Chiroluminophores based on non-conjugated benzenes

Point-chiral groups as pendants conjugated to the aromatic luminophore generate weak chiroptical signals without self-assembly,showing the dependence on the flexibility of tethers,which hinders the development of point-chiral molecular materials with chiroptical properties such as the circularly polarized luminescence(CPL).Herein we introduce the molecular chiroptical materials based on the point chirality on a single benzene luminophore scaffold.Substitutes were stepwise conjugated to single benzene luminophores to boost the steric hindrance and tension,whereby the chirality transfer efficiency from point-chiral substituents to luminophores was enhanced.Multiple intramolecular CH-πinteractions anchor the whole asymmetric geometry with ultra-high rotation energy barriers and excellent thermostability.Dissymmetry g-factors of circular dichroism and CPL spectra up to 10^(-3)order of magnitude were realized in solutions,which are comparable to the inherent-chiral luminophores such as helicene and binaphthyl derivatives.The acridine-appended single benzene system shows the emergence of thermally activated delayed fluorescence(TADF),which extends the potentials of the single benzene chiral system in the TADF-based chiroptical devices.

Clustering-triggered phosphorescence of nonconventional luminophores

Nonconventional luminophores have attracted significant attention for their unique photophysical properties and potential applications in different areas.Unlike classic luminogens consisting of remarkably conjugated segments,nonconventional luminophores generally possess merely nonconjugated or short-conjugated structures based on electron-rich units.Fluorescence,phosphorescence,and even color tunable room temperature phosphorescence(RTP)could be readily obtained from these unique luminophores.Herein,we summarized recent advances in the phosphorescence of nonconventional luminophores,with focus on RTP and color tunable RTP.The clustering-triggered emission(CTE)mechanism could be applied to explain the luminescence as clustering-triggered phosphorescence(CTP).Furthermore,strategies toward the RTP regulation are summarized,and corresponding applications are demonstrated.

Construction of chiral through-space luminophores via symmetry breaking triggered by sequenced chlorination

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.

An Integration Strategy to Develop Dual-State Luminophores with Tunable Spectra,Large Stokes Shift,and Activatable Fluorescence for High-Contrast Imaging

Developing dual-state luminophores(DSLs)with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are either aggregation-induced emission or aggregation-caused quenching molecules.Moreover,limited by the structural conservation of the few existing DSLs,there are not enough response sites that can be used to customize various activatable fluorescent probes for specific molecular imaging.Herein,we engineered a general integration strategy for the fabrication of such DSLs with excellent photophysical properties.The DSLs,with their tunable spectra,a large Stokes shift(>170 nm),and achievable near-infrared(NIR)emission,show great potential for high-contrast imaging.Importantly,DSLs can be used as a universal platform for probe customization due to their activatable fluorescence through protection-deprotection of the phenolic hydroxyl group.Based on this,an NIR fluorescent probe DSL-Gal was developed for sensing of β-galactosidase in solutions,senescent cells,and liver metastases with high contrast,further confirming the superiority and universal feasibility of DSLs in probe design.The integration strategy may provide a novel approach for the generation of other DSLs and have great potential applications in bioimaging.

Pairs of Ln(Ⅲ)dopant ions in crystalline solid luminophores:an ab initio computational study

Formation of dopant ions clusters in solid （glass） luminophores may affect efficiency of non-radiative energy transfer proc- esses between dopant （photoactivator） ions via shortening of the effective distance between them. This study was based on the as- sumption that the distance between the dopant ions affects the energy of crystal volume at proximity. According to this idea, semi-empirical and ab initio density functional theory （DFT） calculations were performed on various supercells of YVO4：Eu3＋ as a model system. It was noted that a shorter Eu-Eu distance resulted in lower total energy of the system, compared to an analogous structure with distant Eu3＋ ions. As lower energy configurations are preferred, the observed phenomenon was considered to be related to dopant ions clusters formation. Additionally, the values of energies obtained from DFT calculations were used to estimate the per- centage of dopant ions occurring as pairs, for different dopant concentrations. The estimation agreed quite well with the available lit- erature data.

Synthesis and Luminescence of MeSiO_3:Eu,Bi Luminophors(Me=Mg,Ca,Sr,Ba)

The luminophors of four kinds of alkaline earth meta-silicates doped with Eu^3 and/or Bi^(3+)ion(s)were synthesized and the luminescence properties of Bi^(3+)and Eu^(3+)ions were studied.The regularities that Me(Ⅱ) ions affect the luminescence of Eu^(3+)ion sensitized by Bi^(3+)ion were investigated.The optimum composition and synthesis condition were obtained.The absorption and emission peak are situated at 283 and 353nm with the optimum concentration 0.02 mol of Bi^(3+)in CaSiO_3:Bi.In CaSiO_3:Bi,the optimum concentration of Bi^(3+)is 0.007 mol and that of Eu^(3+)is 0.040 mol.For all of the alkaline earth ions concerned in MeSiO_3:Eu,Bi,the Bi^(3+)can sensitize the Eu^(3+)and the Me(Ⅱ)ions in host and make a great difference in the adsorption hand of Bi^(3+)ion.by exciting Bi^(3+)ion,the emissions are from both Eu^(3+)and Bi^(3+)ions and the best sensitization effect is achieved when Me(Ⅱ)is Sr.

Design of portable electrochemiluminescence sensing systems for point-of-care-testing applications

Point-of-care testing(POCT)technology is highly desirable for clinical diagnosis,healthcare monitoring,food safety inspection,and environment surveillance,because it enables rapid detection anywhere,anytime,and by anyone.Electrochemiluminescence(ECL)has been widely used in chemo-/bio analysis due to its advantages such as high sensitivity,simplicity,rapidity and easy to control,and is now attracting increasing attention for POCT applications.However,to realize the accurate on-site quantitation,it is still challenging to develop portable devices which can precisely collect,analyze,transmit and display the ECL signals.This review will focus on how to develop a portable ECL device by summarizing recent examples and analyzing their key components part by part.Then the possible solutions to the existing challenges in the development and applications of portable ECL devices are summarized and discussed in detail,followed by offering future perspectives.We attempted to provide an appealing viewpoint to inspire interested researchers to comprehend and explore portable ECL sensing systems for practical applications and even commercialization.

Recent Advances in Boron-Containing Acenes:Synthesis,Properties,and Optoelectronic Applications

Acenes with linearly fused benzene rings have attracted much attention due to their intriguing optical and electronic properties.Nevertheless,the poor ambient stability of longer acenes has hampered the investigation of their physicochemical properties and potential applications.The incorporation of main group elements into the acene backbones provides a viable strategy to enhance the stability,and meanwhile,generates a new family of heteroatom-doped acenes(namely heteroacenes)with modified properties and functions.In particular,boron-containing acenes represent an attractive class of heteroacenes owing to the existence of vacant p orbital of boron,which endows theπ-conjugated systems with appealing features,such as Lewis acidity,electron-accepting capability,stimuli-responsivity,and adjustable photophysical properties.During the past decade,significant progress has been achieved in the synthesis and applications of boron-containing acenes,but a focused review on this topic has been elusive.Here,we summarize the recent advances in the studies on boron-containing acenes,covering their synthesis,intriguing properties,and various applications in electroluminescence and electronic devices,as well as in biosensors,etc.We hope that this timely review will stimulate new research interest in this unique family of materials and promote their optoelectronic applications.

Thermal stability improvement of sprayable fast-responding pressure-sensitive paint for measurement above 100℃

The thermal stability of sprayable fast-responding Pressure-Sensitive Paint(fast PSP)was investigated to explore the possibility for application in turbomachinery and hypersonic research with temperature above 100℃.The first part of the study focused on a widely-used Polymer Ceramic PSP(PC-PSP).The effects of thermal degradation on its key sensing properties,including luminescent intensity,pressure sensitivity and response time,were examined for a temperature range from 60 to 100℃.Severe degradation in intensity and pressure sensitivity was found as temperature reached 70℃or higher,which would cause failure of PSP application in these conditions.Subsequently,a fast-responding Mesoporous-Particle PSP(MP-PSP)was developed which did not show degradation effects until 140℃.The greatly improved thermal stability of MP-PSP was attributed to:selection of polymer with higher glass transition temperature(polystyrene)to delay the saturation effect of oxygen quenching as temperature increased;porous and hollow structure of particles for luminophore deposition that minimizes polymer–luminophore interaction.This new paint formulation has significantly raised the upper temperature limit of fast PSP and offers more opportunities for applications in harsh environment.

Ultralong organic room-temperature phosphorescence of electrondonating and commercially available host and guest molecules through efficient Förster resonance energy transfer

Ultralong organic room-temperature phosphorescence(RTP)materials have attracted tremendous attention recently due to their diverse applications.Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully.However,complicated synthesis and high expenditure are still inevitable in these studies.Herein,we develop a series of novel host-guest organic phosphorescence systems,in which all luminophores are electron-rich,commercially available and halogen-atom-free.The maximum phosphorescence efficiency and the longest lifetime could reach 23.6%and 362 ms,respectively.Experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest,but also show a synergistic effect to the guest through Förster resonance energy transfer(FRET).The commercial availability,facile preparation and unique properties also make these new host-guest materials an excellent candidate for the anti-counterfeiting application.This work will inspire researchers to develop new RTP systems with different wavelengths from commercially available luminophores.

Photoluminescence properties of nanosized strontium-yttrium borate phosphor Sr_3Y_2(BO_3) _4:Eu^(3+) obtained by the sol-gel Pechini method

Mixed strontium-yttrium borate phosphor Sr3Y2（BO3）4 doped with Eu^3＋ ions was obtained by the sol-gel Pechini method. Crystal structure of the synthesized compound was analyzed by X-ray powder diffraction. Optimal conditions for the synthesis were found. Photophysical properties of the phosphor samples were investigated by collecting excitation and luminescence spectra as well as measuring lumi- nescence lifetime. Judd-Ofelt analysis showed that Eu^3＋ ions occupied Y^3＋ sites in the crystalline network. The studied compound showed a red emission with the quantum yield of 54%-55% and can be potentially used as phosphor for plasma display panels and luminescent tubes.

LOW-TEMPERATURE SYNTHESIS AND STUDY OF LUMINOPHOR Al_2O_3-SiO_2:Eu^(3+), Bi^(3+) USING METAL ALKOXIDE

Ⅰ. INTRODUCTION A kind of chemical wet process developed at the beginning of the seventies is the sol-gel method. Because of its lower synthesis temperature in inorganic materials, it is also called lowtemperature synthesis method. The sol-gel method has many obvious advantages compared with the high-temperature solid state reaction. On the one hand, the lower