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题目：Catalyst Designs for the Synthesis of Cyclic Polymers

报告人：Adam Veige, University of Florida Research FoundationProfessor

时间： 5月8日 (周三), 上午09:30

地点： 建工楼B410会议室

邀请人：李新昊 教授

报告摘要：

Employing atrianionic pincer ligand, we have discovered a highly active catalyst for thesynthesis of cyclic polymers from alkynes. Though initiated with a trianionicpincer ligand supported tungsten catalyst the active catalyst features atetraanionic pincer ligand. Details of the catalyst designs and a discussion ofthe polymerization mechanism and active catalyst elucidation will be provided.Access to these cyclic polymers enables the synthesis of commercially relevantpolyolefins. Annually produced at a rate of 170 million tons per year,polyolefin manufacturing has changed human quality of life and planet Earthforever. Isotactic polypropylene comprises 25% of all polyolefins manufacturedand is applied in countless products globally. Polypropylene and allindustrially produced polyolefins are linear molecules containing chain-ends.Exploiting ring expansion polymerization of alkynes, atactic cyclicpolypropylene can now be synthesized. Characterization and confirmation of acyclic topology comes from size exclusion chromatography, dynamic lightscattering, viscometry, and rheology. Importantly, the cyclic topology ofpolypropylene leads to dramatic differences in the physical properties of thepolymer including a > 20 °C increase in its glass transition temperature (T_g)compared to the linear version. Additional polyolefins such as the bulk scalesynthesis of cyclic poly-1-pentene, and the synthesis of a highly transparentcyclic version of the commodity polyolefin TPX^TM,poly(4-methylpentene), will be discussed. Another challenge is to preparestereoregular cyclic polymers. This seminar will discuss catalyst designs forthe ring opening polymerization of norbornene to give cis and syndiotacticenriched cyclic polynorbornene. Featured in the catalyst designs are theconcepts of an “Inorganic Enamine” and “Ynene Metathesis” and theirrelationship to accentuating the nucleophilicity of metal-carbon multiplebonds.

参考文献：

[1] Roland, C. D.; Li, H. Abboud, K. A.;Wagener, K. B.; Veige, A. S.* Cyclic polymers fromalkynes. Nature Chem.2016, 8, 791-796.

[2] Niu, W.; Chen, X.; Tan, W.; Veige,A. S.* N-Heterocyclic carbene gold(I) complexes conjugated to aleukemia specific DNA-aptamer for targeted drug delivery. Angew Chem, Int.Ed. 2016, 128, 9035-9039.

[3] Nadif, S. S.; Kubo, T.; Gonsales,Stella A.; VenkatRamani, S.; Ghiviriga, I.; Sumerlin, B. S.; Veige,A. S.Introducing “ynene” metathesis: ring-expansion metathesispolymerization (REMP) leads to highly cis and syndiotactic cyclic polymers of norbornene.J. Am. Chem. Soc. 2016, 138, 6408-6411.

[4] Nadif, S. S.; O’Reilly, M. E.;Ghiviriga, I.; Abboud, K. A.; Veige, A. S.* Remotemulti- proton storage within a pyrrolide pincer type ligand. Angew Chem, Int.Ed. 2015, 54, 15138.

[5] Gonsales, S. A.; Pascualini, M. E.;Ghiviriga, I.; Abboud, K. A.; Veige, A. S.* Fast“Wittig-like” reactions as a consequence of the inorganic enamine effect. J.Am. Chem. Soc. 2015, 137, 4840-4845.

报告人简介：

Adam Veige, University of Florida Research Foundation Professor. Adam Veige received a Hons. B.Sc. degreein Chemistry in 1997 from the University of Western Ontario, Canada. For aperiod of six months, Dr. Veige worked on the synthesis of chiral titaniumcatalysts for stereoselective polyolefin synthesis in the laboratories of Dr.David McConville at the University of British Columbia. Dr. Veige obtained hisPh.D. in 2003 at Cornell University while working with Dr. Peter T. Wolczanski.His Ph.D. research at Cornell focused on kinetic and mechanistic investigationsof O-atom transfer and a rare metal-olefin to metal-alkylidene isomerization.His postdoctoral work under the guidance of Dr. Daniel G. Nocera, at theMassachusetts Institute of Technology, focused on elucidating the mechanism ofphotocatalytic H₂ evolution from rhodium and iridiummixed-valent complexes. In 2004 he joined the Department of Chemistry at theUniversity of Florida as Assistant Professor in Inorganic Chemistry. Dr.Veige’s research focuses on the synthesis of highly active catalysts forcreating value-added products including the polymerization of olefins andalkynes. Another area of current interest is the synthesis of in-chainmetallopolymers using iClick technology invented by the Veige group. In 2010,Dr. Veige was named Director for the Center for Catalysis, and in 2011 waspromoted to Associate Professor with tenure, and in 2015 he was promoted toProfessor. In 2017 Dr. Veige was named a University of Florida ResearchFoundation Professor. Dr. Veige was awarded a Camille and Henry Dreyfus New FacultyAward, an Alfred P. Sloan Fellowship, an NSF Career award, the Dr. Paul TarrantFellowship, the University of Florida Undergraduate Student Mentor of the YearAward (2012), and the University of Florida Graduate Student Mentor of the YearAward (2019). Dr. Veige’s research is currently funded by the NSF, DOE-BES,ACS-PRF, ExxonMobil, and the University of Florida, Office of TechnologyLicensing.