Thermally activated delayed fluorescence(TADF)materials driven by a through-space charge transfer(TSCT)mechanism have garnered wide interest.However,access of TSCT-TADF molecules with longwavelength emission remains a...Thermally activated delayed fluorescence(TADF)materials driven by a through-space charge transfer(TSCT)mechanism have garnered wide interest.However,access of TSCT-TADF molecules with longwavelength emission remains a formidable challenge.In this study,we introduce a novel V-type DA-D-A’emitter,Trz-mCzCbCz,by using a carborane scaffold.This design strategically incorporates carbazole(Cz)and 2,4,6-triphenyl-1,3,5-triazine(Trz)as donor and acceptor moieties,respectively.Theoretical calculations alongside experimental validations affirm the typical TSCT-TADF characteristics of this luminogen.Owing to the unique structural and electronic attributes of carboranes,Trz-mCzCbCz exhibits an orange-red emission,markedly diverging from the traditional blue-to-green emissions observed in classical Cz and Trz-based TADF molecules.Moreover,bright emission in aggregates was observed for Trz-mCzCbCz with absolute photoluminescence quantum yield(PLQY)of up to 88.8%.As such,we have successfully fabricated five organic light-emitting diodes(OLEDs)by utilizing Trz-mCzCbCz as the emitting layer.It is important to note that both the reverse intersystem crossing process and the TADF properties are profoundly influenced by host materials.The fabricated OLED devices reached a maximum external quantum efficiency(EQE)of 12.7%,with an emission peak at 592 nm.This represents the highest recorded efficiency for TSCT-TADF OLEDs employing carborane derivatives as emitting layers.展开更多
The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through spac...The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.展开更多
Through-space conjugated molecules are interesting building blocks for the construction of functional materials that allow multi-dimensional transport of carrier and energy.However,the well explored through-space conj...Through-space conjugated molecules are interesting building blocks for the construction of functional materials that allow multi-dimensional transport of carrier and energy.However,the well explored through-space conjugated molecules are quite limited,which defers their structure-property correlation establishment and wide-scale application.In this review,we introduce a kind of newly-emerging folded tetraphenylethene derivatives featuring through-space conjugation.Their synthesis,crystal and electronic structures,and optical properties are described,and their representative applications as bipolar charge-transporting materials in organic light-emitting diodes and as single-molecule wires in molecular devices are presented,which are anticipated to provide guidance for the further expansion of through-space conjugated systems.展开更多
Three carbazole derivatives, Ac PTC, Px PTC and Pt PTC, consisting of two 9,9-dimethyl-9,10-dihydroacridine,phenoxazine or phenothiazine donor groups and one diphenyltriazine acceptor group fixed at 1,8,9-positions of...Three carbazole derivatives, Ac PTC, Px PTC and Pt PTC, consisting of two 9,9-dimethyl-9,10-dihydroacridine,phenoxazine or phenothiazine donor groups and one diphenyltriazine acceptor group fixed at 1,8,9-positions of a single carbazole ring via phenylene, are designed and synthesized. X-ray diffraction analysis of Ac PTC reveals that there exist multiple π-π interactions between the donor and acceptor groups to form a sandwich-like structural unit with edge-to-face interaction model. The compounds thus show obvious thermally activated delayed fluorescence with through-space charge transfer character and possess considerable photoluminescence quantum yields of up to 73% in doped films with sky-blue to yellow emissions. The solution-processed electroluminescent devices achieve the highest maximum external quantum efficiencies of 10.0%, 11% and 5.6% for Ac PTC, Px PTC and Pt PTC, respectively, with small efficiency roll-offs.展开更多
Through-space charge transfer(TSCT)is regarded as an effective way to develop thermally activated delayed fluorescence(TADF)emitters.Based on this strategy,many molecular frameworks have been proposed,among which spir...Through-space charge transfer(TSCT)is regarded as an effective way to develop thermally activated delayed fluorescence(TADF)emitters.Based on this strategy,many molecular frameworks have been proposed,among which spirobased scaffolds have been extensively studied due to their unique advantages.In this work,we developed three emitters SPS,SPO,and SPON,which were constructed with the same donor and various acceptors to explore the influence of acceptor modulation at the C9 position of fluorene for spirostructure TSCT emitters.The results show that the acceptor with too weak electronwithdrawing ability will cause the emitter to not have TADF properties,while the acceptor with too much steric hindrance will weaken the face-to-faceπ-πstacking interaction between donor/acceptor(D/A).Since SPO balances the electron-withdrawing strength and steric hindrance of the acceptor,it achieves the highest external quantum efficiency(EQE)of 17.75%.This work shows that appropriate acceptor selection is essential for the TADF properties and high efficiency of the spirobased scaffold TSCT emitter.展开更多
Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene-1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interde...Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene-1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interdeck distance D.The results show the through-space interactions of the title molecule decrease with the increasing of D,the through-space interactions of pi orbital are larger than that of sigma orbital.Furthermore,through-bond interactions of the pi orbtial and sigma orbital were analyzed basing on the calculations of the electronic structure of the title molecule.Both through-space and through-bond interactions are Large and,the net interactions are small.The calculated ionization potential energies of the title molecule which were obtained by transition-state procedure are in good agreement with the PE spectroscopy.展开更多
Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to ...Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to the unclear relationship between the non-conjugated structure and TSI properties.Herein,the TSI in diphenylmethane is manipulated by breaking its symmetric structures and changing the isolated subunits.Finally,the CL wavelength and efficiency of diphenylmethane are successfully regulated at the aggregate state.展开更多
The development of nontraditional luminogens(NTLs)with superior photoluminescence(PL)properties is of great scientific and practical significance and has drawn rapidly growing interest in recent years.An extremely imp...The development of nontraditional luminogens(NTLs)with superior photoluminescence(PL)properties is of great scientific and practical significance and has drawn rapidly growing interest in recent years.An extremely important but unresolved question is that if there are any distinct differences in the structures and PL mechanisms between traditional luminogens(TLs)and NTLs.In this work,four dihydropyridine derivatives with strong non-aromatic through-bond conjugation(TBC)were designed and synthesized,and the influence of strong non-aromatic TBC and through-space conjugation(TSC)effects on their PL behaviors was studied.These compounds in solutions show significant concentration-dependent emission(CDE)and excitation-dependent emission(EDE),which are typical PL behaviors of NTLs.In solid state,the compounds show wide excitation spectra while narrow emission spectra,with high quantum yields up to 57.4%,but they do not show significant EDE,similar to TLs.And very impressively,two kinds of crystals also exhibit optical waveguide property,which is the first report in NTLs.The UV–vis spectra,crystal structures,and theoretical calculations prove the presence of large non-aromatic TBC interactions in these NTLs,and strong non-aromatic TSC can be formed among the molecules that are in a planar conformation and stacked into layers through intermolecular hydrogen bonding and π…π interactions.The combined effect of strong non-aromatic TBC and TSC endows the compounds unique PL behaviors that are between those of TLs and NTLs,thus bridging the gap between TLs and NTLs.展开更多
The emergence of nonconventional luminescent materials(NLMs)has attracted significant attention due to their sustainable synthesis and tunable optical properties.Yet,establishing a clear structure-emission relationshi...The emergence of nonconventional luminescent materials(NLMs)has attracted significant attention due to their sustainable synthesis and tunable optical properties.Yet,establishing a clear structure-emission relationship remains a challenge.In this work,we report a previously unknown class of NLMs:cross-linked protein crystals that exhibit intense photoluminescence(PL)in the visible range(425-680 nm).We systematically investigated seven natural protein crystals(concanavalin,catalase,lysozyme,hemoglobin,α-chymotrypsin,pepsin,and β-lactoglobulin)cross-linked with glutaraldehyde and demonstrated that cross-linking induces broadband emission that is absent in natural crystals.Focusing on polymorphic lysozyme crystals(tetragonal,orthorhombic,and monoclinic),we found excitation-dependent fluorescence with lifetimes in the nanosecond range and quantum yields up to 20%(in themonoclinic phase under 450 nmexcitation).Single-and two-photon spectroscopy,as well as pressure-and solvent-modulated PL studies,confirm that the emission is due to intermolecular through-space interactions(TSI)within the crystal lattice.Compression enhances TSI and redshifts the emission,whereas the solvent(DMSO)-induced swelling reduces TSI and causes a blue shift,establishing a direct structure-emission correlation.This work establishes protein crystals as programmableNLMswith tunable emission and provides a mechanistic framework for the design of nonconventional luminogens through protein crystal engineering.展开更多
Constructing charge transfer(CT)state by introducing donor(D)and acceptor(A)is an efficient strategy to regulate the photophysical properties of luminescent materials.Traditional CT-type luminophores are built onπ-co...Constructing charge transfer(CT)state by introducing donor(D)and acceptor(A)is an efficient strategy to regulate the photophysical properties of luminescent materials.Traditional CT-type luminophores are built onπ-conjugated fused-ring structures,which always show hybrid CT/locally excited(LE)states and luminescence quenching effect in the aggregate state.In this work,eight conjugated biphenyl(BP)and nonconjugated diphenylmethane(DPM)derivatives with different donors and acceptors are synthesized to investigate the CT properties.Systematic photophysical characterization and theoretical calculation demonstrate that the through-space CT(TSCT)in nonconjugated DA-DPM exhibit superior photophysical performance than the conjugated DA-BP with through-bond CT(TBCT),the main manifestations are as follows:(1)TSCT luminophores produce longer maximum emission wavelength(λ_(em))than the corresponding TBCT ones.For example,the longest λ_(em)of DMA-CN-DPM(DMA,dimethylamino)is 621 nm but the corresponding λ_(em)of DMA-CN-BP is only 480 nm.(2)TSCT-based DA-DPM demonstrates more sensitive responsiveness to environmental stimuli such as temperature and polarity.(3)Complete separation of the the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)distribution exists in all kinds of conformation of DA-DPM,which was hard to realize in conjugated DA-BP.展开更多
Photoluminescence(PL)mechanisms of nontraditional luminogens(NTLs)have attracted great interest,and they are generally explained with intra/intermolecular through-space conjugation(TSC)of nonconventional chromophores....Photoluminescence(PL)mechanisms of nontraditional luminogens(NTLs)have attracted great interest,and they are generally explained with intra/intermolecular through-space conjugation(TSC)of nonconventional chromophores.Here a new concept of nonaromatic through-bond conjugation(TBC)is proposed and it is proved that it plays an important role in the PL of NTLs.The PL behaviors of the three respective isomers of cyclohexanedione and gemdimethyl-1,3-cyclohexanedione were studied and correlated with their chemical and aggregate structures.These compounds show differentfluorescence emissions as well as dif-ferent concentration,excitation and solvent-dependent emissions.The compounds which undergo keto-enol tautomerism and hence with a conjugated ketone-enol structure(i.e.,nonaromatic TBC)show more red-shifted emissions.TBC effect reduces the energy gaps and facilitates the formation of stronger TSC in the aggre-gate state.The compounds in the ketone-enol form are also prone to occur excited state intra/intermolecular proton transfer(ESIPT).The cooperative effect of nonaro-matic TBC and TSC determines the PL behaviors of NTLs.This work provides a novel understanding of the PL mechanisms of NTLs and is of great importance for directing the design and synthesis of novel NTLs.展开更多
The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(...The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(PDI),a well-known fluorescent scaffold,offers high thermal and photophysical stability but suffers from fluorescence quenching in solid or aggregate states due to intenseπ-πinteractions.To mitigate this,simple and versatile methods for strong PDI aggregate emission without extensive synthetic demands are highly desirable but still lacking.Here,we report a straightforward strategy to enhance the solid-state emission of PDI by introducing certain degree of through-space charge transfer(TSCT)via controlled radical polymerization,which can efficiently distort the typical face-to-face PDI stacking,enabling greatly enhanced deep red emission.This is achieved by growing electron-donating star-shape styrenic(co)polymers from a multidirectional electron-accepting PDI initiator.The incorporation of polycyclic aromatic monomers further shifted the emission into the near-infrared region,albeit with a reduced intensity.Overall,the emission of the PDI-based TSCT polymers can be systematically manipulated by leveraging the balance between PDI stacking and the TSCT degree,as confirmed by both experimental study and theoretical calculations.Our approach circumvents complex synthetic procedures,offering highly emissive materials with large Stokes shifts and showing broad potential for optoelectronic technology.展开更多
Through-space conjugation(TSC)is a noncovalently electronic interaction that is emerging as a potential complement to through-bond conjugation(TBC)-based strategies for constructing luminescent materials.However,the d...Through-space conjugation(TSC)is a noncovalently electronic interaction that is emerging as a potential complement to through-bond conjugation(TBC)-based strategies for constructing luminescent materials.However,the design of efficient luminogens based on TSC is currently challenging due to a lack of established structure-property understanding.This is particularly true in the case of luminogens displaying aggregation-induced emission(AIE)effects.In this work,three terphenyl derivatives were prepared,and their photophysical properties were systemically studied.It was found that relative to the corresponding m-and p-linked analogues,the electronic interaction of TBC is weakened while the strength of TSC is commensurately enhanced in the constitutional isomer containing an o-linked fjordtype subunit.Within this set of luminogens,the presence of a fjord-type arrangement promotes a transformation from aggregation-caused quenching to AIE.Further investigations involving congeneric quaterphenyl and pentphenyl isomers support the universality of the fjord-type unit as a framework for synthesizing AIE-active luminogens(AIEgens)with inherent TSC.This work not only provides a novel set of AIEgens but also establishes the utility of TSC in controlling the photophysical properties of nonconventional and twisted luminogens.展开更多
Efficient electronic coupling is the key to constructing optoelectronic functionalπsystems.Generally,the delocalization ofπelectrons must comply with the framework constructed by covalent bonds(typicallyσbonds),rep...Efficient electronic coupling is the key to constructing optoelectronic functionalπsystems.Generally,the delocalization ofπelectrons must comply with the framework constructed by covalent bonds(typicallyσbonds),representing classic through-bond conjuga-tion.However,through-space conjugation offers an alternative that achieves spatial electron communica-tionwith closely stacked π systems instead of covalent bonds thus enabling multidimensional energy and charge transport.展开更多
Three kinds of through-space charge transfer(TSCT)blue polymers containing non-conjugated polystyrene backbone together with spatially-separated acridan donor and oxygen-bridged triphenylboron acceptors having differe...Three kinds of through-space charge transfer(TSCT)blue polymers containing non-conjugated polystyrene backbone together with spatially-separated acridan donor and oxygen-bridged triphenylboron acceptors having different substituents of tert-butyl,hydrogen and fluorine are designed and synthesized.The designed TSCT blue polymers possess photoluminescence quantum yields up to 70%in solid-state film,single-triplet energy splitting below 0.1 eV,and typical thermally activated delayed fluorescence(TADF)effect.Meanwhile,the resulting polymers exhibit aggregation-induced emission(AIE)effect with emission intensity increased by up to^27 folds from solution to aggregation state.By changing the substituent of acceptors to tune the charge transfer strength,blue emission with peaks from 444 to 480 nm can be realized for the resulting polymers.Solution-processed organic light-emitting diodes based on the polymers exhibit excellent device performance with Commission Internationale de L’Eclairage(CIE)coordinates of(0.16,0.27),together with the maximum luminous efficiency of 30.7 cd A-1 and maximum external quantum efficiency of 15.0%,which is the best device efficiency for blue TADF polymers.展开更多
Nonconjugated clusteroluminogens(CLgens),such as proteins and polystyrene,have become increasingly important in photophysics.They show many advantages over traditional conjugated dyes with fused aromatic rings in biol...Nonconjugated clusteroluminogens(CLgens),such as proteins and polystyrene,have become increasingly important in photophysics.They show many advantages over traditional conjugated dyes with fused aromatic rings in biological applications.However,CLgens have historically been unheeded because of their weak visible emissions in the aggregate state,namely clusteroluminescence(CL).Changing the electronic structures of CLgens by precisely regulating the intramolecular throughspace interaction(TSI)to improve their photophysical properties remains an enormous challenge.Herein,we propose a general strategy to construct a higher-level intramolecular TSI,namely secondary TSI constructed by the primary TSI and a TSI linker,in multi-aryl-substituted alkanes(MAAs).By introducing methyl and phenyl into 1,1,3,3-tetraphenylpropane,the modified MAAs show efficient CL with high luminescence quantum yield(-40%)and long emission wavelength(-530 nm).Then,comprehensive experiments and theoretical studies demonstrate that molecular rigidity and overlap of subunits play pivotal roles in improving these hierarchical TSIs.This work not only provides a feasible strategy to achieve controllable manipulation of hierarchical TSIs and CL but also establishes comprehensive TSI-based aggregate photophysics.展开更多
Through-space charge transfer(TSCT)polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect,different from conventional lumi...Through-space charge transfer(TSCT)polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect,different from conventional luminescent polymers with conjugated donor-acceptor structure and through-bond charge transfer emission.Their emission comes from the intramolecular charge transfer by through-space pathway because the donor and acceptor segments are spatially proximate to each other in each repeating unit but are physically separated by nonconjugated polymer backbone.In this review,recent advances in TSCT polymers with linear,bottlebrush,and dendritic architectures are presented,with the focus on their molecular design,photophysical behavior,and device performance.We hope that this review shall provide a useful insight of new luminescent polymers with TSCT effect for use in solution-processed organic light-emitting diodes.展开更多
The construction of molecular chirality is crucial for exploring novel luminophores with chiroptical properties.Classic asymmetric synthesis of chiral center or axial is not powerful enough on through-space architectu...The construction of molecular chirality is crucial for exploring novel luminophores with chiroptical properties.Classic asymmetric synthesis of chiral center or axial is not powerful enough on through-space architecture.Accessible methodologies for breaking molecular symmetry could be promising but remain less investigated.Herein,we report a novel methodology for constructing chiral through-space luminophores via simple chlorination on bridged carbazole motifs.The chlorination breaks the molecular symmetry and thus results in molecular chirality by eliminating the mirror plane or rotating axis.Interestingly,continuous multiple chlorinations can rebuild and break the symmetry of the skeleton in succession.Several chiral and achiral isomeric analogues are synthesized and characterized with impressive chiroptical properties.Results of chiral high performance liquid chromatography(HPLC),single-crystal X-ray diffraction,kinetic racemization,and chiroptical property investigation demonstrate the effectiveness of our rational design strategy.It provides a feasible methodology for exploring novel chiral luminescent materials based on versatile though-space skeletons.展开更多
Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl ra...Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl radical sites are coupled antiferromagnetically via a through-space interaction.The results of quantum chemical,physicochemical(^(1)H NMR,electronic absorption,cyclic voltammetry,SQUID,ESR),and chemical reactivity studies show that this diradicaloid has singlet diradical character.An assessment of the nature of the bonding interaction between two radical sites in this species using DFT calculations demonstrates that a small spatial overlap between the two SOMOs in this diradicaloid provides an efficient electron exchange path for the singlet state to be substantially lower in energy than the triplet state.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province(No.BZ2022007)the National Natural Science Foundation of China(No.92261202)+1 种基金the Ministry of Science and Technology of the People’s Republic of China(No.2021YFE0114800)the Ministry of Science and Higher Education of the Russian Federation(No.075-15-2021-1027).
文摘Thermally activated delayed fluorescence(TADF)materials driven by a through-space charge transfer(TSCT)mechanism have garnered wide interest.However,access of TSCT-TADF molecules with longwavelength emission remains a formidable challenge.In this study,we introduce a novel V-type DA-D-A’emitter,Trz-mCzCbCz,by using a carborane scaffold.This design strategically incorporates carbazole(Cz)and 2,4,6-triphenyl-1,3,5-triazine(Trz)as donor and acceptor moieties,respectively.Theoretical calculations alongside experimental validations affirm the typical TSCT-TADF characteristics of this luminogen.Owing to the unique structural and electronic attributes of carboranes,Trz-mCzCbCz exhibits an orange-red emission,markedly diverging from the traditional blue-to-green emissions observed in classical Cz and Trz-based TADF molecules.Moreover,bright emission in aggregates was observed for Trz-mCzCbCz with absolute photoluminescence quantum yield(PLQY)of up to 88.8%.As such,we have successfully fabricated five organic light-emitting diodes(OLEDs)by utilizing Trz-mCzCbCz as the emitting layer.It is important to note that both the reverse intersystem crossing process and the TADF properties are profoundly influenced by host materials.The fabricated OLED devices reached a maximum external quantum efficiency(EQE)of 12.7%,with an emission peak at 592 nm.This represents the highest recorded efficiency for TSCT-TADF OLEDs employing carborane derivatives as emitting layers.
基金supported by the National Natural Science Foundation of China(No.22273057)the Universities Joint Laboratory of Guangdong,Hong Kong and Macao(No.2021LSYS009)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2022A1515011661,2023A1515012631)the Chemistry and Chemical Engineering Guangdong Laboratory(No.1922003)Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302009)。
文摘The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.
基金the financial support from the National Natural Science Foundation of China(No.51273053)the National Basic Research Program of China(973 Program,Nos.2015CB655004 and 2013CB834702)+5 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar(No.2014A030306035)the Guangdong Innovative Research Team Program of China(No.201101C0105067115)the Science and Technology Project of Guangdong Province(No.2016B090907001)the ITC-CNERC14S01,the Fundamental Research Funds for the Central Universities(Nos.2015PT020 and 2015ZY013)the Natural Science Foundation of Guangdong Province(No.2016A030312002)the National Undergraduate Innovative and Entrepreneurial Training Program(No.201410561032)
文摘Through-space conjugated molecules are interesting building blocks for the construction of functional materials that allow multi-dimensional transport of carrier and energy.However,the well explored through-space conjugated molecules are quite limited,which defers their structure-property correlation establishment and wide-scale application.In this review,we introduce a kind of newly-emerging folded tetraphenylethene derivatives featuring through-space conjugation.Their synthesis,crystal and electronic structures,and optical properties are described,and their representative applications as bipolar charge-transporting materials in organic light-emitting diodes and as single-molecule wires in molecular devices are presented,which are anticipated to provide guidance for the further expansion of through-space conjugated systems.
基金supported by the National Natural Science Foundation of China (Nos. 51973210, 21805271 and 21674110)the Science and Technology Development Project of Jilin Province, China (No. 20190201071JC)。
文摘Three carbazole derivatives, Ac PTC, Px PTC and Pt PTC, consisting of two 9,9-dimethyl-9,10-dihydroacridine,phenoxazine or phenothiazine donor groups and one diphenyltriazine acceptor group fixed at 1,8,9-positions of a single carbazole ring via phenylene, are designed and synthesized. X-ray diffraction analysis of Ac PTC reveals that there exist multiple π-π interactions between the donor and acceptor groups to form a sandwich-like structural unit with edge-to-face interaction model. The compounds thus show obvious thermally activated delayed fluorescence with through-space charge transfer character and possess considerable photoluminescence quantum yields of up to 73% in doped films with sky-blue to yellow emissions. The solution-processed electroluminescent devices achieve the highest maximum external quantum efficiencies of 10.0%, 11% and 5.6% for Ac PTC, Px PTC and Pt PTC, respectively, with small efficiency roll-offs.
基金financial support from the National Natural Science Foundation of China(Nos.51773141,51873139,61961160731,62175171 and 22175124)funded by the Suzhou Science and Technology Plan Project(No.SYG202010)+2 种基金supported by Suzhou Key Laboratory of Functional Nano&Soft Materials,Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 ProjectJoint International Research Laboratory of Carbon-Based Functional Materials and Devices。
文摘Through-space charge transfer(TSCT)is regarded as an effective way to develop thermally activated delayed fluorescence(TADF)emitters.Based on this strategy,many molecular frameworks have been proposed,among which spirobased scaffolds have been extensively studied due to their unique advantages.In this work,we developed three emitters SPS,SPO,and SPON,which were constructed with the same donor and various acceptors to explore the influence of acceptor modulation at the C9 position of fluorene for spirostructure TSCT emitters.The results show that the acceptor with too weak electronwithdrawing ability will cause the emitter to not have TADF properties,while the acceptor with too much steric hindrance will weaken the face-to-faceπ-πstacking interaction between donor/acceptor(D/A).Since SPO balances the electron-withdrawing strength and steric hindrance of the acceptor,it achieves the highest external quantum efficiency(EQE)of 17.75%.This work shows that appropriate acceptor selection is essential for the TADF properties and high efficiency of the spirobased scaffold TSCT emitter.
基金The project is supported by National Nature Scrence Funds of China.
文摘Through-space interactions of pi orbiatl and sigma orbital in molecule tricycle 4,2,2,2,dodecadiene-1.5 were studied by means of DV-X alpha SVF method using a model molecule that consists of two ethylenes with interdeck distance D.The results show the through-space interactions of the title molecule decrease with the increasing of D,the through-space interactions of pi orbital are larger than that of sigma orbital.Furthermore,through-bond interactions of the pi orbtial and sigma orbital were analyzed basing on the calculations of the electronic structure of the title molecule.Both through-space and through-bond interactions are Large and,the net interactions are small.The calculated ionization potential energies of the title molecule which were obtained by transition-state procedure are in good agreement with the PE spectroscopy.
基金the National Science Foundation of China(22205197)the project funded by China Postdoctoral Science Foundation(2022M712721)the Youth Talent Excellence Program of ZJU-Hangzhou Global Scientific and Technological Innovation Center.
文摘Through-space interaction(TSI)has been proven to play an important role in the newly emerging clusteroluminescence(CL)phenomenon.However,it is still a big challenge to manipulate the TSI at the molecular level due to the unclear relationship between the non-conjugated structure and TSI properties.Herein,the TSI in diphenylmethane is manipulated by breaking its symmetric structures and changing the isolated subunits.Finally,the CL wavelength and efficiency of diphenylmethane are successfully regulated at the aggregate state.
基金supported by National Natural Science Foundation of China(Grant 22472010)the Program for Changjiang Scholars and Innovative Research Team(PCSIRT)in university.
文摘The development of nontraditional luminogens(NTLs)with superior photoluminescence(PL)properties is of great scientific and practical significance and has drawn rapidly growing interest in recent years.An extremely important but unresolved question is that if there are any distinct differences in the structures and PL mechanisms between traditional luminogens(TLs)and NTLs.In this work,four dihydropyridine derivatives with strong non-aromatic through-bond conjugation(TBC)were designed and synthesized,and the influence of strong non-aromatic TBC and through-space conjugation(TSC)effects on their PL behaviors was studied.These compounds in solutions show significant concentration-dependent emission(CDE)and excitation-dependent emission(EDE),which are typical PL behaviors of NTLs.In solid state,the compounds show wide excitation spectra while narrow emission spectra,with high quantum yields up to 57.4%,but they do not show significant EDE,similar to TLs.And very impressively,two kinds of crystals also exhibit optical waveguide property,which is the first report in NTLs.The UV–vis spectra,crystal structures,and theoretical calculations prove the presence of large non-aromatic TBC interactions in these NTLs,and strong non-aromatic TSC can be formed among the molecules that are in a planar conformation and stacked into layers through intermolecular hydrogen bonding and π…π interactions.The combined effect of strong non-aromatic TBC and TSC endows the compounds unique PL behaviors that are between those of TLs and NTLs,thus bridging the gap between TLs and NTLs.
基金support from the National Key R&D Program of China(2021YFF0502900)the National Natural Science Foundation of China(62127819,T2421003,62435011,32471230,W2431056)+2 种基金the Shenzhen Key Laboratory of Photonics and Biophotonics(ZDSYS20210623092006020)the Shenzhen Science and Technology Program(JCYJ20220818100202005)and the Fundamental Research Funds for the Central Universities(23GH02021).
文摘The emergence of nonconventional luminescent materials(NLMs)has attracted significant attention due to their sustainable synthesis and tunable optical properties.Yet,establishing a clear structure-emission relationship remains a challenge.In this work,we report a previously unknown class of NLMs:cross-linked protein crystals that exhibit intense photoluminescence(PL)in the visible range(425-680 nm).We systematically investigated seven natural protein crystals(concanavalin,catalase,lysozyme,hemoglobin,α-chymotrypsin,pepsin,and β-lactoglobulin)cross-linked with glutaraldehyde and demonstrated that cross-linking induces broadband emission that is absent in natural crystals.Focusing on polymorphic lysozyme crystals(tetragonal,orthorhombic,and monoclinic),we found excitation-dependent fluorescence with lifetimes in the nanosecond range and quantum yields up to 20%(in themonoclinic phase under 450 nmexcitation).Single-and two-photon spectroscopy,as well as pressure-and solvent-modulated PL studies,confirm that the emission is due to intermolecular through-space interactions(TSI)within the crystal lattice.Compression enhances TSI and redshifts the emission,whereas the solvent(DMSO)-induced swelling reduces TSI and causes a blue shift,establishing a direct structure-emission correlation.This work establishes protein crystals as programmableNLMswith tunable emission and provides a mechanistic framework for the design of nonconventional luminogens through protein crystal engineering.
基金supported by the National Natural Science Foundation of China(22205197)the project funded by China Postdoctoral Science Foundation(2022M712721)。
文摘Constructing charge transfer(CT)state by introducing donor(D)and acceptor(A)is an efficient strategy to regulate the photophysical properties of luminescent materials.Traditional CT-type luminophores are built onπ-conjugated fused-ring structures,which always show hybrid CT/locally excited(LE)states and luminescence quenching effect in the aggregate state.In this work,eight conjugated biphenyl(BP)and nonconjugated diphenylmethane(DPM)derivatives with different donors and acceptors are synthesized to investigate the CT properties.Systematic photophysical characterization and theoretical calculation demonstrate that the through-space CT(TSCT)in nonconjugated DA-DPM exhibit superior photophysical performance than the conjugated DA-BP with through-bond CT(TBCT),the main manifestations are as follows:(1)TSCT luminophores produce longer maximum emission wavelength(λ_(em))than the corresponding TBCT ones.For example,the longest λ_(em)of DMA-CN-DPM(DMA,dimethylamino)is 621 nm but the corresponding λ_(em)of DMA-CN-BP is only 480 nm.(2)TSCT-based DA-DPM demonstrates more sensitive responsiveness to environmental stimuli such as temperature and polarity.(3)Complete separation of the the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)distribution exists in all kinds of conformation of DA-DPM,which was hard to realize in conjugated DA-BP.
基金Program for Changjiang Scholars and Innovative Research Team(PCSIRT)in UniversityNational Natural Science Foundation of China,Grant/Award Number:21574015。
文摘Photoluminescence(PL)mechanisms of nontraditional luminogens(NTLs)have attracted great interest,and they are generally explained with intra/intermolecular through-space conjugation(TSC)of nonconventional chromophores.Here a new concept of nonaromatic through-bond conjugation(TBC)is proposed and it is proved that it plays an important role in the PL of NTLs.The PL behaviors of the three respective isomers of cyclohexanedione and gemdimethyl-1,3-cyclohexanedione were studied and correlated with their chemical and aggregate structures.These compounds show differentfluorescence emissions as well as dif-ferent concentration,excitation and solvent-dependent emissions.The compounds which undergo keto-enol tautomerism and hence with a conjugated ketone-enol structure(i.e.,nonaromatic TBC)show more red-shifted emissions.TBC effect reduces the energy gaps and facilitates the formation of stronger TSC in the aggre-gate state.The compounds in the ketone-enol form are also prone to occur excited state intra/intermolecular proton transfer(ESIPT).The cooperative effect of nonaro-matic TBC and TSC determines the PL behaviors of NTLs.This work provides a novel understanding of the PL mechanisms of NTLs and is of great importance for directing the design and synthesis of novel NTLs.
基金supported by Swiss National Science Foundation(190313)Fondation Claude et Giuliana(1-005137)the Australian Research Council(ARC)under the Centre of Excellence Scheme(CE170100026)。
文摘The molecular engineering of fluorescent organic/polymeric materials,specifically those emitting in the deep red to near-infrared spectrum,is vital for advancements in optoelectronics and biomedicine.Perylene diimide(PDI),a well-known fluorescent scaffold,offers high thermal and photophysical stability but suffers from fluorescence quenching in solid or aggregate states due to intenseπ-πinteractions.To mitigate this,simple and versatile methods for strong PDI aggregate emission without extensive synthetic demands are highly desirable but still lacking.Here,we report a straightforward strategy to enhance the solid-state emission of PDI by introducing certain degree of through-space charge transfer(TSCT)via controlled radical polymerization,which can efficiently distort the typical face-to-face PDI stacking,enabling greatly enhanced deep red emission.This is achieved by growing electron-donating star-shape styrenic(co)polymers from a multidirectional electron-accepting PDI initiator.The incorporation of polycyclic aromatic monomers further shifted the emission into the near-infrared region,albeit with a reduced intensity.Overall,the emission of the PDI-based TSCT polymers can be systematically manipulated by leveraging the balance between PDI stacking and the TSCT degree,as confirmed by both experimental study and theoretical calculations.Our approach circumvents complex synthetic procedures,offering highly emissive materials with large Stokes shifts and showing broad potential for optoelectronic technology.
基金F.H.thanks National Key Research and Development Program of China (grant no.2021YFA0910100)National Natural Science Foundation of China (grant no.22035006)+5 种基金Zhejiang Provincial Natural Science Foundation of China (grant no.LD21B020001)the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study (grant no.SN-ZJU-SIAS-006)the Leading Innovation Team grant from Department of Science and Technology of Zhejiang Province (grant no.2022R01005)for financial supportH.Z.thanks the National Science Foundation of China (grant no.22205197)for supportY.-Q.H.acknowledges support from the Chinese Postdoctoral Science Foundation (grant no.2022M712735)J.L.S.thanks the Robert A.Welch Foundation for chair support (grant no.F-0018).
文摘Through-space conjugation(TSC)is a noncovalently electronic interaction that is emerging as a potential complement to through-bond conjugation(TBC)-based strategies for constructing luminescent materials.However,the design of efficient luminogens based on TSC is currently challenging due to a lack of established structure-property understanding.This is particularly true in the case of luminogens displaying aggregation-induced emission(AIE)effects.In this work,three terphenyl derivatives were prepared,and their photophysical properties were systemically studied.It was found that relative to the corresponding m-and p-linked analogues,the electronic interaction of TBC is weakened while the strength of TSC is commensurately enhanced in the constitutional isomer containing an o-linked fjordtype subunit.Within this set of luminogens,the presence of a fjord-type arrangement promotes a transformation from aggregation-caused quenching to AIE.Further investigations involving congeneric quaterphenyl and pentphenyl isomers support the universality of the fjord-type unit as a framework for synthesizing AIE-active luminogens(AIEgens)with inherent TSC.This work not only provides a novel set of AIEgens but also establishes the utility of TSC in controlling the photophysical properties of nonconventional and twisted luminogens.
基金This work was financially supported by the National Natural Science Foundation of China(21788102 and 21673082)the National Basic Research Program of Chi-na(973 Program,2015CB655004)founded by MOST+2 种基金the Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306035)the Natural Science Foundation of Guangdong Province(2016A030312002)the Innovation and Technology Commission of Hong Kong(ITC-CNERC14SC01).
文摘Efficient electronic coupling is the key to constructing optoelectronic functionalπsystems.Generally,the delocalization ofπelectrons must comply with the framework constructed by covalent bonds(typicallyσbonds),representing classic through-bond conjuga-tion.However,through-space conjugation offers an alternative that achieves spatial electron communica-tionwith closely stacked π systems instead of covalent bonds thus enabling multidimensional energy and charge transport.
基金supported by the National Natural Science Foundation of China(51833009,21975247,51573182)the National Program on Key Basic Research Project of China(2015CB655000)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2015180)。
文摘Three kinds of through-space charge transfer(TSCT)blue polymers containing non-conjugated polystyrene backbone together with spatially-separated acridan donor and oxygen-bridged triphenylboron acceptors having different substituents of tert-butyl,hydrogen and fluorine are designed and synthesized.The designed TSCT blue polymers possess photoluminescence quantum yields up to 70%in solid-state film,single-triplet energy splitting below 0.1 eV,and typical thermally activated delayed fluorescence(TADF)effect.Meanwhile,the resulting polymers exhibit aggregation-induced emission(AIE)effect with emission intensity increased by up to^27 folds from solution to aggregation state.By changing the substituent of acceptors to tune the charge transfer strength,blue emission with peaks from 444 to 480 nm can be realized for the resulting polymers.Solution-processed organic light-emitting diodes based on the polymers exhibit excellent device performance with Commission Internationale de L’Eclairage(CIE)coordinates of(0.16,0.27),together with the maximum luminous efficiency of 30.7 cd A-1 and maximum external quantum efficiency of 15.0%,which is the best device efficiency for blue TADF polymers.
基金the National Science Foundation of China(grant no.22205197)the project funded by China Postdoctoral Science Foundation(grant no.2022M712721)the Youth Talent Excellence Program of ZJU-Hangzhou Global Scientific and Technological Innovation Center for their financial support.
文摘Nonconjugated clusteroluminogens(CLgens),such as proteins and polystyrene,have become increasingly important in photophysics.They show many advantages over traditional conjugated dyes with fused aromatic rings in biological applications.However,CLgens have historically been unheeded because of their weak visible emissions in the aggregate state,namely clusteroluminescence(CL).Changing the electronic structures of CLgens by precisely regulating the intramolecular throughspace interaction(TSI)to improve their photophysical properties remains an enormous challenge.Herein,we propose a general strategy to construct a higher-level intramolecular TSI,namely secondary TSI constructed by the primary TSI and a TSI linker,in multi-aryl-substituted alkanes(MAAs).By introducing methyl and phenyl into 1,1,3,3-tetraphenylpropane,the modified MAAs show efficient CL with high luminescence quantum yield(-40%)and long emission wavelength(-530 nm).Then,comprehensive experiments and theoretical studies demonstrate that molecular rigidity and overlap of subunits play pivotal roles in improving these hierarchical TSIs.This work not only provides a feasible strategy to achieve controllable manipulation of hierarchical TSIs and CL but also establishes comprehensive TSI-based aggregate photophysics.
基金National Natural Science Foundation of China,Grant/Award Numbers:51833009,52073282,91833306973 Project,Grant/Award Number:2015CB655000Youth Innovation Promotion Association of Chinese Academy of Sciences,Grant/Award Number:2015180。
文摘Through-space charge transfer(TSCT)polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect,different from conventional luminescent polymers with conjugated donor-acceptor structure and through-bond charge transfer emission.Their emission comes from the intramolecular charge transfer by through-space pathway because the donor and acceptor segments are spatially proximate to each other in each repeating unit but are physically separated by nonconjugated polymer backbone.In this review,recent advances in TSCT polymers with linear,bottlebrush,and dendritic architectures are presented,with the focus on their molecular design,photophysical behavior,and device performance.We hope that this review shall provide a useful insight of new luminescent polymers with TSCT effect for use in solution-processed organic light-emitting diodes.
基金supported by the National Natural Science Foundation of China(21975061)Shenzhen Fundamental Research Program(JCYJ20190806142403535,GXWD20201230155427003-20200728150952003)
文摘The construction of molecular chirality is crucial for exploring novel luminophores with chiroptical properties.Classic asymmetric synthesis of chiral center or axial is not powerful enough on through-space architecture.Accessible methodologies for breaking molecular symmetry could be promising but remain less investigated.Herein,we report a novel methodology for constructing chiral through-space luminophores via simple chlorination on bridged carbazole motifs.The chlorination breaks the molecular symmetry and thus results in molecular chirality by eliminating the mirror plane or rotating axis.Interestingly,continuous multiple chlorinations can rebuild and break the symmetry of the skeleton in succession.Several chiral and achiral isomeric analogues are synthesized and characterized with impressive chiroptical properties.Results of chiral high performance liquid chromatography(HPLC),single-crystal X-ray diffraction,kinetic racemization,and chiroptical property investigation demonstrate the effectiveness of our rational design strategy.It provides a feasible methodology for exploring novel chiral luminescent materials based on versatile though-space skeletons.
基金the JSPS for KAKENHI funding(Grant No.JP21H01918 and JP20K21194)a Grant-in-Aid for Transformative Research Areas(A)“Condensed Conjugation”(JSPS for KAKENHI funding Grant No.JP20H05865)from MEXT,Japan.
文摘Knowledge about electronic structures is important to gain an understanding of the unique functional properties of diradicaloids.In this study,we synthesized and characterized a diradicaloid in which two phenalenyl radical sites are coupled antiferromagnetically via a through-space interaction.The results of quantum chemical,physicochemical(^(1)H NMR,electronic absorption,cyclic voltammetry,SQUID,ESR),and chemical reactivity studies show that this diradicaloid has singlet diradical character.An assessment of the nature of the bonding interaction between two radical sites in this species using DFT calculations demonstrates that a small spatial overlap between the two SOMOs in this diradicaloid provides an efficient electron exchange path for the singlet state to be substantially lower in energy than the triplet state.
