Betina Mayr

Monolithic Materials: New High‐Performance Supports for Permanently Immobilized Metathesis Catalysts

Polymerchemistry and materials sciences have seen the introductionof new trends by metathesis-based techniques, such as ring-opening metathesis polymerization (ROMP) or acyclic dienepolymerization (ADMET). Complementary, cross-metathesisand ring-closing metathesis find ample application in organicchemistry.

Influences of surface chemistry on the separation behavior of stationary phases for reversed-phase and ion-exchange chromatography: a comparison of coated and grafted supports prepared by ring-opening metathesis polymerization

A series of poly(norborn-2-ene) (poly-NBE), poly(7-oxanorborne-2-ene-5,6-dicarboxylic acid) (poly-ONDCA), as well as poly(norborn-2-ene-co-7-oxanorborne-2-ene-5,6-dicarboxylic acid) (poly-NBE-co-ONDCA) based silica supports were prepared via ring-opening metathesis polymerization (ROMP) using both coating and grafting techniques. Poly-NBE-grafted and poly-NBE-coated supports were used for the reversed-phase separation of phenols; poly-NBE, poly-ONDCA as well as poly-NBE-co-ONDCA-grafted supports were used for comparative studies on the separation of a series of anilines and lutidines. As expected, grafted supports possess superior separation capabilities compared to their coated analogues. Compared to pure poly-NBE- and poly-ONDCA-grafted stationary phases, supports consisting of poly-NBE-co-ONDCA block-copolymers possess both hydrophobic and ion-exchange sites and represent optimum stationary phases for the separation of isomeric basic analytes.

Separation of planar chiral ferrocene derivatives on β-cyclodextrin-based polymer supports prepared via ring-opening metathesis graft-polymerization

A series of beta-cyclodextrin (beta-CD) based chiral stationary phases (CSPs) were synthesized by ring-opening metathesis graft polymerization of various norborn-2-ene (NBE) substituted CDs. Chiral selectors based on endo/exo-6-O-(norborn-2-ene-5-ylmethoxymethylsilyl)-beta-CD, tris(endo/exo-6-O-norborn-2-ene-5-ylmethoxymethylsilyl)-beta-CD, tetrakis(endolexo-6-0-norborn-2-ene-5-ylmethoxymethylsilyl)-beta-CD, hexakis(endo/exo-6-O-norborn-2-ene-5-ylmethoxymethylsilyl)-beta-CD and tetrakis(endo-6-O-norborn-2-ene-5-carboxyl)-beta-CD were grafted onto Nucleosil 300-5 using well-established grafting procedures. CSPs were investigated for their separation capabilities for a series of the planar chiral ferrocene derivatives, rac-ferroceno[2,3a]inden-1-one (1a, 1b), rac-6-(3-hydroxy-3-methylbut-1-yn-1-yl)ferroceno[2,3a]inden-1-one (2a, 2b), rac-ferrocene[2,3a]indene (3a, 3b), rac-endo 1-methoxy-1-allylferroceno[2,3a]indene (4a, 4b) and rac-1,4-dihydroxybutylferrocene (5a, 5b). Compounds la, lb and 2a, 2b bearing a carbonyl group were successfully separated on these CSPs, while compounds 3-5 do not undergo enantioselective interaction under the conditions applied. General aspects of separation as well as mechanistic implementations are discussed.

Novel well-defined heterogeneous metathesis catalysts

The synthesis of heterogeneous, N-heterocyclic carbene-based metathesis catalysts is described. Heterogenization based on various grafting approaches was performed on both monolithic and silicious supports. The general principles of heterogenization, the synthetic approach, selected applications as well as advantages and disadvantages of the resulting heterogeneous catalysts are discussed.