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Blue/red dual color up-conversion emission from Tm3+, Yb3+ co-activated nephelline particles derived from LTA zeolites
摘要： Up-converted blue/red dual color emitting Tm3+, Yb3+ co-activated crystalline (NaAlSiO4:Tm3+, Yb3+) materials have been fabricated via a facile, highly controllable, and cost-effective method, that is, the combination of ion exchange and thermal treatment in air. Under the 980 nm excitation, the NaAlSiO4:Tm3+, Yb3+ phosphor powders showed bright visible color blue (480 am) and red(650 nm) emission，which were attributed to the 1G4 →3H6 and 1G4→3F4 transitions of Tm3+ ion，respectively. The blue/red dual color up-conversion emission from this kind of phosphor may have applications in bio-imaging and optogenetics.
关键词： nepheline,LTA zeolite,zeolite derivatives,up-conversion emission
更新于2025-09-10 09:29:36
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Emissive Azobenzenes Delivered on a Silver Coordination Polymer
摘要： Azobenzene has become a ubiquitous component of functional molecules and polymeric materials because of the light-induced trans → cis isomerization of the diazene group. In contrast, there are very few applications utilizing azobenzene luminescence, since the excitation energy typically dissipates via nonradiative pathways. Inspired by our earlier studies with 2,2′-bis[N,N′-(2-pyridyl)methyl]diaminoazobenzene (AzoAMoP) and related compounds, we investigated a series of five aminoazobenzene derivatives and their corresponding silver complexes. Four of the aminoazobenzene ligands, which exhibit no emission under ambient conditions, form silver coordination polymers that are luminescent at room temperature. AzoAEpP (2,2′-bis[N,N′-(4-pyridyl)ethyl]diaminoazobenzene) assembles into a three-dimensional coordination polymer (AgAAEpP) that undergoes a reversible loss of emission upon the addition of metal-coordinating analytes such as pyridine. The switching behavior is consistent with the disassembly and reassembly of the coordination polymer driven by displacement of the aminoazobenzene ligands by coordinating analytes.
关键词： Reversible emission switching,Aminoazobenzene derivatives,Silver coordination polymers,Luminescence,Azobenzene
更新于2025-09-10 09:29:36
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Internal Oriented Electric Fields as a Strategy for Selectively Modifying Photochemical Reactivity
摘要： Time dependent density functional theory calculations have been performed on acetophenone derivatives to explore the possibility of using charged functional groups as internal electric fields, the orientation of which can be altered to change photochemical behavior at will. Results demonstrate that non-conjugated charged groups can significantly alter, by up to -1.44 eV, the stabilities of excited states. Specifically, a non-conjugated negatively charged group in the para-position will destabilize the nπ* and stabilize the ππ* transitions, while a positively charged group will do the opposite. These electrostatic effects can be tuned by moving these substituents into the meta and ortho positions. Through use of acids and bases, these charged groups can switched on or off with pH, allowing for selective alteration of the energy levels and photochemical reactivity. Solvent effects are shown to attenuate the electric field effect with increasing dielectric permittivity; however electrostatic effects are shown remain significant even in quite polar solvents. Using charged functional groups to deliver the position-dependent electrostatic (de)stabilization effects is therefore a potential route to improving the efficiency of desirable photochemical processes.
关键词： electric fields,acetophenone derivatives,TD-DFT,excited states,photochemical reactivity
更新于2025-09-10 09:29:36
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Suzuki-Miyaura micellar one pot synthesis of symmetrical and unsymmetrical 4,7-Diaryl-5,6-difluoro-2,1,3-benzothiadiazole luminescent derivatives in water and under air
摘要： The Suzuki-Miyaura cross coupling reaction of 4,7-dibromo-5,6-difluoro-2,1,3-benzothiadiazole (DBBF) with different arylboronic acids can be efficiently carried out in water and under air by means of micellar coupling. The careful tuning of reaction conditions enables preparation of symmetrically and unsymmetrically substituted derivatives. The moderate to good yields obtained, alongside with the wide variety of available substitution patterns, makes this sustainable methodology very resourceful for the preparation of building blocks for luminescent optoelectronic materials.
关键词： optoelectronic materials,sustainable methodology,Suzuki-Miyaura cross coupling,micellar coupling,luminescent derivatives
更新于2025-09-10 09:29:36
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Al <sup>18</sup> F-NODA Benzothiazole Derivatives as Imaging Agents for Cerebrovascular Amyloid in Cerebral Amyloid Angiopathy
摘要： In this study, we synthesized four novel Al18/19F-labeled 2-phenylbenzothiazole derivatives conjugated to 1,4,7-triazacyclononane-1,4-diacetic acid via alkyl linkers and evaluated them as imaging agent targets to amyloid-β (Aβ) plaques deposited in the blood vessels of cerebral amyloid angiopathy (CAA) brain. The four ligands exhibited moderate-to-high binding ability to Aβ1?42 aggregates, of which complex 17 possessing the most potent affinity (Ki = 11.3 nM) was selected for further biological evaluations. In vitro fluorescent staining and in vitro autoradiography studies on brain sections from CAA patients proved that this ligand could label Aβ deposits in blood vessels selectively. In biodistribution study, [18F]17 can hardly penetrate the blood?brain barrier (brain2 min = 0.3% ID/g) and displayed a rapid blood washout rate (blood2 min/blood60 min = 25.2), which is favorable as CAA imaging agents. In conclusion, this Al18F-labeled 2-phenylbenzothiazole complex was developed and proved to be a promising CAA positron emission tomography agent.
关键词： Al18F-NODA,cerebrovascular amyloid,benzothiazole derivatives,cerebral amyloid angiopathy,imaging agents
更新于2025-09-10 09:29:36
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Dual Catalytic Switchable Divergent Synthesis: An Asymmetric Visible-light Photocatalytic Approach to Fluorine-containing γ-Keto Acid Frameworks
摘要： Herein, we describe a novel and efficient method for constructing a series of fluorine-containing γ-keto acid derivatives through combining visible-light photoredox catalysis and chiral Lewis acid catalysis. With this dual catalytic strategy, a variety of chiral γ-keto amides containing a gem-difluoroalkyl group and a series of fluorine-containing α,β-unsaturated-γ-keto esters were successfully constructed with high stereoselectivities, respectively. A series of experiments showed that the chemoselectivity of this process was highly dependent on the fluorine reagents besides the Lewis acid catalysts. This approach facilitates rapid access to γ-keto acid derivatives, an important class of precursors for pharmaceuticals, plasticizers, and various other additives.
关键词： γ-keto acid derivatives,chiral Lewis acid catalysis,visible-light photocatalysis,asymmetric difluoroalkylation
更新于2025-09-10 09:29:36
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Wavelength-optimized Two-Photon Polymerization Using Initiators Based on Multipolar Aminostyryl-1,3,5-triazines
摘要： Two-photon induced polymerization (2PP) based 3D printing is a powerful microfabrication tool. Specialized two-photon initiators (2PIs) are critical components of the employed photosensitive polymerizable formulations. This work investigates the cooperative enhancement of two-photon absorption cross sections (σ2PA) in a series of 1,3,5-triazine-derivatives bearing 1-3 aminostyryl-donor arms, creating dipolar, quadrupolar and octupolar push-pull systems. The multipolar 2PIs were successfully prepared and characterized, σ2PA were determined using z-scan at 800 nm as well as spectrally resolved two-photon excited fluorescence measurements, and the results were compared to high-level ab initio computations. Modern tunable femtosecond lasers allow 2PP-processing at optimum wavelengths tailored to the absorption behavior of the 2PI. 2PP structuring tests revealed that while performance at 800 nm is similar, at their respective σ2PA-maxima the octupolar triazine-derivative outperforms a well-established ketone-based quadrupolar reference 2PI, with significantly lower fabrication threshold at exceedingly high writing speeds up to 200 mm/s and a broader window for ideal processing parameters.
关键词： two-photon initiators,femtosecond lasers,3D printing,two-photon induced polymerization,1,3,5-triazine-derivatives
更新于2025-09-10 09:29:36
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Synthesis and mesomorphic properties of the nematic mesophase benzoxazole derivatives with big twist angle of difluoro-biphenyl unit
摘要： Modifying the position and numbers of lateral fluorine substituent is a common method to design and adjust the mesophase of liquid crystal compounds. Here, a series of 2-(2,2?-difluoro-4?-alkoxy-1,1?-biphenyl-4-yl)-5-substituted benzoxazole with both non-polar (H, CH3) and polar (NO2) groups (coded as nPF(2)PF(2)Bx) is synthesised and characterised. All of the compounds show a conspicuous inter-ring twist angle of 38° compared with corresponding reference compounds I and II which are calculated by density functional theory method, and it is interesting to note that the final compounds nPF(2)PF(2)Bx show only nematic mesophase during heating or cooling. Meanwhile, the UV-vis absorption bands and photoluminescence emission peaks both display remarkable blue-shifted. The aforementioned results reveal that lateral difluoro substituents play a key role to stable the nematic mesophase by increasing the dihedral angle of biphenyl.
关键词： benzoxazole derivatives,enantiotropic mesophase,Lateral difluoro substituent,liquid crystal properties
更新于2025-09-09 09:28:46
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Bionic SiO2@Fc(COCH3)2 Core-Shell Nanostructure for Enhancing the Electrochromic Properties of Ferrocene
摘要： Although the properties of electrochromic materials (ECMs) have been enhanced using fabricated porous materials, the effect of materials porosity on such an enhancement remains unclear. Here, we report a novel ECMs with an adjustable pore hierarchy based on quasi-amorphous and ordered arrays of SiO2@Fc(COCH3)2. ECMs with different pore systems were generated by modifying Fc(COCH3)2 concentration and self-assembly temperature. The composition and core-shell structure of the SiO2@Fc(COCH3)2 nanospheres were confirmed through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and EDX mapping. The influence of adjustable pore system on the electrochemical behavior was studied. Experimental results showed that the current density of the redox couple peaks of the quasi-amorphous porous SiO2@Fc(COCH3)2 films are considerably lower than those of the ordered porous films but are higher than those of the dense Fc(COCH3)2 films. At 550 nm, the transmittance variation of the quasi-amorphous porous SiO2@Fc(COCH3)2 film is 19 %, whereas that of the ordered porous film is 35 %. The coloration and bleaching times of the quasi-amorphous porous SiO2@Fc(COCH3)2 film are 17.1 s and 4.5 s, respectively, whereas those of the ordered porous film are only 16.5 s and 3.5 s, respectively. Furthermore, the porosities of the films are solved numerically by the finite-element method. For the ordered porous SiO2@Fc(COCH3)2 film, the porosity is 0.26, while the quasi-amorphous film became larger (0.31～ 0.41). This work is the first step in combining ferrocene derivative and colloidal crystal porous structures to develop a green, simple and efficient electrochromic process.
关键词： electrochromism,adjustable porosity,colloidal crystals,ferrocene derivatives,core-shell structure
更新于2025-09-09 09:28:46
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Isophorone-boronate ester: A simple chemosensor for optical detection of fluoride anion
摘要： A highly selective isophorone‐boronate ester based chemosensor, (1), having a dicyanovinyl moiety as a convenient colorimetric probe, has been designed. Different types of anionic analyte such as CH3COO?, Br?, Cl?, ClO4? and HSO4?, PF6? were tested and among them only highly nucleophilic F? anion displayed significant response towards the sensor. Addition of the fluoride anion across the boron atom disrupts the π‐conjugation thereby shifts the absorption wavelength towards the redshift region due to the decrease in the HOMO‐LUMO energy gap and a colour change from yellow to blue is observed under visible light condition. The detection limit of this probe was calculated to be 3.25 × 10?8 M for fluoride anion. The binding constants and the detection limits of the sensor were calculated using absorption titration studies. The silica gel TLC strips dip‐coated by the chemosensor (1) revealed a colour change from yellow to brick red to naked eye.
关键词： chemosensor,boron derivatives,optical Spectroscopy,fluoride anion sensing
更新于2025-09-09 09:28:46