Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications but remain difficult to access in stable concentrated forms.We disclose easy generation of stable,concentrated ...Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications but remain difficult to access in stable concentrated forms.We disclose easy generation of stable,concentrated radicals from various alkynyl phenyl motifs,including 1)sulfur-functionalized alkyne-rich organic linkers in crystalline frameworks;2)the powders of these molecules alone;3)simple diethynylbenzenes.For Zr-based framework,the generation of radical-rich crystalline framework was achieved by thermal annealing in the range of 300-450℃.For terminal alkynes,electron paramagnetic resonance signals(EPR,indicative of free radicals)arise after air exposure or mild heating(e.g,70℃).Further heating(e.g.,150℃for 3 h)raises the radical concentrations up to 3.30 mol kg^(-1).For more stable internal alkynes,transformations into porous radical solids can also be triggered,albeit at higher temperatures(e.g.,250-500℃).The resulted radical-containing solids are porous,stable to air as well as heat(up to 300-450℃)and exhibit photothermal conversion and solar-driven water evaporation capacity.The formation of radicals can be ascribed to extensive alkyne cycliza-tions,forming defects,dangling bonds and the associated radicals stabilized by polycyclicπ-systems.展开更多
Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductiv...Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms,Im@Ni L1 and Im@Ni L2,were measured and compared.Upon introduction of imidazole molecules,the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72×10^(-2)S/cm(at 98%RH and 80℃).Also,whether imidazole molecules were introduced or not,Ni_(8)O_(6)-based MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities.Beyond the active Ni_(8)O_(6)-cluster,tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.展开更多
基金fundings by the National Natural Science Foundation of China(22371054,22301045)the Foundation of Basic and Applied Basic Research of Guangdong Province(2020B1515120024,2024A1515012801)+1 种基金Science and Technology Planning Project of Guangdong Province(2021A0505030066,2023A0505050164)Z.X.acknowledges a startup fund from A^(*)STAR(SC25/22-119116).
文摘Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications but remain difficult to access in stable concentrated forms.We disclose easy generation of stable,concentrated radicals from various alkynyl phenyl motifs,including 1)sulfur-functionalized alkyne-rich organic linkers in crystalline frameworks;2)the powders of these molecules alone;3)simple diethynylbenzenes.For Zr-based framework,the generation of radical-rich crystalline framework was achieved by thermal annealing in the range of 300-450℃.For terminal alkynes,electron paramagnetic resonance signals(EPR,indicative of free radicals)arise after air exposure or mild heating(e.g,70℃).Further heating(e.g.,150℃for 3 h)raises the radical concentrations up to 3.30 mol kg^(-1).For more stable internal alkynes,transformations into porous radical solids can also be triggered,albeit at higher temperatures(e.g.,250-500℃).The resulted radical-containing solids are porous,stable to air as well as heat(up to 300-450℃)and exhibit photothermal conversion and solar-driven water evaporation capacity.The formation of radicals can be ascribed to extensive alkyne cycliza-tions,forming defects,dangling bonds and the associated radicals stabilized by polycyclicπ-systems.
基金the National Natural Science Foundation of China(No.21871061)the Foundation of Basic and Applied Basic Research of Guangdong Province(No.2021A1515010274)+2 种基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032)the Science and Technology Planning Project of Guangdong Province(No.2021A0505030066)the Science and Technology Program of Guangzhou(No.201807010026)。
文摘Two primitive metal-organic frameworks(MOFs),Ni L1 and Ni L2,based on Ni_(8)O_(6)-cluster and ditopic pyrazolate linkers,L1(with rigid alkyne arms)and L2(with flexible alkyne chains),were prepared.The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms,Im@Ni L1 and Im@Ni L2,were measured and compared.Upon introduction of imidazole molecules,the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72×10^(-2)S/cm(at 98%RH and 80℃).Also,whether imidazole molecules were introduced or not,Ni_(8)O_(6)-based MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities.Beyond the active Ni_(8)O_(6)-cluster,tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.
