BCBNT/eosin,TCBNT/eosin, G1.0(EBNP)4/eosin were studied.It was found that all the synthesized molecules could partially transfer their absorption energy to eosin at a certain range of concentrations. The maximum fluorescent enhancement by CBNT,NCBNT,BCBNT,TCBNT, G1.0(EBNP)4 to eosin was 6.6,9.4,14.6,12.0,5.9 fold respectively.The rank of their fluorescence-enhancement abilities was BCBNT >TCBNT > NCBNT > CBNT > G1.0(EBNP)4.