We report the synthesis and characterization of a fan-shaped chiral nanographene 1,which is composed of 6 hexabenzocoronene subunits with 216 conjugated carbon atoms.In the dehydrocyclization reaction,38 C–C bonds ar...We report the synthesis and characterization of a fan-shaped chiral nanographene 1,which is composed of 6 hexabenzocoronene subunits with 216 conjugated carbon atoms.In the dehydrocyclization reaction,38 C–C bonds are formed simultaneously.1 exhibits strong panchromatic absorption from the ultraviolet to the near-infrared,with an absorption coefficient of 209,000 L mol^(-1)cm^(-1)at 564 nm.Optically pure samples,obtained via chiral HPLC,show distinct ECD signals(|Δε|=704 L mol^(-1)cm^(-1)at 405 nm).Upon excitation,1 emits near-infrared fluorescence at 820 nm with a quantum yield of 5.5%.These photophysical properties of 1 were analyzed with the assistance of DFT calculations.展开更多
Two molecular nanocarbons result from merging a negatively curved nanographene and a carbon nanoring in two constitutional isomers of D2 and C2v symmetry,respectively.They were synthesized by attachment o f C-shaped p...Two molecular nanocarbons result from merging a negatively curved nanographene and a carbon nanoring in two constitutional isomers of D2 and C2v symmetry,respectively.They were synthesized by attachment o f C-shaped paraphenylene precurso rsto 2,11,18,27-tetrabromooctabenzo[8]circulene and the subsequent intramolecular Yamamoto coupling and reductive aromatization reactions.The flexible nature of octabenzo[8]circulene enabled two different ways of connection in the Yamamoto coupling reactions,leading to the two constitutional isomers.The D2 isomer is shaped like a figure eight,as revealed by X-ray crystallography,and is resolved into two enantiomers by chiral HPLC.The synthesis of the C2v isomer is regarded as a further step toward precision synthesis of carbon schwarzites through a bottom-up approach.展开更多
SBA-15介孔分子筛内填充蔗糖并炭化后,分别在碱性和弱酸性条件下,用含铝源及TPABr的溶液浸渍,将SBA-15分子筛孔壁的无定形结构转化成ZSM-5分子筛的晶体结构,除碳后得到含介孔的ZSM-5分子筛.用X射线衍射、N2吸附-脱附、27Al MAS NMR、NH3...SBA-15介孔分子筛内填充蔗糖并炭化后,分别在碱性和弱酸性条件下,用含铝源及TPABr的溶液浸渍,将SBA-15分子筛孔壁的无定形结构转化成ZSM-5分子筛的晶体结构,除碳后得到含介孔的ZSM-5分子筛.用X射线衍射、N2吸附-脱附、27Al MAS NMR、NH3-TPD、TEM、SEM等对样品进行了表征,考察了晶化时间等参数对样品的影响.结果表明,碱性条件下合成的ZSM-5分子筛晶体中含有少量孔径约3.2～4.2nm的介孔孔道,其酸强度接近与常规ZSM-5分子筛的酸强度;弱酸性条件下合成的ZSM-5分子筛晶体中含有大量孔径约1.4～1.6nm的孔道,其酸强度明显低于常规ZSM-5分子筛的酸强度.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21871298,91956118)。
文摘We report the synthesis and characterization of a fan-shaped chiral nanographene 1,which is composed of 6 hexabenzocoronene subunits with 216 conjugated carbon atoms.In the dehydrocyclization reaction,38 C–C bonds are formed simultaneously.1 exhibits strong panchromatic absorption from the ultraviolet to the near-infrared,with an absorption coefficient of 209,000 L mol^(-1)cm^(-1)at 564 nm.Optically pure samples,obtained via chiral HPLC,show distinct ECD signals(|Δε|=704 L mol^(-1)cm^(-1)at 405 nm).Upon excitation,1 emits near-infrared fluorescence at 820 nm with a quantum yield of 5.5%.These photophysical properties of 1 were analyzed with the assistance of DFT calculations.
基金supported by the General Research Fund 14300919 from the Research Grant Council of Hong Kong and a Research Matching Grant from the University Grants Committee(Hong Kong).
文摘Two molecular nanocarbons result from merging a negatively curved nanographene and a carbon nanoring in two constitutional isomers of D2 and C2v symmetry,respectively.They were synthesized by attachment o f C-shaped paraphenylene precurso rsto 2,11,18,27-tetrabromooctabenzo[8]circulene and the subsequent intramolecular Yamamoto coupling and reductive aromatization reactions.The flexible nature of octabenzo[8]circulene enabled two different ways of connection in the Yamamoto coupling reactions,leading to the two constitutional isomers.The D2 isomer is shaped like a figure eight,as revealed by X-ray crystallography,and is resolved into two enantiomers by chiral HPLC.The synthesis of the C2v isomer is regarded as a further step toward precision synthesis of carbon schwarzites through a bottom-up approach.
文摘SBA-15介孔分子筛内填充蔗糖并炭化后,分别在碱性和弱酸性条件下,用含铝源及TPABr的溶液浸渍,将SBA-15分子筛孔壁的无定形结构转化成ZSM-5分子筛的晶体结构,除碳后得到含介孔的ZSM-5分子筛.用X射线衍射、N2吸附-脱附、27Al MAS NMR、NH3-TPD、TEM、SEM等对样品进行了表征,考察了晶化时间等参数对样品的影响.结果表明,碱性条件下合成的ZSM-5分子筛晶体中含有少量孔径约3.2～4.2nm的介孔孔道,其酸强度接近与常规ZSM-5分子筛的酸强度;弱酸性条件下合成的ZSM-5分子筛晶体中含有大量孔径约1.4～1.6nm的孔道,其酸强度明显低于常规ZSM-5分子筛的酸强度.
