A chiral metasurface is proposed to realize a tri-band polarization angle insensitive cross-polarization converter. The unit cell of the chiral metamaterial is composed by four twisted anisotropic structure pairs in f...A chiral metasurface is proposed to realize a tri-band polarization angle insensitive cross-polarization converter. The unit cell of the chiral metamaterial is composed by four twisted anisotropic structure pairs in four-fold rotation symmetry. The simulation results show that this device can work at 9.824 GHz, 11.39 GHz, and 13.37 GHz with low loss and a high polarization conversion ratio （PCR） of more than 99%. The proposed design can transmit the co-polarization wave at 14.215 GHz, like a frequency selective surface. The study of the current and electric fields distributions indicates that the cross-polarization transmission is due to electric dipole coupling.展开更多
Enantioselective alternating copolymerization of carbon monoxide with ω undecylenic acid was carried out using cationic palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol...Enantioselective alternating copolymerization of carbon monoxide with ω undecylenic acid was carried out using cationic palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol (DDPPI). The chiral diphosphine was proved to be effective in the enantioselective copolymerization. The pure poly(1,4 ketone) was obtained by dissolving the copolymer containing spiroketal and 1,4 ketone units in 1,1,1,3,3,3 hexafluoro 2 propanol and reprecipitating with methanol. Optical rotation, elemental analysis, spectra of 1H, 13 C NMR and IR showed that our copolymer was an optically active, isotatic, alternating poly(1,4 ketone) structure. The copolymerization was carried out at 45 ℃ for 20 h. Molecular weight: n=1.1× 10 4 versus polystyrene, w/ n=1.84. Molar optical rotation: 20 589 =+43°(CH 3COOC 2H 5, 5.0 mg/mL). The productivity of the copolymer of ω undecylenic acid with carbon monoxide was 40.6 g copolymer/(g Pd·h).展开更多
Enantioselective alternating copolymerization of carbon monoxide with 1 heptene was carried out using palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol (DDPPI). The chira...Enantioselective alternating copolymerization of carbon monoxide with 1 heptene was carried out using palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol (DDPPI). The chiral diphosphine was proved to be effective at enantioselective copolymerization. The pure poly(1,4 ketone) was obtained by dissolving the copolymer containing spiroketal and 1,4 ketone units in 1,1,1,3,3,3 hexafluoro 2 propanol and reprecipitating with methanol. Optical rotation, elemental analysis, spectra of 1H\|NMR, 13 C NMR and IR showed that our copolymer was optically active, isotatic, alternating poly(1,4 ketone) structure. The copolymerization was carried out at 45℃ for 48?h. Molecular weight: M n=4 02×10 3, M w/ M n=1 55 (GPC measurements with polystyrene standards). Optical rotation:[ α ] 20 589 =+63° (CH 2Cl 2, 5 0?mg/mL). T m=194℃, T g=11℃.展开更多
The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepare...The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepared and characterized by specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in thc polymerization of N-vinylcarbazole is in an order of A*B-+*(-) > A(+)B*(-) > A*B-+(-). The specific rotations of obtained poly(N-vinylcarbazole) (PVCZ) generally are in accordance with mentioned order.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.61331005,61001039,and 41390454)
文摘A chiral metasurface is proposed to realize a tri-band polarization angle insensitive cross-polarization converter. The unit cell of the chiral metamaterial is composed by four twisted anisotropic structure pairs in four-fold rotation symmetry. The simulation results show that this device can work at 9.824 GHz, 11.39 GHz, and 13.37 GHz with low loss and a high polarization conversion ratio （PCR） of more than 99%. The proposed design can transmit the co-polarization wave at 14.215 GHz, like a frequency selective surface. The study of the current and electric fields distributions indicates that the cross-polarization transmission is due to electric dipole coupling.
文摘Enantioselective alternating copolymerization of carbon monoxide with ω undecylenic acid was carried out using cationic palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol (DDPPI). The chiral diphosphine was proved to be effective in the enantioselective copolymerization. The pure poly(1,4 ketone) was obtained by dissolving the copolymer containing spiroketal and 1,4 ketone units in 1,1,1,3,3,3 hexafluoro 2 propanol and reprecipitating with methanol. Optical rotation, elemental analysis, spectra of 1H, 13 C NMR and IR showed that our copolymer was an optically active, isotatic, alternating poly(1,4 ketone) structure. The copolymerization was carried out at 45 ℃ for 20 h. Molecular weight: n=1.1× 10 4 versus polystyrene, w/ n=1.84. Molar optical rotation: 20 589 =+43°(CH 3COOC 2H 5, 5.0 mg/mL). The productivity of the copolymer of ω undecylenic acid with carbon monoxide was 40.6 g copolymer/(g Pd·h).
文摘Enantioselective alternating copolymerization of carbon monoxide with 1 heptene was carried out using palladium catalyst modified by 1,4 3,6 dianhydro 2,5 dideoxy 2,5 bis(diphenylphosphino) L iditol (DDPPI). The chiral diphosphine was proved to be effective at enantioselective copolymerization. The pure poly(1,4 ketone) was obtained by dissolving the copolymer containing spiroketal and 1,4 ketone units in 1,1,1,3,3,3 hexafluoro 2 propanol and reprecipitating with methanol. Optical rotation, elemental analysis, spectra of 1H\|NMR, 13 C NMR and IR showed that our copolymer was optically active, isotatic, alternating poly(1,4 ketone) structure. The copolymerization was carried out at 45℃ for 48?h. Molecular weight: M n=4 02×10 3, M w/ M n=1 55 (GPC measurements with polystyrene standards). Optical rotation:[ α ] 20 589 =+63° (CH 2Cl 2, 5 0?mg/mL). T m=194℃, T g=11℃.
文摘The organic salts as initiators [A*B-+(-):Ph*3C+ClO4-, Ph(3)*C+SbCl6-, (-)Sp*(ClO4-)-Cl-+ and (-)(Sp)(2)*(+3)(ClO4-)(3)] and catalysts [A(+)B*(-):(+)CSA*, A*B-+*(-):Ph(3)*C+(+)CSA*(-) and (-)Sp*(+)(+)CSA*] are prepared and characterized by specific rotation. The asymmetrically stereoselective induction of the initiators and catalysts in thc polymerization of N-vinylcarbazole is in an order of A*B-+*(-) > A(+)B*(-) > A*B-+(-). The specific rotations of obtained poly(N-vinylcarbazole) (PVCZ) generally are in accordance with mentioned order.
