Sp~2-carbon-linked Conjugated Organic Porous Polymers

Conjugated organic porous polymers are one of the porous materials withπ-conjugation skeleton strcture.In recent years,conjugated organic porous polymers have been widely used in gas adsorption,oil-water separation,energy storage and other fields due to their high specific surface area,good stability,controllable porous features and molecular design.In particular,theπ-conjugated systems in the polymer networks always exhibit typical semiconductor property.However,their investigation in the field of photocatalysis is just beginning.Construction of sp²-carbon-linked porous polymer skeleton can enlarge theπ-conjugation of a system,and improve the light stability of the skeleton,as well as obtain good photocatalytic activity.Regard to these,herein,the sp²-carbon-linked conjugated organic porous polymers were synthesized by Knoevenagel condensation reaction,and the electron donor and acceptor units were introduced into their main backbone or pendant groups to form the donor-acceptor structure（D-A）,for narrowing the band gap,and strengthening the visible light harvesting absorption in the low energy regions.In the mean time,hydrophilic properties were improved to enhance the visible light catalytic performance of these polymers.Corresponding results are listed as below:1.Knoevenagel condensation of 2,5-Bis（cyanomethyl）-1,4-dimethoxy-benzene or 2,5-Dimethyl-1,4-bis（cyanomethyl）benzene with1,3,5-tris-（4-formylphenyl）benzene led to the formation of two porous polymers termed as POP-OCH₃ and POP-CH₃,respectively.Both polymers exhibited excellent chemical,thermal stabilities as well as abundant photophysical and electrochemical properties.The as-prepared polymers showed good visible light catalytic activity and could effectively degrade dye pollutants.POP-OCH₃ showed better photocatalytic activity because of its narrower optical band gap and better hydrophilicity than POP-CH₃.2.Starting from TFPT and TFPPy,a series of D-A-type porous polymers donated as TFPT-OCH₃,TFPT-CH₃,TFPPy-OCH₃ and TFPPy-CH₃ were synthesized in high yields upon metal-free Knoevenagel condensation.The obtained polymers can harvest visible light efficiently,and the optical band gap of the polymers can be effectively tuned by the incoroporation of different monomers.As visible light catalysts,the materials effectively undergo photocatalytic activities,for water cleaving to produce hydrogen or dye degradation,with good catalytic activity and recyclability.