查看更多>>摘要：In this study, a tetraphenylethene derivative 2-(4-(4-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)benzyloxy) phenyl)-3-(4-(l,2,2-triphenylvinyl)phenyl)acrylonitrile (abbreviated as TPEB) modified with borate ester group had been designed and synthesized, which exhibited high quantum yield in solid state (Φ = 0.66) and multi-stimuli-responsive performance. For the first one, TPEB showed aggregation induced emission (A1E) feature, the fluorescence intensity of which in water/THF mixture (fw = 90%) was 131.4 times that in pure THF. Secondly, TPEB can respond to viscosity and the fluorescence intensity increased by 43.8 times in high-viscosity solvent (1400 cP) from that in 2 cP. Thirdly, TPEB exhibited reversible mechanofluorochromic (MFC) character between blue (482 nm) and yellow-green-coloured (505 nm) fluorescence during grinding-fuming process. Moreover, TPEB can recognize hypochlorite (C10~) under both UV-vis absorption and fluorescence emission modes with high selectivity. In the presence of C10~, the UV-vis absorption band of TPEB red-shifted from 375 nm to 414 nm, which shifted from 501 m to 566 nm for fluorescence emission with 1.24 fold increase in intensity. The mechanism of multi-stimuli responsive performance was thoroughly studied through single crystal structure, scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), differential scanning calo-rimetry (DSC) and hybrid density functional theory (HDFT) calculation.
查看更多>>摘要：Recently, near infrared (NIR) organic photodetectors (OPDs) have been extensively studied. Bulk heterojunction NIR OPDs composed of a high-bandgap polymer donor (PD) and a low-bandgap non-fullerene acceptor (NFA) showed the best performance, whereas the low-bandgap PD-based OPDs were relatively unsuccessful due to the high level of dark current density (J_d) under a negative bias. In this study, we synthesized three low-bandgap PDs based on a thieno[3,4-b]pyrazine (TP) moiety and developed red-NIR OPDs by blending them with a low-bandgap NFA. We found that the PD having a shallow HOMO energy level generated the largest ground-state electron transfer at negative bias, which overestimated the responsivity (i?) and detectivity CD*) in OPDs. Notably, under weak light irradiation of 0.1 mW/cm2 at-2V, the contribution of J_d on Jph reached 99.6%. Thus, we modified the existing R and D* equations to better understand photodetecting properties at low light intensity, and these modified equations gave more realistic R and D* values in OPDs. On the other hand, a low-bandgap PD showing low J_d in OPDs was highly beneficial to detect a low light signal because the J_d negligibly contributed to Jph in OPDs. The low J_d values of OPDs at negative bias resulted in a high on/off signal ratio and constant R and D* values at different light intensities.
查看更多>>摘要：Liquid-crystalline D-A dyads and A-D-A triads, based on the chemical association of electron-donor (D) triphe-nylene discogens and electron-acceptor (A) perylene/benzoperylene diimides, have been synthesized by the Pd-catalyzed Sonogashira coupling/DBU-promoted cyclization reactions tandem. These molecular heterojunctions spontaneously self-organize into columnar hexagonal (Colhex) or/and rectangular (Col_(rec)) mesophases, over broad temperature ranges including room temperature, with the antagonist moieties segregated into alternated homo-molecular (homolithic) stacks within mixed columns. Their intramolecular electron and energy transfers have been studied by UV/Vis absorption and fluorescence emission spectroscopies. Due to photo-induced electron transfer between donor and acceptor units, fluorescence quenching is systematically observed for all the dyads and triads. This study further reveals that perylenediimide is a stronger electron acceptor than the larger benzoperylenediimide building block. Density function theory calculations of their molecular structures and HOMO-LUMO energy levels and gaps support the experimental results and demonstrate that these donor-acceptor systems have potential applications in various optoelectronic devices.
查看更多>>摘要：Fluorescence thermometers have attracted wide interesting owing to their advantages of ultra-high sensitivity, fast response speed, high spatial resolution, safe and non-invasive detection signal etc. However, conventional fluorescence thermometers are sensitive only in a certain range. In 2016, we found that one of C6-unsubstituted tetrahydro-pyrimidines (THPs) that synthesized by an efficient five-multicomponent reaction (5CR) shows unusual temperature-range-tunable (TRT) fluorescence characteristic: showing sensitive fluorescence-color/-on-off changes in different temperature ranges by only changing excitation wavelength. Here, the influences of molecular structures, packing modes and chirality on the TRT fluorescence characteristic of THPs were investigated in detail. In addition, the crucial parameter evaluating the TRT characteristics and the selection of the suitable excitation wavelengths in different T-ranges are explored. The obtained experimental results indicate that: (a) the TRT characteristics of THPs mainly depends on molecular structures rather than their R-and S-enantiomer molecular packing modes; (b) although the pure enantiomeric alignments of THPs significantly decrease their fluorescence quantum yields, they favor the TRT characteristics; (c) the response (S_(λrex)) of red-edge excitation wavelength (λ_(rex)) to temperature is a crucial parameter for evaluating TRT characteristic; (d) the suitable excitation wavelengths for fluorescence measurement in different temperature ranges can be simply identified by the good linear relationship between λ_(rex) and temperature; (e) Racemic THP 5c is the most sensitive thermometer in different T-ranges. From 10-430 K (-263 °C-157 °C), 5c could show sensitive fluorescence-on-off change in any narrow T-range (<40 K), such as 10-30 K, 30-60 K ... 300-330 K, 400-430 K, by selecting suitable λ_(rex) values (the thermo-response sensitivities ranges from 0.83 to 4.20% K-1). The work reported here is expected to promote the development and application of different kinds of fluorescence thermometers with TRT characteristics.
查看更多>>摘要：Two highly efficient artificial light-harvesting systems (ALHSs) in water have been successfully fabricated through the supramolecular assembly of an anthryl-cinnamonitrile derivative (ABTA), a water-soluble pillar[5] arene (WP5), and two conventional fluorescent dye molecules (Nile Red (NiR) and sulforhodamine (SR101)). The fabricated ALHSs display efficient energy transfer efficiency (85.7% for WP5DABTA-NiR and 83.2% for WP5DABTA-SR101) and possess ultrahigh donor-acceptor molar ratio ([ABTA]/[NiR] = 250:1 and [ABTA]/[SR101] = 250:1). Significantly, the formed WP5DABTA nanoparticles enhance the aggregation-induced emission ability of ABTA and function as a brilliant donor to transfer the harvested energy to acceptors NiR and SR101 in aqueous solution with high antenna effects (21.8 for WP5DABTA-NiR and 26.1 for WP5DABTA-SR101).
Anastasiya I. ErshovaAnastasiya U. AlekseevaOleg V. Ershov
9页
查看更多>>摘要：The synthesis of novel highly efficient fluorescent dyes of 4-amino-2-chloro-6-arylpyridine-3,5-dicarbonitrile series via heterocyclization of aryl(heteryl)methylidene derivatives of malononitrile dimer bearing electron-donor groups was described. Solvatochromic behavior and substituents effect on the spectral-luminescent properties were also investigated. Strong solvatochromism and high relative fluorescence quantum yields up to 0.92 despite the large Stokes shift values and were observed.
查看更多>>摘要：Quantitative recognition of human serum albumin (HSA) is of great importance in the fields of biology and biomedicine. In biological fluids, HSA has been used as an important biomarker for disease early diagnosis. For example, microalbuminuria has been regarded as an early indicator of diabetic nephropathy. Therefore, it is of great significance to monitor HSA in urine. In this work, a BODIPY-based fluorescence probe, BDY-OH, was constructed for HSA detection, which showed a high signal to noise ratio and high selectivity. In addition, plot of fluorescence intensity exhibited a 90-fold enhancement and a good linear correlation from 0 mg/mL to 0.4 mg/mL. Encouraged by the outstanding properties, the ability of BDY-OH to distinguish proteinuria from normal urine was tested among 39 clinical urine samples and the excellent recognition rate of 89.7% suggested a great significance for the early diagnosis of kidney related diseases. We look forward to using the BDY-OH method as a new tool for preclinical diagnosis of HSA in urine in the future.
查看更多>>摘要：Most of the mechanoresponsive luminescent (MRL) materials function based on phase transition (crystalline-to-amorphous or crystalline-to-crystalline) or solid-state chemical reaction of the organic solid emitters. However, it is difficult to enable a turn-on type mechanoresponsive luminescence using such strategy. In this work, the defect-induced emission (DIE) of (E)-(4-((2-hydroxy-4-methoxybenzylidene)amino)phenyl)(phenyl) methanone (HMPM) was disclosed, which endows the resulting material with reversible turn-on MRL. The crystalline powder of HMPM is non-emissive, but the emission intensity can be greatly enhanced by external mechanical stimuli, showing high contrast. In the semiquantitative experiment, pressure up to 1.78 N would generate crystal defects, and further induces DIE. Crystallographic data demonstrate that the dark-state stems from the closely-connected plane-style aggregation of neighboring molecules, which allows the intermolecular orbital-overlapping to the disadvantage of radiative transition. Mechanical stimuli would destroy the plane-style aggregation to block intermolecular orbital overlap and the possible energy transfer, resulting in emission-enhancement. Taking advantage of the DIE nature, an information storage film is fabricated, capable of data-writing via mechanical force and data-erasing by fumigation treatment, showing rewritability as well as high signal contrast.
查看更多>>摘要：Photoinduced electron transfer (PET) with the formation of stable radicals plays an importance role in many areas. However, the discovery of new photoresponsive moieties is still a challenge. In this work, pyridine W-oxide group itself was demonstrated to possess photoinduced electron transfer (PET) property for the first time. The radical of 4-phenyl-pyridine-W-oxide (ppno), generated by PET from oxygen atom to 4-phenyl-pyridine part, remained stable in dark in air at least for two weeks. [ZnCl2(ppno)2], one ppno-based novel crystalline coordination compound, has two electron donors, chlorine and oxygen atoms. In particular, experimental and theoretical calculation results showed that oxygen atoms in [ZnCl2(ppno)2] have dual actions. Firstly, oxygen atom as electron-withdrawing group increased the electron accepting ability of 4-phenyl-pyridine. Then, oxygen atoms tiiemselves are rich in electrons and can act as electron donors. This is exactly why the performance of PET and radical yield and stability of [ZnCl2(ppno)2] much better than ppno. Thus, pyridine W-oxide group as an effective photoresponsive functional motif, whether by interspersion or by coordination, could construct various novel photoresponsive materials.
查看更多>>摘要：Cost-effective fluorescence turn-on indicator-displacement-assay (IDA) sensors based on octamethylcalix [4] pyrrole receptor and tetrabutylammonium salts of 4-methylumbelliferone and fluorescein indicators were developed for highly sensitive detection of fluoride anion. The IDA sensor assembly relies on the hydrogen bonding between calix[4] pyrrole and carboxylate units of indicators and further displacement replacement of receptors with target analyte. While all the sensors displayed rapid and selective sensitivity towards fluoride over the other anions, 4-methylumbelliferone based IDA system was also found to have a visual color change for the sensing of fluoride anion. The experimental results revealed that fluorescein-based IDA sensor could be used for the sensing of fluoride anion with a detection limit as low as 3.2 nM.
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