Air-stable di-nuclear yttrium complexes as versatile catalysts for lactide polymerization and copolymerization of epoxides with carbon dioxide or phthalic anhydride. (22nd March 2019)

• Record Type: Journal Article
• Authors: Su, Yu-Chia; Liu, Wan-Ling; Li, Chen-Yu; Ko, Bao-Tsan
• Is Part Of: Polymer. Volume 167(2019)
• Page Start: 21
• Page End: 30
• Publication Date: 2019-03-22
• Subjects: Versatile catalyst -- Di-nuclear yttrium complex -- CO2-Based polycarbonate; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2019.01.060
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Four novel di-nuclear yttrium catalysts coordinated by bis(benzotriazole iminophenolate) (BiIBTP) ligands have been synthesized and structurally characterized. The one-pot procedure of BiIBTP pro-ligand with [Y(NO3 )3 . 6H2 O] (1.0 equiv.) and 2-nitrophenol derivative (1.0 equiv.) in the presence of triethylamine (5.0 equiv.) under refluxing MeOH solution gave bimetallic yttrium nitrophenolate complexes1 –4, [(μ-BiIBTP)Y(L)]2 (BiIBTP = C13C BiIBTP or C83C BiIBTP; L = 2-nitrophenolate or 2, 4-dinitrophenolate) with good to high yields. The solid-state structure of1 and3 –4 exhibits a di-yttrium(III) di-nitrophenolate species with the pentadentate BiIBTP ligand chelating two metal atoms. Versatile catalysis towards ring-opening polymerization of cyclic ester and copolymerization of internal epoxides with carbon dioxide (CO2 ) or phthalic anhydride (PA) catalyzed by these di-yttrium nitrophenolate complexes was systematically studied. Experimental results revealed that air-stable complexes3 and4 were shown to effectively catalyze not only lactide polymerization but also copolymerization of cyclohexene oxide (CHO) with CO2 or PA. Among these compounds, di-Y complex4 was the most active catalyst for the ring-opening polymerization ofl -lactide in combination with 9-anthracenemethanol, providing poly(l -lactide)s having the expected molecular weight and narrow molecular weight distribution. Furthermore, catalyst3 was capable of copolymerizing CO2 and CHO in the presence of co-catalysts under mild conditions, producing perfectly alternating poly(cyclohexene carbonate)s with the controllable character. In addition, the molecular weight controllable poly(PA- co -CHO)s with high ester linkage contents could be afforded on copolymerizing PA and CHO utilizing di-yttrium complex3 as the catalyst. This work provides the facilely synthesized di-nuclear yttrium complexes as versatile catalysts for three different types of polymerization catalysis. Graphical abstract: Structurally well-defined di-nuclear yttrium di-nitrophenolate catalysts coordinated by bis(benzotriazole iminophenolate) (BiIBTP) ligands were synthesized through one-pot procedure for versatile polymerization catalysis. Air-stable di-yttrium complex3 was demonstrated to effectively catalyze not only lactide polymerization but also alternating copolymerization of cyclohexene oxide with CO2 or phthalic anhydride, producing biodegradable polyesters and polycarbonates, respectively.Image 1 Highlights: Well-defined dinuclear Y catalysts bearing BiIBTP ligands were facilely synthesized. Versatile catalysis for three different types of polymerizations was studied. NP-ligated di-Y4 was able to catalyze ROP of lactide in a controlled fashion. DNP-modified di-Y3 could efficiently catalyze CO2 -copolymerization of CHO or VCHO. 3 is an effective catalyst for CHO/PA copolymerization with a controllable manner.