The aromaticity and electronic properties of monocyclic or polycyclicπ-conjugated molecules have been widely studied.However,the related research on fullyπ-conjugated multicyclic macrocycles(MMCs)remains limited mai...The aromaticity and electronic properties of monocyclic or polycyclicπ-conjugated molecules have been widely studied.However,the related research on fullyπ-conjugated multicyclic macrocycles(MMCs)remains limited mainly due to the synthetic challenges.Herein,we report a straightforward synthesis of two MMCs(T8 and T12)in which unilateral and bilateral thiophene-based macrocycles merged with a cyclooctatetrathiophene unit by employing intramolecular Yamamoto coupling reactions of the designed precursors(8 and 12)followed by oxidative dehydrogenation.The neural compounds,their dications,and even tetracations were isolated in single-crystal form.Their geometry,aromaticity,open-shell diradical character,and physical properties were investigated by experiments such as X-ray crystallographic analysis,nuclear magnetic resonance(NMR),electron spin resonance(ESR),and theoretical calculations,which revealed changes in local/global aromatic/antiaromatic characteristics at different oxidation states.展开更多
Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic tr...Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic transistors with a facile fabrication process and highefficiency information processing ability are highly desired,while it remains a tremendous challenge.Herein,a new approach based on spin coating of a blend of CsPbBr_(3) perovskite quantum dot(QD)and PDVT-10 conjugated polymer is reported for the fabrication of photonic synaptic transistors.The combination of flat surface,outstanding optical absorption,and remarkable charge transporting performance contributes to high-efficiency photon-to-electron conversion for such perovskite-based synapses.High-performance photonic synaptic transistors are thus fabricated with essential synaptic functionalities,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),and long-term memory.By utilizing the photonic potentiation and electrical depression features,perovskite-based photonic synaptic transistors are also explored for neuromorphic computing simulations,showing high pattern recognition accuracy of up to 89.98%,which is one of the best values reported so far for synaptic transistors used in pattern recognition.This work provides an effective and convenient pathway for fabricating perovskite-based neuromorphic systems with high pattern recognition accuracy.展开更多
We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopro...We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopropylsilyl ethynylene (HZ-TIPS) and its homologue,octazethrene (OZ-TIPS) on an all-inorganic perovskite cesium lead bromide (CsPbBr3) surface.The photoluminescence behavior of the underlying perovskites upon differing molecular doping conditions was examined.It turns out that the charge transfer dynamics of thermally-evaporated OZ-TIPS molecule exhibited a faster average lifetime than that of the HZ-TIPS case suggesting the importance of the biradical state in the former molecule.An interfacial dipole was formed at the interface due to the competing interaction between the dispersion force of the bulky TIPS-substituent group and the attractive van der Waals interaction at the first few layers.Photoemission spectroscopy of the physisorbed HZ-TIPS shows chemical shifts,which indicates electron transfer from HZ-TIPS molecules to the CsPbBr3 perovskite single crystal.In contrast,the adsorbed OZ-TIPS molecular layer on CsPbBr3 demonstrates the opposite trend indicating a hole transfer process.The average molecular orientation as determined by near edge X-ray absorption fine structure (NEXAFS) suggests that the HZ-TIPS molecular plane is generally lifted with respect to the perovskite surface.We suggest that the nature of the closed-shell electronic ground state of HZ-TIPS could contribute to the formation of interfacial dipole at the molecule/perovskite interface.展开更多
The incorporation of heteroatoms into carbon nanohoops can significantly overcome aromatic stabilization energy and enrich their physicochemical properties depending on the positions and numbers of the doped atoms.Uti...The incorporation of heteroatoms into carbon nanohoops can significantly overcome aromatic stabilization energy and enrich their physicochemical properties depending on the positions and numbers of the doped atoms.Utilizing a V-shaped dipyreneo[c,e]dihydrophenazine as the building block,herein we report a novel kind of axially N-embedded quasi-carbon nanohoops by integratingπ-extended dihydropyrazine and para-phenylene subunits.Singlecrystal X-ray diffraction analyses revealed that their geometrical structures varied from droplet-shaped geometry for DPP-M and suppressed elliptical cross-section configuration for DPP-D to triangularly prismatic configuration for DPP-T.Spectroscopic measurements confirmed rich electronic properties,especially multioxidation behaviors due to the embedding of graphitic-N atoms,which are not observed in carbonaceous nanohoops and other analogs.Further investigations,including electron spin resonance spectroscopy,theoretical calculations,and single-crystal structure analyses,on the oxidized species of both DPP-D and DPP-T demonstrated their tunable open-shell ground states for the dications.This work provides a new synthetic strategy to axially N-embedded quasi-carbon nanohoops and gives insights into the design of structure-precise segments of graphitic-N-doped single-walled carbon nanotubes.展开更多
We report a facile synthesis of a [l,12-b,c,d]- cyclopenta-fused perylene 5 from the parent perylene via a formylation-oxidative esterification-nucleophilic additionfollowed-by-Friedel-Crafts alkylation strategy. Comp...We report a facile synthesis of a [l,12-b,c,d]- cyclopenta-fused perylene 5 from the parent perylene via a formylation-oxidative esterification-nucleophilic additionfollowed-by-Friedel-Crafts alkylation strategy. Compared with the perylene, dye 5 exhibits much higher solubility, smaller energy gap, and can undergo regio-selective bromination at the peri-positions. Compared with the N- annulated perylene 8, compound 5 shows lower HOMO energy level and is more stable in air. Therefore, 5 can be regarded a new versatile building block for the development of high-order soluble and stable rylenes and various perylene-based functional materials.展开更多
Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure,but their synthesis is very challenging.Herein,we report a facile synthetic strategy primarily involving macrocyc...Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure,but their synthesis is very challenging.Herein,we report a facile synthetic strategy primarily involving macrocyclization by the Suzuki coupling reaction,followed by bismuth(III)triflate-catalyzed cyclization of vinyl ethers.By utilizing this approach,aryl-substituted soluble cycloarenes 7 and 8 with different sizes were obtained.X-ray crystallographic analysis revealed a slightly distorted backbone in the kekulene derivative 7 and a saddle-shaped skeleton in the octulene derivative 8.Bond length analysis suggested that both of the cycloarenes mainly complied with the Clar’s bonding model with dominant local aromaticity,which was also in accord with our NMR measurements and the theoretical calculations[nucleus-independent chemical shift[NICS],anisotropy of the induced current density(ACID),three-dimensional isochemical shielding surface(3D ICSS)].The optical properties were investigated by UV-Vis absorption and fluorescence spectral measurements.Our method opens opportunities to access various expanded and core-modified cycloarenes in the future.展开更多
We report an air-stable tetraradicaloid based on a rarely explored perylenequinonoid(PQ)core,namely,tetrabenzo-annulated tetracyclopenta[b,e,k,n]perylene(TBCP),which has a quadruple helical structure.As validated by X...We report an air-stable tetraradicaloid based on a rarely explored perylenequinonoid(PQ)core,namely,tetrabenzo-annulated tetracyclopenta[b,e,k,n]perylene(TBCP),which has a quadruple helical structure.As validated by X-ray crystallographic analysis and theoretical calculations,the nonplanar TBCP possesses unique hybrid resonance structures of two open-shell singlet diradicaloids.Remarkably,magnetic measurements reveal that TBCP in powder form shows unusual magnetic hysteresis upon heating followed by cooling,corresponding to interconversion of structure isomers with different magnetic properties.Such electronic properties can be rationalized as the response of structural changes to external thermal stimuli,accompanied by a subtle balance of two types of intramolecular magnetic interactions between four-site spin centers.The results provide a novel organic polyradicaloid as an unprecedented example of a functional material with the potential for intramolecular magnetic switching.展开更多
Benzo[1,2-c;4,5-cʹ]bis[1,2,5]thiadiazole(BBT)has intrinsic diradical character and herein it is used to construct organic near-infrared(NIR)dyes together with the aromatic porphyrin unit.Three BBT-porphyrin hybrid dye...Benzo[1,2-c;4,5-cʹ]bis[1,2,5]thiadiazole(BBT)has intrinsic diradical character and herein it is used to construct organic near-infrared(NIR)dyes together with the aromatic porphyrin unit.Three BBT-porphyrin hybrid dyes 1-3 with different linkage modes are synthesized by Pd-catalyzed Sonogashira crosscoupling between meso-ethynylene porphyrin units and monobromo-/dibromo-BBT,or through unexpected homocoupling between the BBT units.They all possess small open-shell diradical character and display intense NIR absorption in the range of 800-1000 nm.They also exhibit amphoteric redox behavior.BBT-based diradicaloids are thus good candidates for organic NIR dyes.展开更多
基金supported financially by the Singapore Ministry of Education(MOE)Academic Research Fund(AcRF)Tier 2 grant(MOE-T2EP10222-0003)the Agency for Science,Technology and Research Manufacturing,Trade,and Connectivity(A*STAR MTC)project,Singapore(M22K2c0083).
文摘The aromaticity and electronic properties of monocyclic or polycyclicπ-conjugated molecules have been widely studied.However,the related research on fullyπ-conjugated multicyclic macrocycles(MMCs)remains limited mainly due to the synthetic challenges.Herein,we report a straightforward synthesis of two MMCs(T8 and T12)in which unilateral and bilateral thiophene-based macrocycles merged with a cyclooctatetrathiophene unit by employing intramolecular Yamamoto coupling reactions of the designed precursors(8 and 12)followed by oxidative dehydrogenation.The neural compounds,their dications,and even tetracations were isolated in single-crystal form.Their geometry,aromaticity,open-shell diradical character,and physical properties were investigated by experiments such as X-ray crystallographic analysis,nuclear magnetic resonance(NMR),electron spin resonance(ESR),and theoretical calculations,which revealed changes in local/global aromatic/antiaromatic characteristics at different oxidation states.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2018YFA0703200)the National Natural Science Foundation of China(91833306,51633006,51703160,51733004,51725304,and 52003189)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ130 and 2021ZZ129)。
文摘Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic transistors with a facile fabrication process and highefficiency information processing ability are highly desired,while it remains a tremendous challenge.Herein,a new approach based on spin coating of a blend of CsPbBr_(3) perovskite quantum dot(QD)and PDVT-10 conjugated polymer is reported for the fabrication of photonic synaptic transistors.The combination of flat surface,outstanding optical absorption,and remarkable charge transporting performance contributes to high-efficiency photon-to-electron conversion for such perovskite-based synapses.High-performance photonic synaptic transistors are thus fabricated with essential synaptic functionalities,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),and long-term memory.By utilizing the photonic potentiation and electrical depression features,perovskite-based photonic synaptic transistors are also explored for neuromorphic computing simulations,showing high pattern recognition accuracy of up to 89.98%,which is one of the best values reported so far for synaptic transistors used in pattern recognition.This work provides an effective and convenient pathway for fabricating perovskite-based neuromorphic systems with high pattern recognition accuracy.
文摘We present an optical and photoelectron spectroscopic study to elucidate the interfacial electronic properties of organic-inorganic semiconductor heterojunctions formed in a kinetically blocked heptazethrene triisopropylsilyl ethynylene (HZ-TIPS) and its homologue,octazethrene (OZ-TIPS) on an all-inorganic perovskite cesium lead bromide (CsPbBr3) surface.The photoluminescence behavior of the underlying perovskites upon differing molecular doping conditions was examined.It turns out that the charge transfer dynamics of thermally-evaporated OZ-TIPS molecule exhibited a faster average lifetime than that of the HZ-TIPS case suggesting the importance of the biradical state in the former molecule.An interfacial dipole was formed at the interface due to the competing interaction between the dispersion force of the bulky TIPS-substituent group and the attractive van der Waals interaction at the first few layers.Photoemission spectroscopy of the physisorbed HZ-TIPS shows chemical shifts,which indicates electron transfer from HZ-TIPS molecules to the CsPbBr3 perovskite single crystal.In contrast,the adsorbed OZ-TIPS molecular layer on CsPbBr3 demonstrates the opposite trend indicating a hole transfer process.The average molecular orientation as determined by near edge X-ray absorption fine structure (NEXAFS) suggests that the HZ-TIPS molecular plane is generally lifted with respect to the perovskite surface.We suggest that the nature of the closed-shell electronic ground state of HZ-TIPS could contribute to the formation of interfacial dipole at the molecule/perovskite interface.
基金financially supported by the National Natural Science Foundation of China(grant nos.22235005,21871084,and 21790361)the Shanghai Municipal Science and Technology Major Project(grant no.2018SHZDZX03)+3 种基金the Fundamental Research Funds for the Central Universities,the Programme of Introducing Talents of Discipline to Universities(grant no.B16017)the Program of Shanghai Academic/Technology Research Leader(grant no.19XD1421100)the Shanghai Science and Technology Committee(grant no.17520750100)the China Postdoctoral Science Foundation(grant no.2020M671018).
文摘The incorporation of heteroatoms into carbon nanohoops can significantly overcome aromatic stabilization energy and enrich their physicochemical properties depending on the positions and numbers of the doped atoms.Utilizing a V-shaped dipyreneo[c,e]dihydrophenazine as the building block,herein we report a novel kind of axially N-embedded quasi-carbon nanohoops by integratingπ-extended dihydropyrazine and para-phenylene subunits.Singlecrystal X-ray diffraction analyses revealed that their geometrical structures varied from droplet-shaped geometry for DPP-M and suppressed elliptical cross-section configuration for DPP-D to triangularly prismatic configuration for DPP-T.Spectroscopic measurements confirmed rich electronic properties,especially multioxidation behaviors due to the embedding of graphitic-N atoms,which are not observed in carbonaceous nanohoops and other analogs.Further investigations,including electron spin resonance spectroscopy,theoretical calculations,and single-crystal structure analyses,on the oxidized species of both DPP-D and DPP-T demonstrated their tunable open-shell ground states for the dications.This work provides a new synthetic strategy to axially N-embedded quasi-carbon nanohoops and gives insights into the design of structure-precise segments of graphitic-N-doped single-walled carbon nanotubes.
基金supported by MOE Tier 2 Grant(MOE2011-T2-2-130)A*STAR-DST joint Grant(IMRE/14-2C0239)A*STAR JCO Grant(1431AFG100)
文摘We report a facile synthesis of a [l,12-b,c,d]- cyclopenta-fused perylene 5 from the parent perylene via a formylation-oxidative esterification-nucleophilic additionfollowed-by-Friedel-Crafts alkylation strategy. Compared with the perylene, dye 5 exhibits much higher solubility, smaller energy gap, and can undergo regio-selective bromination at the peri-positions. Compared with the N- annulated perylene 8, compound 5 shows lower HOMO energy level and is more stable in air. Therefore, 5 can be regarded a new versatile building block for the development of high-order soluble and stable rylenes and various perylene-based functional materials.
基金The authors acknowledge financial support from the MOE Tier 3 program(no.MOE2014-T3-1-004)Tier 2 grant(no.MOE2018-T2-2-094)NRF Investigatorship(no.NRF-NRFI05-2019-0005).
文摘Cycloarenes are an essential class of polycyclic aromatic hydrocarbons with unique electronic structure,but their synthesis is very challenging.Herein,we report a facile synthetic strategy primarily involving macrocyclization by the Suzuki coupling reaction,followed by bismuth(III)triflate-catalyzed cyclization of vinyl ethers.By utilizing this approach,aryl-substituted soluble cycloarenes 7 and 8 with different sizes were obtained.X-ray crystallographic analysis revealed a slightly distorted backbone in the kekulene derivative 7 and a saddle-shaped skeleton in the octulene derivative 8.Bond length analysis suggested that both of the cycloarenes mainly complied with the Clar’s bonding model with dominant local aromaticity,which was also in accord with our NMR measurements and the theoretical calculations[nucleus-independent chemical shift[NICS],anisotropy of the induced current density(ACID),three-dimensional isochemical shielding surface(3D ICSS)].The optical properties were investigated by UV-Vis absorption and fluorescence spectral measurements.Our method opens opportunities to access various expanded and core-modified cycloarenes in the future.
基金The authors thank the National Natural Science Foundation of China(nos.51922039 and 21671003)the Science and Technology Innovation Program of Hunan Province(no.2020RC5033)the Shenzhen Outstanding Science and Technology Innovation Talent Cultivation Project for financial support.
文摘We report an air-stable tetraradicaloid based on a rarely explored perylenequinonoid(PQ)core,namely,tetrabenzo-annulated tetracyclopenta[b,e,k,n]perylene(TBCP),which has a quadruple helical structure.As validated by X-ray crystallographic analysis and theoretical calculations,the nonplanar TBCP possesses unique hybrid resonance structures of two open-shell singlet diradicaloids.Remarkably,magnetic measurements reveal that TBCP in powder form shows unusual magnetic hysteresis upon heating followed by cooling,corresponding to interconversion of structure isomers with different magnetic properties.Such electronic properties can be rationalized as the response of structural changes to external thermal stimuli,accompanied by a subtle balance of two types of intramolecular magnetic interactions between four-site spin centers.The results provide a novel organic polyradicaloid as an unprecedented example of a functional material with the potential for intramolecular magnetic switching.
基金supported by NRF(NRF-NRFI05-2019-0005)MOE Tier 2 grant(MOE2018-T2-2-094).
文摘Benzo[1,2-c;4,5-cʹ]bis[1,2,5]thiadiazole(BBT)has intrinsic diradical character and herein it is used to construct organic near-infrared(NIR)dyes together with the aromatic porphyrin unit.Three BBT-porphyrin hybrid dyes 1-3 with different linkage modes are synthesized by Pd-catalyzed Sonogashira crosscoupling between meso-ethynylene porphyrin units and monobromo-/dibromo-BBT,or through unexpected homocoupling between the BBT units.They all possess small open-shell diradical character and display intense NIR absorption in the range of 800-1000 nm.They also exhibit amphoteric redox behavior.BBT-based diradicaloids are thus good candidates for organic NIR dyes.
