Novel photoactive transition metal catalysts for the UV-Light-Triggered Metathesis Polymerization of Functional Monomers

• Applicant: Professor Dr. Michael R. Buchmeiser
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2006 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 25106151

• Final Report Year: 2011

Final Report Abstract

The following accomplishments have been made: 1. The first UV-triggerable Ru-based precatalyst for ROMP, which is stable in the presence of cyclic olefins up to T=65°C in the absence of light, has been prepared. 2. The mechanism of activation has been elucidated using both quantum chemical calculations as well as laser flash photolysis. 3. The role of all ligands involved, i.e. the N-heterocyclic carbene, the tert.-butylnitrile as well as of the anionic ligand has been clearly identified. 4. Based on the above-mentioned accomplishments, an entire new family of UV- triggerable precatalyts for photo-ROMP has been created. All members of this family fulfill the stringent criteria defined for latency and selective UV-activation. 5. The novel precatalysts have successfully been used for the spatially resolved surface-functionalization of monolithic capillary devices. 6. So far, the new precatalysts cannot be used for the UV-triggered cyclopolymerization of 1,6-heptadiynes. 7. Ru(IV) precatalysts have been investigated in terms of their propensity to trigger ROMP, either via thermal or UV activation. Bis(methallyl)Ru(IV) systems are in fact latent UV-catalysts, however, these precatalysts cannot compete with the cationic Ru(II) systems in terms of latency. 8. An alternative system, containing a UV-switchable ligand i.e. a triazene attached to the alkylidene moiety has been prepared. Again these preformed Ru-alkylidenes cannot compete with the cationic Ru(II) systems in terms of latency.

Publications

• "Novel Initiators for Thermally and UV-Triggered ROMP". Macromol. Symp., 2006, 236, 30-37
  Y. Zhang, D. Wang, P. Lönnecke, T. Scherzer, M. R. Buchmeiser
  
• "Novel Ru (II) N- Heterocyclic Carbene Complexes as Catalyst Precursors for the Ring-Opening Metathesis Polymerization (ROMP) of Enantiomerically Pure Monomers: X-ray Structures, Reactivity and Quantum Chemical Considerations". Eur. J. Inorg. Chem., 2007, 3988-4000
  M. R. Buchmeiser, D. Wang, Y. Zhang, S. Naumov, K. Wurst
  
• "Cationic RuII-N-Heterocyclic Carbene Complexes for UV-Induced Ring-Opening Metathesis Polymerization". Angew. Chem., 2008, Vol. 120, 3311-3314; Angew. Chem. Int. Ed. 2008, 47, 3267-3270
  D. Wang, K. Wurst, W. Knolle, U. Decker, L. Prager, S. Naumov, M. R. Buchmeiser
  
• Int. Pat. Appl. “Latente photoaktivierbare Präkatalysatoren für die Metathesepolymerisation”. DE 102008008299, Institut für Textilchemie und Chemiefasern
  D. Wang, M. R. Buchmeiser
  
• "Cationic vs. Neutral RuII-N-Heterocyclic Carbene Complexes as Latent Precatalysts for the UV- Induced Ring-Opening Metathesis Polymerization". Chem. Eur. J., 2010, 16, 12928-12934
  D. Wang, K. Wurst, M. R. Buchmeiser
  
• "Latent Ruthenium(II)-Based Photocatalysts for Ring-Opening Metathesis Polymerization". Polym. Prepr. (Div. Polym. Chem., Am. Chem. Soc.), 2010, 51, 384-385
  D. Wang, U. Decker, C. Kühnel, M. R. Buchmeiser
  
• „UV- and Thermally Triggered Ring-Opening Metathesis Polymerization for the Spatially Resolved Functionalization of Polymeric Monolithic Devices“. J. Appl. Polym. Sci., 2011, 121, 2551- 2558
  C. Ernst, C. Elsner, A. Prager, B. Scheibitz, M. R. Buchmeiser