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2021 Volume 37 Issue 3
2021, 37(3): 385-400
doi: 10.11862/CJIC.2021.068
Abstract:
The pollution of heavy metal ions has long been a big concern to the society. The development and utilization of porous materials for the adsorptive removal of heavy metal ions in water represents one of the hottest research subjects in related areas, such as materials science and environmental science. Due to their structural variety, large specific surface area, adjustable pore size, and tailorable pore surface characteristics, metal-organic frameworks (MOFs) show great potential in many applications, such as gas separation, catalysis, and sensing. In the past few years, many major breakthroughs have been made in the construction of highly stable MOFs. A lot of research works have been explored for the applications of MOFs in water systems, including the adsorptive removal of heavy metal ions in water. Cr(Ⅵ) ions are a kind of wide-distributed heavy metal ions with high toxicity, existing in water in various forms under different conditions. The study on the removal of Cr(Ⅵ) ions from water is of significance academically and practically. Herein, the published research works about adsorptive removal of Cr(Ⅵ) ions with MOFs or MOFbased materials are reviewed. These materials are classified into four classes: (1) highly stable zirconium-based MOF, (2) cationic MOF, (3) post-modified MOF, and (4) MOF-based composite materials. The adsorption mechanism, adsorption capacity, and regenerability of these materials for Cr(Ⅵ) ions are also discussed. The existing problems and the trend of future works for the practical application of MOFs in the removal of heavy metal ions are analyzed at last.
The pollution of heavy metal ions has long been a big concern to the society. The development and utilization of porous materials for the adsorptive removal of heavy metal ions in water represents one of the hottest research subjects in related areas, such as materials science and environmental science. Due to their structural variety, large specific surface area, adjustable pore size, and tailorable pore surface characteristics, metal-organic frameworks (MOFs) show great potential in many applications, such as gas separation, catalysis, and sensing. In the past few years, many major breakthroughs have been made in the construction of highly stable MOFs. A lot of research works have been explored for the applications of MOFs in water systems, including the adsorptive removal of heavy metal ions in water. Cr(Ⅵ) ions are a kind of wide-distributed heavy metal ions with high toxicity, existing in water in various forms under different conditions. The study on the removal of Cr(Ⅵ) ions from water is of significance academically and practically. Herein, the published research works about adsorptive removal of Cr(Ⅵ) ions with MOFs or MOFbased materials are reviewed. These materials are classified into four classes: (1) highly stable zirconium-based MOF, (2) cationic MOF, (3) post-modified MOF, and (4) MOF-based composite materials. The adsorption mechanism, adsorption capacity, and regenerability of these materials for Cr(Ⅵ) ions are also discussed. The existing problems and the trend of future works for the practical application of MOFs in the removal of heavy metal ions are analyzed at last.
2021, 37(3): 401-411
doi: 10.11862/CJIC.2021.052
Abstract:
Two novel iridium(Ⅲ) complexes (Ir1 and Ir2) containing rotatable groups were designed and synthesized for viscosity probes and photosensitizers. Firstly, they freely rotated and showed weak phosphorescence in lowviscosity environment, while in viscous media, the phosphorescence intensity increased significantly (35.7-fold for Ir1, 1 311.6 -fold for Ir2). The cellular uptake and co -localization studies indicated that the probes could easily cross the cell membrane and aggregate in mitochondria, and the results showed that they could be used for detection of mitochondrial viscosity. Moreover, Ir1 and Ir2 displayed high potent photo-cytotoxicity to cancer cells (A549 and Hep-G2) under light irradiation but exhibited lower photo-cytotoxicity to normal cells (MRC-5 and LO2). The generation of 1O2 under light irradiation were also measured by electron paramagnetic resonance (EPR) and confocal microscopy.
Two novel iridium(Ⅲ) complexes (Ir1 and Ir2) containing rotatable groups were designed and synthesized for viscosity probes and photosensitizers. Firstly, they freely rotated and showed weak phosphorescence in lowviscosity environment, while in viscous media, the phosphorescence intensity increased significantly (35.7-fold for Ir1, 1 311.6 -fold for Ir2). The cellular uptake and co -localization studies indicated that the probes could easily cross the cell membrane and aggregate in mitochondria, and the results showed that they could be used for detection of mitochondrial viscosity. Moreover, Ir1 and Ir2 displayed high potent photo-cytotoxicity to cancer cells (A549 and Hep-G2) under light irradiation but exhibited lower photo-cytotoxicity to normal cells (MRC-5 and LO2). The generation of 1O2 under light irradiation were also measured by electron paramagnetic resonance (EPR) and confocal microscopy.
2021, 37(3): 412-420
doi: 10.11862/CJIC.2021.045
Abstract:
Nano-porous Ni and nano-porous Ni3S2/Ni composite electrodes were prepared by dealloying and hydrothermal synthesis. The pore size distribution, phase and microstructure of the electrode were characterized by N2 adsorption-desorption test, XRD, SEM, TEM. In 1 mol·L-1 NaOH solution, the electrocatalytic properties toward hydrogen evolution reaction of the electrode was evaluated using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and constant current electrolysis method. As a result, when the current density was 50 mA·cm-2, the nano-porous Ni3S2/Ni composite electrode had a lower overpotential for hydrogen evolution reaction and higher electrocatalytic hydrogen evolution activity than the nano-porous Ni, while nano-porous Ni3S2/Ni composite electrode had lower apparent activation energy and electron transfer resistance, it further clarifies the special contribution of transition metal sulfides to the performance of electrocatalytic hydrogen evolution.
Nano-porous Ni and nano-porous Ni3S2/Ni composite electrodes were prepared by dealloying and hydrothermal synthesis. The pore size distribution, phase and microstructure of the electrode were characterized by N2 adsorption-desorption test, XRD, SEM, TEM. In 1 mol·L-1 NaOH solution, the electrocatalytic properties toward hydrogen evolution reaction of the electrode was evaluated using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and constant current electrolysis method. As a result, when the current density was 50 mA·cm-2, the nano-porous Ni3S2/Ni composite electrode had a lower overpotential for hydrogen evolution reaction and higher electrocatalytic hydrogen evolution activity than the nano-porous Ni, while nano-porous Ni3S2/Ni composite electrode had lower apparent activation energy and electron transfer resistance, it further clarifies the special contribution of transition metal sulfides to the performance of electrocatalytic hydrogen evolution.
2021, 37(3): 421-430
doi: 10.11862/CJIC.2021.048
Abstract:
A novel fluorescent sensor 1, 5-diphenyl-3-(10-(morpholinemethyl)anthracene-2-yl)pyrazoline (PMAP) was synthesized successfully, and characterized by 1H NMR and 13C NMR spectracopy and X ray single crystal diffraction. Selective recognition of PMAP for cations was investigated by fluorescence emission spectrum and ultraviolet-visible absorption spectrum.The results showed that the PMAP exhibited high selective and sensitive to Fe3+ (for a ca. 45 nm red shift) and Cu2+, showing color change from pale yellow to blue and the fluorescence quantum yield decreased from 0.14 to 0.05 and 0.04, respectively. The sensor demonstrated a 1:1 binding stoichiometry to Fe3+/Cu2+ as well as a low detection limit of ca. 1 μmol·L-1, and interference experiments revealed that this sensor had an excellent anti-interference ability. Furthermore, the sensor can be effectively applied for the detection of Cu2+ and Fe3+ in practical water samples. In addition, a three-input NOR logic gate circuit was constructed at the molecular level by the quantum yield of PMAP for Fe3+, Cu2+and H+ in different combinations. CCDC: 2051694.
A novel fluorescent sensor 1, 5-diphenyl-3-(10-(morpholinemethyl)anthracene-2-yl)pyrazoline (PMAP) was synthesized successfully, and characterized by 1H NMR and 13C NMR spectracopy and X ray single crystal diffraction. Selective recognition of PMAP for cations was investigated by fluorescence emission spectrum and ultraviolet-visible absorption spectrum.The results showed that the PMAP exhibited high selective and sensitive to Fe3+ (for a ca. 45 nm red shift) and Cu2+, showing color change from pale yellow to blue and the fluorescence quantum yield decreased from 0.14 to 0.05 and 0.04, respectively. The sensor demonstrated a 1:1 binding stoichiometry to Fe3+/Cu2+ as well as a low detection limit of ca. 1 μmol·L-1, and interference experiments revealed that this sensor had an excellent anti-interference ability. Furthermore, the sensor can be effectively applied for the detection of Cu2+ and Fe3+ in practical water samples. In addition, a three-input NOR logic gate circuit was constructed at the molecular level by the quantum yield of PMAP for Fe3+, Cu2+and H+ in different combinations. CCDC: 2051694.
2021, 37(3): 431-436
doi: 10.11862/CJIC.2021.047
Abstract:
Three ruthenium-arene complexes with curcuminoids (1~3) were synthesized through the reaction of[(η6-p-cymene)RuCl2]2 and the corresponding curcuminoids derivative (L1~L3) followed by the reaction with 1, 3, 5-tiaza-7-phosphaadamantane (PTA). The complexes were structurally characterized by single crystal XRD, 1H NMR, MS and elemental analysis. The inhibitory activities of the complexes towards HepG2 human liver cancer cell lines were investigated by MTT with light (λ>400 nm). The results show that three complexes present half-sandwich structure. Anticancer activity of the complexes was significantly improved by light, among which the IC50 of complex 3 decreased from (60.3±1.1) μmol·L-1 to (45.0±6.1) μmol·L-1 against HepG2, indicating that light can effectively improve the anticancer activity of this kind of complexes. CCDC: 1514601, 1; 1514600, 2; 1514603, 3.
Three ruthenium-arene complexes with curcuminoids (1~3) were synthesized through the reaction of[(η6-p-cymene)RuCl2]2 and the corresponding curcuminoids derivative (L1~L3) followed by the reaction with 1, 3, 5-tiaza-7-phosphaadamantane (PTA). The complexes were structurally characterized by single crystal XRD, 1H NMR, MS and elemental analysis. The inhibitory activities of the complexes towards HepG2 human liver cancer cell lines were investigated by MTT with light (λ>400 nm). The results show that three complexes present half-sandwich structure. Anticancer activity of the complexes was significantly improved by light, among which the IC50 of complex 3 decreased from (60.3±1.1) μmol·L-1 to (45.0±6.1) μmol·L-1 against HepG2, indicating that light can effectively improve the anticancer activity of this kind of complexes. CCDC: 1514601, 1; 1514600, 2; 1514603, 3.
Application in Removal of Formaldehyde in Air by Flower Spherical Bi2S3/BiOI Composite Photocatalyst
2021, 37(3): 437-442
doi: 10.11862/CJIC.2021.030
Abstract:
Flower spherical Bi2S3/BiOI composite photocatalysts fabricated by nanosheets were synthesized by the hydrothermal anion transfer method from BiOI microspheres using thioacetamide as the sulfur source. The formaldehyde was used as the model pollutant to test the removal performance of the composite photocatalyst. The results showed that formaldehyde in air was removed under visible light. Bi2S3/BiOI composite photocatalyst with heterojunction structure had high photocatalytic activity and good cycling stability.
Flower spherical Bi2S3/BiOI composite photocatalysts fabricated by nanosheets were synthesized by the hydrothermal anion transfer method from BiOI microspheres using thioacetamide as the sulfur source. The formaldehyde was used as the model pollutant to test the removal performance of the composite photocatalyst. The results showed that formaldehyde in air was removed under visible light. Bi2S3/BiOI composite photocatalyst with heterojunction structure had high photocatalytic activity and good cycling stability.
2021, 37(3): 443-447
doi: 10.11862/CJIC.2021.049
Abstract:
Single crystals of KCa1-xEuxCl3 (x=0.005, 0.01, 0.02, 0.03, 0.05) doped with different Eu2+ ion molar fractions have been grown successfully by Bridgman-Stockbarger technique. The crystals were characterized by powder X-ray diffraction, thermogravimetry, transmittance, photoluminescence spectrum, decay time and X-ray excitation emission spectrum. Through phase diagram and structure analysis, the crystal is regarded as a congruent compound and belongs to orthorhombic system. The unit cell parameters are determined as: a=0.756 04 nm, b=1.048 23 nm, c=0.726 57 nm, space group: Pnma(62). Under the excitation of ultraviolet light, the crystal exhibited a broad emission around 434 nm, which can be attributed to the 4f65d1→4f7 transition of Eu2+. The result exhibited that the emission spectra with the maximum which position was shifted from 427 to 436 nm with the increase of Eu2+ doped concentration. The photolumimnescence decay time was 1.473 μs, moreover, the intensity of X-ray luminescence spectra continued to increase with the Eu2+ ion concentration.
Single crystals of KCa1-xEuxCl3 (x=0.005, 0.01, 0.02, 0.03, 0.05) doped with different Eu2+ ion molar fractions have been grown successfully by Bridgman-Stockbarger technique. The crystals were characterized by powder X-ray diffraction, thermogravimetry, transmittance, photoluminescence spectrum, decay time and X-ray excitation emission spectrum. Through phase diagram and structure analysis, the crystal is regarded as a congruent compound and belongs to orthorhombic system. The unit cell parameters are determined as: a=0.756 04 nm, b=1.048 23 nm, c=0.726 57 nm, space group: Pnma(62). Under the excitation of ultraviolet light, the crystal exhibited a broad emission around 434 nm, which can be attributed to the 4f65d1→4f7 transition of Eu2+. The result exhibited that the emission spectra with the maximum which position was shifted from 427 to 436 nm with the increase of Eu2+ doped concentration. The photolumimnescence decay time was 1.473 μs, moreover, the intensity of X-ray luminescence spectra continued to increase with the Eu2+ ion concentration.
2021, 37(3): 448-456
doi: 10.11862/CJIC.2021.067
Abstract:
ZrCdOx metal oxides with various Zr/Cd atomic ratios (nZr/nCd) were prepared by parallel coprecipitation method, the sheet-like SAPO-18 zeolites with molar ratio of SiO2 to Al2O3 (nSiO2/nAl2O3) of 0.1 and 0.01 were hydrothermally synthesized. The metal oxide and SAPO-18 were physically mixed to prepare ZrCdOx/SAPO-18 bifunctional catalyst, and to study the catalytic performance for CO2 hydrogenation to light olefins. Transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption-desorption, temperature-programmed desorption of CO2 (CO2TPD), temperature programmed desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) were applied to analyze the catalysts. Compared with the sole ZrO2, the introduction of CdO decreased the BET (Brunauer Emmett Teller) surface area of ZrCdOx. The Zr8Cd1 oxide prepared with nZr/nCd=8 exhibited the small amorphous particles, the strong synergetic effect between Zr and Cd led to the generation of more oxygen vacancies in ZrCdOxoxide, which was beneficial to the adsorption and activation of CO2. The effect of mass ratio of Zr8Cd1 oxide to SAPO-18 (nSiO2/nAl2O3=0.1), and the reaction temperature, pressure and space velocity on catalytic performance were investigated, and the optimal reaction conditions were obtained. Moreover, it is also found that when the ratio of nSiO2/nAl2O3 decreased from 0.1 to 0.01, the content of Brønsted acid reduced, the molar ratio of olefins to paraffin increased from 18.6 to 37.2; however, the content of by-product CO increased rapidly, and the space-time yield of light olefins decreased remarkably.
ZrCdOx metal oxides with various Zr/Cd atomic ratios (nZr/nCd) were prepared by parallel coprecipitation method, the sheet-like SAPO-18 zeolites with molar ratio of SiO2 to Al2O3 (nSiO2/nAl2O3) of 0.1 and 0.01 were hydrothermally synthesized. The metal oxide and SAPO-18 were physically mixed to prepare ZrCdOx/SAPO-18 bifunctional catalyst, and to study the catalytic performance for CO2 hydrogenation to light olefins. Transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption-desorption, temperature-programmed desorption of CO2 (CO2TPD), temperature programmed desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS) were applied to analyze the catalysts. Compared with the sole ZrO2, the introduction of CdO decreased the BET (Brunauer Emmett Teller) surface area of ZrCdOx. The Zr8Cd1 oxide prepared with nZr/nCd=8 exhibited the small amorphous particles, the strong synergetic effect between Zr and Cd led to the generation of more oxygen vacancies in ZrCdOxoxide, which was beneficial to the adsorption and activation of CO2. The effect of mass ratio of Zr8Cd1 oxide to SAPO-18 (nSiO2/nAl2O3=0.1), and the reaction temperature, pressure and space velocity on catalytic performance were investigated, and the optimal reaction conditions were obtained. Moreover, it is also found that when the ratio of nSiO2/nAl2O3 decreased from 0.1 to 0.01, the content of Brønsted acid reduced, the molar ratio of olefins to paraffin increased from 18.6 to 37.2; however, the content of by-product CO increased rapidly, and the space-time yield of light olefins decreased remarkably.
2021, 37(3): 457-464
doi: 10.11862/CJIC.2021.029
Abstract:
Nitrogen-doped carbon foam material was prepared by using hydrolyzed vinyl imidazolium nitrate ([Hvim] NO3) as a blowing agent and a primary nitrogen source to realize self-foaming of the material during the carbonization process. The secondary nitrogen source melamine (C3H6N6) was innovatively introduced. The nitrogen doped carbon foam material (HxMy-T, where x: y was the mass ratio of the primary and secondary nitrogen source, T corresponded the carbonization temperature) were obtained. This method increased the nitrogen doping content of the catalyst and constructed more active nitrogen sites which improved the oxygen reduction reaction (ORR) activity. Electron microscope images showed that the H1M1-1000 with typical foam-like pore structure and abundant layered fold. The X-ray photoelectron spectroscopy indicated that the H1M1-1000 possessed a high N atomic fraction of 6.77%, and the content of pyridinic-N and graphitic-N were up to 22.23% and 55.59% (atomic fraction), respectively. For electrochemistry test, the half wave potential of H1M1 1000 in alkaline medium was 0.834 V (vs RHE), which was comparable to that of commercial Pt/C. In addition, the catalyst had superior long-time stability and methanol resistance than that of commercial Pt/C.
Nitrogen-doped carbon foam material was prepared by using hydrolyzed vinyl imidazolium nitrate ([Hvim] NO3) as a blowing agent and a primary nitrogen source to realize self-foaming of the material during the carbonization process. The secondary nitrogen source melamine (C3H6N6) was innovatively introduced. The nitrogen doped carbon foam material (HxMy-T, where x: y was the mass ratio of the primary and secondary nitrogen source, T corresponded the carbonization temperature) were obtained. This method increased the nitrogen doping content of the catalyst and constructed more active nitrogen sites which improved the oxygen reduction reaction (ORR) activity. Electron microscope images showed that the H1M1-1000 with typical foam-like pore structure and abundant layered fold. The X-ray photoelectron spectroscopy indicated that the H1M1-1000 possessed a high N atomic fraction of 6.77%, and the content of pyridinic-N and graphitic-N were up to 22.23% and 55.59% (atomic fraction), respectively. For electrochemistry test, the half wave potential of H1M1 1000 in alkaline medium was 0.834 V (vs RHE), which was comparable to that of commercial Pt/C. In addition, the catalyst had superior long-time stability and methanol resistance than that of commercial Pt/C.
2021, 37(3): 465-472
doi: 10.11862/CJIC.2021.051
Abstract:
One new 3D metal-organic framework with formula[Cd(L)0.5(1, 3-bib)(H2O)]·H2O (1) was prepared under hydrothermal conditions by employing the rigid 1, 2, 4, 5-benzenetetracarboxilic acid (H4L) as the primary ligand and 1, 3-bis(1H-imidazole-1-ylmethyl)benzene(1, 3-bib) as the ancillary ligand. Complex 1 was characterized by elemental analysis, infrared spectroscopy, X-ray single crystal diffractometer, thermogravimetric analysis and X-ray powder diffractometer. The results show that complex 1 belongs to orthorhombic system, Pbca space group with cell parameters: a=0.857 08(4) nm, b=1.912 23(10) nm, c=2.451 60(12) nm. In complex 1, the carboxyl ligand L4- chelates the metal centers via bidentate mode. The metal centers are coordinated by L4- and 1, 3-bib to form a three-dimensional structure. The fluorescent properties of 1 were studied. Complex 1 shows strong luminescent peak at 454 nm. The luminescence of complex 1 can be quenched by acetone, MnO4- and Hg2+ ions, indicating that complex 1 was a good sensor for them. CCDC: 1966559.
One new 3D metal-organic framework with formula[Cd(L)0.5(1, 3-bib)(H2O)]·H2O (1) was prepared under hydrothermal conditions by employing the rigid 1, 2, 4, 5-benzenetetracarboxilic acid (H4L) as the primary ligand and 1, 3-bis(1H-imidazole-1-ylmethyl)benzene(1, 3-bib) as the ancillary ligand. Complex 1 was characterized by elemental analysis, infrared spectroscopy, X-ray single crystal diffractometer, thermogravimetric analysis and X-ray powder diffractometer. The results show that complex 1 belongs to orthorhombic system, Pbca space group with cell parameters: a=0.857 08(4) nm, b=1.912 23(10) nm, c=2.451 60(12) nm. In complex 1, the carboxyl ligand L4- chelates the metal centers via bidentate mode. The metal centers are coordinated by L4- and 1, 3-bib to form a three-dimensional structure. The fluorescent properties of 1 were studied. Complex 1 shows strong luminescent peak at 454 nm. The luminescence of complex 1 can be quenched by acetone, MnO4- and Hg2+ ions, indicating that complex 1 was a good sensor for them. CCDC: 1966559.
2021, 37(3): 473-481
doi: 10.11862/CJIC.2021.059
Abstract:
New porous carbon nanosheets/carbon nanotubes (PC/CNT) materials showed a rich hierarchical pore structure with high tin oxide (SnO2) loading. The three-dimensional structure formed by the cross-linking of PC and CNT can improve Li+ transmission rate and electron conduction. In addition, lithium fluoride (LiF) doped in the electrode can not only reduce the charge transfer resistance of the SnO2-PC/CNT-LiF electrode, but also supplement the Li+ consumed during the formation of the SEI film, reduce the irreversible capacity and enhance the stability of the SEI film. The first reversible specific capacity of SnO2-PC/CNT-LiF electrode reached 1 642.98 mAh·g-1 at current density of 100 mA·g-1, and the utilization rate of active material was as high as 90.12%. After 100 cycles, the specific discharge capacity still reached above 745.11 mAh·g-1, and the coulombic efficiency remained above 95.1%, showing excellent rate and cycle performance.
New porous carbon nanosheets/carbon nanotubes (PC/CNT) materials showed a rich hierarchical pore structure with high tin oxide (SnO2) loading. The three-dimensional structure formed by the cross-linking of PC and CNT can improve Li+ transmission rate and electron conduction. In addition, lithium fluoride (LiF) doped in the electrode can not only reduce the charge transfer resistance of the SnO2-PC/CNT-LiF electrode, but also supplement the Li+ consumed during the formation of the SEI film, reduce the irreversible capacity and enhance the stability of the SEI film. The first reversible specific capacity of SnO2-PC/CNT-LiF electrode reached 1 642.98 mAh·g-1 at current density of 100 mA·g-1, and the utilization rate of active material was as high as 90.12%. After 100 cycles, the specific discharge capacity still reached above 745.11 mAh·g-1, and the coulombic efficiency remained above 95.1%, showing excellent rate and cycle performance.
2021, 37(3): 482-490
doi: 10.11862/CJIC.2021.058
Abstract:
Transition metal supported catalysts were prepared by impregnation method with nano MgO as support. Among several supported transition metals, Ag/MgO showed the best performance in degradation of azo dyes and the structure and micro morphology of selected Ag/MgO catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), extended X-ray absorption fine structure spectroscopy (EXAFS) and X-ray absorption near edge structure (XANES). The results show that Ag was evenly dispersed on the surface of MgO in the form of nano clusters, and the formation of bimetallic sites between Ag and Mg and the high electron density of Ag in the catalysts give it high catalytic activity. In formaldehyde solution, azo dye AR1 could be efficiently degraded at room temperature without illuminating or heating treatment. Temperature and formaldehyde concentration are the main factors affecting the degradation efficiency. The degradation efficiency increased with temperature and the optimal formaldehyde concentration was 1 mol·L-1. Two kinds of free radicals were detected by electron paramagnetic resonance (EPR) trapping experiment to play significant roles in azo dyes degradation process. The reductive hydrogen radical and oxidizing superoxide radical synergistic effect could easily break the chromogenic group (-N=N-) in dye molecules. This "reduction-oxidation" synergistic mechanism improves the reaction efficiency. Moreover, as one of the common pollutants, using aldehyde promoter achieves the "dual treatment of pollutants".
Transition metal supported catalysts were prepared by impregnation method with nano MgO as support. Among several supported transition metals, Ag/MgO showed the best performance in degradation of azo dyes and the structure and micro morphology of selected Ag/MgO catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), extended X-ray absorption fine structure spectroscopy (EXAFS) and X-ray absorption near edge structure (XANES). The results show that Ag was evenly dispersed on the surface of MgO in the form of nano clusters, and the formation of bimetallic sites between Ag and Mg and the high electron density of Ag in the catalysts give it high catalytic activity. In formaldehyde solution, azo dye AR1 could be efficiently degraded at room temperature without illuminating or heating treatment. Temperature and formaldehyde concentration are the main factors affecting the degradation efficiency. The degradation efficiency increased with temperature and the optimal formaldehyde concentration was 1 mol·L-1. Two kinds of free radicals were detected by electron paramagnetic resonance (EPR) trapping experiment to play significant roles in azo dyes degradation process. The reductive hydrogen radical and oxidizing superoxide radical synergistic effect could easily break the chromogenic group (-N=N-) in dye molecules. This "reduction-oxidation" synergistic mechanism improves the reaction efficiency. Moreover, as one of the common pollutants, using aldehyde promoter achieves the "dual treatment of pollutants".
2021, 37(3): 491-498
doi: 10.11862/CJIC.2021.020
Abstract:
Indium tin oxide (ITO) nanofibers and ITO nanoparticles with enriched oxygen-defects were synthesized through facile electrospinning and sol gel method. SnCl2, InCl3, and PVP (polyvinylpyrrolidone) were selected as precursors, while ethanolamine was employed as a hydrolysis controlling agent. The morphology, crystal structure, oxygen defects, and electrical performance of the ultrafine ITO nanofibers and nanoparticles were systematically characterized by transmission electron microscope (TEM), selection electron diffraction (SAED), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray electron spectroscopy (XPS), and four point resistance tester. The ITO nanofibers were obtained by removal of the PVP matrix at 400℃, and featured with ultrafine diameter, porous structure, and cubic phase. Furthermore, the resultant ITO nanofibers changed to oxygen-deficient nanoparticles with a high oxygen vacancy content of 38.9% at 800℃. The doping of Sn4+ ions into the In2O3 lattices leads to the expansion of the lattice and thus the increase of crystal plane spacing at elevated temperatures. When the temperature increased from 400 to 800℃, the size of ITO nanoparticles grown from 32 to 44 nm. Meanwhile, the lattice strain (ε0) decreased from 1.943×10-3 to 1.422×10-3 and the strain-induced lattice relaxation decreased accordingly. No phase change from cubic structure to hexagonal structure was observed. Additionally, calcination at elevated temperature could hamper the (111) growth and thus cause the increase in the ratio of I(400)/I(222) in In2O3 that is proportional to the electrical conductivity of ITO. The maximized electrical conductivity of ITO nanoparticles was obtained upon a calcination temperature of 800℃.
Indium tin oxide (ITO) nanofibers and ITO nanoparticles with enriched oxygen-defects were synthesized through facile electrospinning and sol gel method. SnCl2, InCl3, and PVP (polyvinylpyrrolidone) were selected as precursors, while ethanolamine was employed as a hydrolysis controlling agent. The morphology, crystal structure, oxygen defects, and electrical performance of the ultrafine ITO nanofibers and nanoparticles were systematically characterized by transmission electron microscope (TEM), selection electron diffraction (SAED), scanning electron microscope (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray electron spectroscopy (XPS), and four point resistance tester. The ITO nanofibers were obtained by removal of the PVP matrix at 400℃, and featured with ultrafine diameter, porous structure, and cubic phase. Furthermore, the resultant ITO nanofibers changed to oxygen-deficient nanoparticles with a high oxygen vacancy content of 38.9% at 800℃. The doping of Sn4+ ions into the In2O3 lattices leads to the expansion of the lattice and thus the increase of crystal plane spacing at elevated temperatures. When the temperature increased from 400 to 800℃, the size of ITO nanoparticles grown from 32 to 44 nm. Meanwhile, the lattice strain (ε0) decreased from 1.943×10-3 to 1.422×10-3 and the strain-induced lattice relaxation decreased accordingly. No phase change from cubic structure to hexagonal structure was observed. Additionally, calcination at elevated temperature could hamper the (111) growth and thus cause the increase in the ratio of I(400)/I(222) in In2O3 that is proportional to the electrical conductivity of ITO. The maximized electrical conductivity of ITO nanoparticles was obtained upon a calcination temperature of 800℃.
2021, 37(3): 499-508
doi: 10.11862/CJIC.2021.057
Abstract:
A simple two step electrodeposition method was applied to effectively integrate the amorphous Ni3S2 material and the defect-rich NiFe bimetallic oxyhydroxide on the surface of the nickel foam, thereby constructing a NiFe/Ni3S2/NF three-dimensional hierarchical heterogeneous electrode. Benefiting from the structural and catalytic advantages of amorphous Ni3S2 and defect-rich NiFe materials, as well as the strong electronic interaction at the heterogeneous interface, the NiFe/Ni3S2/NF catalytic electrode exhibited excellent oxygen evolution performance: only an overpotential of 273 mV was needed to attain a current density of 100 mA·cm-2, which is far superior to most of the reported Ni/Fe-based composite materials. It can stably output a high current density of 1 000 mA·cm-2 at the overpotential of 372 mV for more than 27 h in 1 mol·L-1 KOH solution.
A simple two step electrodeposition method was applied to effectively integrate the amorphous Ni3S2 material and the defect-rich NiFe bimetallic oxyhydroxide on the surface of the nickel foam, thereby constructing a NiFe/Ni3S2/NF three-dimensional hierarchical heterogeneous electrode. Benefiting from the structural and catalytic advantages of amorphous Ni3S2 and defect-rich NiFe materials, as well as the strong electronic interaction at the heterogeneous interface, the NiFe/Ni3S2/NF catalytic electrode exhibited excellent oxygen evolution performance: only an overpotential of 273 mV was needed to attain a current density of 100 mA·cm-2, which is far superior to most of the reported Ni/Fe-based composite materials. It can stably output a high current density of 1 000 mA·cm-2 at the overpotential of 372 mV for more than 27 h in 1 mol·L-1 KOH solution.
2021, 37(3): 509-515
doi: 10.11862/CJIC.2021.063
Abstract:
The UV light photocatalytic performances of p-block metal oxides Ga2O3 and Sb2O3 synthesized by a precipitation method for the degradation of tetracycline hydrochloride were explored. The effects of synthesis conditions on the photocatalytic activity were discussed. The Ga2O3-900 and Sb2O3-500 samples prepared under optimal conditions exhibited a remarkable photocatalytic activity difference, which were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption-desorption tests, fluorescence spectrum, Raman spectrum, electrochemical analysis and trapping experiment of active species. The photocatalytic degradation mechanisms of tetracycline hydrochloride over the photocatalysts were proposed and the essential factors influencing the difference of photocatalytic performance were revealed. The results show that the different photocatalytic activities observed for Ga2O3 and Sb2O3 can be attributed to their different electronic and crystal structures, the amount of hydroxyl group in the surface and the photocatalytic degradation mechanisms.
The UV light photocatalytic performances of p-block metal oxides Ga2O3 and Sb2O3 synthesized by a precipitation method for the degradation of tetracycline hydrochloride were explored. The effects of synthesis conditions on the photocatalytic activity were discussed. The Ga2O3-900 and Sb2O3-500 samples prepared under optimal conditions exhibited a remarkable photocatalytic activity difference, which were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption-desorption tests, fluorescence spectrum, Raman spectrum, electrochemical analysis and trapping experiment of active species. The photocatalytic degradation mechanisms of tetracycline hydrochloride over the photocatalysts were proposed and the essential factors influencing the difference of photocatalytic performance were revealed. The results show that the different photocatalytic activities observed for Ga2O3 and Sb2O3 can be attributed to their different electronic and crystal structures, the amount of hydroxyl group in the surface and the photocatalytic degradation mechanisms.
2021, 37(3): 516-524
doi: 10.11862/CJIC.2021.066
Abstract:
Two series of phosphors of Tb3+ single doped LiBa1-xBO3: xTb3+ (molar fraction x=0.02, 0.03, 0.04, 0.05, 0.06, 0.07) and Bi3+/Tb3+ co-doped LiBa0.95-yBO3: 0.05Tb3+, yBi3+ (molar fraction y=0.02, 0.03, 0.04, 0.05, 0.06, 0.07) of which can be effectively excited by (near) ultraviolet at 369, 254 nm light were prepared by high temperature solid state reaction from boric acid and carbonates. The structures and morphology of the samples were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy. PXRD measurement shows that the products of the two series are pure phase LiBaBO3. By measuring the fluorescent spectra of the first series of products, the product with the best luminescent intensity was screened out, and the optimal doping amount of Tb3+ was determined accordingly; on this basis, the second series of phosphors with different doping amounts of Bi3+ were prepared. The experimental results of fluorescent spectra show that the luminescent intensity of Tb3+/Bi3+ co doped phosphors was better than that of Tb3+ single-doped phosphors, indicating that Bi3+ sensitizes to Tb3+; the fluorescent intensity of the products increased first and then decreased with the increase of Bi3+ content, and the luminescence intensity of the products reached the maximum when the doped molar fraction y of Bi3+ was 0.03. The energy transfer from Bi3+ to Tb3+ ions is attributed to the dipole quadrupole interaction. The CIE chromaticity coordinates of the phosphors show that the luminescent color exhibited a gradual trend from green to white in some degree.
Two series of phosphors of Tb3+ single doped LiBa1-xBO3: xTb3+ (molar fraction x=0.02, 0.03, 0.04, 0.05, 0.06, 0.07) and Bi3+/Tb3+ co-doped LiBa0.95-yBO3: 0.05Tb3+, yBi3+ (molar fraction y=0.02, 0.03, 0.04, 0.05, 0.06, 0.07) of which can be effectively excited by (near) ultraviolet at 369, 254 nm light were prepared by high temperature solid state reaction from boric acid and carbonates. The structures and morphology of the samples were characterized by powder X-ray diffraction (PXRD) and scanning electron microscopy. PXRD measurement shows that the products of the two series are pure phase LiBaBO3. By measuring the fluorescent spectra of the first series of products, the product with the best luminescent intensity was screened out, and the optimal doping amount of Tb3+ was determined accordingly; on this basis, the second series of phosphors with different doping amounts of Bi3+ were prepared. The experimental results of fluorescent spectra show that the luminescent intensity of Tb3+/Bi3+ co doped phosphors was better than that of Tb3+ single-doped phosphors, indicating that Bi3+ sensitizes to Tb3+; the fluorescent intensity of the products increased first and then decreased with the increase of Bi3+ content, and the luminescence intensity of the products reached the maximum when the doped molar fraction y of Bi3+ was 0.03. The energy transfer from Bi3+ to Tb3+ ions is attributed to the dipole quadrupole interaction. The CIE chromaticity coordinates of the phosphors show that the luminescent color exhibited a gradual trend from green to white in some degree.
2021, 37(3): 525-530
doi: 10.11862/CJIC.2021.050
Abstract:
A mononuclear Co(Ⅱ)complex (NHEt3)[Co(HL)2] ·3H2O (1) based on a pyrazine-containing hydrazone Schiff base ligand H2L was synthesized and characterized by IR, thermogravimetric analysis, X-ray single diffraction and magnetic susceptibility measurements. X-ray single crystal analysis reveals that it consists of a Co(Ⅱ)ion, two deprotonated HL- ligands, three uncoordinated H2O and a protonated triethylamine. The central Co(Ⅱ)ion is six- coordinated with N2O4 donor sets to form distorted octahedral geometry. Magnetic susceptibility measurement of both complex 1 and the dehydrated 1 showed a gradual high spin to low spin transition, and the differences can be attributed to the hydrogen bonding effects on the magnetic properties. CCDC: 1973542, 1 (298 K); 20274281, 1 (100 K).
A mononuclear Co(Ⅱ)complex (NHEt3)[Co(HL)2] ·3H2O (1) based on a pyrazine-containing hydrazone Schiff base ligand H2L was synthesized and characterized by IR, thermogravimetric analysis, X-ray single diffraction and magnetic susceptibility measurements. X-ray single crystal analysis reveals that it consists of a Co(Ⅱ)ion, two deprotonated HL- ligands, three uncoordinated H2O and a protonated triethylamine. The central Co(Ⅱ)ion is six- coordinated with N2O4 donor sets to form distorted octahedral geometry. Magnetic susceptibility measurement of both complex 1 and the dehydrated 1 showed a gradual high spin to low spin transition, and the differences can be attributed to the hydrogen bonding effects on the magnetic properties. CCDC: 1973542, 1 (298 K); 20274281, 1 (100 K).
2021, 37(3): 531-540
doi: 10.11862/CJIC.2021.055
Abstract:
A novel Ag/Ag2MoO4/Bi2MoO6 ternary photocatalyst was successfully prepared by hydrothermal, chemical deposition and in-situ photoreduction process. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflection spectroscopy (UV-Vis DRS) to investigate the composition, morphology, optical absorption characteristics and photoelectrochemical properties. The photocatalytic performance of Ag/Ag2MoO4/Bi2MoO6 photocatalyst was evaluated with tetracycline as the target pollutant under visible light. The research results show that, compared with pure Ag2MoO4 and Bi2MoO6, the surface plasmon resonance (SPR) effect of Ag significantly broadens the visible light absorption capacity and response range of the catalytic system. When the theoretical loading (mass fraction) of Ag2MoO4 was 24.6%, Ag/Ag2MoO4/Bi2MoO6 ternary photocatalyst could completely degrade tetracycline within 20 min, and maintained high catalytic activity after 5 cycles of use, showing good cycle stability.
A novel Ag/Ag2MoO4/Bi2MoO6 ternary photocatalyst was successfully prepared by hydrothermal, chemical deposition and in-situ photoreduction process. The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflection spectroscopy (UV-Vis DRS) to investigate the composition, morphology, optical absorption characteristics and photoelectrochemical properties. The photocatalytic performance of Ag/Ag2MoO4/Bi2MoO6 photocatalyst was evaluated with tetracycline as the target pollutant under visible light. The research results show that, compared with pure Ag2MoO4 and Bi2MoO6, the surface plasmon resonance (SPR) effect of Ag significantly broadens the visible light absorption capacity and response range of the catalytic system. When the theoretical loading (mass fraction) of Ag2MoO4 was 24.6%, Ag/Ag2MoO4/Bi2MoO6 ternary photocatalyst could completely degrade tetracycline within 20 min, and maintained high catalytic activity after 5 cycles of use, showing good cycle stability.
2021, 37(3): 541-554
doi: 10.11862/CJIC.2021.064
Abstract:
A novel Zn-doped β-Bi2O3 nanomaterial (OV-Zn: Bi2O3) with two crystal defects, oxygen vacancy (OV) and doped Zn2+, was prepared via a sol-gel method followed by in-situ carbon thermal reduction treatment. The concentration of OV of OV-Zn: Bi2O3 sample can be modulated by regulating the content of doped Zn2+. As a reference, the novel β-Bi2O3 having OV but without doped Zn2+ (OV-β-Bi2O3) was also synthesized via a similar process. The comprehensive effect of OV and doped Zn2+ on the visible-light-activity of OV-Zn: Bi2O3 for the degradation of methylene blue (MB) and 2, 4, 6-trichlorophenol (2, 4, 6-TCP) was investigated by ultraviolet-visible light diffuse reflectance spectra, X-ray photoelectron spectra, electron spin resonance, photoluminescence spectrum and photoelectrochemical measurements. The results show that introduction of OV can not only drastically extend the photoabsorption into longer wavelength region but also promote the separation of photo-generated charge carriers. So, compared to traditional β-Bi2O3, OV-β-Bi2O3 demonstrated highly promoted activity for the degradation of methylene blue (MB) and 2, 4, 6-trichlorophenol (2, 4, 6-TCP). For OV-Zn: Bi2O3 catalysts, Znic doping can make the valence band edge of catalysts move down and the oxidation ability of photo-excited holes increase. And appropriate amount of zinc doping can also improve the separation efficiency of photogenerated carriers. In contrast to OV-β-Bi2O3, the visible light activity of OV-Zn: Bi2O3 was further improved and OV-Zn: Bi2O3-0.3 with a molar ratio (nZn/nBi) of 0.3 exhibited the highest activity for the degradation of MB and 2, 4, 6-TCP.
A novel Zn-doped β-Bi2O3 nanomaterial (OV-Zn: Bi2O3) with two crystal defects, oxygen vacancy (OV) and doped Zn2+, was prepared via a sol-gel method followed by in-situ carbon thermal reduction treatment. The concentration of OV of OV-Zn: Bi2O3 sample can be modulated by regulating the content of doped Zn2+. As a reference, the novel β-Bi2O3 having OV but without doped Zn2+ (OV-β-Bi2O3) was also synthesized via a similar process. The comprehensive effect of OV and doped Zn2+ on the visible-light-activity of OV-Zn: Bi2O3 for the degradation of methylene blue (MB) and 2, 4, 6-trichlorophenol (2, 4, 6-TCP) was investigated by ultraviolet-visible light diffuse reflectance spectra, X-ray photoelectron spectra, electron spin resonance, photoluminescence spectrum and photoelectrochemical measurements. The results show that introduction of OV can not only drastically extend the photoabsorption into longer wavelength region but also promote the separation of photo-generated charge carriers. So, compared to traditional β-Bi2O3, OV-β-Bi2O3 demonstrated highly promoted activity for the degradation of methylene blue (MB) and 2, 4, 6-trichlorophenol (2, 4, 6-TCP). For OV-Zn: Bi2O3 catalysts, Znic doping can make the valence band edge of catalysts move down and the oxidation ability of photo-excited holes increase. And appropriate amount of zinc doping can also improve the separation efficiency of photogenerated carriers. In contrast to OV-β-Bi2O3, the visible light activity of OV-Zn: Bi2O3 was further improved and OV-Zn: Bi2O3-0.3 with a molar ratio (nZn/nBi) of 0.3 exhibited the highest activity for the degradation of MB and 2, 4, 6-TCP.
Y-Mn-O Supported Ni-Based Catalyst for Hydrogen Production via Auto-thermal Reforming of Acetic Acid
2021, 37(3): 555-560
doi: 10.11862/CJIC.2021.032
Abstract:
To effectively achieve high hydrogen yield from biomass-derived acetic acid (HAc), a series of NiMnY catalysts were prepared by hydrothermal method and tested in auto-thermal reforming (ATR) of HAc. X-ray diffraction (XRD), N2 adsorption-desorption test and H2-temperature-programmed reduction (H2-TPR) were carried out to explore the internal relationship within these NiMnY catalysts. Over the Ni0.39Mn0.61YO3.11±δ catalyst, perovskite-like (Ni, Mn)YO3 phase was formed after calcination, and converted into thermostable Ni-Mn-Y-O species after reduction in H 2, along with the highly dispersed nickel nanoparticles. As a result, over the promoted Ni0.39Mn0.61YO3.11±δ catalyst, a stable catalytic performance with high HAc conversion (100%) and hydrogen yield (2.68 molH2 ·molHAc-1) was recorded, showing potential for hydrogen production.
To effectively achieve high hydrogen yield from biomass-derived acetic acid (HAc), a series of NiMnY catalysts were prepared by hydrothermal method and tested in auto-thermal reforming (ATR) of HAc. X-ray diffraction (XRD), N2 adsorption-desorption test and H2-temperature-programmed reduction (H2-TPR) were carried out to explore the internal relationship within these NiMnY catalysts. Over the Ni0.39Mn0.61YO3.11±δ catalyst, perovskite-like (Ni, Mn)YO3 phase was formed after calcination, and converted into thermostable Ni-Mn-Y-O species after reduction in H 2, along with the highly dispersed nickel nanoparticles. As a result, over the promoted Ni0.39Mn0.61YO3.11±δ catalyst, a stable catalytic performance with high HAc conversion (100%) and hydrogen yield (2.68 molH2 ·molHAc-1) was recorded, showing potential for hydrogen production.
2021, 37(3): 561-568
doi: 10.11862/CJIC.2021.054
Abstract:
Two new copper(Ⅱ) complexes, trans-[Cu(L1)2(MeOH)2](ClO4)2 (1) and trans-[Cu(L2)2(ClO4)2]·2MeCN (2) (L1=3-(2-pyridyl)-4-phenyl-5-(2-thienyl)-1, 2, 4-triazole, L2=3-(2-pyridyl)-4-(p-chlorophenyl)-5-(2-thienyl)-1, 2, 4triazole), were synthesized and structurally characterized by FT-IR, elemental analyses, single-crystal X-ray crystallography and powder X-ray diffraction. Both 1 and 2 crystallize in monoclinic system with a space group P21/c. Xray crystallography analysis reveals that the copper ion in 1 and 2 sits in a distorted octahedral environment[CuN4O2] with two MeOH in the trans-position in 1 but two ClO4- in the trans-position in 2. Each L ligand in the equatorial plane adopts a chelating bidentate mode through the pyridyl N atom and one triazole N atom, while the thienyl group does not coordinate. 2 contains two MeCN guest molecules which produce π-π stacking interactions with the triazole ring. In 1 and 2 there are some intermolecular O-H…O, C-H…O and C-H…N hydrogen bonds and C-H…π interactions, linking the mononuclear complexes to form a 3D framework. CCDC: 2423470, 1; 2423471, 2.
Two new copper(Ⅱ) complexes, trans-[Cu(L1)2(MeOH)2](ClO4)2 (1) and trans-[Cu(L2)2(ClO4)2]·2MeCN (2) (L1=3-(2-pyridyl)-4-phenyl-5-(2-thienyl)-1, 2, 4-triazole, L2=3-(2-pyridyl)-4-(p-chlorophenyl)-5-(2-thienyl)-1, 2, 4triazole), were synthesized and structurally characterized by FT-IR, elemental analyses, single-crystal X-ray crystallography and powder X-ray diffraction. Both 1 and 2 crystallize in monoclinic system with a space group P21/c. Xray crystallography analysis reveals that the copper ion in 1 and 2 sits in a distorted octahedral environment[CuN4O2] with two MeOH in the trans-position in 1 but two ClO4- in the trans-position in 2. Each L ligand in the equatorial plane adopts a chelating bidentate mode through the pyridyl N atom and one triazole N atom, while the thienyl group does not coordinate. 2 contains two MeCN guest molecules which produce π-π stacking interactions with the triazole ring. In 1 and 2 there are some intermolecular O-H…O, C-H…O and C-H…N hydrogen bonds and C-H…π interactions, linking the mononuclear complexes to form a 3D framework. CCDC: 2423470, 1; 2423471, 2.
2021, 37(3): 569-576
doi: 10.11862/CJIC.2021.065
Abstract:
A series of efficient red platinum based emitter with functionalized diphenylamine moiety (M1~M3) were designed and investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The effect of different substituent positions on the electronic structures and optical properties were fully explored by compared with the synthesized complex. The introduction of diphenylamine moiety could effectively strengthen the π-conjugation interaction between the metal and ligand. By gradually increasing the amount of diphenylamine moiety, the intensities and the participation of metal-to-ligand charge-transfer (MLCT) for the absorption bands of M3 were enhanced, which are beneficial to collect light energy participation of metals and increase the spin-orbital coupling effect. M1~M3 exhibited red emission with the peak wavelengths at 602~630 nm. These emission spectra are mixtures of 3MLCT and ligand to ligand charge transfer (3LLCT) character. The possible non radiative process T1 (3MLCT) → TS → triplet metal-centered 3MC (d-d) state were deeply investigated, and the results show that the possibility of the non-radiative process will decrease because the surface crossing at a minimum energy crossing point (MECP) between T1 and S0 state is difficult to populate when the functionalized diphenylamine moiety is useful to enhance steric hindrance.
A series of efficient red platinum based emitter with functionalized diphenylamine moiety (M1~M3) were designed and investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The effect of different substituent positions on the electronic structures and optical properties were fully explored by compared with the synthesized complex. The introduction of diphenylamine moiety could effectively strengthen the π-conjugation interaction between the metal and ligand. By gradually increasing the amount of diphenylamine moiety, the intensities and the participation of metal-to-ligand charge-transfer (MLCT) for the absorption bands of M3 were enhanced, which are beneficial to collect light energy participation of metals and increase the spin-orbital coupling effect. M1~M3 exhibited red emission with the peak wavelengths at 602~630 nm. These emission spectra are mixtures of 3MLCT and ligand to ligand charge transfer (3LLCT) character. The possible non radiative process T1 (3MLCT) → TS → triplet metal-centered 3MC (d-d) state were deeply investigated, and the results show that the possibility of the non-radiative process will decrease because the surface crossing at a minimum energy crossing point (MECP) between T1 and S0 state is difficult to populate when the functionalized diphenylamine moiety is useful to enhance steric hindrance.
