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 interd...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
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
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
为研究热气流固结过程中纤维网串珠结构的可控性,采用二次热处理方法,通过调控聚乙烯/聚对苯二甲酸乙二醇酯(PE/PET)皮芯复合纤维处理温度、处理时间、纤维皮芯比制备不同的串珠结构;利用Image Pro Plus图像处理软件分析串珠结构的变化...为研究热气流固结过程中纤维网串珠结构的可控性,采用二次热处理方法,通过调控聚乙烯/聚对苯二甲酸乙二醇酯(PE/PET)皮芯复合纤维处理温度、处理时间、纤维皮芯比制备不同的串珠结构;利用Image Pro Plus图像处理软件分析串珠结构的变化规律。借助X射线衍射仪研究纤维网中串珠纤维的结晶性能,并从结晶动力学角度,采用差式扫描量热法对纤维网中串珠纤维的结晶过程进行跟踪分析。结果表明:皮芯比为50 ∶50的聚乙烯/涤纶皮芯复合纤维在140 ℃、 120 s 的二次热处理条件下可得到不规则参数值接近于1的串珠纤维;随热处理温度升高,串珠纤维结晶度先增加后降低,处理温度为140 ℃时结晶度最大;串珠纤维皮层Avrami指数在1左右,随着结晶温度的增加,串珠纤维结晶速率呈下降趋势。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 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.
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.
文摘为研究热气流固结过程中纤维网串珠结构的可控性,采用二次热处理方法,通过调控聚乙烯/聚对苯二甲酸乙二醇酯(PE/PET)皮芯复合纤维处理温度、处理时间、纤维皮芯比制备不同的串珠结构;利用Image Pro Plus图像处理软件分析串珠结构的变化规律。借助X射线衍射仪研究纤维网中串珠纤维的结晶性能,并从结晶动力学角度,采用差式扫描量热法对纤维网中串珠纤维的结晶过程进行跟踪分析。结果表明:皮芯比为50 ∶50的聚乙烯/涤纶皮芯复合纤维在140 ℃、 120 s 的二次热处理条件下可得到不规则参数值接近于1的串珠纤维;随热处理温度升高,串珠纤维结晶度先增加后降低,处理温度为140 ℃时结晶度最大;串珠纤维皮层Avrami指数在1左右,随着结晶温度的增加,串珠纤维结晶速率呈下降趋势。
