Sythesis And Properties Studies Of Schiff Base And Naphthalimide As Ion Probe

As the transition metal ions perform important roles in many fundamental physiological processes in life, the selective mearsurement and monitoring of them is of considerable significance for human health, environment protection, medicine science, industry and argriculture. In recent years, the fluorescent sensor has drawn much research interest owing to its fast response time, high selectivity and sensitivity.As a special class of environmentally sensitive chromophore, interest in investigating 1, 8-naphthalimide derivatives has continually increased owing to their strong absorption and emission in the visible region, high photostability, large Stokes shift and high fluorescence quantum yields. Additionally, it‘s well known that Schiff bases have been widely applied in ion recognition. In view of this, four 1,8-naphthalimide Schiff base ligands: 4-allylamine-N-?N-salicylidene?-1,8-naphthalimide Schiff base?HL¹?, 4-allylamine-N-?N-5-methylsalicylidene?-1,8-naphthalimide Schiff base?HL²?, N-allyl-4-?ethylenediaminesalicylidene?-1,8-naphthalimide Schiff base?HL³?, N-allyl-4-?ethylenediamine-3-methoxysalicylidene?-1,8-naphthalimide Schiff base?HL⁴? were designed, synthesized and characterized by IR, NMR and MS spectra in this paper. Furthermore, the ion regognition performances of the ligands were studied by UV-vis and Fluorescence spectra. This thesis contains four parts:Chapter 1: The current situation of anion and ion recognition was illustrated.Chapter 2: Two 1,8-naphthalimide Schiff base ligands: 4-allylamine-N-?N-salicylidene?-1,8-naphthalimide Schiff base?HL¹?, 4-allylamine-N-?N-5-methylsalicylidene?-1,8-naphthalimide Schiff base?HL²? were designed, synthesized and characterized. HL¹ and HL² show high selectivity for Cu²⁺ over other ions with fluorescence-quenching in DMF/Tris-HCl?v:v=1:1, pH=7.2?. HL¹ and HL² can be applied to detect the quantification of Cu²⁺ in a linear fashion from 0.5 to 5 ?M with the detection limit of 0.32?M and 0.23 ?M, respectively. The reason of fluorescence quenching should be attributed to the formation of a complex between HL¹ and HL² with Cu²⁺ by 1:1 complex ratio according to the Job plot and fluorescence titration. Additionally, the association constant?Ka? between between HL¹ and HL² with Cu²⁺ achieve 1.088×106 M-1 and 1.328 × 106 M-1, respectively.Chapter 3: Two novel and simple 1,8-naphthalimide Schiff base ligands: N-allyl-4-?ethylenediaminesalicylidene?-1,8-naphthalimide Schiff base?HL³?, N-allyl-4-?ethylenediamine-3-methoxysalicylidene?-1,8-naphthalimide Schiff base?HL⁴? have been designed by combining a 1,8-naphthalimide moiety as fluorophore and a Schiff base as recognition group. HL³ and HL⁴ can detect Hg²⁺ over various transition metal ions with fluorescence-enhancement in DMF/Tris-HCl?v:v=1:1, pH=7.2?. However, the copper?II? ions will distorb HL³ recognition of Hg²⁺, HL⁴ exhibits highly selective and sensitive response to Hg²⁺??Hg+HL⁴/?HL⁴=2.28? over other metal ions by forming a 1:2 metal-to-ligand complex with a binding constant of 1.56×1012 M-2 in aqueous solution. Additionally,HL⁴ can be applied to detect the quantification of Hg²⁺ in a linear fashion from 0.5 to 4 ?M with the detection limit of 0.18?M.Chapter 4: This chapter, a copper?II? complex?CuL⁴₂? based on HL⁴ was developed and characterized by elemental analyses, IR spectra and X-ray single crystal diffraction. The interactions of the compounds with calf thymus DNA?CT-DNA? have been investigated by electronic absorption titration, fluorescent spectroscopy and viscosity measurements.The experimental results suggest that the compunds bind to DNA in an intercalation mode, and their binding affinity for DNA follows the order: CuL⁴₂> HL⁴. Moreover, the antioxidant assay in vitro also shows that HL⁴ and its copper?II? complex?CuL⁴₂? possess significant antioxidant activities and the copper?II? complex is more effective than the free ligand HL⁴.