Synthesis And Catalytic Performance Of Functionalized CMPs

Conjugated Microporous Polymers(CMPs)are organic microporous polymers with highspecific surface area,excellent chemical/thermal stability.The organic nature of CMPs allows to design catalytic active materials based on specific ligand design,for example,by incooperation of catalytic active sites on ligands.Astrategy based on functional group appended on sidegroup was used,and TEMPO radical(2,2,6,6-tetramethylpiperidine-1-oxyl)was serving as catalytic moiety,to react with three different alkyne terminated aromatic compounds,inform of four TEMPO decorated CMPs,via coupling reaction.The main text can be divided into three parts as following:(1)By the condensation reaction of 4-amino-TEMPO with 2,5-dibromobenzoic acid and 2,5-dibromoterephthalic acid,two TEMPO functionalized ligands,named N-(2,2,6,6-tetramethylpiperidine)-2,5-dibro mo-benzamide and N,N'-bis(2,2,6,6-tetramethylpiperidine)-2,5-dibromoterephthalamide were synthesized,respectively.Three alkyne terminated aromatic compouds,tetrakis(4-ethynylphenyl)methane with tetrahedral structure,1,3,6,8-tetramethylpyrene and 1,1,2,2-tetrakis(4-ethynylphenyl)ethane with axial symmetry,were synthesized.Nuclearmagneticresonancespectroscopy(NMR),high reolution mass spectroscopy(HRMS),FT-IR spectroscopy,and electron paramagnetic spectroscopy(EPR)were used to investigate the chemical structure of these molecules.(2)By Sonogashira-Hagihara coupling reaction,CMP-1-TEMPO,CMP-2-TEMPO,and CMP-3-TEMPO were synthesized by combination of N-(2,2,6,6-tetramethylpiperidine)-2,5-dibromo-benzamide with tetrakis(4-ethynylphenyl)methane,1,3,6,8-tetramethylpyrene,and 1,1,2,2-tetrakis(4-ethynylphenyl)ethane,respectively.CMP-1-(TEMPO)2,which shows higher TEMPO density,was synthesized by reaction of N,N'-bis(2,2,6,6-tetramethylpiperidine)-2,5-dibromo-terephthalamide with tetrakis(4-ethynylphenyl)methane.Scanning electron microscopy(SEM),powder X-ray diffraction(PXRD),FT-IR and EPR were used to study the morphology,composition,and structural information of the obtained CMPs-TEMPO.(3)The oxidationof 5-Hydroxymethylfurfural(5-HMF)into 2,5-diformylfuran(2,5-DFF)was used as a model reaction to optimize the reaction conditions,such as solvents and reaction time,stability,andrecyclability of CMPs-TEMPO.The results indicated that CMPsTEMPO show excellent catalytic activityfor the convertion of 5-HMF into 2,5-DFF with high selectivity.Moreover,no free TEMPO radicals in the reaction solution can be examined by EPR,suggesting excellent stability of CMPs-TEMPO.However,recycle testing indicated that the effiency of CMPs-TEMPO show showly decrease after three runs of catalytic reactions.Finally,CMPs-TEMPO are able to catalyze a broad range of alcohols,including primary aromatic alcohols,secondary aromatic alcohols,aliphaticalcohols and heteroatomic alcohols,into corresponding aldehydes or ketones.