RESEARCH ON CHEMICAL INTERMEDIATES
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2021
·Vol. 47
·期 10
·4173-4192
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IF 2.914
Fu Fengping,He Qian,Zhao Shizheng,Zhu Ting,Liao Fang
The design and fabricate new metal-free photocatalysts is one of the topics in current chemistry. In this paper, we demonstrate the ultrahigh photocatalytic performance of visible light-driven metal-free photocatalyst for selective catalytic reduction of nitro-compounds. The synthesis of 1.5–4.5-nm m-phenylenediamine-Rhodamine B copolymer dots (PmRDs) via simple hydrothermal reaction of Rhodamine B and m-phenylenediamine mixed solution. The obtained PmRDs can be used as visible light-driven metal-free photocatalyst with ultrahigh photocatalytic performance for elective catalytic reduction of nitro-compounds. Due to the hydrogen-bond and specific C–N–N bonding model between the m-phenylenediamine-Rhodamine B copolymer dots (PmRDs) and nitro-compounds, the PmRDs show high photocatalytic activity and selectivity for catalytic reduction of nitro-compounds. Under the irradiation of xenon lamp, 40 ml of 1 mM 4-nitrophenol (4-PN) could be catalyzed by 12 mg catalyst within 5 min, by calculating the rate constants up to 0.766 min −1 (25 °C). In the same way, the PmRDs are also excellent photocatalytic activity and selectivity for different nitro-compounds. Meanwhile, the efficient fast photoinduced electron transfer between the m-phenylenediamine and the Rhodamine B progress significantly improved the photocatalytic performance of PmRDs which is much higher than metal-based (such as: Ag, Ni and Cu) or metallic composite photocatalysts.
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Molecular Catalysis
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2020
·
IF 3.687
Fu Yang,Jin Wang,Shuying Gao,Shijian Zhou,Yan Kong
Herein, we report an excellent in-situ exsolution triggered hydrogenated catalyst F-Ni/Cu-P-RT started from bimetallic phosphate Ni/Cu-P-RT, affording an ultrafast catalytic hydrogenated rate (20 s even 5 s) in nitrophenol reduction. In the first catalytic cycle, we proved the enhanced catalytic reduction activity of bimetallic Ni/Cu-P-RT within 50 s compared to monometallic counterparts. The kinetics results revealed Ni/Cu-P-RT affords the reaction rate K of 2.85/4.23/6.6 min −1 at 20, 30, and 40 °C with the activation energy 32 kJ/mol. Impressively, the involved reaction induction period is visibly observed and interpreted by reconstruction and evolution of active metal during the reaction, but was eliminated through integrating two metal Cu-Ni by regulation of electronic band energy of phosphate from 4.1–3.5 eV. The nascent Cu and Ni nanoparticles as reaction-preferred active species were in-situ exsolved partially after adding NaBH 4 , triggering the resulted higher active and stable F-Ni/Cu-P-RT(20 s, 14.1 min −1 ) in later multiple cycles.
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Polymer Chemistry
·
2018
·Vol. 9
·期 20
·2785-2796
·
IF 4.927
Lala Rukh Sidra,Guofei Chen,Nafeesa Mushtaq,Kai Ma,Beenish Bashir,Xingzhong Fang
Two asymmetric diamine monomers, incorporating both aryl ether and non-linear benzoxazole groups, namely 5-amino-2-(4-(4-aminophenoxy)phenyl)benzoxazole (p-BOODA) and 5-amino-2-(3-(4-aminophenoxy)phenyl)benzoxazole (m-BOODA), were designed and synthesized. Two novel series of poly(benzoxazole imide)s (PBOIs), PI-3(a–e) and PI-4(a–e), were prepared via thermal imidization of commercial tetracarboxylic dianhydrides with diamines p-BOODA and m-BOODA, respectively. The effects of chain isomerism on molecular packing and the physical properties of PBOIs are investigated. These PBOIs showed excellent mechanical properties with tensile strengths of 106–168 MPa, tensile moduli of 2.7–5.5 GPa and elongations at break of 4.4–9.3%; in addition, they exhibited good thermal stability (T5% = 488–570 °C) and high glass transition temperatures (Tgs) up to 333 °C. Moreover, BTDA (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) derived PBOIs, PI-3b and PI-4b, showed crystalline transition in spite of bent groups and the asymmetric chain structure. The incorporation of the asymmetric benzoxazole structure with flexible ether connecting groups improved the solubility of the PBOI system. Furthermore, the controlled molecular weight (Mw) polymer PI-4e-PA derived from m-BOODA demonstrated excellent solution and melt processability with the lowest complex viscosity of 44 Pa s at 380 °C.
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LIQUID CRYSTALS
·
2013
·
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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MOLECULAR CRYSTALS AND LIQUID CRYSTALS
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2014
·
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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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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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
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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