Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited ...Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited SF materials as a result of stringent requirements for atypical energetic arrangement and high ambient stability.Here we show that excited-state antiaromaticity(ESAA)relief can be used to simultaneously regulate the energy separation between T_(1) and S_(0) and design SF-capable materials with favorable energetic conditions and excellent stability.We achieve this by facilitatingπ-electron migration between the seven-and fivemembered rings in acepleiadylene(APD),which alleviates Baird’s antiaromaticity in the T_(1) state while maintaining Hückel’s aromaticity in S_(0).This leads to a lowered T_(1)’s energy relative to S_(0).Aromaticity index calculations reveal the aromaticity reversal and electron density redistribution between S_(0) and T_(1) to mitigate ESAA.This results in an energetic relationship suitable for SF,enabling a rapid fission process with an impressive yield of 165%.Moreover,ESAA relief endows APD with superior stability under ambient conditions.Our work not only introduces a new SF scaffold based on nonbenzenoid hydrocarbons,but it also provides valuable insights for the design of stable SF-active materials.展开更多
Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing ...Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing an antiaromatic reactant.However,both aromaticity and transition states cannot be directly measured in experiment.Thus,computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms.In this review,we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity.Specifically,we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation,Csingle bondF bond activation,rearrangement,as well as metathesis reactions.In addition,antiaromaticity-promoted dihydrogen activation,CO_(2)capture,and oxygen reduction reactions will be also briefly discussed.Finally,caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases.Thus,a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states.展开更多
This paper highlights the compounds containing Sb cluster fragments, either synthesized in the solid-state, discovered from the gas phase, or only theoretically predicted. These Sbn clusters feature unique chemical bo...This paper highlights the compounds containing Sb cluster fragments, either synthesized in the solid-state, discovered from the gas phase, or only theoretically predicted. These Sbn clusters feature unique chemical bonding, fascinating structures, and special stabilities that can be well rational- ized by aromaticity or antiaromaticity. A deep understanding to their electronic structures is essential and will greatly facilitate the experimental synthesis of new Sbn cluster-based materials.展开更多
Binary polyantimony clusters,namely[Cu_(2)Sb_(14)]^(4–) and [Ag_(2)Sb_(14)]^(4–),containing coinage metals,were successfully synthesized and characterized,in which two homoatomic Sb73–subunits are bridged by two co...Binary polyantimony clusters,namely[Cu_(2)Sb_(14)]^(4–) and [Ag_(2)Sb_(14)]^(4–),containing coinage metals,were successfully synthesized and characterized,in which two homoatomic Sb73–subunits are bridged by two coinage metals in η^(4):η^(1) and η^(1):η^(1) coordination modes,respectively.In[M_(2)Sb_(14)]^(4-),two bridging Cu ions and two Sb atoms form a planar rhombic unit,which was revealed to have antiaromatic properties by theoretical calculations.Further electron structure and bonding analysis confirmed the presence of delocalized bonds in the rhombic unit and the metallophilic interaction between two formal M^(+) ions.展开更多
基金supported by the National Natural Science Foundation of China(grant nos.22173062,21833005,22090022,and 22275125)the Beijing Natural Science Foundation of China(grant nos.Z230019 and 2212005)the Youth Innovative Research Team of Capital Normal University.
文摘Singlet fission(SF)offers the potential to improve the efficiency of photovoltaic devices(PVs)by harnessing high-energy photons to produce doubled photocurrents.However,progress in SF-based PVs is hindered by limited SF materials as a result of stringent requirements for atypical energetic arrangement and high ambient stability.Here we show that excited-state antiaromaticity(ESAA)relief can be used to simultaneously regulate the energy separation between T_(1) and S_(0) and design SF-capable materials with favorable energetic conditions and excellent stability.We achieve this by facilitatingπ-electron migration between the seven-and fivemembered rings in acepleiadylene(APD),which alleviates Baird’s antiaromaticity in the T_(1) state while maintaining Hückel’s aromaticity in S_(0).This leads to a lowered T_(1)’s energy relative to S_(0).Aromaticity index calculations reveal the aromaticity reversal and electron density redistribution between S_(0) and T_(1) to mitigate ESAA.This results in an energetic relationship suitable for SF,enabling a rapid fission process with an impressive yield of 165%.Moreover,ESAA relief endows APD with superior stability under ambient conditions.Our work not only introduces a new SF scaffold based on nonbenzenoid hydrocarbons,but it also provides valuable insights for the design of stable SF-active materials.
基金the National Natural Science Foundation of China(22073079,22025105 and 21873079)the Ministry of Education of China(H20200504)+2 种基金the Top-Notch Young Talents Program of China is gratefully acknowledgedM.S.thanks the Ministerio de Ciencia e Innovación of Spain(project PID2020-113711GB-I00)the Generalitat de Catalunya(project 2017SGR39).
文摘Aromaticity,in general,can promote a given reaction by stabilizing a transition state or a product via a mobility ofπelectrons in a cyclic structure.Similarly,such a promotion could be also achieved by destabilizing an antiaromatic reactant.However,both aromaticity and transition states cannot be directly measured in experiment.Thus,computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms.In this review,we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity.Specifically,we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation,Csingle bondF bond activation,rearrangement,as well as metathesis reactions.In addition,antiaromaticity-promoted dihydrogen activation,CO_(2)capture,and oxygen reduction reactions will be also briefly discussed.Finally,caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases.Thus,a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states.
基金This work was supported in China by National Natural Science Foundation of China （Nos. 21722106 and 21571171）, CAS-TWAS President Fellowship, and Youth Foundation project of Jilin prov- ince 20180520009JH, and in USA by NSF-CREST Center for Innova- tion, Research and Education in Environmental Nanotechnology （CIRE2N） （Grant Number HRD-1736093）.
文摘This paper highlights the compounds containing Sb cluster fragments, either synthesized in the solid-state, discovered from the gas phase, or only theoretically predicted. These Sbn clusters feature unique chemical bonding, fascinating structures, and special stabilities that can be well rational- ized by aromaticity or antiaromaticity. A deep understanding to their electronic structures is essential and will greatly facilitate the experimental synthesis of new Sbn cluster-based materials.
基金supported by the National Natural Science Foundation of China(Nos.92161102,22371140 to Z.-M.Sun and 22301143 to L.Qiao)the Fundamental Research Program of Shanxi Province(202103021224028 and 202204021301010 to W.-J.Tian)the Natural Science Foundation of Tianjin City(21JCZXJC00140 to Z.-M.Sun).
文摘Binary polyantimony clusters,namely[Cu_(2)Sb_(14)]^(4–) and [Ag_(2)Sb_(14)]^(4–),containing coinage metals,were successfully synthesized and characterized,in which two homoatomic Sb73–subunits are bridged by two coinage metals in η^(4):η^(1) and η^(1):η^(1) coordination modes,respectively.In[M_(2)Sb_(14)]^(4-),two bridging Cu ions and two Sb atoms form a planar rhombic unit,which was revealed to have antiaromatic properties by theoretical calculations.Further electron structure and bonding analysis confirmed the presence of delocalized bonds in the rhombic unit and the metallophilic interaction between two formal M^(+) ions.
