Synthesis And Properties Of Boron Azadipyrromethene Derivatives

The precursor of Boron Azadipyrromethene?Aza-BODIPY?is a planar structure consisting of two pyrrole rings and one boron-nitrogen six-membered heterocycle in the middle,which is a typical derivative of fluoroborine dipyrromethane?BODIPY?.Because the central structure of this kind of compound is particularly stable,and there is a lone pair of electrons in the nitrogen atom,the energy difference is very small,and the absorption wavelength and the emission wavelength are red shifted.In addition,these compounds not only have a high molar extinction coefficient and fluorescence quantum yield,and are easy to introduce various types of substituent groups,but also have high stability and light resistance.These characteristics of Aza-BODIPY make that the research on its synthesis and properties has become one of the main research focuses for researchers.This article mainly discusses from the following two aspects:In this dissertation,firstly,the target compounds were obtained through a series of reaction processes with p-methoxyacetophenone and benzaldehyde with different para-substituents:Aza-BODIPYs with the substituents respectively-CH₃,-H,and–F.The single crystal diffraction analysis of the Aza-BODIPY containing a methyl group confirmed the accuracy of its structure.By nuclear magnetic resonance spectroscopy,it can be seen that when the para-substituents of the 1,7-position phenyl ring are different electron-donating groups and electron-withdrawing groups,the hydrogen on the pyrrole ring of the Aza-BODIPY are respectively shifted to the high field,and the signal peak of the hydrogen at the 1,7-position phenyl ring also splits.It can be seen that the introduction of substituents at the para-position of the 1,7-position phenyl ring courses a certain influence on the Aza-BODIPY.Secondly,the UV-Vis absorption and fluorescence spectra of three compounds in acetonitrile,toluene,and methylene chloride solutions were measured.The experimental data shows that in the more polar solvent,the fluorescence intensity of the three substances is obviously enhanced,but in the weaker solution,the compounds have a weak self-absorption so that its fluorescence intensity will be decreased.Then the electrochemical performances of the three compounds were measured in methylene chloride solution.All three compounds had a two-stage reversible reduction process and a first-order reversible oxidation,a first-order irreversible oxidation process,and when the electron-withdrawing ability of the para-substituents of the 1,7-phenyl ring of Aza-BODIPY was increased,The first-reduction half-wave potentials and the first-order half-wave potentials of the three compounds showed a positive shift.Then,the thiophene-substituted Boron Azadipyrromethene compound was synthesized and then reacted with pentacarbonyl rhenium?I?chloride as a ligand to obtain a rhenium?I?thiophene substituted Boron Azadipyrromethene metal complex.The analysis of the NMR spectrum shows that the signal peak of the hydrogen on the thiophene ring of the thiophene substituted Boron Azadipyrromethene shifts to a high field after coordination with rhenium?I?and the hydrogen of the pyrrole ring is also shifted toward the high field.By testing the spectra of the two compounds in methylene chloride solution,the experimental results show that the coordination with the metal ruthenium?I?causes the maximum absorption wavelength and the emission wavelength of the thiophene-substituted azafluroboroborin ligand to be blue shift.The electrochemical performance of the two compounds in methylene chloride containing 0.1 M TBAP was determined,both with two-stage reversible reduction and two-stage irreversible oxidation.Finally,the single crystal diffraction analysis of the thiophene-substituted Aza-BODIPY compound confirmed the accuracy of the structure of the material.