A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-ca...A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.展开更多
Schiff-base metal complexes as efficient catalysts are widely used in ring-opening polymerization of cycle esters. The salen Fe complexes were formed with their excellent biocompatibility and less toxicity. A series o...Schiff-base metal complexes as efficient catalysts are widely used in ring-opening polymerization of cycle esters. The salen Fe complexes were formed with their excellent biocompatibility and less toxicity. A series of salen Fe complexes were designed in this work in order to study the activity and control of polymerization of lactide. The salen Fe complexes＇ activities changed with the ligands configuration and substituent groups.展开更多
Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we de...Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.展开更多
A series of Salen-Co(Ⅱ)complexes were synthesized to study the effect of O2 on the catalytic performance of Salen-Co complexes for the copolymerization of PO/CO2 The Salen-Co(Ⅱ) complexes showed low activity on the ...A series of Salen-Co(Ⅱ)complexes were synthesized to study the effect of O2 on the catalytic performance of Salen-Co complexes for the copolymerization of PO/CO2 The Salen-Co(Ⅱ) complexes showed low activity on the cyclo addition of CO2 to PO with the aid of a cocatalyst such as PPNCI Unexpectedly,with the addition of O2 the activity of Salen-C(Ⅱ)complexes was obviously increased and 100%cylic carbonate was obtained.As the pressure of O2 increased,the activity of the complex also increased.With the existence of 02 the activity of the complexes was influenced by their structures and the pressure of 02,and the camplexes with the conjugated structure showed higher activity.The structures of cocatalyst also played a crucial role as for the change of the activity By altering the electrophilit of Salen-Co(Ⅲ),O2 can also be used as cocatalyst for the copolymerization of PO/CO2。展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21574124,51503203 and51233004)
文摘A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.
基金financially supported by the National Natural Science Foundation of China (Nos. 21574124 and 51503203)
文摘Schiff-base metal complexes as efficient catalysts are widely used in ring-opening polymerization of cycle esters. The salen Fe complexes were formed with their excellent biocompatibility and less toxicity. A series of salen Fe complexes were designed in this work in order to study the activity and control of polymerization of lactide. The salen Fe complexes＇ activities changed with the ligands configuration and substituent groups.
基金financially supported by the National Key R&D Program of China (No. 2021YFA1501700)the National Natural Science Foundation of China+1 种基金Basic Science Center Program (No.51988102)the National Natural Science Foundation of China (No. 52073272)
文摘Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.
基金This work was financially supported by National Key Research and Development Program of China(No.2016YFC1100701)the National Natural Science Foundation of China(Nos.21574124,51503203,and 51773200).
文摘A series of Salen-Co(Ⅱ)complexes were synthesized to study the effect of O2 on the catalytic performance of Salen-Co complexes for the copolymerization of PO/CO2 The Salen-Co(Ⅱ) complexes showed low activity on the cyclo addition of CO2 to PO with the aid of a cocatalyst such as PPNCI Unexpectedly,with the addition of O2 the activity of Salen-C(Ⅱ)complexes was obviously increased and 100%cylic carbonate was obtained.As the pressure of O2 increased,the activity of the complex also increased.With the existence of 02 the activity of the complexes was influenced by their structures and the pressure of 02,and the camplexes with the conjugated structure showed higher activity.The structures of cocatalyst also played a crucial role as for the change of the activity By altering the electrophilit of Salen-Co(Ⅲ),O2 can also be used as cocatalyst for the copolymerization of PO/CO2。
