The Synthesis Of 4-Dimethylamino-benzamide Derivations For Molecule Recognition

Molecular recognition based on fluorescence detection has many merits,it has attracted much attention and has been applied to many fields,such as life sciences, environmental sciences and information sciences.In this thesis,ICT fluorescence chemosensors containing N-amino thioureas were synthesized,their spectra properties and application in molecular recognition have been investigated in the following five chapters.In chapter 1,the development of molecular recognition and main fluorescence mechanisms of recognition were reviewed.The fluorescence based on intramolecular charge transfer(ICT) is sensitive to the external environment.Thus the fluorescent compound containing ICT fluorophore is a good candidate for proteins and transition metal ions.Chapter 2 described synthesis,characterization by IR and ¹HNMR and the spectral properties of the five receptors designed in this thesis for sensing for proteins and Cu²⁺.These receptors include[N-carboxymethyl-N'(4-dimethylamino-benzoyl)-hydrazino] -acetic acid(1),[(4-Dimethylamino-benzoyl)-ethoxycarbonylmethylamino] -acetic acid ethyl ester(2),Carboxymethyl-(4-dimethylamino-benzoyl)-amino] -acetic acid(3),(4-Dimethylamino-benzoylamino)-acetic acid ethyl ester(4) and(4-Dimethylamino-benzoylamino)-acetic acid(5).In chapter 3,the interaction between[N-carboxymethyl-N'(4-dimethylaminobenzoyl) -hydrazino]-acetic acid(1) and serum albumins was investigated by absorption spectroscopy and fluorescence spectroscopy.In pH 7.4 Tris-HCl buffer solution,the presence of serum albumin led the fluorescence intensity to increase along with spectrum blue shift.However,obvious spectral change couldn't be observed while adding proteins into the solution of Carboxymethyl-(4-dimethylamino-benzoyl)-amino]-acetic acid(3) or (4-Dimethylamino-benzoylamino)-acetic acid(5),although their structures are similar. It was obvious that the linker-NH-NH-broke the communication between signal moiety and binding moiety.While 1 bound with protein via multi-hydrogen bonds on the-N(CH₂COOH)₂ and CONH moieties,the communication was restored and dramatic spectra change occurred.The linker-NH-NH-between fluorophore moiety and binding site played key roles.In chapter 4,absorption spectroscopy and fluorescence spectroscopy were used to investigate the interaction between serum albumins and[N-carboxymethyl- N'(4-dimethylamino-benzoyl)-hydrazino]-acetic acid(1) zinc complex.The experiments indicated that in pH 7.4 Tris-HCl buffer solution,the enhanced intensity of fluorescence was in proportion to the concentration of proteins such as bovine serum albumin(BSA),human serum albumin(HSA) in the wide range,and their detection limits are 2.5×10^-8 and 9.0×10^-9 mol·L^-1,respectively.The binding distance between complex and serum albumins and the energy transfer efficiency were obtained based on the theory of F(o|¨)rester spectroscopy energy transfer.The binding constants were estimated as 6.45×10⁴ mol·L^-1 and 7.08×10⁴ mol·L^-1 for bovine serum albumin(BSA) and human serum albumin(HSA) respectively,and the number of binding sites was 1 for each.The effect of complex on the conformation of serum albumins was further analyzed using synchronous fluorescence spectrometry. Synchronous fluorescence spectroscopy revealed that the secondary structure of BSA changed in the presence of complex but that of HSA didn't.In chapter 5,the fluorescent chemosensors based on 4-Dimethylamino-benzamide derivatives for the recognition of Cu²⁺ in acetonitrile solution was proposed.The interaction of(4-Dimethylamino-benzoylamino)-acetic acid ethyl ester(4) and [(4-Dimethylamino-benzoyl)-ethoxycarbonylmethyl-amino]-acetic acid ethyl ester(2) with Cu²⁺ was investigated by absorption spectroscopy and fluorescence spectroscopy. The fluorogenic chemodosimetric behaviors toward various metal ions were also studied.High sensitivity as well as selectivity was achieved for Cu²⁺.The presence of Cu²⁺ induced the formation 1:1 complex with both receptors.The binding constants were estimated as 5.1×10⁷ mol^-1·L and 8.5×10⁶ mol^-1·L,respectively.