Complex [(DB18C6 ) (CH3OH )]2W6O19. (DB18C6 ) - (CH3OH),Mr=2630. 43, monoclinic, space group P21/c, a=18. 699 (5), b= 19. 568 (4), c=22. 785(5) A, β= 112. 91(2)°, V=7679(7) A, Z=4, D.=2- 275 g/cm3, F(000)= 4992,...Complex [(DB18C6 ) (CH3OH )]2W6O19. (DB18C6 ) - (CH3OH),Mr=2630. 43, monoclinic, space group P21/c, a=18. 699 (5), b= 19. 568 (4), c=22. 785(5) A, β= 112. 91(2)°, V=7679(7) A, Z=4, D.=2- 275 g/cm3, F(000)= 4992, p= 92. 52 cm-1. The final R=0. 035 and Rw =0. 041 for 5689 observed reflections (I>3σ(I) ). The complex contains one hexatungstate anion and two sodiumcations. Each Na cation is inlaid in the cavity of one dibenzo-18-crown-6 (DB18C6)with six Na-O coordination bonds. In addition, it linked to O atom of CH3OH fromone side of DB18C6 and bonded to one of the terminal O atoms in hexatungstate anionfrom the other side. The two DB18C6 connected with hexatungstate symmetrically bythe long-distance interaction through the O- Na -O bonds with Na- O distances of2. 28(1)~2- 37(1 ) A W-O distances are 1. 68(2) ~2. 34(2) A. C-O distancesin methanol coordinated with cation are 1. 38 (4 ) ~ 1- 41 (4) A.展开更多
The current responses of a generation/collection (G/C) system based on dual micropipettes are simulated by the boundary element (BE) method, from which the collection efficiencies for various pipettes with different g...The current responses of a generation/collection (G/C) system based on dual micropipettes are simulated by the boundary element (BE) method, from which the collection efficiencies for various pipettes with different geometries are calculated. The influence of the shape of a dual micropipette on the collection efficiency, such as curvature and symmetry of the pipette, as well as the thickness of glassy band between generator and collector, is presented and discussed in detail. Moreover, the simulation results have been tested using the experiments of potassium and sodium ions transfers facilitated by dibenzo-18-crown-6 (DB18C6) at the water/1,2-dichloroethane (W/DCE) interface. These results demonstrate that the BE method is an efficient and useful approach for the simulation of collection efficiency of symmetric geometries of dual micropipettes operating in the G/C mode under transport conditions of diffusion control. However, there are still some problems for the cases of asymmetric dual micropipettes, which show rather large differences between the values of simulated and experimental ones. This work also indicates that such an ionic G/C technique should have advantages in applications when the dual pipettes have symmetric geometries.展开更多
文摘Complex [(DB18C6 ) (CH3OH )]2W6O19. (DB18C6 ) - (CH3OH),Mr=2630. 43, monoclinic, space group P21/c, a=18. 699 (5), b= 19. 568 (4), c=22. 785(5) A, β= 112. 91(2)°, V=7679(7) A, Z=4, D.=2- 275 g/cm3, F(000)= 4992, p= 92. 52 cm-1. The final R=0. 035 and Rw =0. 041 for 5689 observed reflections (I>3σ(I) ). The complex contains one hexatungstate anion and two sodiumcations. Each Na cation is inlaid in the cavity of one dibenzo-18-crown-6 (DB18C6)with six Na-O coordination bonds. In addition, it linked to O atom of CH3OH fromone side of DB18C6 and bonded to one of the terminal O atoms in hexatungstate anionfrom the other side. The two DB18C6 connected with hexatungstate symmetrically bythe long-distance interaction through the O- Na -O bonds with Na- O distances of2. 28(1)~2- 37(1 ) A W-O distances are 1. 68(2) ~2. 34(2) A. C-O distancesin methanol coordinated with cation are 1. 38 (4 ) ~ 1- 41 (4) A.
基金supported by the National Natural Science Foundation of China (20735001, 21075004, 60372024 & 60532080)
文摘The current responses of a generation/collection (G/C) system based on dual micropipettes are simulated by the boundary element (BE) method, from which the collection efficiencies for various pipettes with different geometries are calculated. The influence of the shape of a dual micropipette on the collection efficiency, such as curvature and symmetry of the pipette, as well as the thickness of glassy band between generator and collector, is presented and discussed in detail. Moreover, the simulation results have been tested using the experiments of potassium and sodium ions transfers facilitated by dibenzo-18-crown-6 (DB18C6) at the water/1,2-dichloroethane (W/DCE) interface. These results demonstrate that the BE method is an efficient and useful approach for the simulation of collection efficiency of symmetric geometries of dual micropipettes operating in the G/C mode under transport conditions of diffusion control. However, there are still some problems for the cases of asymmetric dual micropipettes, which show rather large differences between the values of simulated and experimental ones. This work also indicates that such an ionic G/C technique should have advantages in applications when the dual pipettes have symmetric geometries.
