Increasing interest has been paid to the development of earth‐abundant metal complexes as promising surrogates of platinum for the electrocatalytically and photocatalytically driven hydrogen evolution reaction.In thi...Increasing interest has been paid to the development of earth‐abundant metal complexes as promising surrogates of platinum for the electrocatalytically and photocatalytically driven hydrogen evolution reaction.In this work,we report on molecular H2‐evolving catalysts based on two octahedral complexes of cobalt thiosemicarbazide,fac‐[Co(Htsc)3]Cl3·3H2O(C1,Htsc=thiosemicarbazide)and mer‐[Co(Htsc)3]Cl3·4H2O(C2),which have facial(fac)and meridional(mer)geometry,respectively.Electrochemical studies confirmed that both C1and C2are active electrocatalysts in MeOH solution using acetic acid as the proton source,with the same overpotential of^640mV and TOF of^210s–1.The complex C1also exhibits electrocatalytic activity for hydrogen evolution reaction in aqueous media free of organic solvent with a moderate overpotential(560mV).Visible light‐driven hydrogen evolution experiments were carried out in combination with fluorescein as photosensitizer and triethylamine as sacrificial reductant in homogeneous environments.Our studies showed that both C1and C2can be used as efficient proton‐reduction catalysts in purely aqueous solution and have the same photocatalytic activities.A TOF of125h–1with a TON of900for photocatalytic H2generation using C1and C2in water were achieved for the noble‐metal‐free homogeneous system.It should be noted that this is the first reported study investigating the effect on the catalytic hydrogen production performance of using fac‐and mer‐isomers of molecular catalysts.展开更多
A series of E and Z-isomers of 3-（4＇-substituted benzylidene）-indolin-2-one derivatives were synthesized and separated. Based on their 1H NMR characterization, an unusual counterintuitive deshielding phenomenon for...A series of E and Z-isomers of 3-（4＇-substituted benzylidene）-indolin-2-one derivatives were synthesized and separated. Based on their 1H NMR characterization, an unusual counterintuitive deshielding phenomenon for the protons presenting in the shielding zone of phenyl ring was observed and analyzed for the first time.展开更多
A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiol...A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.展开更多
基金supported by the National Natural Science Foundation of China (21641011, 21773313)the Natural Science Foundation of Fujian Province (2015J01053, 2016J01060)+1 种基金Program for New Century Excellent Talents in Fujian Province UniversityPromotion Program for Young and Middle-aged Teacher in Science, Technology Research of Huaqiao University (ZQN-PY104)~~
文摘Increasing interest has been paid to the development of earth‐abundant metal complexes as promising surrogates of platinum for the electrocatalytically and photocatalytically driven hydrogen evolution reaction.In this work,we report on molecular H2‐evolving catalysts based on two octahedral complexes of cobalt thiosemicarbazide,fac‐[Co(Htsc)3]Cl3·3H2O(C1,Htsc=thiosemicarbazide)and mer‐[Co(Htsc)3]Cl3·4H2O(C2),which have facial(fac)and meridional(mer)geometry,respectively.Electrochemical studies confirmed that both C1and C2are active electrocatalysts in MeOH solution using acetic acid as the proton source,with the same overpotential of^640mV and TOF of^210s–1.The complex C1also exhibits electrocatalytic activity for hydrogen evolution reaction in aqueous media free of organic solvent with a moderate overpotential(560mV).Visible light‐driven hydrogen evolution experiments were carried out in combination with fluorescein as photosensitizer and triethylamine as sacrificial reductant in homogeneous environments.Our studies showed that both C1and C2can be used as efficient proton‐reduction catalysts in purely aqueous solution and have the same photocatalytic activities.A TOF of125h–1with a TON of900for photocatalytic H2generation using C1and C2in water were achieved for the noble‐metal‐free homogeneous system.It should be noted that this is the first reported study investigating the effect on the catalytic hydrogen production performance of using fac‐and mer‐isomers of molecular catalysts.
基金National Natural Science Foundation of China(Grant No.21172008 and 21372015)
文摘A series of E and Z-isomers of 3-（4＇-substituted benzylidene）-indolin-2-one derivatives were synthesized and separated. Based on their 1H NMR characterization, an unusual counterintuitive deshielding phenomenon for the protons presenting in the shielding zone of phenyl ring was observed and analyzed for the first time.
文摘A convenient synthesis of cis-（±） isomer 1 and trans-（±） isomer 2 of lamivudine starting from benzoyloxyacetaldehyde and 1,4-dithiane-2,5-diol is described. The key steps include chlorination of oxathiolane lactol 5 by SOCl2/DMF, followed by coupling with silylated N^4- acetylcytosine and deprotection. The overall yield was 42.6 % and 20,1%, respectively.
