Study On The One-step Protocol For The Synthesis Of Covalently Linked Porphyrin Oligomers

In recent years, research on covalently linked porphyrin oligomers has become, a hot spot. It was difficult to synthesize porphyrin oligomers. In the past, the oligomers were synthesized by traditional coupling method. However, the disadvantages of traditional coupling method, such as long synthesis steps, many by-products, poor solubility and difficulty purification have blocked the development of the porphyrin oligomers. Herein, one-step protocol method for synthesis of porphyrin oligomers, that is condensation-cyclization-polymerization reaction, was developed by our group. Porphyrin dimers were synthesized through one-step protocol method via pyrromethanes and their derivatives.Firstly, one series of aldehyde and six series of dialdehydes were synthesized, then pyrromethanes were synthesized via these aldehydes. Among them,3 dialdehydes,2 dipyrromethanes and 11 bis(dipyrromethanes) were not reported. All the novel compounds have been characterized by 1H-NMR、13C-NMR. MALDI-TOF-MS. We have developed the method for synthesis of bis(dipyrromethanes) into a universal method:bis(dipyrromethanes) were synthesized through an InCl3-catalyzed condensation reaction between dialdehydes and pyrrole, pyrrole were recovered by vacuum distillation. This method has many advantages, such as simple operation process, convenient purification, high yield and so on. The success of synthesizing pyrromethanes and other monomers that provided enough raw material for synthesizing porphyrin dimers through one-step protocol method and our next reaserch work.Then, eigth novel different linkers porphyrin dimers were synthesized via an InCl3-catalyzed condensation reaction between various bis(dipyrromethanes) and dipyrromethane-dicarbinol. The one-step synthesis of dimmers has been developed into a universal synthetic method. All the dimers have been characterized by 1H-NMR、MALDI-TOF-MS and UV-vis. The successful construction of one-step protocol method provide technology to synthesize porphyrin polymers.Based on the success of synthesizing pyrromethanes and establishing the universal synthetic method of porphyrin dimers, we probed the one-step method to synthesize porphyrin polymers:① Only dimmers were obtained through the simultaneous condensation-cyclization-polymerization reaction via dipyrromethanes and dialdehydes, the reaction conditions to synthesize higher mulporphyrin degrees are still groping.② Triporphyrins were synthesized through the simultaneous condensation-cyclization-polymerization reaction via bis(dipyrromethanes) and dipyrromethane-dicarbinol, but the end pyrroles were acid-cleaved. Due to time pressures and experiment conditions, we didn’t achieve desired reasults through one-step synthetic method to synthesize porphyrin polymers.The finished work has laid a good foundation for the following task of our group.