Rare-earth And Zinc Complexes Supported By Bis (Amino-Oxazoline) Ligands: Synthesis And Their Catalytic Performance

In this thesis,the bis(amio-oxazoline)-ligated rare-earth and zinc complexes were synthesized successfully.Their structures were characterized by IR,NMR and X-ray diffraction.The reaction with several small molecule compounds,ring-opening polymerization(ROP)of rac-lactide(rac-LA),coordination-addition polymerization of methacrylates and photo-induced reversible addition-fragmentation chain transfer polymerization(RAFT)could be achieved by using these complexes.The details are as followings:(1)Bis(amio-oxazoline)-ligated rare-earth complexes 1–5 were designed and synthesized.The structures of the complexes were verified by ¹H,¹³C NMR and X-ray diffraction.The geometric structures of 1 and 4 are triangular bipyramid,and the geometric structures of 2 and3 are octahedral.Upon excitation at 365 nm,complexes 1–4 displayed green fluorescence with Stokes shifts of about 175 nm.The complex 1 could generate complex 6 via addition reaction at high temperature,and the complexes 2 and 3 could generate binuclear complexes 7and 8 via ring-opening reactions at high temperature.Complex 1 could react with several small molecule compounds,such as aniline,[NHEt3]⁺[BPh4]^-,selenium and sulfur,indicating its good reactivity.(2)The ROP of rac-LA could be initiated by rare-earth complexes 1–5.In comparison to the Sc complexes with low activity,the good activity in ROP of rac-LA were observed by using Y and Lu complexes with TOF up to 792 h^-1.The resultant PLAs are heterotactic.The ROP of?-caprolactone could also be achieved by complexes 2 and 3 with lower activity comparing with ROP of rac-LA.In addition,the coordination-addition polymerization of methacrylates could also be initiated by rare-earth complexes.The polymerization was with living mode,and the diblock copolymer PMMA-b-PAMA could be produced by this system.The allyl groups in the copolymer remained,which could be functionalized.(3)Bis(amio-oxazoline)-ligated zinc complexes 13–15 were successfully synthesized.The structures of the complexes were verified by ¹H,¹³C NMR and X-ray diffraction.The geometric structures of the Zn complexes are tetrahedral.The Zn complexes showed good fluorescence properties.Upon excitation at 380 nm,the complexes displayed strong green fluorescence with emission maxima of 489-493 nm.The lifetime of fluorescence were observed at 7.84-9.29 ns,and the fluorescence quantum yields were up to 47.6%,showing their good fluorescence properties.Moreover,photo-induced reversible addition-fragmentation chain transfer polymerization(RAFT)could be achieved by the Zn complexes initiated by visible light.