Initiator Control of Conjugated Polymer Topology in Ring-Opening Alkyne Metathesis Polymerization.
Molybdenum carbyne complexes [RC≡Mo(OC(CH3)(CF3)2)3] featuring a mesityl (R = Mes) or an ethyl (R = Et) substituent initiate the living ring-opening alkyne metathesis polymerization of the strained cyclic alkyne, 5,6,11,12-tetradehydrobenzo[a,e][8]annulene, to yield fully conjugated poly(o-phenylene ethynylene). The difference in the steric demand of the polymer end-group (Mes vs Et) transferred during the initiation step determines the topology of the resulting polymer chain. While [MesC≡Mo(OC(CH3)(CF3)2)3] exclusively yields linear poly(o-phenylene ethynylene), polymerization initiated by [EtC≡Mo(OC(CH3)(CF3)2)3] results in cyclic polymers ranging in size from n = 5 to 20 monomer units. Kinetic studies reveal that the propagating species emerging from [EtC≡Mo(OC(CH3)(CF3)2)3] undergoes a highly selective intramolecular backbiting into the butynyl end-group.
Department of Chemistry, University of California , Berkeley, California 94720, United States.
Stephen
S
von Kugelgen
Department of Chemistry, University of California , Berkeley, California 94720, United States.
Donatela E
DE
Bellone
Department of Chemistry, University of California , Berkeley, California 94720, United States.
Ryan R
RR
Cloke
Department of Chemistry, University of California , Berkeley, California 94720, United States.
Wade S
WS
Perkins
Department of Chemistry, University of California , Berkeley, California 94720, United States.|Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Kavli Energy Nanosciences Institute at the University of California Berkeley and Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Felix R
FR
Fischer
D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry*; D002384:Catalysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D008970:Molecular Weight; D008982:Molybdenum / Q000737:chemistry; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D014961:X-Ray Diffraction
D000480:Alkynes; D011108:Polymers; C508010:o-phenylene ethynylene; D008982:Molybdenum