Ligands designed to provide highly active catalyst complexes
AssigneeCarnegie Mellon University
InventorsKrzysztof Matyjaszewski, Yungwan Kwak, Joanna Burdynska, Andrea Elsen, Kristin Schroeder
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Abstract
A series of ligands with site specific electron donating substituents that form a catalyst complex with a transition metal and are suitable for catalysis of atom transfer radical reactions, including ATRP are described. Faster catalysis rates were observed allowing for low catalyst concentrations and linear increases in molecular weight with monomer conversion, and narrow molecular weight distributions. Cyclic voltammetry revealed that increasing the strength and number of conjugated electron donating groups resulted in more stable complexes and larger ATRP equilibrium constants.
Claims32
A catalyst complex for a redox-based atom transfer radical addition reaction, an atom transfer radical coupling reaction or a controlled radical polymerization reaction, the catalyst comprising:
- a transition metal;
- and
- a ligand comprising from 2 to 6 heteroatom containing groups capable of bonding to or chelating with a transition metal, wherein at least one of the heteroatom containing groups comprises a structure selected from an aromatic ring comprising an anionic heteroatomic donor substituent or a nitrogen containing heteroaromatic ring, wherein the aromatic ring or heteroaromatic ring further comprises one or more electron donating substituents,
- wherein the ligand forms a ligand/metal catalyst complex with the transition metal.
A ligand for forming a transition metal catalyst capable of catalyzing a redox-based atom transfer radial addition reaction, an atom transfer radical coupling reaction, or a controlled radical polymerization reaction, the ligand comprising:
- 2 to 6 heteroatom containing groups capable of bonding to or chelating with a transition metal, wherein at least one of the heteroatom containing groups comprises a structure selected from an aromatic ring comprising an anionic heteroatomic donor substituent or a nitrogen containing heteroaromatic ring, wherein the aromatic ring or heteroaromatic ring further comprises one or more electron donating substituents,
- wherein the ligand has a structure:
- wherein each R′ is independently an electron donating substituent selected from straight chain (C1-C20)alkyl, branched (C1-C20)alkyl, —NR2, hydroxylamine, hydrazine, —N(R)C(═O)R, —NHC(═O)NR2, —OR, —OC(═O)R, —OC(═O)OR, —CH2CH(OR)CH3, —CH2NR2, —NHC(═O)OR, —OC(═O)NR2, —CH2Si(CH3)3, —OCH2CH2OR, or —NHCH2SO3R;
- where each R is independently selected from —H, straight chain (C1-C20)alkyl, or branched (C1-C20)alkyl;
- each R1 is independently selected from —H, straight chain (C1-C20)alkyl, or branched (C1-C20)alkyl;
- and
- k, m, n and p are each independently an integer from 0 to 3 provided that at least one of k, m, n, and p is not zero.
A system for conducting a controlled radical polymerization reaction comprising:
- radically (co)polymerizable monomers;
- an initiator comprising one or more radically transferable atoms or groups;
- less than 500 ppm of a catalyst complex comprising:
- a transition metal;
- and
- a ligand comprising 2 to 6 heteroatom containing groups capable of bonding to or chelating with a transition metal, wherein at least one of the heteroatom containing groups comprises a structure selected from an aromatic ring comprising an anionic heteroatomic donor substituent or a nitrogen containing heteroaromatic ring, wherein the aromatic ring or heteroaromatic ring further comprises one or more electron donating substituents;
- and
- optionally, a solvent.
A transition metal mediated controlled polymerization process comprising polymerizing radically (co)polymerizable monomer(s) in the presence of:
- an initiator comprising one or more radically transferable atoms or groups;
- less than 500 ppm of a catalyst complex comprising:
- a transition metal;
- and
- a ligand comprising 2 to 6 heteroatom containing groups capable of bonding to or chelating with a transition metal, wherein at least one of the heteroatom containing groups comprises a structure selected from an aromatic ring comprising an anionic heteroatomic donor substituent or a nitrogen containing heteroaromatic ring, wherein the aromatic ring or heteroaromatic ring further comprises one or more electron donating substituents;
- and
- optionally, a solvent.
Dependencies are inferred from the claim text.