Synthesis And Application Of Polypyridine-bonded Porphyrins

The fluorescence method is not only simple but also excellent in real space, real time, high sensitivity, high selectivity and nondestructive analysis, which has aroused chemists'great interest. Generally, a fluorescent probe contains three elements: receptor, spacer, fluorophore. The physical and chemical properties of molecular probe changed upon binding the analyte, which is measured as a change in fluorescence intensity, fluorescence quantum yield, or a shift of the excitation or emission. Porphyrin is chosen as the fluorophore bacause it has high molar absorbance coefficient, high fluorescence quantum yield, large Stokes shift, relatively long excitation and emission wavelength. Bis(2-picolyl)amine is chosen as the receptor owing to its strong afillity to many transition-metal ions such as Cd, Zn, Cu, Pb. In this thesis, we designed and synthesised six new fluorescence molecular probes based on porphyrin.The probe a was synthesised in three steps. First, Aniline was reacted with 2-(Chloromethyl)pyridine hydrochloride under the catalysis of hexadecytrimethylammonium chloride, affored N,N-bis(2-pyridinylmethyl)aniline. Then it undergoing Vilsmeier reaction and Adler reaction gave 5-{4-[bis(2-pyridinylmethyl)amino]phenyl}-10,15,20-triphenylporphyrin. Probe a displayed a high selectivity and quick response to Cu2+over other metal ions (Na+, K+, Ca2+, Mg2+, Co2+, Pb2+, Ni2+, Mn2+, Cd2+, Cu2+, Zn2+, Ag+, Fe2+, Hg2+, Fe3+, La3+, Ce3+, Y3+)in THF/H2O(10:1, v/v) solution. The fluorescence intensity of probe 1 was almost completely quenched with 2 equiv of Cu2+ added. This change can be directly observed with the naked eyes, the orange solution becomed colorless upon adding 2 equiv of Cu2+. And its fluorescent signal can be revived by the addition of disodium EDTA solution. The reversibility of this complex is conducive to further development as a fluorescent sensor.On the basis of probe 1, we synthesised other five fluorescence molecular probes by the following two ways:.extending the link chain between the fluorophore and the receptor, introducing more amine and pyridyl to the fluorescence molecular probe. The five fluorescence molecular probes are 5-{4-[bis(2-pyridylmethyl) aminomethyl]phenyl}-10,15,20-triphenylporphyrin,5-(4-[2-(bis[2-pyridylmethyl]amin o)ethylamino]phenyl)-10,15,20-triphenylporphyrin,5-(4-{[2-(bis[2-pyridylmethyl]ami no)ethylamino]ethylamino}phenyl)-10,15,20-triphenylporphyrin,5-[4-({[2-(bis[2-pyri dylmethyl]amino)ethyl]pyridin-2-ylmethylamino}ethylamino)phenyl]-10,15,20-triphe nylporphyrin,5-[4-({[2-(bis[2-pyridylmethyl]amino)ethyl]pyridin-2-ylmethylamio}met hyl)phenyl]-10,15,20-triphenylporphyrin. The fluorescence intensity of the five probes was quenched upon adding 30 equiv of Cu2+. But these probes still suffered strong interference from other metal ions. The fluorescence spectrum of 5-(4-[2-(bis[2-pyridylmethyl]amino)ethylamino]phenyl)-10,15,20-triphenylporphyrin and 5-[4-({[2-(bis[2-pyridylmethyl]amino)ethyl]pyridin-2-ylmethylamino}ethylamin-o)phenyl]-10,15,20-triphenylporphyrin appeared two peaks, which lies at 648 nm and 710 nm. They have the potetial to design as rational fluorescent probe.Besides, we improved the synthetic routine of some intermediates. Operating according to the improved synthetic route, the yield of bis(2-pyridylmethyl)amine increased to 85%; the synthetic routine of N,N,N-tris-pyridin-2-ylmethylethane-1,2-diamine was shortten to three steps, and the total yield increased to 41%; 5-(4-bromomethyl)phenyl-10,15,20-triphenylporphyrin was easy to separate and purify.