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
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
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 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
Electronic coupling between individual building blocks plays an essential role in charge transport through molecular materials and devices.However,the investigation of the transmission mechanism in charge transport vi...Electronic coupling between individual building blocks plays an essential role in charge transport through molecular materials and devices.However,the investigation of the transmission mechanism in charge transport via intramolecular coupling remains challenging.Herein,we demonstrate the transition of the intramolecular through-bond and through-space coupling in a single-molecule junction with a family of diketopyrrolopyrrole(DPP)derivative by varying intramolecular donor–acceptor(D–A)interactions.The transition is accomplished by regulating D–A interactions by inserting different aromatic rings inside,leading to two orders of magnitude difference of the single-molecule conductance.The flicker noise analysis demonstrates that the conductance difference arises from the control of the contribution between through-bond and through-space coupling.These findings are further supported by the calculation that the intramolecular coupling among molecular building blocks correlates with the D–A interaction,providing a promising way to regulate the contribution between through-bond and through-space coupling in the charge transport through molecular materials and devices.展开更多
A diad compound 3 beta(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-androst-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at lamb...A diad compound 3 beta(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-androst-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at lambda > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.展开更多
随着摩尔定律指引下的晶体管微缩逼近物理极限,先进封装技术通过系统微型化与异构集成,成为突破芯片性能瓶颈的关键路径。作为先进封装的核心分支,2.5D封装通过硅/玻璃中介层实现高密度互连与多芯片异构集成,兼具高带宽、低延迟和小型...随着摩尔定律指引下的晶体管微缩逼近物理极限,先进封装技术通过系统微型化与异构集成,成为突破芯片性能瓶颈的关键路径。作为先进封装的核心分支,2.5D封装通过硅/玻璃中介层实现高密度互连与多芯片异构集成,兼具高带宽、低延迟和小型化优势,广泛应用于人工智能、高性能计算及移动电子领域。系统阐述了2.5D封装的核心结构(如Co Wo S、EMIB和I-Cube)及其技术特征,重点剖析了Chiplet模块化设计、硅通孔(TSV)工艺优化、微凸点可靠性提升、铜-铜直接键合界面工程以及再布线层多物理场协同设计等关键技术的最新进展。未来研究需聚焦低成本玻璃基板、原子层沉积技术抑制界面氧化以及多物理场协同设计等方面,以突破良率和散热瓶颈,推动2.5D封装在后摩尔时代高算力场景中的广泛应用。展开更多
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 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supported by Natural Science Foundation of China(nos.21722305,21673195,21703188,51733004,and 51525303)the National Key R&D Program of China(nos.2017YFA0204902 and 2017YFA0204903)+1 种基金the Beijing National Laboratory for Molecular Sciences(no.BNLMS202005)the China Postdoctoral Science Foundation(no.2017M622060).
文摘Electronic coupling between individual building blocks plays an essential role in charge transport through molecular materials and devices.However,the investigation of the transmission mechanism in charge transport via intramolecular coupling remains challenging.Herein,we demonstrate the transition of the intramolecular through-bond and through-space coupling in a single-molecule junction with a family of diketopyrrolopyrrole(DPP)derivative by varying intramolecular donor–acceptor(D–A)interactions.The transition is accomplished by regulating D–A interactions by inserting different aromatic rings inside,leading to two orders of magnitude difference of the single-molecule conductance.The flicker noise analysis demonstrates that the conductance difference arises from the control of the contribution between through-bond and through-space coupling.These findings are further supported by the calculation that the intramolecular coupling among molecular building blocks correlates with the D–A interaction,providing a promising way to regulate the contribution between through-bond and through-space coupling in the charge transport through molecular materials and devices.
基金Project supported by the National Natural Science Foundation of China.
文摘A diad compound 3 beta(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-androst-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at lambda > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.
文摘随着摩尔定律指引下的晶体管微缩逼近物理极限,先进封装技术通过系统微型化与异构集成,成为突破芯片性能瓶颈的关键路径。作为先进封装的核心分支,2.5D封装通过硅/玻璃中介层实现高密度互连与多芯片异构集成,兼具高带宽、低延迟和小型化优势,广泛应用于人工智能、高性能计算及移动电子领域。系统阐述了2.5D封装的核心结构(如Co Wo S、EMIB和I-Cube)及其技术特征,重点剖析了Chiplet模块化设计、硅通孔(TSV)工艺优化、微凸点可靠性提升、铜-铜直接键合界面工程以及再布线层多物理场协同设计等关键技术的最新进展。未来研究需聚焦低成本玻璃基板、原子层沉积技术抑制界面氧化以及多物理场协同设计等方面,以突破良率和散热瓶颈,推动2.5D封装在后摩尔时代高算力场景中的广泛应用。
