Intramolecular acid-base cooperative catalysis is a powerful strategy to promote the nucleophilic additions in synthetic chemistry,since both substrates and nucleophiles can be activated simultaneously,yielding a lowe...Intramolecular acid-base cooperative catalysis is a powerful strategy to promote the nucleophilic additions in synthetic chemistry,since both substrates and nucleophiles can be activated simultaneously,yielding a lower energy reaction pathway.However,the systems often suffer from catalyst quenching due to the mutual neutralization of acid/base sites.Herein,we doped the boron(B)atoms in the tri-s-triazine ring of graphite-like carbon nitride(g-C_(3)N_(4))framework,to develop the acid-base cooperative catalyst for nucleophilic addition.Characterization results demonstrated a foam-like hierarchical porous structure,as well as the coexistence of Lewis acid and base sites in the as-synthesized samples.As a result,the B-doped g-C_(3)N_(4) acted as the efficient acidbase cooperative catalysts,significantly promoting the Knoevenagel condensation whose key step involves in nucleophilic addition.A wide range of α,β-unsaturated carbonyl compounds with remarkably high yields(>90%)was achieved even within 1 h in water,whereas the acid-free or base-free counterpart was far less efficient.In addition,the bifunctional catalysts exhibited excellent reusability with simple treatment.The novel B-doped g-C_(3)N_(4) catalytic system offers several advantages,such as operational simplicity,mild reaction conditions,high efficiency,and facile reuse of catalyst.All these advantages make it a benign protocol from the sustainability point of view,and inspired us to design the other bifunctional cooperative catalysts for a wide range of sustainable industrial applications.展开更多
Limited empirical investigation has been devoted to understanding the multipleeffect mechanisms of moral leadership, especially the relationship between mediators. Drawing from both social learning and social exchange...Limited empirical investigation has been devoted to understanding the multipleeffect mechanisms of moral leadership, especially the relationship between mediators. Drawing from both social learning and social exchange theories, this study examines whether value congruenee and leader-member exchange (LMX) mediate the effect of moral leadership on followers' positive work behaviors. Using two-wave survey data from 395 Chinese employees, the results indicate that both value congruence and LMX act as mediators in the relationship between moral leadership and positive work behaviors. Furthermore, a sequential mediation link from moral leadership to value congruenee, then to LMX, and finally to positive work behaviors was established. Theoretical and practical implications are further discussed.展开更多
基金The authors are grateful for the financial support provided by the National Natural Science foundation of China(21676078)the Scientific Research fund of Hunan Provincial Education Department(19A323)the Key Laboratory of the Assembly and Application of Organic functional Molecules of Hunan Province.
文摘Intramolecular acid-base cooperative catalysis is a powerful strategy to promote the nucleophilic additions in synthetic chemistry,since both substrates and nucleophiles can be activated simultaneously,yielding a lower energy reaction pathway.However,the systems often suffer from catalyst quenching due to the mutual neutralization of acid/base sites.Herein,we doped the boron(B)atoms in the tri-s-triazine ring of graphite-like carbon nitride(g-C_(3)N_(4))framework,to develop the acid-base cooperative catalyst for nucleophilic addition.Characterization results demonstrated a foam-like hierarchical porous structure,as well as the coexistence of Lewis acid and base sites in the as-synthesized samples.As a result,the B-doped g-C_(3)N_(4) acted as the efficient acidbase cooperative catalysts,significantly promoting the Knoevenagel condensation whose key step involves in nucleophilic addition.A wide range of α,β-unsaturated carbonyl compounds with remarkably high yields(>90%)was achieved even within 1 h in water,whereas the acid-free or base-free counterpart was far less efficient.In addition,the bifunctional catalysts exhibited excellent reusability with simple treatment.The novel B-doped g-C_(3)N_(4) catalytic system offers several advantages,such as operational simplicity,mild reaction conditions,high efficiency,and facile reuse of catalyst.All these advantages make it a benign protocol from the sustainability point of view,and inspired us to design the other bifunctional cooperative catalysts for a wide range of sustainable industrial applications.
基金financial support provided by Natural Science Foundation of China (Grant Nos71772171 and 71372159)the project of "985" in China.
文摘Limited empirical investigation has been devoted to understanding the multipleeffect mechanisms of moral leadership, especially the relationship between mediators. Drawing from both social learning and social exchange theories, this study examines whether value congruenee and leader-member exchange (LMX) mediate the effect of moral leadership on followers' positive work behaviors. Using two-wave survey data from 395 Chinese employees, the results indicate that both value congruence and LMX act as mediators in the relationship between moral leadership and positive work behaviors. Furthermore, a sequential mediation link from moral leadership to value congruenee, then to LMX, and finally to positive work behaviors was established. Theoretical and practical implications are further discussed.
