SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2018
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IF 2.88
Juan Han,Xu Tang,Yun Wang,Renjie Liu,Lei Wang,Liang Ni
A novel fluorescent probe based 8-hydroxyquinoline (8-HQ) has been designed and synthesized. The probe 1 exhibits fast relay recognition performance for Cu 2+ and Cd 2+ via a fluorescence “on−off−on” response signal. The probe 1 itself has a strong emission peak at 471 nm in EtOH/H 2 O (v/v = 1:9) solution with a blue fluorescence. The addition of Cu 2+ immediately results in the quenching of fluorescence and the limit of detection is 2.7 × 10 −8 M. Moreover, the formation of [1-Cu 2+ ] complexes can also serve as a new efficient probe system for the relay recognition of Cd 2+ with the emergence of a new fluorescence signal under the same conditions. The study also found that the probe 1 has high selectivity for target ions in the presence of other competing ions. The probe 1 has been successfully applied to detect and analyze the trace amount of Cu 2+ and Cd 2+ in environmental water samples.
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产品关联
DOI
PubMed
高影响因子
LIQUID CRYSTALS
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2013
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IF 1.959
Yiwei Xu,Xinbing Chen,Fengqi Zhao,Xuezhong Fan,Pei Chen,Zhongwei An
The synthesis and characterisation, and mesomorphic and photophysical properties of a new type of benzoxazole-terminated heterocyclic compounds, 2-(4ʹ-alkoxybiphenyl-4-yl)-benzoxazole derivatives (nB-x), are reported. For better understanding of the structure–property relationships, compounds bearing a variety of polar substituents in the 5-position of the benzoxazole moiety were prepared, including H (nB-H), NO2 (nB-N), CH3 (nB-M) and Cl (nB-C). Their phase transition behaviour was investigated by differential scanning calorimetry and polarising optical microscopy. In the case of carbon atoms in the alkoxy chain between 2 and 10 they exhibited enantiotropic smectic mesophases, for which the mesophase ranges were 101–175°C and 159–182°C on heating and cooling for nB-N, 5–63°C and 19–63°C for nB-H, 81–90°C and 78–96°C for nB-M, and 131–132°C and 131–132°C for nB-C, respectively. The effect of the length of the alkoxy chain on mesomorphic properties was studied. Compounds nB-N, nB-M and nB-C exhibited a much wider mesophase range either on heating or cooling than the corresponding nB-H series, which indicated that the substituent on the benzoxazole moiety was helpful in increasing the mesophase stability. Substituents with stronger electron-withdrawing properties gave a wider mesomorphic temperature domain, in the order NO2 > Cl > CH3 > H, which was similar to the effect of the substituents on the UV absorption bands of nB-x. The opposite effect was found for the corresponding Schiff base liquid crystals (nS-x). With the exception of nB-N, the nB-x series displayed intense photoluminescence emission in methylene chloride solution, with absorption maxima within the range 395–404 nm.
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DOI
高影响因子
LIQUID CRYSTALS
·
2015
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IF 2.486
Kun Hu,Pei Chen,Qiang Weng,Dingqian Shi,Ran Chen,Xinbing Chen,Zhongwei An
A series of 2-(3ʹ-fluoro-4ʹ-alkoxy-1,1ʹ-biphenyl-4-yl)-benzoxazole liquid crystals (coded as nPF(3)PBx) were prepared, where a lateral fluorine substituent, as well as methyl, chlorine and nitro terminal groups, was introduced into the molecules to investigate the effects of different polar substituents on the liquid crystal properties. The mesomorphic and photophysical properties were investigated. The results show that compounds nPF(3)PBx have enantiotropic mesophases; meanwhile, they exhibit UV–vis absorption bands with maxima at 323–326 nm and photoluminescence emission peaks at 389–395 nm, respectively. It is noted that nPF(3)PBx with terminal polar groups or electron-withdrawing groups (NO2, Cl) display higher clearing temperatures and wider mesophase range than those of the corresponding homologues with terminal non-polar groups or electron-donating groups (CH3, H). Meanwhile, compared with two lateral fluorine-substituted analogues containing 3,5-difluorophenyl unit, lateral monofluoro-substituted nPF(3)PBx display enhanced mesophase range both in heating and cooling except for terminal methyl-substituted compounds, as well as show obvious red-shifted UV–vis absorption bands and photoluminescence emission, which are attributed to the enhanced dipole–dipole interaction caused by increased dipole moment.
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产品关联
DOI
高影响因子
MOLECULAR CRYSTALS AND LIQUID CRYSTALS
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2014
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IF 0.491
Pei Chen,Yiwei Xu,Weisong Du,Guangping Zhang,Xinbing Chen,Zhongwei An
A series of novel mesogenic 2-(4-alkoxyphenyl-1-yl)-benzoxazole derivatives bearing different substituents (H, NO2, CH3, Cl, coded as nPB-H, nPB-N, nPB-M, and nPB-C, respectively) at the 5-position were prepared and characterized. nPB-N, nPB-M, and nPB-C exhibited enantiotropic smectic mesophases with the mesophase ranges 3 °C–32 °C and 3 °C–82 °C on heating and cooling processes, whereas nPB-H showed no mesophases. The substituents with the stronger electron withdrawing effect let to the wider mesomorphic temperature domain. The nPB-M, nPB-C, and nPB-H displayed intense emission in CH2Cl2 solutions with λmax peaks of the photoluminescence spectra at 350–355 nm when excited at their absorption maxima.
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产品关联
DOI
高影响因子
LIQUID CRYSTALS
·
2015
·
IF 2.486
Kun Hu,Pei Chen,Qiang Weng,Dingqian Shi,Ran Chen,Xinbing Chen,Zhongwei An
By modifying the molecular dipole moments with lateral monofluorine substituent, improved mesophase stabilities were obtained for novel benzoxazole derivatives, 2-(4ʹ-alkoxy-3-fluorobiphenyl-4-yl)-benzoxazole liquid crystals (coded as nPPF(3)Bx). The series of nPPF(3)Bx with lateral monofluorine substituent ortho to benzoxazole group have larger calculated dipole moments by about 2 D than the corresponding fluorine-substituted analogs (compounds I) with lateral monofluorine ortho to alkoxy group; it is interesting to note that they show lower melting and clearing points but better mesophase stability with wider mesophase ranges for the molecules with both polar (NO2, Cl) and nonpolar (CH3, H) terminal groups. Meanwhile, compounds nPPF(3)Bx show greater red-shifted photoluminescence emissions than compounds I, which suggest that π–π interaction between molecules is reinforced by the enhanced dipole–dipole interaction caused by increased dipole moments. These results suggest that modification of the molecular dipole moment is an effective method to improve the mesophase stability of the classical mesogenic compounds.
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产品关联
DOI
高影响因子
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