Study On Synthesis And Photochemical Application Of New Pyrrole [3,2-b] Pyrrole Compounds

Pyrrolo [3,2-b] pyrrole is a 10-π-electron heterocycle.Tetraarylpyrrolo [3,2-b]pyrrole can be obtained by cyclization from aromatic aldehydes,aromatic amines and2,3-butanedione.In this paper,six new pyrrole compounds were synthesized by introducing different substituents into pyrrole aromatic ring with pyrrole as the parent core.By studying their photochemical properties,they are applied in the field of photoinitiators and inverted planar perovskite cells.The specific research contents are as follows:Firstly,a new type of photoinitiator with pyrrole structure was designed and synthesized,and its photoinitiation properties and mechanism were studied.The stereoscopic products were prepared by using the wavelength selectivity.Moreover,it can also be used for long wavelength curing when camphorquinone and camphor quinone are used as two-component photoinitiators.Two pyrrolo [3,2-b] pyrrole-based compounds including 1,4-bis(4-bromophenyl)-2,5-bis(4-nitrophenyl)-1,4-dihydropyrrole [3,2-b] pyrrole(Py BN)and 1,4-bis(4-methylphenyl)-2,5-bis(4-nitrophenyl)-1,4-dihydropyrrole [3,2-b] pyrrole(Py BC)were synthesized.The double bond conversions of nine kinds of acrylate resins were determined with the initiation of nitro containing Py BN under 365 nm LED light source.The highest conversion of monomer and prepolymer reached 89.87% and 99.86%respectively.The gel rate results showed that their photoinitiating activity was different,and Py BN exhibited better performance than Py BC.By analyzing their absorption spectra and steady-state photolysis,it was found that with the increase of photolysis time,their UV-vis absorption spectra changed,and new absorption peaks with blue shift appeared.The photolysis products were characterized by nuclear magnetic resonance(NMR),infrared spectroscopy(IR),high performance liquid chromatography(HP-LC)and liquid mass spectrometry(LC/MS).The electron paramagnetic resonance(EPR)showed that carbonyl radicals were probably produced in the photolysis process,which made these pyrroles have photoinitiator activity.Py BN and camphorquinone(CQ)were used as two-component initiation system by co-initiation,facilitating long-wavelength light curing under LED irradiation of 470 nm.The photoelectron transfer reaction between them is thermodynamically allowed,which was demonstrated on basis of photochemical and electrochemcial measurements.Secondly,four kinds of hole transport materials Py X1,Py X2,Py X3 and Py X4 with pyrrole as parent core and naphthalene,pyrene,diphenylamine and asymmetric diphenylamine as substituents were synthesized and characterized.The photoelectric conversion efficiency of the device based on Py X1,Py X2,Py X3 and Py X4 as hole transport layers is 13.53%,12.64%,17.37% and 16.93%,respectively.The synthesized pyrrole hole transport materials can make full use of solar energy.Six pyrrolo [3,2-b] pyrrole structures synthesized in this paper can make full use of the light energy of different wavelengths,which provides experimental basis for the study of photochemical application of pyrrolo.