2016年11月8日,近日,医疗信息技术领域全球领导者Inter Systems与荣科科技股份有限公司正式签署战略合作伙伴协议。双方将共享先进技术、本土经验与市场资源,基于Inter Systems Health Share互联互通解决方案进行开发,联合打造智慧工作...2016年11月8日,近日,医疗信息技术领域全球领导者Inter Systems与荣科科技股份有限公司正式签署战略合作伙伴协议。双方将共享先进技术、本土经验与市场资源,基于Inter Systems Health Share互联互通解决方案进行开发,联合打造智慧工作流程、标准化及可共享的医疗信息、临床数据中心等多种集成的、互联互通的医疗应用,满足中国医疗机构对全面医疗信息化的需求,帮助中国医疗机构优化业务流程、提升医疗效率、改进医疗服务质量。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
Most of acridine based thermally activated delayed fluorescence(TADF)emitters are characterized by advantageous reverse intersystem crossing(RISC)rate(kRISCs)due to the perpendicular orientation of the acridine donor ...Most of acridine based thermally activated delayed fluorescence(TADF)emitters are characterized by advantageous reverse intersystem crossing(RISC)rate(kRISCs)due to the perpendicular orientation of the acridine donor to the acceptor moiety,but suffer from a poor radiation rate(kr)typically in the order of 10^(6) s^(−1).Herein,two sky blue TADF emitters 3,6-DMAC-AD-Py and 3,6-SFAC-AD-Py were developed by linking acridine(DMAC)and spiro-fluorene-acridine(SFAC)donors to 10-(pyridin-2-yl)acridin-9(10H)-one(AD-Py)acceptor.Larger SFAC and electron-deficient pyridyl groups are deliberately incorporated in 3,6-SFACAD-Py since the unique through-space interaction between them is designed to drive the rotation of inner acridine ring in SFAC for enhancing frontier molecular orbitals overlap while keeping a decent TADF behavior.Thus,the kr of 3,6-SFACAD-Py is increased to 1.5×10^(7) s^(−1).Simultaneously,SFAC donors improve spin orbital coupling strength and reduce the energy gaps,generating kRISC of 1.8×10^(6) s^(−1).This is the first acridine donor based TADF emitter realizing kr of 10^(7) s^(−1) and kRISC of 10^(6) s^(−1) by a through-space interaction strategy.3,6-SFACAD-Py enables a highly efficient sky-blue organic light-emitting diode with a maximum external quantum efficiency(EQE)of 34.7%and Commission International de I'Eclairage coordinates of(0.19,0.37).More importantly,the EQE still remained 27.6%and 16.9%at high brightness of 1000 and 10,000 cd m^(−2).展开更多
The reaction of Nb＋ with CS2, producing cationic transition-metal sulfide and CS, was taken as a representative example to elucidate the overall mechanism of reactions of second- row early transition metal ions with ...The reaction of Nb＋ with CS2, producing cationic transition-metal sulfide and CS, was taken as a representative example to elucidate the overall mechanism of reactions of second- row early transition metal ions with CS2. The reactions in both triplet and quintet state were studied by using the UB3LYP density functional method with the Stuttgart pseudo potentials and corresponding basis sets for Nb＋ and the standard 6-311＋G（2d） basis sets for C and S. The geometries for reactants, the transition states, and the products were completely optimized. All the transition states were verified by vibrational analysis and intrinsic reaction coordinate calculations. The results show that the reaction mechanism between niobium ion and CS2 is an insertion-elimination mechanism. Intersystem crossing may occur in the reaction Nb＋ with CS2 and a minimum energy crossing point was found.展开更多
Room-temperature phosphorescence（RTP） materials have attracted great attention due to their involvement of excited triplet states and comparatively long decay lifetimes.In this short review,recent progress on enhanc...Room-temperature phosphorescence（RTP） materials have attracted great attention due to their involvement of excited triplet states and comparatively long decay lifetimes.In this short review,recent progress on enhancement of RTP from purely organic materials is summarized.According to the mechanism of phosphorescence emission,two principles are discussed to construct efficient RTP materials：one is promoting intersystem crossing（ISC） efficiency by using aromatic carbonyl,heavyatom,or/and heterocycle/heteroatom containing compounds;the other is suppressing intramolecular motion and intermolecular collision which can quench excited triplet states,including embedding phosphors into polymers and packing them tightly in crystals.With aforementioned strategies,RTP from purely organic materials was achieved both in fluid and rigid media.展开更多
Thermally activated delayed fluorescence(TADF)organic molecules feature with long-lived delayed fluorescence,because they can undergo not only efficient intersystem crossing(ISC),but also efficient reverse intersystem...Thermally activated delayed fluorescence(TADF)organic molecules feature with long-lived delayed fluorescence,because they can undergo not only efficient intersystem crossing(ISC),but also efficient reverse intersystem crossing(RISC)at room temperature.As a new type of luminescent molecules,they have exhibited successful applications in organic light emitting diodes(OLEDs).Aside from OLEDs,they are also found to have potential applications in time-resolved luminescence imaging based on long-lived fluorescence property.Meanwhile,due to their excited triplet characteristic originated from efficient ISC,they were found to be applied in triplet-triplet annihilation upconversion(TTA-UC),photodynamic therapy(PDT)and organic photocatalytic synthesis.This review briefly summarizes the characteristics and excellent photophysical properties of TADF organic compounds,then covers their applications to date aside from OLEDs based on their highly efficient ISC ability and RISC ability at room temperature.展开更多
Thioxo/dithioxo-naphthalimide is a class of rarely visited fluorophore,first synthesized in 1999.Facile chemistry was devised to achieve mono or dual thionation of the two carbonyl groups of 1,8-naphthalimide.Thionati...Thioxo/dithioxo-naphthalimide is a class of rarely visited fluorophore,first synthesized in 1999.Facile chemistry was devised to achieve mono or dual thionation of the two carbonyl groups of 1,8-naphthalimide.Thionation effectively shifts absorption maximum to longer spectral wavelength,significantly increase absorption coefficients,and dramatically enhances intersystem crossing efficiency with respect to their oxo-analogues.They were first explored as potent photocleavers to induce DNA strand break and novel photosensitizers for photodynamic therapies.In recent years,the unique chemistry of thioxo groups has been harnessed to achieve new applications,such as fluorescent sensors for heave metal ions.These unique photochemical and photophysical characteristics revitalize them intriguing functional molecules to investigate.In this short review,we wish to revisit their first discovery,facile synthesis,and the endeavors on the use of thioxo/dithioxo-naphthalimides for novel chemical and biomedical applications.展开更多
Efficient yield of^(1)O_(2)determines the photocatalytic degradation rate of antibiotics,but the regulatory mechanism for^(1)O_(2)selective generation in O_(2)activation is still lacking exploration.Herein,oxygen vaca...Efficient yield of^(1)O_(2)determines the photocatalytic degradation rate of antibiotics,but the regulatory mechanism for^(1)O_(2)selective generation in O_(2)activation is still lacking exploration.Herein,oxygen vacancy(OV)modification strategy of MIL-125 was successfully practiced to promote the selective generation of^(1)O_(2).Multiple characterizations including extended X-ray absorption fine structure(EXAFS)and electron paramagnetic resonance spectra(EPR)confirmed the formation of oxygen vacancy in OV-MIL-125.The synthesized OV-MIL-125 exhibited greatly enhanced^(1)O_(2)selective(~90%)and antibiotics removal rate in water with high mineralization rate.Dynamics analysis of excitons by transient-steady state fluorescence and phosphorescence,transient absorption spectra(TAS)revealed that oxygen vacancy greatly enhanced the intersystem crossing(ISC)of singlet exciton,promoting triplet exciton generation.Density functional theoretical(DFT)calculation also proved the reduced gap of intersystem(ΔE_(ST))and the modulated highest occupied molecular orbital(HOMO)-lowest unoccupied molecular orbital(LUMO)population which was conducive to intersystem crossing process.Calculation of transition state further confirmed the lower energy barrier forπ^(*)orbital spin flip of O_(2)adsorbed on OV-MIL-125.The Dexter energy transfer involving triplet annihilation dominated the O_(2)activation mechanism to generate^(1)O_(2)instead of the charge transfer to generate O_(2)^(·-)which happened in MIL-125.This study provides new thinking for photocatalytic activation of molecular oxygen and is expected to guide the design of MOF-based catalysts for water treatment.展开更多
Clinical phototheranostic agents suffer from low absorption in near-infrared(NIR)region,decreasing singlet oxygen quantum yield(^(1)O_(2)QY)caused by aggregation in water,and low photothermal conversion efficiency(PCE...Clinical phototheranostic agents suffer from low absorption in near-infrared(NIR)region,decreasing singlet oxygen quantum yield(^(1)O_(2)QY)caused by aggregation in water,and low photothermal conversion efficiency(PCE),all of which are factors weakening their phototheranostic efficacy.Herein,we designed and synthesized a donor-acceptor-donor(D-A-D)structured boron-dipyrromethene derivative(B-2TPA)which exhibited NIR absorption and fluorescence.After being encapsulated in amphiphilic distearoyl phosphoethanolamine polyethyleneglycol 2000(DSPE-PEG-2000),the water-soluble B-2TPA nanoparticles(NPs)had increasing^(1)O_(2)QY(6.7%)due to the intermolecular aggregation-induced decrease in the energy gap between singlet and triplet excited states.Moreover,the quenched fluorescence and stable twisted intramolecular charge transfer in aggregates further increased the PCE of B-2TPA NPs to 60.1%.In vitro and in vivo studies confirmed that B-2TPA NPs could be used in NIR fluorescence and photoacoustic imagingguided synergistic photodynamic and photothermal therapy in tumor treatment.展开更多
2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED...2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.展开更多
The behavior of room temperature phosphorescence quenching and fluorescence enhancing of gadolinium labeled sinoporphyrin sodium(Gd-DVDMS) in the aqueous solution were studied.Gd-DVDMS was characterized by various tec...The behavior of room temperature phosphorescence quenching and fluorescence enhancing of gadolinium labeled sinoporphyrin sodium(Gd-DVDMS) in the aqueous solution were studied.Gd-DVDMS was characterized by various techniques including mass spectra,Fourier transform infrared spectra and transmission electron microscopy.The optical behavior was monitored through UV-vis absorption spectra and photoluminescence spectra.The result shows that the phosphorescence intensity gradually quenches,almost disappears after dissolved 120 min,meanwhile the fluorescence intensity enhances 5 times.The above behavior is attributed to the decreased population of Gd-DVDMS as first excited triplet state(T1),Based on the time-invariant of both absorption spectra and phosphorescence decay curves at710 nm of Gd-DVDMS in different dissolution time,the reason for the decreased population of GdDVDMS in T1 state is that the intersystem crossing from first excited state(S1) to T1 is prevented.In addition,the fluorescent decay curves of Gd-DVDMS initially dissolved in the aqueous solution and dissolved for 120 min were also measured for comparison.The big change in fluorescent lifetime further proves the conclusion that intersystem crossing is prevented,meanwhile,the increase in fluorescence intensity is demonstrated.In this work,the possibility of decomposition of Gd-DVDMS is excluded because the phosphorescence decay curve in Gd-DVDMS aqueous solution is sensible to DVDMS.展开更多
First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence（TADF） molecules on their geometrical structures an...First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence（TADF） molecules on their geometrical structures and transition properties as well as reverse intersystem crossing（RISC） processes. Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state（Ti） of carbazole-xanthone molecule. As the electron donating ability of donor groups is increased, the overlap between the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO） is decreased. As the diphenylamine groups are added in donor part, the delocalization of HOMO is enlarged,which brings a decreased energy gap(△ES1-T1) between the lowest singlet excited state（S1）and T1 state. Furthermore, with the calculated spin-orbit coupling coefficient(HSO), one finds that the larger value of ■ is, the faster the RISC is. The results show that all investigated molecules are promising candidates as TADF molecules. Overall, a wise molecular design strategy for TADF molecules,in which a small △ES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO, is proposed.展开更多
We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet （UV） to near infrared （NIR） in a low power glow discharge system. Th...We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet （UV） to near infrared （NIR） in a low power glow discharge system. This glow discharge electronic excitation populates different quartet and doublet states of NO in its proximity such as the A2Z （/9 = 2）, b4∑- （υ= 3）, B2М （1） = 4）, and X2Л （u= 33-32） states. Due to inter-system crossing, emission lines originating from these levels to lower lying states are recorded and spectral line assignments are performed. The observed systems include b4∑- a4∏, B21∏-a4∏, a4∏-X2I∏, A2∑X2∏, X2∏-X2∏ （33-15）, X2∏-X2∏ （33-17）, X2∏-X2∏ （33-20）, and X2∏-X2∏ （33- 18）. This new information will conduce to the better understanding of the interesting features of NO molecule. Such parameters that affect the recording of low density of NO molecules are also discussed In addition to the factors such as the time evolution, argon gas concentration relative to NO mixture, the percentage of NO molecular gas concentration, discharge electric current signals and discharge applied voltage are studied. Those factors would enhance the fluorescence signal intensity of NO molecules. The recent results might be significant as reference data for optimizing the glow discharge spectrometer and diagnostics of NO gas.展开更多
In the present work, the photoisomerization of 2-methylfuran to 3-methylfuran is investigated with the complete active space SCF （CASSCF） molecular orbital method. Geometries of minima and transition states on the e...In the present work, the photoisomerization of 2-methylfuran to 3-methylfuran is investigated with the complete active space SCF （CASSCF） molecular orbital method. Geometries of minima and transition states on the excited and ground states are fully optimized at the CAS level with a 6-3 IG＊ basis set. A multireference MP2 algorithm that has been implemented in Gaussian is used to correct the energetics for dynamic correlation. The topology and reaction funnels of the singlet, triplet （S0, T1, T2） and potential energy surfaces have been characterized along the reaction coordinates corresponding to the mechanism. The reaction proceeds via two diradical intermediates, one intermediate product and four transition states. The two diradical S 1/T2 and T1/S0 energy surface crossing points are located along the reaction path and a T1/T2 conical intersection is also located. From this point the reaction soon returns to T1 surface. It is the most reasonable that the intersystem crossing from T1 to S0 takes place.展开更多
In the present work, the triplet-sensitized photolysis of 2,5-dimethylfuran has been investigated with the complete active space SCF （CASSCF） molecular orbital method. Two different reaction routes through diradical...In the present work, the triplet-sensitized photolysis of 2,5-dimethylfuran has been investigated with the complete active space SCF （CASSCF） molecular orbital method. Two different reaction routes through diradical and carbene intermediates respectively have been systematically studied, and the reaction via carbene intermediate is the major part well compatible with experiment. Geometries of minima and transition states on S0T1 surface were fully optimized at the CAS level with a 6-31G^＊ basis set. A multireference MP2 algorithm that has been implemented in Gaussian was used to correct the energetics for dynamic correlation. Four intersystem crossing points have been located and discussed, and two of them are efficient. Our computation indicates that the reaction must occur on the triplet-excited state.展开更多
Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the orig...Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.展开更多
Inspired by the activity-based sensing method, the hydrazine-modified naphthalene derivative(Naph1) was synthesized and used as a fluorescent probe to detect formaldehyde(FA) in living cells. Through the condensation ...Inspired by the activity-based sensing method, the hydrazine-modified naphthalene derivative(Naph1) was synthesized and used as a fluorescent probe to detect formaldehyde(FA) in living cells. Through the condensation reaction between the probe Naph1 and analyte FA, researchers observed a ~14 folds enhancement of fluorescent signal around 510 nm in an experiment, realizing the high selectivity and sensitivity detection of FA. However, a theoretical understanding of the sensing mechanism was not provided in the experimental work. Given this, the light-up fluorescent detecting mechanism was in-depth unveiled by performing the time-dependent density functional theory(TDDFT) and the complete active space self-consistent field(CASSCF) theoretical calculations on excited-state intramolecular proton transfer(ESIPT)and non-adiabatic excited-state dynamics simulation. The deactivation channel of S_1/T_2 intersystem crossing(ISC) was turned off to successfully recognize FA. Insight into the ESIPT-based fluorescent detecting mechanism indicated that ESIPT was essential to light-up fluorescent probes. This work would provide a new viewpoint to develop ESIPT-based fluorescent probes for detecting reactive carbon species in vivo or vitio.展开更多
The mechanism of photocycloaddition reaction between 6-azauracll and acetone was studied by using semiemptrical SCFMO AMI method. It was found that this reaction is not a concerted one. The calculated results are as f...The mechanism of photocycloaddition reaction between 6-azauracll and acetone was studied by using semiemptrical SCFMO AMI method. It was found that this reaction is not a concerted one. The calculated results are as follows:(1) A T1 state exciplex is on the T1 state energy surface; (2) T exciplex as a reactant will proceed along the energy surface of T1 state to form a diradical intermediate. The energy barrier of this reaction step is 63. 6 kJ/mol; (3) The T1 state diradical intermediate happens to be close in energy to the ground state intermediate with a similar geometry. Such a situation turns out to be very favorable for an intersystem crossing (jump from the T, state to the ground state) ; (4) The final product will be formed from the ground S0 state intermediate via an energy barrier 88. 2 kJ/mol.展开更多
文摘2016年11月8日,近日,医疗信息技术领域全球领导者Inter Systems与荣科科技股份有限公司正式签署战略合作伙伴协议。双方将共享先进技术、本土经验与市场资源,基于Inter Systems Health Share互联互通解决方案进行开发,联合打造智慧工作流程、标准化及可共享的医疗信息、临床数据中心等多种集成的、互联互通的医疗应用,满足中国医疗机构对全面医疗信息化的需求,帮助中国医疗机构优化业务流程、提升医疗效率、改进医疗服务质量。
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 National Natural Science Foundation of China(22078051,22478063,22408035)the Fundamental Research Funds for the Central Universities(DUT22-LAB610)the Open Fund of the Key Laboratory of Advanced Display and System Applications,Ministry of Education,Shanghai University(OF202401)for financial support of this work.
文摘Most of acridine based thermally activated delayed fluorescence(TADF)emitters are characterized by advantageous reverse intersystem crossing(RISC)rate(kRISCs)due to the perpendicular orientation of the acridine donor to the acceptor moiety,but suffer from a poor radiation rate(kr)typically in the order of 10^(6) s^(−1).Herein,two sky blue TADF emitters 3,6-DMAC-AD-Py and 3,6-SFAC-AD-Py were developed by linking acridine(DMAC)and spiro-fluorene-acridine(SFAC)donors to 10-(pyridin-2-yl)acridin-9(10H)-one(AD-Py)acceptor.Larger SFAC and electron-deficient pyridyl groups are deliberately incorporated in 3,6-SFACAD-Py since the unique through-space interaction between them is designed to drive the rotation of inner acridine ring in SFAC for enhancing frontier molecular orbitals overlap while keeping a decent TADF behavior.Thus,the kr of 3,6-SFACAD-Py is increased to 1.5×10^(7) s^(−1).Simultaneously,SFAC donors improve spin orbital coupling strength and reduce the energy gaps,generating kRISC of 1.8×10^(6) s^(−1).This is the first acridine donor based TADF emitter realizing kr of 10^(7) s^(−1) and kRISC of 10^(6) s^(−1) by a through-space interaction strategy.3,6-SFACAD-Py enables a highly efficient sky-blue organic light-emitting diode with a maximum external quantum efficiency(EQE)of 34.7%and Commission International de I'Eclairage coordinates of(0.19,0.37).More importantly,the EQE still remained 27.6%and 16.9%at high brightness of 1000 and 10,000 cd m^(−2).
文摘The reaction of Nb＋ with CS2, producing cationic transition-metal sulfide and CS, was taken as a representative example to elucidate the overall mechanism of reactions of second- row early transition metal ions with CS2. The reactions in both triplet and quintet state were studied by using the UB3LYP density functional method with the Stuttgart pseudo potentials and corresponding basis sets for Nb＋ and the standard 6-311＋G（2d） basis sets for C and S. The geometries for reactants, the transition states, and the products were completely optimized. All the transition states were verified by vibrational analysis and intrinsic reaction coordinate calculations. The results show that the reaction mechanism between niobium ion and CS2 is an insertion-elimination mechanism. Intersystem crossing may occur in the reaction Nb＋ with CS2 and a minimum energy crossing point was found.
基金the financial support from The National Basic Research Program of China(No.2014CB643802)Ministry of Science and Technology(No.2016YFB0401001)the State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals
文摘Room-temperature phosphorescence（RTP） materials have attracted great attention due to their involvement of excited triplet states and comparatively long decay lifetimes.In this short review,recent progress on enhancement of RTP from purely organic materials is summarized.According to the mechanism of phosphorescence emission,two principles are discussed to construct efficient RTP materials：one is promoting intersystem crossing（ISC） efficiency by using aromatic carbonyl,heavyatom,or/and heterocycle/heteroatom containing compounds;the other is suppressing intramolecular motion and intermolecular collision which can quench excited triplet states,including embedding phosphors into polymers and packing them tightly in crystals.With aforementioned strategies,RTP from purely organic materials was achieved both in fluid and rigid media.
基金financially supported by the National Natural Science Foundation of China(Nos.21877011,21576038,21421005)the Talent Fund of Shandong Collaborative Innovation Center of Eco-Chemical Engineering(No.XTCXYX03)
文摘Thermally activated delayed fluorescence(TADF)organic molecules feature with long-lived delayed fluorescence,because they can undergo not only efficient intersystem crossing(ISC),but also efficient reverse intersystem crossing(RISC)at room temperature.As a new type of luminescent molecules,they have exhibited successful applications in organic light emitting diodes(OLEDs).Aside from OLEDs,they are also found to have potential applications in time-resolved luminescence imaging based on long-lived fluorescence property.Meanwhile,due to their excited triplet characteristic originated from efficient ISC,they were found to be applied in triplet-triplet annihilation upconversion(TTA-UC),photodynamic therapy(PDT)and organic photocatalytic synthesis.This review briefly summarizes the characteristics and excellent photophysical properties of TADF organic compounds,then covers their applications to date aside from OLEDs based on their highly efficient ISC ability and RISC ability at room temperature.
基金the National Natural Science Foundation of China(Nos.21822805 and 21908065)Shanghai Municipal Science and Technology Commission(No.18DZ1112703)China Postdoctoral Science Foundation(No.2019M651427)。
文摘Thioxo/dithioxo-naphthalimide is a class of rarely visited fluorophore,first synthesized in 1999.Facile chemistry was devised to achieve mono or dual thionation of the two carbonyl groups of 1,8-naphthalimide.Thionation effectively shifts absorption maximum to longer spectral wavelength,significantly increase absorption coefficients,and dramatically enhances intersystem crossing efficiency with respect to their oxo-analogues.They were first explored as potent photocleavers to induce DNA strand break and novel photosensitizers for photodynamic therapies.In recent years,the unique chemistry of thioxo groups has been harnessed to achieve new applications,such as fluorescent sensors for heave metal ions.These unique photochemical and photophysical characteristics revitalize them intriguing functional molecules to investigate.In this short review,we wish to revisit their first discovery,facile synthesis,and the endeavors on the use of thioxo/dithioxo-naphthalimides for novel chemical and biomedical applications.
基金supported by the National Natural Science Foundation of China(Nos.22276086 and 21976078)the Natural Science Foundation of Jiangxi Province(Nos.20202ACB213001 and20232BAB213029)。
文摘Efficient yield of^(1)O_(2)determines the photocatalytic degradation rate of antibiotics,but the regulatory mechanism for^(1)O_(2)selective generation in O_(2)activation is still lacking exploration.Herein,oxygen vacancy(OV)modification strategy of MIL-125 was successfully practiced to promote the selective generation of^(1)O_(2).Multiple characterizations including extended X-ray absorption fine structure(EXAFS)and electron paramagnetic resonance spectra(EPR)confirmed the formation of oxygen vacancy in OV-MIL-125.The synthesized OV-MIL-125 exhibited greatly enhanced^(1)O_(2)selective(~90%)and antibiotics removal rate in water with high mineralization rate.Dynamics analysis of excitons by transient-steady state fluorescence and phosphorescence,transient absorption spectra(TAS)revealed that oxygen vacancy greatly enhanced the intersystem crossing(ISC)of singlet exciton,promoting triplet exciton generation.Density functional theoretical(DFT)calculation also proved the reduced gap of intersystem(ΔE_(ST))and the modulated highest occupied molecular orbital(HOMO)-lowest unoccupied molecular orbital(LUMO)population which was conducive to intersystem crossing process.Calculation of transition state further confirmed the lower energy barrier forπ^(*)orbital spin flip of O_(2)adsorbed on OV-MIL-125.The Dexter energy transfer involving triplet annihilation dominated the O_(2)activation mechanism to generate^(1)O_(2)instead of the charge transfer to generate O_(2)^(·-)which happened in MIL-125.This study provides new thinking for photocatalytic activation of molecular oxygen and is expected to guide the design of MOF-based catalysts for water treatment.
基金supported by National Key Research and Development Program of China(No.2022YFA1207600)National Natural Science Foundation of China(Nos.62175262,62375289)+2 种基金The Science and Technology Innovation Program of Hunan Province(No.2022RC1201)The Climb Plan of Hunan Cancer Hospital(No.ZX2021005)The Hunan Provincial Natural Science Foundation of China(No.2023JJ60464)。
文摘Clinical phototheranostic agents suffer from low absorption in near-infrared(NIR)region,decreasing singlet oxygen quantum yield(^(1)O_(2)QY)caused by aggregation in water,and low photothermal conversion efficiency(PCE),all of which are factors weakening their phototheranostic efficacy.Herein,we designed and synthesized a donor-acceptor-donor(D-A-D)structured boron-dipyrromethene derivative(B-2TPA)which exhibited NIR absorption and fluorescence.After being encapsulated in amphiphilic distearoyl phosphoethanolamine polyethyleneglycol 2000(DSPE-PEG-2000),the water-soluble B-2TPA nanoparticles(NPs)had increasing^(1)O_(2)QY(6.7%)due to the intermolecular aggregation-induced decrease in the energy gap between singlet and triplet excited states.Moreover,the quenched fluorescence and stable twisted intramolecular charge transfer in aggregates further increased the PCE of B-2TPA NPs to 60.1%.In vitro and in vivo studies confirmed that B-2TPA NPs could be used in NIR fluorescence and photoacoustic imagingguided synergistic photodynamic and photothermal therapy in tumor treatment.
基金supported by National Natural Science Foundation of China(No. 61605158)the Science and TechnologyDepartment of Shaanxi Province(No. 2016JQ2028)the Education Department of Shaanxi Province(No. 16JK1790)
文摘2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.
基金supported by the National Natural Science Foundation of China (81571720,81530052,81727809)。
文摘The behavior of room temperature phosphorescence quenching and fluorescence enhancing of gadolinium labeled sinoporphyrin sodium(Gd-DVDMS) in the aqueous solution were studied.Gd-DVDMS was characterized by various techniques including mass spectra,Fourier transform infrared spectra and transmission electron microscopy.The optical behavior was monitored through UV-vis absorption spectra and photoluminescence spectra.The result shows that the phosphorescence intensity gradually quenches,almost disappears after dissolved 120 min,meanwhile the fluorescence intensity enhances 5 times.The above behavior is attributed to the decreased population of Gd-DVDMS as first excited triplet state(T1),Based on the time-invariant of both absorption spectra and phosphorescence decay curves at710 nm of Gd-DVDMS in different dissolution time,the reason for the decreased population of GdDVDMS in T1 state is that the intersystem crossing from first excited state(S1) to T1 is prevented.In addition,the fluorescent decay curves of Gd-DVDMS initially dissolved in the aqueous solution and dissolved for 120 min were also measured for comparison.The big change in fluorescent lifetime further proves the conclusion that intersystem crossing is prevented,meanwhile,the increase in fluorescence intensity is demonstrated.In this work,the possibility of decomposition of Gd-DVDMS is excluded because the phosphorescence decay curve in Gd-DVDMS aqueous solution is sensible to DVDMS.
基金This work was supported by the National Natural Science Foundation of China(No.11374195 and No.21403133),the Taishan Scholar Project of Shandong Province,the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2014CL001),and the General Financial Grant from the China Postdoctoral Science Foundation(No.2014M560571).
文摘First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence（TADF） molecules on their geometrical structures and transition properties as well as reverse intersystem crossing（RISC） processes. Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state（Ti） of carbazole-xanthone molecule. As the electron donating ability of donor groups is increased, the overlap between the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO） is decreased. As the diphenylamine groups are added in donor part, the delocalization of HOMO is enlarged,which brings a decreased energy gap(△ES1-T1) between the lowest singlet excited state（S1）and T1 state. Furthermore, with the calculated spin-orbit coupling coefficient(HSO), one finds that the larger value of ■ is, the faster the RISC is. The results show that all investigated molecules are promising candidates as TADF molecules. Overall, a wise molecular design strategy for TADF molecules,in which a small △ES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO, is proposed.
基金Project supported by the Funds from Laser Sciences and Interactions Department,National Institute of Laser Enhanced Sciences(NILES),Cairo University,Giza,Egyptthe Fund from the Department of Physics,Faculty of Science for Girls,Imam Abdulrahman Ben Faisal University(x-Dammam University)+1 种基金the Fund from Dammam 31441,Saudi Arabiathe Physics Department of King Fahd University of Petroleum and Minerals(KFUPM),Dhahran,Saudi Arabia
文摘We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet （UV） to near infrared （NIR） in a low power glow discharge system. This glow discharge electronic excitation populates different quartet and doublet states of NO in its proximity such as the A2Z （/9 = 2）, b4∑- （υ= 3）, B2М （1） = 4）, and X2Л （u= 33-32） states. Due to inter-system crossing, emission lines originating from these levels to lower lying states are recorded and spectral line assignments are performed. The observed systems include b4∑- a4∏, B21∏-a4∏, a4∏-X2I∏, A2∑X2∏, X2∏-X2∏ （33-15）, X2∏-X2∏ （33-17）, X2∏-X2∏ （33-20）, and X2∏-X2∏ （33- 18）. This new information will conduce to the better understanding of the interesting features of NO molecule. Such parameters that affect the recording of low density of NO molecules are also discussed In addition to the factors such as the time evolution, argon gas concentration relative to NO mixture, the percentage of NO molecular gas concentration, discharge electric current signals and discharge applied voltage are studied. Those factors would enhance the fluorescence signal intensity of NO molecules. The recent results might be significant as reference data for optimizing the glow discharge spectrometer and diagnostics of NO gas.
基金This project was supported by the Yunnan Provincial Science and Technology Department (2003A0003M)
文摘In the present work, the photoisomerization of 2-methylfuran to 3-methylfuran is investigated with the complete active space SCF （CASSCF） molecular orbital method. Geometries of minima and transition states on the excited and ground states are fully optimized at the CAS level with a 6-3 IG＊ basis set. A multireference MP2 algorithm that has been implemented in Gaussian is used to correct the energetics for dynamic correlation. The topology and reaction funnels of the singlet, triplet （S0, T1, T2） and potential energy surfaces have been characterized along the reaction coordinates corresponding to the mechanism. The reaction proceeds via two diradical intermediates, one intermediate product and four transition states. The two diradical S 1/T2 and T1/S0 energy surface crossing points are located along the reaction path and a T1/T2 conical intersection is also located. From this point the reaction soon returns to T1 surface. It is the most reasonable that the intersystem crossing from T1 to S0 takes place.
文摘In the present work, the triplet-sensitized photolysis of 2,5-dimethylfuran has been investigated with the complete active space SCF （CASSCF） molecular orbital method. Two different reaction routes through diradical and carbene intermediates respectively have been systematically studied, and the reaction via carbene intermediate is the major part well compatible with experiment. Geometries of minima and transition states on S0T1 surface were fully optimized at the CAS level with a 6-31G^＊ basis set. A multireference MP2 algorithm that has been implemented in Gaussian was used to correct the energetics for dynamic correlation. Four intersystem crossing points have been located and discussed, and two of them are efficient. Our computation indicates that the reaction must occur on the triplet-excited state.
基金The financial supports of the National Natural Science Foundation of China (grant nos. 21373042, 21677029 and 51402036)the Fundamental Research Funds for the Central Universities (grant no. DUT15YQ109)
文摘Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing （RISC） from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials.
基金the National Natural Science Foundation of China (Grant No. 12104392)the Natural Science Foundation of Hebei Province, China (Grant No. B2021203017)+1 种基金the High-Level Innovative Talents Program of Shenyang City (Grant No. RC200565)the Innovation Capability Improvement Project of Hebei Province, China (Grant No. 22567605H)。
文摘Inspired by the activity-based sensing method, the hydrazine-modified naphthalene derivative(Naph1) was synthesized and used as a fluorescent probe to detect formaldehyde(FA) in living cells. Through the condensation reaction between the probe Naph1 and analyte FA, researchers observed a ~14 folds enhancement of fluorescent signal around 510 nm in an experiment, realizing the high selectivity and sensitivity detection of FA. However, a theoretical understanding of the sensing mechanism was not provided in the experimental work. Given this, the light-up fluorescent detecting mechanism was in-depth unveiled by performing the time-dependent density functional theory(TDDFT) and the complete active space self-consistent field(CASSCF) theoretical calculations on excited-state intramolecular proton transfer(ESIPT)and non-adiabatic excited-state dynamics simulation. The deactivation channel of S_1/T_2 intersystem crossing(ISC) was turned off to successfully recognize FA. Insight into the ESIPT-based fluorescent detecting mechanism indicated that ESIPT was essential to light-up fluorescent probes. This work would provide a new viewpoint to develop ESIPT-based fluorescent probes for detecting reactive carbon species in vivo or vitio.
文摘The mechanism of photocycloaddition reaction between 6-azauracll and acetone was studied by using semiemptrical SCFMO AMI method. It was found that this reaction is not a concerted one. The calculated results are as follows:(1) A T1 state exciplex is on the T1 state energy surface; (2) T exciplex as a reactant will proceed along the energy surface of T1 state to form a diradical intermediate. The energy barrier of this reaction step is 63. 6 kJ/mol; (3) The T1 state diradical intermediate happens to be close in energy to the ground state intermediate with a similar geometry. Such a situation turns out to be very favorable for an intersystem crossing (jump from the T, state to the ground state) ; (4) The final product will be formed from the ground S0 state intermediate via an energy barrier 88. 2 kJ/mol.
