The Scholl cyclization for creating seven-membered rings is of great importance in synthesizing negatively curved polycyclic aromatic compounds.In this study,we systematically report a methodical approach for converti...The Scholl cyclization for creating seven-membered rings is of great importance in synthesizing negatively curved polycyclic aromatic compounds.In this study,we systematically report a methodical approach for converting[6]helicenes into negatively curved hexa[7]circulene using Scholl cyclization.The reaction revealed that the electron-donating substituents on the helicene terminal rings of helicenes facilitate the cyclization process while electron-withdrawing substituents would impede the cyclization.This was supported by theoretical calculations on the reaction process focusing on the arenium cation pathways.Through the application of this Scholl cyclization,a series of negatively curved hexa[7]circulene derivatives were synthesized,showing highly curved and twisted geometries.Notably,2,15-substituted derivatives exhibited high conformational stability against racemization,thereby performing circularly polarized luminescence with|glum|up to 4×10^(-3).展开更多
Recently,multiple helicenes have attracted enormous attention due to their exceptionally distorted conjugated architectures,appealing optical properties and unique spatial stacking patterns.The electronic and optical ...Recently,multiple helicenes have attracted enormous attention due to their exceptionally distorted conjugated architectures,appealing optical properties and unique spatial stacking patterns.The electronic and optical properties of multiple helicenes could be modulated by heteroatom doping.Herein,the first triple aza[6]helicene was reported by an intramolecular oxidation reaction,which exhibited highly distorted propeller-like geometry revealed by single crystal X-ray diffraction analysis.In comparison to the reported triple oxa[6]helicene,the triple aza[6]helicene demonstrated increased quantum yield(5.5%),and chiroptical properties with a|gabs|value of 0.012 and a|glum|value of 3.0×10^(-3).Furthermore,the stability and chiroptical properties of the triple aza[6]helicene could be enhanced by N-alkylation.展开更多
We report a facile and tailored method to prepare globally twisted chiral molecular cages through tunable coordination of bis-bipyridine-terminated helicene ligands to a series of transition metals including Fe(Ⅱ),Co...We report a facile and tailored method to prepare globally twisted chiral molecular cages through tunable coordination of bis-bipyridine-terminated helicene ligands to a series of transition metals including Fe(Ⅱ),Co(Ⅱ),Ni(Ⅱ)and Zn(Ⅱ).This system shows an efficient remote transfer of stereogenecity from the helicene core to the bipyridine-metal coordination sites and subsequently the entire cages.While the Fe(Ⅱ),Co(Ⅱ)and Ni(Ⅱ)-derived M_(2)L_(3)(M for metal and L for ligand)cages exhibit quasi-reversible redox features,the Zn(Ⅱ)analogues reveal prominent yellow circularly polarized luminescence.Interestingly,with the addition of Na_(2)SO_(4),the Zn_(2)L_(3)cages reassemble into sextuple-stranded Zn_(6)L_(6)(SO_(4))_(4)cages in which three Zn_(2)L_(2)units are bound together by four sulfates and further coalesced by offset inter-ligandπ-πinteractions.展开更多
Multiresonance organoboron helicenes are promising narrowband circularly polarized luminescence(CPL)emitters,which,however,still face formidable challenges to balance a large luminescence dissymmetry factor(glum)and a...Multiresonance organoboron helicenes are promising narrowband circularly polarized luminescence(CPL)emitters,which,however,still face formidable challenges to balance a large luminescence dissymmetry factor(glum)and a high luminescence efficiency.Here,two pairs of organoboron enantiomers(P/M-BN[8]H-ICz and P/M-BN[8]H-BO)with the same hetero[8]helicene geometric structures are developed through polycyclization decoration.We find that it is the helicity of helicene electronic structures rather than the geometrical one that determines the molecular dissymmetry property as a larger electronic helicity could enhance the electron-orbital coupling of the helicene structure.Therefore,P/M-BN[8]H-BO who possesses a hetero[8]helicene electronic structure realizes a nearly one-order-of-magnitude higher glum(+2.75/-2.52×10^(-3))and a higher photoluminescence quantum yield(PLQY)of 99%compared with P/M-BN[8]H-ICz bearing only a hetero[6]helicene electronic distribution structure(glum of only+2.41/-2.37×10^(-4)and PLQY of 95%).Moreover,BN[8]H-BO exhibits a narrowband green emission peaking at 538 nm with a full-width at half-maxima of merely 34 nm,narrower than most multiresonance CPL helicenes.The corresponding organic light-emitting diodes simultaneously realize a high external quantum efficiency of 31.7%,an electroluminescence dissymmetry factors(gEL)of+5.23/-5.07×10^(-3),and an extremely long LT95(time to 95%of the initial luminance)of over 731 h at an initial luminance of 1000 cd m^(-2).展开更多
A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic li...A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.展开更多
Two diastereoisomers(NTPH-P and NTPH-T1) as a C2-symmetric triple [5]helicene based on N-annulated triperylene hexaimide were synthesized.Aided by nuclear magnetic resonance spectroscopy(NMR) and theoretical calculati...Two diastereoisomers(NTPH-P and NTPH-T1) as a C2-symmetric triple [5]helicene based on N-annulated triperylene hexaimide were synthesized.Aided by nuclear magnetic resonance spectroscopy(NMR) and theoretical calculations,NTPH-P was assigned to three-blade propeller conformation while NTPH-T1 tended to exhibit twisted conformation with pyrrole ring fusing on a bowl-shaped PDI foil.Characterized by circular dichroism(CD) and circular polarized luminescence(CPL) measurements,the enantiomerically pure NTPH-P exhibited fairly good chiral activities both in the absorption and emission range with dissymmetry factors |gabs| of 4.1×10^-3 and |glum| of 1.2×10^-3.The diastereoisomers were further employed as acceptors for organic solar cells with distinct PCEs of 8.11% and 5.24% for NTPH-P and NTPH-T1 based devices,respectively,signifying the prospects in chiroptical electronics by designing molecularly defined aromatics.展开更多
Helicene-based emitters with unique inherent circularly polarized luminescence(CPL)are promising yet remain a formidable challenge for highly efficient circularly polarized organic light-emitting diodes(CP-OLEDs),ascr...Helicene-based emitters with unique inherent circularly polarized luminescence(CPL)are promising yet remain a formidable challenge for highly efficient circularly polarized organic light-emitting diodes(CP-OLEDs),ascribed to their tough synthesis,low emission efficiency,and easy racemization in the thermal deposition process.Herein,a pair of helicenebased enantiomers,namely(P)-helicene-BN and(M)-helicene-BN,were developed,which merge helical chirality and the B/N/S inserted polycyclic aromatic framework to concurrently feature CPL and narrow thermally activated delayed fluorescence(TADF)characteristics.Benefiting from the excellent thermal/photophysical/chiroptical properties,the narrowband green CP-OLEDs based on enantiomers achieved maximum external quantum efficiencies(EQE_(max))of up to 31.5%,and dissymmetry factor(|g_(EL)|)of 2.2×10^(−3).This work reveals the great potential of helicene-based emitters in CP-OLEDs.展开更多
Near-infrared(NIR)chiroptical response has been less explored because it is chal-lenging to achieve both chirality and NIR absorption/emission.Herein,we describe the design of heterohelicene-typeβ-isoindigo-based bor...Near-infrared(NIR)chiroptical response has been less explored because it is chal-lenging to achieve both chirality and NIR absorption/emission.Herein,we describe the design of heterohelicene-typeβ-isoindigo-based boron-dipyrromethene(BOD-IPY)analogs(β-IBs),which shift the absorption peak to 800 nm and produce significant Cotton effects(127.8 M-1 cm-1)and absorbance dissymmetry factors(|gabs|3.5=×10-3).The luminescence dissymmetry factor(glum)and circu-larly polarized luminescence(CPL)brightness(BCPL)of up to 1.24×10-3 and 1.78 M-1 cm-1 were realized beyond 800 nm.Theseβ-IBs are thefirst examples of helicene-type compounds with the highest gabs in the NIR region and CPL beyond 800 nm.Theoretical calculations demonstrate that the strong chiroptical activities are triggered by their large transition magnetic dipole moments.This study not only provides a new approach to the synthesis of a larger variety of unprecedented helicene-type BODIPY analogs but also demonstrates excellent NIR chiroptical properties.展开更多
Benefited from direct generation of circularly polarized(CP) emission with tunable colors, high efficiencies and facile device architectures, CP organic light-emitting diodes(CP-OLEDs) have attracted great attention a...Benefited from direct generation of circularly polarized(CP) emission with tunable colors, high efficiencies and facile device architectures, CP organic light-emitting diodes(CP-OLEDs) have attracted great attention and are expected to meet industrial applications. Particularly, CP electroluminescence(CPEL) originated from CP-OLEDs has wide potential applications in 3D displays, optical information storage, quantum communication, and biological sensors. The diverse design strategies of chiral luminescent materials for CP-OLEDs, including small organic emitters, lanthanide and transition-metal complexes and conjugated polymers, have been extensively explored. Helicene with twisted extended π-conjugated molecular structure could exhibit special helical chirality and excellent circularly polarized luminescence properties, which has been employed as the ingenious chirality core for constructing efficient chiral luminescent materials. In addition, significant improvements have been made in terms of CP photoluminescence research, however, the development of CPEL with more application prospects in optoelectronic technology still lags behind. In this review, we systematically summarize the recent advances in chiral luminescent materials based on helicene structure and their CPEL properties, including helicene-based chiral fluorescence molecules, transition metal complexes and thermally activated delayed fluorescence molecules, and discuss current challenges and future perspectives for this hot research field. We believe this progress report will provide a promising perspective of OLEDs based on helicene emitters with CPEL properties for extensive researchers, including chemical, physical and material scientists in different disciplinary fields and attract them to this rapidly developing field.展开更多
This article describes comparison of the anchoring effect on electronic properties of the helicene-like bibenzothiophene between o-carborane and 5,6-dicarba-nido-decaborane. The o-carborane and nido-decaborane-fused b...This article describes comparison of the anchoring effect on electronic properties of the helicene-like bibenzothiophene between o-carborane and 5,6-dicarba-nido-decaborane. The o-carborane and nido-decaborane-fused bibenzothiophenes were simultaneously obtained in the same reaction and successfully isolated. Initially, the X-ray single crystal analysis revealed that the helicene-like distorted structure was realized in the nido-decaborane-fused bibenzothiophene. From optical measurements in the solution state, distinct different characteristics depending on the type of anchors were observed. It was summarized that the absorption and luminescent properties originated from weak π-conjugation at the bibenzothiophene moiety in the o-carboranefused compound were obtained, whereas robust π-conjugation and significant emission from the intramolecular charge transfer state were detected from the nido-decaborane-fused compound. These data can be explained by the theoretical results that π-conjugation was restrictedly developed within the bibenzothiophene moiety in frontier orbitals of the o-carborane-fused compound. In contrast, π-conjugation can be constructed even through the distorted bibenzothiophene because of the nido-decaborane unit. Moreover, the intramolecular charge transfer state should be realized because of electronic interaction involving the nido-decaborane unit in the excited state. Furthermore, it was demonstrated that the nido-decaborane-fused compound possessed solid-state emission and mechanochromic luminescent properties. The π-conjugation on the distorted structure supported by the nido-decaborane anchor should play a significant role in suppressing aggregation-caused quenching followed by presenting solid-state emission with stimuli responsiveness.展开更多
Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron...Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron-rich NBN-coved edges.The structure of the NBN-coved multiple helicene was confirmed by single-crystal X-ray diffraction analysis,revealing a twisted double[5]helicene motif with a saddle-shaped skeleton.This NBN-coved helicene showed strong green fluorescence with good photoluminescence quantum yield.Both theoretical calculations and experimental investigation have been exploited to probe the impact of electron-rich NBN units on aromaticity and photophysical properties of the helicene.展开更多
We report the synthesis of a quadruple helicene with a rubicene core R1 by a Scholl reaction.Among the 10 stereoisomers including 4 pairs of enantiomers and 2 meso isomers,only 2 pairs of enantiomers and 1 meso isomer...We report the synthesis of a quadruple helicene with a rubicene core R1 by a Scholl reaction.Among the 10 stereoisomers including 4 pairs of enantiomers and 2 meso isomers,only 2 pairs of enantiomers and 1 meso isomer have been isolated.The sample structures were unambiguously determined by X-ray crystallography to be(P,P)_(6)-(P,P)_(5)/(M,M)_(6)-(M,M)_(5)-R1-A,which has a propeller-shaped structure,and(M,M)_(6)-(P,P)_(5)/(P,P)_(6)-(M,M)_(5)-R1-B and(M,P)_(6)-(P,M)_(5)-R1-C,which have saddle-shaped structures.The chiral resolutions of R1 were carried out by chiral HPLC,revealing two pairs of chiral stereoisomers(P,P)_(6)-(P,P)_(5)/(P,P)_(6)-(M,M)_(5),(M,M)_(6)-(P,P)_(5)/(M,M)_(6)-(M,M)_(5) as well as a meso isomer(M,P)_(6)-(P,M)_(5),which were further characterized by CD spectroscopy and time-dependent density functional theory(TD-DFT)calculations.Surprisingly,the UV-vis absorption and emission spectra of these resolved stereoisomers and unresolved R1 were almost identical.In addition,the chemical oxidation of R1 led to the formation of radical cations and dications at room temperature.展开更多
Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helic...Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helicenes are effective strategies for introducing unique photoelectric properties.Despite the disclosure of numerous helicenes,the inaccessible precursors and the lack of synthetic routes pose a challenge in achieving desired helicene structures fused with non-benzenoid rings.Herein,we report the synthesis of multiple non-benzenoid carbohelicenes fused with fluorene unit(s)through intramolecular cyclodehydrogenation of 9,10-di(naphthalen-1-yl)anthracene on Au(111)surface.Two potential cyclodehydrogenation manners between naphthyl and anthracene lead to the formation of fluorene-fused[5]helicene and[4]helicene moiety.Consequently,a total of four stable products were observed.The atomic topographies of products are characterized by bond-resolving scanning tunneling microscopy.The chiral helicity of targeted products can be switched by tip manipulation.Density-functional-theory calculations unveils the reaction pathway of four products.The comparative analysis of their respective energy barriers exhibits a correlation with the experimentally determined yields.Furthermore,we synthesize the polymer chains incorporating non-benzenoid carbohelicenes via the Ullmann reaction of 2,6-dibromo-9,10-di(1-naphthyl)anthracene precursors.Our work proposes a synthetic methodology for several novel helicene-like structures fused with fluorene units and the polymer bearing helicene subunits,thus highlighting the immense potential of these compounds in the application fields of luminescent electronic devices.展开更多
Unraveling the key structural features to maximize the chiroptical properties is of significance for developing high-performance chiral materials.Here we present our first attempt to elucidate and understand the molec...Unraveling the key structural features to maximize the chiroptical properties is of significance for developing high-performance chiral materials.Here we present our first attempt to elucidate and understand the molecular design of excellent chiroptical properties via the combination of multiplicity and the alignment of subhelicenes.Two stereoisomeric PDI-bladed quintuple[6]helicenes,namely D_(5)-CRP and C_(2)-CRP,were revealed to show distinct spatial arrangements of subhelicenes.Circular dichroism(CD)spectra showed that the Cotton effects(Δε)are reaching 1,412 mol-1L cm-1for D_(5)-CRP and 669 mol^(-1)L cm^(-1)for C_(2)-CRP in the visible spectrum.The greatly amplifiedΔεrelative to the smaller analogue NPDH arises from the circular annulation of helicenes and high molecular symmetry that could significantly regulate the transition dipole moments and thereby make them tend to be(anti)parallel,as supported by TDDFT calculations for the rotatory strength(R).Consequently,the maximal dissymmetry factors(|g_(abs)|and|g_(lum)|)of this kind of chiral molecular carbon imides were estimated to be up to 0.021 and 0.012,respectively.This study provides a deep insight into the chiroptical properties of complicated chiral systems.展开更多
An expedient synthesis of a series of configurationally stable oxa[5]helicenes,oxa[6]helicenes,and dioxa[6]helicenes has been developed using an intramolecular,highly enantioselective,Au-catalyzed,alkyne hydroarylatio...An expedient synthesis of a series of configurationally stable oxa[5]helicenes,oxa[6]helicenes,and dioxa[6]helicenes has been developed using an intramolecular,highly enantioselective,Au-catalyzed,alkyne hydroarylation reaction.The absolute configuration of the newly prepared structures has been established by crystallography,their inversion barriers have been determined theoretically and experimentally,and their chiroptical properties have been investigated.Comparison of these data with those reported for thia-or carbohelicenes sharing an otherwise identical helical framework enables the establishment of comprehensive correlations between the nature of the embedded(hetero)atom(s)and the magnitude of these properties.Preliminary studies on the postsynthetic functionalization of the oxahelicenes obtained are also described.Specifically,siteselective bromination at the 15-position in oxa[5]helicene 5d allows its subsequent manipulation into pyridine-containing aza-oxa[7]helicene 13d;while the two termini of oxa[6]helicene 7d have been intramolecularly cyclised into the pleiadeno[1,12,11-bcde]benzofuran derivative 15d by acidic treatment.Both transformations take place without erosion of the enantiopurity.展开更多
The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,...The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.展开更多
Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene moieties.Diversifying these aromatic cores unlocks avenues for creating multi...Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene moieties.Diversifying these aromatic cores unlocks avenues for creating multiple helicenes with distinct properties and topologies.Herein we report the synthesis of a quadruple[6]helicene featuring pyrene as the aromatic core.The synthesis involved key steps of the annulativeπ-extension reaction and Scholl reaction.By extending multiple helicenes along the axial direction,the degree of contortion of the aromatic core can be controlled from nearly flat to highly twisted.Notably,quadruple[6]-helicene exhibits a significant red-shift of 0.49 eV compared to quadruple[4]-helicenes,of which the red-shift arises from bothπ-extension and augmented effective conjugation due to enhanced twisting.Quantum chemical calculations demonstrate that the degree of contortion in the pyrene core adeptly governs the energy levels of the HOMO and LUMO,which offers an alternative strategy beyond mere enlargement of theπbackbone.An intriguing serendipitous finding reveals the formation of one-molecule-thick supramolecular homochiral nanosheets through selfinterlocking interactions of enantiomers in single crystals,a rare packing motif for multiple helicenes.展开更多
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
Nanographenes(NGs)with twisted backbones are emerging as new candidates for chiroptical materials.In this work,we describe a new strategy for synthesizing a[10]twistacene-embedded NG which exhibits a rare flag-hinge-l...Nanographenes(NGs)with twisted backbones are emerging as new candidates for chiroptical materials.In this work,we describe a new strategy for synthesizing a[10]twistacene-embedded NG which exhibits a rare flag-hinge-like geometry.By neatly creating steric crowding on the[6]helicene breaches of the NG skeleton,the synthesis only provided homochiral isomers without generating the“meso-”isomer.The formed NGs showed high luminescence with quantum yield up to 52%,and promising circularly polarized luminescence(CPL)performance with|glum|up to 5.0×10^(-3).Besides,these NGs also showed outstanding CPL brightness(BCPL)up to 305 L mol^(-1)cm^(-1)among chiral NGs.展开更多
The authors did not obtain permission to use some of the data from Prof.Hiroyuki Isobe,who supervised the reported study in itsearlystages.The concept of cyclo[n]helicenes was initiated by Prof.Hiroyuki Isobe(The Univ...The authors did not obtain permission to use some of the data from Prof.Hiroyuki Isobe,who supervised the reported study in itsearlystages.The concept of cyclo[n]helicenes was initiated by Prof.Hiroyuki Isobe(The University of Tokyo),then at Tohoku University.Specifically,the molecules 1-a,1-t,2-c,and 2-r were synthesized by Yong Yang who was employed with the funding of Professor Isobe,and the crystal data,CCDC 2306989-2306991 and 2306993,were obtained and analyzed by Sota Sato who was working in Professor Isobe’s group.The necessary expenses for these parts of the work were covered by JST ERATO(JPMJER1301,H.I.).The concept of cyclo[n]helicenes was initiated years ago by Prof.Isobe,when Dr.Yong Yang was a postdoc and Dr.Sota Sata was also a member of the group.The starting materials used in this work,[4]CH and[5]CH,were synthesized by Dr.Yang and structurally characterized by Dr.Sato in the group.展开更多
基金financially supported by the Zhejiang Provincial Natural Science Foundation,China(No.LY23B040003)the Science Foundation of Zhejiang Sci-Tech University,China(No.22062026-Y)。
文摘The Scholl cyclization for creating seven-membered rings is of great importance in synthesizing negatively curved polycyclic aromatic compounds.In this study,we systematically report a methodical approach for converting[6]helicenes into negatively curved hexa[7]circulene using Scholl cyclization.The reaction revealed that the electron-donating substituents on the helicene terminal rings of helicenes facilitate the cyclization process while electron-withdrawing substituents would impede the cyclization.This was supported by theoretical calculations on the reaction process focusing on the arenium cation pathways.Through the application of this Scholl cyclization,a series of negatively curved hexa[7]circulene derivatives were synthesized,showing highly curved and twisted geometries.Notably,2,15-substituted derivatives exhibited high conformational stability against racemization,thereby performing circularly polarized luminescence with|glum|up to 4×10^(-3).
文摘Recently,multiple helicenes have attracted enormous attention due to their exceptionally distorted conjugated architectures,appealing optical properties and unique spatial stacking patterns.The electronic and optical properties of multiple helicenes could be modulated by heteroatom doping.Herein,the first triple aza[6]helicene was reported by an intramolecular oxidation reaction,which exhibited highly distorted propeller-like geometry revealed by single crystal X-ray diffraction analysis.In comparison to the reported triple oxa[6]helicene,the triple aza[6]helicene demonstrated increased quantum yield(5.5%),and chiroptical properties with a|gabs|value of 0.012 and a|glum|value of 3.0×10^(-3).Furthermore,the stability and chiroptical properties of the triple aza[6]helicene could be enhanced by N-alkylation.
基金supported by the National Key R&D Program of China(No.2020YFA0908100)the National Natural Science Foundation of China(Nos.92056110 and 22075180)the Science and Technology Commission of Shanghai Municipality(Nos.18JC1415500,195271040,20JC1415000)。
文摘We report a facile and tailored method to prepare globally twisted chiral molecular cages through tunable coordination of bis-bipyridine-terminated helicene ligands to a series of transition metals including Fe(Ⅱ),Co(Ⅱ),Ni(Ⅱ)and Zn(Ⅱ).This system shows an efficient remote transfer of stereogenecity from the helicene core to the bipyridine-metal coordination sites and subsequently the entire cages.While the Fe(Ⅱ),Co(Ⅱ)and Ni(Ⅱ)-derived M_(2)L_(3)(M for metal and L for ligand)cages exhibit quasi-reversible redox features,the Zn(Ⅱ)analogues reveal prominent yellow circularly polarized luminescence.Interestingly,with the addition of Na_(2)SO_(4),the Zn_(2)L_(3)cages reassemble into sextuple-stranded Zn_(6)L_(6)(SO_(4))_(4)cages in which three Zn_(2)L_(2)units are bound together by four sulfates and further coalesced by offset inter-ligandπ-πinteractions.
基金National Key Research and Development Program of China,Grant/Award Number:2023YFB3609100National Natural Science Foundation of China,Grant/Award Number:2240051296+1 种基金National Key Research and Development Program,Grant/Award Numbers:2022YFA1204404,2021YFB3602702Postdoctoral Fellowship Program of CPSF,Grant/Award Number:GZC20231250。
文摘Multiresonance organoboron helicenes are promising narrowband circularly polarized luminescence(CPL)emitters,which,however,still face formidable challenges to balance a large luminescence dissymmetry factor(glum)and a high luminescence efficiency.Here,two pairs of organoboron enantiomers(P/M-BN[8]H-ICz and P/M-BN[8]H-BO)with the same hetero[8]helicene geometric structures are developed through polycyclization decoration.We find that it is the helicity of helicene electronic structures rather than the geometrical one that determines the molecular dissymmetry property as a larger electronic helicity could enhance the electron-orbital coupling of the helicene structure.Therefore,P/M-BN[8]H-BO who possesses a hetero[8]helicene electronic structure realizes a nearly one-order-of-magnitude higher glum(+2.75/-2.52×10^(-3))and a higher photoluminescence quantum yield(PLQY)of 99%compared with P/M-BN[8]H-ICz bearing only a hetero[6]helicene electronic distribution structure(glum of only+2.41/-2.37×10^(-4)and PLQY of 95%).Moreover,BN[8]H-BO exhibits a narrowband green emission peaking at 538 nm with a full-width at half-maxima of merely 34 nm,narrower than most multiresonance CPL helicenes.The corresponding organic light-emitting diodes simultaneously realize a high external quantum efficiency of 31.7%,an electroluminescence dissymmetry factors(gEL)of+5.23/-5.07×10^(-3),and an extremely long LT95(time to 95%of the initial luminance)of over 731 h at an initial luminance of 1000 cd m^(-2).
基金the National Natural Science Foundation of China(21871272,91956119 and 21521002)the Youth Innovation Promotion Association CAS(2019034)Qingdao University of Science and Technology(QUSTHX201929)。
文摘A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.
基金supported by the National Natural Science Foundation of China(21790361,21734009)the National Key R&D Program of China(2017YFA0204701)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(2017048)DFG within TRR 61
文摘Two diastereoisomers(NTPH-P and NTPH-T1) as a C2-symmetric triple [5]helicene based on N-annulated triperylene hexaimide were synthesized.Aided by nuclear magnetic resonance spectroscopy(NMR) and theoretical calculations,NTPH-P was assigned to three-blade propeller conformation while NTPH-T1 tended to exhibit twisted conformation with pyrrole ring fusing on a bowl-shaped PDI foil.Characterized by circular dichroism(CD) and circular polarized luminescence(CPL) measurements,the enantiomerically pure NTPH-P exhibited fairly good chiral activities both in the absorption and emission range with dissymmetry factors |gabs| of 4.1×10^-3 and |glum| of 1.2×10^-3.The diastereoisomers were further employed as acceptors for organic solar cells with distinct PCEs of 8.11% and 5.24% for NTPH-P and NTPH-T1 based devices,respectively,signifying the prospects in chiroptical electronics by designing molecularly defined aromatics.
基金This work was supported by the National Natural Science Foundation of China(grant nos.52130308,51903160,and 52022071)Shenzhen Science and Technology Program(grant no.KQTD20170330110107046)the Shenzhen Technology and Innovation Commission(grant no.JCYJ20180507182244027).
文摘Helicene-based emitters with unique inherent circularly polarized luminescence(CPL)are promising yet remain a formidable challenge for highly efficient circularly polarized organic light-emitting diodes(CP-OLEDs),ascribed to their tough synthesis,low emission efficiency,and easy racemization in the thermal deposition process.Herein,a pair of helicenebased enantiomers,namely(P)-helicene-BN and(M)-helicene-BN,were developed,which merge helical chirality and the B/N/S inserted polycyclic aromatic framework to concurrently feature CPL and narrow thermally activated delayed fluorescence(TADF)characteristics.Benefiting from the excellent thermal/photophysical/chiroptical properties,the narrowband green CP-OLEDs based on enantiomers achieved maximum external quantum efficiencies(EQE_(max))of up to 31.5%,and dissymmetry factor(|g_(EL)|)of 2.2×10^(−3).This work reveals the great potential of helicene-based emitters in CP-OLEDs.
基金National Natural Science Foundation of China,Grant/Award Numbers:21871072,22003014Hangzhou Normal University。
文摘Near-infrared(NIR)chiroptical response has been less explored because it is chal-lenging to achieve both chirality and NIR absorption/emission.Herein,we describe the design of heterohelicene-typeβ-isoindigo-based boron-dipyrromethene(BOD-IPY)analogs(β-IBs),which shift the absorption peak to 800 nm and produce significant Cotton effects(127.8 M-1 cm-1)and absorbance dissymmetry factors(|gabs|3.5=×10-3).The luminescence dissymmetry factor(glum)and circu-larly polarized luminescence(CPL)brightness(BCPL)of up to 1.24×10-3 and 1.78 M-1 cm-1 were realized beyond 800 nm.Theseβ-IBs are thefirst examples of helicene-type compounds with the highest gabs in the NIR region and CPL beyond 800 nm.Theoretical calculations demonstrate that the strong chiroptical activities are triggered by their large transition magnetic dipole moments.This study not only provides a new approach to the synthesis of a larger variety of unprecedented helicene-type BODIPY analogs but also demonstrates excellent NIR chiroptical properties.
基金National Natural Science Foundation of China(No.22005158)Program of High Level Talents(Nos.03083064 and JSSCBS20211122)Large Instruments Open Foundation of Nantong University.
文摘Benefited from direct generation of circularly polarized(CP) emission with tunable colors, high efficiencies and facile device architectures, CP organic light-emitting diodes(CP-OLEDs) have attracted great attention and are expected to meet industrial applications. Particularly, CP electroluminescence(CPEL) originated from CP-OLEDs has wide potential applications in 3D displays, optical information storage, quantum communication, and biological sensors. The diverse design strategies of chiral luminescent materials for CP-OLEDs, including small organic emitters, lanthanide and transition-metal complexes and conjugated polymers, have been extensively explored. Helicene with twisted extended π-conjugated molecular structure could exhibit special helical chirality and excellent circularly polarized luminescence properties, which has been employed as the ingenious chirality core for constructing efficient chiral luminescent materials. In addition, significant improvements have been made in terms of CP photoluminescence research, however, the development of CPEL with more application prospects in optoelectronic technology still lags behind. In this review, we systematically summarize the recent advances in chiral luminescent materials based on helicene structure and their CPEL properties, including helicene-based chiral fluorescence molecules, transition metal complexes and thermally activated delayed fluorescence molecules, and discuss current challenges and future perspectives for this hot research field. We believe this progress report will provide a promising perspective of OLEDs based on helicene emitters with CPEL properties for extensive researchers, including chemical, physical and material scientists in different disciplinary fields and attract them to this rapidly developing field.
基金supported by Konica Minolta Science and Technology Foundation (for K.T.)a Grant-in-Aid for Scientific Research on Innovative Areas "New Polymeric Materials Based on Element-Blocks (No.2401)" (JP24102013)
文摘This article describes comparison of the anchoring effect on electronic properties of the helicene-like bibenzothiophene between o-carborane and 5,6-dicarba-nido-decaborane. The o-carborane and nido-decaborane-fused bibenzothiophenes were simultaneously obtained in the same reaction and successfully isolated. Initially, the X-ray single crystal analysis revealed that the helicene-like distorted structure was realized in the nido-decaborane-fused bibenzothiophene. From optical measurements in the solution state, distinct different characteristics depending on the type of anchors were observed. It was summarized that the absorption and luminescent properties originated from weak π-conjugation at the bibenzothiophene moiety in the o-carboranefused compound were obtained, whereas robust π-conjugation and significant emission from the intramolecular charge transfer state were detected from the nido-decaborane-fused compound. These data can be explained by the theoretical results that π-conjugation was restrictedly developed within the bibenzothiophene moiety in frontier orbitals of the o-carborane-fused compound. In contrast, π-conjugation can be constructed even through the distorted bibenzothiophene because of the nido-decaborane unit. Moreover, the intramolecular charge transfer state should be realized because of electronic interaction involving the nido-decaborane unit in the excited state. Furthermore, it was demonstrated that the nido-decaborane-fused compound possessed solid-state emission and mechanochromic luminescent properties. The π-conjugation on the distorted structure supported by the nido-decaborane anchor should play a significant role in suppressing aggregation-caused quenching followed by presenting solid-state emission with stimuli responsiveness.
基金the National Natural Science Foundation of China(22001211)the Key Research and Development Program of Shaanxi Province(2023YBGY-454)+2 种基金Shaanxi Fundamental Science Research Project for Chemistry&Biology(Grant No.22JHQ015)for financial supportThis project is also supported by the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education,Jianghan University(No.JDGD-202208)the Fundamental Research Funds for the Central Universities.
文摘Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron-rich NBN-coved edges.The structure of the NBN-coved multiple helicene was confirmed by single-crystal X-ray diffraction analysis,revealing a twisted double[5]helicene motif with a saddle-shaped skeleton.This NBN-coved helicene showed strong green fluorescence with good photoluminescence quantum yield.Both theoretical calculations and experimental investigation have been exploited to probe the impact of electron-rich NBN units on aromaticity and photophysical properties of the helicene.
基金supported by the National Natural Science Foundation of China(21672026,21971020)。
文摘We report the synthesis of a quadruple helicene with a rubicene core R1 by a Scholl reaction.Among the 10 stereoisomers including 4 pairs of enantiomers and 2 meso isomers,only 2 pairs of enantiomers and 1 meso isomer have been isolated.The sample structures were unambiguously determined by X-ray crystallography to be(P,P)_(6)-(P,P)_(5)/(M,M)_(6)-(M,M)_(5)-R1-A,which has a propeller-shaped structure,and(M,M)_(6)-(P,P)_(5)/(P,P)_(6)-(M,M)_(5)-R1-B and(M,P)_(6)-(P,M)_(5)-R1-C,which have saddle-shaped structures.The chiral resolutions of R1 were carried out by chiral HPLC,revealing two pairs of chiral stereoisomers(P,P)_(6)-(P,P)_(5)/(P,P)_(6)-(M,M)_(5),(M,M)_(6)-(P,P)_(5)/(M,M)_(6)-(M,M)_(5) as well as a meso isomer(M,P)_(6)-(P,M)_(5),which were further characterized by CD spectroscopy and time-dependent density functional theory(TD-DFT)calculations.Surprisingly,the UV-vis absorption and emission spectra of these resolved stereoisomers and unresolved R1 were almost identical.In addition,the chemical oxidation of R1 led to the formation of radical cations and dications at room temperature.
基金supported by the National Natural Science Foundation of China(Nos.62271238,22372074,62301240)Yunnan Fundamental Research Projects(Nos.202201AT070078,202201BE070001-009 and 202301AW070017)+3 种基金the Major Basic Research Project of Science and Technology of Yunnan(202302AG050007)Yunnan Innovation Team of Graphene Mechanism Research and Application Industrialization(202305AS350017)Graphene Application and Engineering Research Centre of Education Department of Yunnan Providence(KKPP202351001)the Analysis and Testing Foundation of KUST(2021T20170056).
文摘Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helicenes are effective strategies for introducing unique photoelectric properties.Despite the disclosure of numerous helicenes,the inaccessible precursors and the lack of synthetic routes pose a challenge in achieving desired helicene structures fused with non-benzenoid rings.Herein,we report the synthesis of multiple non-benzenoid carbohelicenes fused with fluorene unit(s)through intramolecular cyclodehydrogenation of 9,10-di(naphthalen-1-yl)anthracene on Au(111)surface.Two potential cyclodehydrogenation manners between naphthyl and anthracene lead to the formation of fluorene-fused[5]helicene and[4]helicene moiety.Consequently,a total of four stable products were observed.The atomic topographies of products are characterized by bond-resolving scanning tunneling microscopy.The chiral helicity of targeted products can be switched by tip manipulation.Density-functional-theory calculations unveils the reaction pathway of four products.The comparative analysis of their respective energy barriers exhibits a correlation with the experimentally determined yields.Furthermore,we synthesize the polymer chains incorporating non-benzenoid carbohelicenes via the Ullmann reaction of 2,6-dibromo-9,10-di(1-naphthyl)anthracene precursors.Our work proposes a synthetic methodology for several novel helicene-like structures fused with fluorene units and the polymer bearing helicene subunits,thus highlighting the immense potential of these compounds in the application fields of luminescent electronic devices.
基金supported by the National Natural Science Foundation of China(22122503,22235005,and 22275112)the Shandong Provincial Natural Science Foundation(ZR2019ZD50)。
文摘Unraveling the key structural features to maximize the chiroptical properties is of significance for developing high-performance chiral materials.Here we present our first attempt to elucidate and understand the molecular design of excellent chiroptical properties via the combination of multiplicity and the alignment of subhelicenes.Two stereoisomeric PDI-bladed quintuple[6]helicenes,namely D_(5)-CRP and C_(2)-CRP,were revealed to show distinct spatial arrangements of subhelicenes.Circular dichroism(CD)spectra showed that the Cotton effects(Δε)are reaching 1,412 mol-1L cm-1for D_(5)-CRP and 669 mol^(-1)L cm^(-1)for C_(2)-CRP in the visible spectrum.The greatly amplifiedΔεrelative to the smaller analogue NPDH arises from the circular annulation of helicenes and high molecular symmetry that could significantly regulate the transition dipole moments and thereby make them tend to be(anti)parallel,as supported by TDDFT calculations for the rotatory strength(R).Consequently,the maximal dissymmetry factors(|g_(abs)|and|g_(lum)|)of this kind of chiral molecular carbon imides were estimated to be up to 0.021 and 0.012,respectively.This study provides a deep insight into the chiroptical properties of complicated chiral systems.
基金the Deutsche Forschungsgemeinschaft(INST 186/1352-1 and INST 186/1237-1)is gratefully acknowledged.W.Fthanks the China Scholarship Council for PhD fellowship support.R.C.-L.gratefully acknowledges grant PID2021-127964NB-C22 funded by the MCIN/AEI/10.13039/501100011033.
文摘An expedient synthesis of a series of configurationally stable oxa[5]helicenes,oxa[6]helicenes,and dioxa[6]helicenes has been developed using an intramolecular,highly enantioselective,Au-catalyzed,alkyne hydroarylation reaction.The absolute configuration of the newly prepared structures has been established by crystallography,their inversion barriers have been determined theoretically and experimentally,and their chiroptical properties have been investigated.Comparison of these data with those reported for thia-or carbohelicenes sharing an otherwise identical helical framework enables the establishment of comprehensive correlations between the nature of the embedded(hetero)atom(s)and the magnitude of these properties.Preliminary studies on the postsynthetic functionalization of the oxahelicenes obtained are also described.Specifically,siteselective bromination at the 15-position in oxa[5]helicene 5d allows its subsequent manipulation into pyridine-containing aza-oxa[7]helicene 13d;while the two termini of oxa[6]helicene 7d have been intramolecularly cyclised into the pleiadeno[1,12,11-bcde]benzofuran derivative 15d by acidic treatment.Both transformations take place without erosion of the enantiopurity.
基金supported by the Hong Kong Research Grants Council(27301720,17304021)National Natural Science Foundation of China(22122114,22122503,21790361).
文摘The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.
基金supported by Deutsche Forschungsgemeinschaft(DFG)through RTG 2591“Template-Designed Organic Electronics”the Manchot Foundation for a doctoral scholarship.
文摘Multiple helicenes display distinct aromatic cores characterized by highly twisted rings that are shared or fused with constituent helicene moieties.Diversifying these aromatic cores unlocks avenues for creating multiple helicenes with distinct properties and topologies.Herein we report the synthesis of a quadruple[6]helicene featuring pyrene as the aromatic core.The synthesis involved key steps of the annulativeπ-extension reaction and Scholl reaction.By extending multiple helicenes along the axial direction,the degree of contortion of the aromatic core can be controlled from nearly flat to highly twisted.Notably,quadruple[6]-helicene exhibits a significant red-shift of 0.49 eV compared to quadruple[4]-helicenes,of which the red-shift arises from bothπ-extension and augmented effective conjugation due to enhanced twisting.Quantum chemical calculations demonstrate that the degree of contortion in the pyrene core adeptly governs the energy levels of the HOMO and LUMO,which offers an alternative strategy beyond mere enlargement of theπbackbone.An intriguing serendipitous finding reveals the formation of one-molecule-thick supramolecular homochiral nanosheets through selfinterlocking interactions of enantiomers in single crystals,a rare packing motif for multiple helicenes.
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financially supported by the Zhejiang Provincial Natural Science Foundation,China(No.LY23B040003)the Science Foundation of Zhejiang Sci-Tech University,China(No.22062026-Y)。
文摘Nanographenes(NGs)with twisted backbones are emerging as new candidates for chiroptical materials.In this work,we describe a new strategy for synthesizing a[10]twistacene-embedded NG which exhibits a rare flag-hinge-like geometry.By neatly creating steric crowding on the[6]helicene breaches of the NG skeleton,the synthesis only provided homochiral isomers without generating the“meso-”isomer.The formed NGs showed high luminescence with quantum yield up to 52%,and promising circularly polarized luminescence(CPL)performance with|glum|up to 5.0×10^(-3).Besides,these NGs also showed outstanding CPL brightness(BCPL)up to 305 L mol^(-1)cm^(-1)among chiral NGs.
文摘The authors did not obtain permission to use some of the data from Prof.Hiroyuki Isobe,who supervised the reported study in itsearlystages.The concept of cyclo[n]helicenes was initiated by Prof.Hiroyuki Isobe(The University of Tokyo),then at Tohoku University.Specifically,the molecules 1-a,1-t,2-c,and 2-r were synthesized by Yong Yang who was employed with the funding of Professor Isobe,and the crystal data,CCDC 2306989-2306991 and 2306993,were obtained and analyzed by Sota Sato who was working in Professor Isobe’s group.The necessary expenses for these parts of the work were covered by JST ERATO(JPMJER1301,H.I.).The concept of cyclo[n]helicenes was initiated years ago by Prof.Isobe,when Dr.Yong Yang was a postdoc and Dr.Sota Sata was also a member of the group.The starting materials used in this work,[4]CH and[5]CH,were synthesized by Dr.Yang and structurally characterized by Dr.Sato in the group.
