Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions an...Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions and 6-(3',4'-dicarboxylphenoxy)-1,2,4-benzenetricarboxylic acid(H_(5)L)in the presence of N-auxiliary ligands 1,10-phenanthroline(phen)and1,4-bis(1H-imidazol-1-yl)benzene(1,4-bib).The structures of coordination polymers 1 and 2 were characterized by infrared spectroscopy,single-crystal X-ray diffraction,thermogravimetric analysis,and powder X-ray diffraction.Single-crystal X-ray diffraction reveals that 1 has a 1D chain structure based on binuclear Mn(Ⅱ)units,while 2 features a(3,8)-connected 3D network structure based on tetranuclear Mn(Ⅱ)units.Magnetic studies show that 1 and 2exhibit antiferromagnetic interactions between manganese ions.2 shows stronger antiferromagnetic interactions due to the shorter Mn…Mn distances within the tetranuclear manganese units.CCDC:2357601,1;2357602,2.展开更多
Grassland is a key component of the ecosystem in the Qinghai Lake Basin,China.Understanding the effects of climate change and human activities on grassland productivity significantly improves ecological conservation a...Grassland is a key component of the ecosystem in the Qinghai Lake Basin,China.Understanding the effects of climate change and human activities on grassland productivity significantly improves ecological conservation and promotes sustainable vegetation growth in this area.Based on the net primary productivity(NPP)products of MOD17A3HGF(a moderate-resolution imaging spectroradiometer(MODIS)product that provides annual NPP at 500 m resolution)and meteorological data,we analyzed the spatial and temporal evolution of grassland NPP and its interaction with climate factors in the Qinghai Lake Basin from 2001 to 2022 via partial correlation and trend analysis methods.We also used the deflecting trend residual method and scenario analysis method to quantitatively assess the relative contributions of climatic factors and human activities to grassland NPP.The results revealed that:(1)during the past 22 a,grassland NPP increased considerably,with a gradient change from the northwest to the southeast of the study area;(2)sunshine duration,precipitation,and temperature positively influenced grassland NPP,with sunshine duration exerting a stronger effect on grassland NPP than precipitation and temperature;and(3)98.47%of the grassland in the study area was restored,with an average contribution of 65.00%from human activities and 35.00%from climatic alterations.Compared with climate change,human-induced factors had a greater effect on grassland NPP in this area.The results of the study not only provide important scientific support for ecological restoration and sustainable development of the basin but also offer new ideas for research on similar ecologically fragile areas.展开更多
文摘Two new Mn(Ⅱ)coordination polymers,namely{[Mn_(2)(HL)(phen)_(3)(H_(2)O)_(2)]·7.5H_(2)O}_n(1)and[Mn_(4)(HL)_(2)(1,4-bib)_(3)(H_(2)O)_(2)]_n(2),were synthesized under hydrothermal conditions by using Mn(Ⅱ)ions and 6-(3',4'-dicarboxylphenoxy)-1,2,4-benzenetricarboxylic acid(H_(5)L)in the presence of N-auxiliary ligands 1,10-phenanthroline(phen)and1,4-bis(1H-imidazol-1-yl)benzene(1,4-bib).The structures of coordination polymers 1 and 2 were characterized by infrared spectroscopy,single-crystal X-ray diffraction,thermogravimetric analysis,and powder X-ray diffraction.Single-crystal X-ray diffraction reveals that 1 has a 1D chain structure based on binuclear Mn(Ⅱ)units,while 2 features a(3,8)-connected 3D network structure based on tetranuclear Mn(Ⅱ)units.Magnetic studies show that 1 and 2exhibit antiferromagnetic interactions between manganese ions.2 shows stronger antiferromagnetic interactions due to the shorter Mn…Mn distances within the tetranuclear manganese units.CCDC:2357601,1;2357602,2.
基金financially supported by the Lanzhou Youth Science and Technology Talent Innovation Project(2023-QN-2)the Gansu Haizhi Plan Project(GSHZJH 12-2025-04)+1 种基金the National Key Research and Development Program of China(2019YFC0507404)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20100101)。
文摘Grassland is a key component of the ecosystem in the Qinghai Lake Basin,China.Understanding the effects of climate change and human activities on grassland productivity significantly improves ecological conservation and promotes sustainable vegetation growth in this area.Based on the net primary productivity(NPP)products of MOD17A3HGF(a moderate-resolution imaging spectroradiometer(MODIS)product that provides annual NPP at 500 m resolution)and meteorological data,we analyzed the spatial and temporal evolution of grassland NPP and its interaction with climate factors in the Qinghai Lake Basin from 2001 to 2022 via partial correlation and trend analysis methods.We also used the deflecting trend residual method and scenario analysis method to quantitatively assess the relative contributions of climatic factors and human activities to grassland NPP.The results revealed that:(1)during the past 22 a,grassland NPP increased considerably,with a gradient change from the northwest to the southeast of the study area;(2)sunshine duration,precipitation,and temperature positively influenced grassland NPP,with sunshine duration exerting a stronger effect on grassland NPP than precipitation and temperature;and(3)98.47%of the grassland in the study area was restored,with an average contribution of 65.00%from human activities and 35.00%from climatic alterations.Compared with climate change,human-induced factors had a greater effect on grassland NPP in this area.The results of the study not only provide important scientific support for ecological restoration and sustainable development of the basin but also offer new ideas for research on similar ecologically fragile areas.
