Monoliths with chiral surface functionalization for enantioselective capillary electrochromatography

The state-of-the-art in CEC enantiomer separations with monolithic capillary columns is comprehensively reviewed. The various types of monolithic columns comprising in situ organic polymer monoliths, molecularly imprinted polymer (MIP) monoliths, silica monoliths and monoliths made from particles are discussed with a focus on materials’ synthesis, chemistry and properties as well as column aspects. Monolithic MIP-type porous layer open-tubular (PLOT) columns are treated herein as well. From this survey of the literature, the authors come to the conclusion that monolithic silica capillaries appear to become the preferred column type for CEC enantiomer separations of low-molecular drugs and other chiral pharmaceuticals or chemicals.     

Nonaqueous and Aqueous Emulsion ROMP Reactions Induced by Environment‐Friendly Latent Ruthenium Indenylidene Catalyst Bearing Morpholine Substituted Bidentate (N,O) Schiff Bases

In this study, a novel latent ruthenium indenylidene catalyst, bearing morpholine substituted bidentate (N, O) Schiff base is used in nonaqueous emulsion ring‐opening metathesis polymerization (ROMP) reactions for the first time. This novel catalyst has unique features such as latency and high silica gel affinity. The performance of the catalyst is tested on ring‐closing metathesis (RCM), ROMP reactions, and aqueous emulsion ROMP reactions. In addition, nonaqueous (using immiscible binary organic solvents: n‐hexane and dimethylformamide) emulsion ROMP reactions are carried out for the first time using latent ruthenium catalysts. The latency of the catalyst allows us to control the molecular weight of emulsion ROMP polymers by varying HCl/Ru ratio, keeping the nanoparticle sizes stable between 26 and 75 nm in aqueous emulsion and 51 and 208 nm in nonaqueous emulsion ROMP reactions. In addition, high silica gel affinity of the catalyst allows us to synthesize pure RCM products with ruthenium contamination less than 1 ppm.

     

Conductive Polymer Electrolytes Derived from Poly(norbornene)s with Pendant Ionic Imidazolium Moieties

Poly(norbornene)s with pendant imidazolium moieties and three different counter anions, i.e. poly[exo,endo‐5‐norbornene‐2‐yl‐carboxyethyl‐3‐ethylimidazolium bis(trifluoromethyl‐sulfonyl)imide], poly(exo,endo‐5‐norbornene‐2‐yl‐carboxyethyl‐3‐ethylimidazolium tetrafluoroborate), and poly(exo,endo‐5‐norbornene‐2‐yl‐carboxyethyl‐3‐ethylimidazolium hexafluorophosphate) were prepared via ROMP using ionic liquids as the reaction medium. The ionic polymers possessed in the range 8.1–44 × 10³ and ionic conductivity up to 1.13 × 10⁻⁵ and 1.44 × 10⁻⁴ S · cm⁻¹ at 20 and 50 °C, respectively. The solubility of the new polymeric ionic liquids, their thermal stability and their glass transition temperatures were investigated in detail. Ionic conductivities were found to depend on the nature of the counter‐anion and on the polymers' glass transition temperature rather than its molecular weight.

     

Synthesis and Self‐Assembly of Functionalized Cyclooctene Block Copolymers via ROMP

A novel block copolymer consisted of MACIT and HCO segments was synthesized via ROMP in the ionic liquid [bmim][PF₆] with good control over the polymerization process. The molecular weight of the block copolymer was estimated by ¹H NMR, and the molar composition ratio of repeating units in the MACIT block to those in the HCO block was 100:120 (120:120 in feed). The micellar characterization was carried out by DLS, AFM, and TEM. The hydrodynamic diameter of the micelles, measured by DLS, was 129 ± 0.09 nm with a narrow distribution (PDI = 0.034). The TEM image showed spherical micelles.

     

Fluorescent ROMP Monomers and Copolymers for Biomedical Applications

The synthesis and characterization of a series of green‐, blue‐, and red‐fluorescent exo‐oxanorbornene acid and imide monomers carrying nitrobenzofurazan, coumarin, and rhodamin B, respectively, as fluorophores are presented. These monomers carry oxanorbornene as polymerizable unit, and are readily copolymerized with bioactive functional oxanorbornene monomers by ring‐opening metathesis polymerization, as demonstrated by gel permeation chromatography and NMR spectroscopy. Due to the ease of synthesis of these monomers, and their cost‐effectiveness compared many to other fluorescent probes, they are useful for biomaterial applications.     

Heritability analysis of IgG4 antibodies in autoimmune thyroid disease

Abstract

A study of IgG4 autoantibody levels in juvenile thyroid disease patients showed evidence of heritability using the ROMP screening method. These levels increased with time despite the fact that total IgG antibody decreased with time. Evidence of heritability was demonstrated only in patients with high titers of autoantibodies to both thyroglobulin (Tg) and thyroperoxidase (TPO) unlike family members who may show high titers of one or the other and be asymptomatic at the time of sampling. Since high and low IgG4 levels give different heritability plots, these findings may represent a more severe fibrotic form of thyroiditis with a distinct genetic background. Hence a simple predictive approach is offered by this screening tool for the disease in patients and family members which may be helpful in the future to identify IgG4-related thyroiditis early in the course of disease without the requirement for biopsy.     

Synthesis and self‐assembly of polymers containing dicarboximide groups by living ring‐opening metathesis polymerization

Polymers with narrow molecular weight distributions and controlled architectures were generated by living ring‐opening metathesis polymerization of exo‐7‐oxabicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboximide. The dicarboximide units have been previously shown to exhibit biological activity, can selectively bind to the nucleic acid base adenine by hydrogen‐bonding, and are readily functionalizable. Block copolymers containing these moieties were generated, and underwent self‐assembly into nanoscale spherical aggregates, with surface localized molecular recognition motifs.

     

Poly(ethylene)‐co‐Poly(norborn‐2‐ene) Prepared by Group IV Bisamido and Half‐Sandwich Amido Complexes with Pendant Aminoborane Groups: Vinyl Insertion vs Ring‐Opening Metathesis Polymerization

A series of Zr^IV and Ti^IV complexes containing the 6‐(2‐(diethylboryl)phenyl)pyridyl‐2‐yl motif are used in the methylalumoxane‐triggered copolymerization of ethylene (E) with norborn‐2‐ene (NBE). ¹³C NMR analyses reveal that vinyl insertion polymerization (VIP)‐derived poly(E)‐co‐poly(NBE) is obtained with pre‐catalysts 1–4 and 6 , while pre‐catalyst 5 allows for the synthesis of a copolymer that contains both VIP‐ and ring‐opening metathesis polymerization (ROMP)‐derived structures. All the VIP‐derived poly(E)‐co‐poly(NBE) sequences show predominantly isolated NBE/alternating‐syndiotactic E‐NBE, as well as alternating‐isotactic E‐NBE sequences. The microstructure of the copolymers is correlated with the propensity of the pre‐catalysts to allow tandem ROMP‐VIP.

     

Synthesis of Comb‐Like Macromolecules via Semi‐Batch Miniemulsion RAFT Polymerizations

Construction of macromolecule topology and control of chain sequence are foundations to endow macromolecules with complex functionalities. Comb‐like macromolecules have more designable freedom because their backbones and branched chains can be independently designed and synthesized. Herein, the rigid backbones of comb‐like macromolecules are synthesized by ring‐opening metathesis polymerizations of norbornene derivatives anchoring reversible addition–fragmentation chain transfer (RAFT) agent. The gradient branched chains with controlled sequence structure are synthesized through a modified RAFT miniemulsion polymerization of 4‐vinylpyridine and t‐butyl acrylate in a semi‐batch manner. These comb‐like macromolecules self‐assemble into aggregates when a dilute solution of comb‐like macromolecules are brushed onto a silicon wafer. The self‐assembly behavior of comb‐like macromolecules is affected by grafting ratio and sequence structure of branched chains. The effect of these comb‐like macromolecules on water contact angle of silicon wafer is also studied.     

Combining ATRP and ROMP with Thio‐Bromo,Copper‐Catalyzed,and Strain‐Promoted Click Reactions for Brush Copolymer Synthesis Starting from a Single Initiator/Monomer/Click Partner

The preparation of functionalized graft copolymers utilizing a combination of ATRP, ROMP, thio‐bromo, and Huisgen‐type click chemistries is described. The construction of these polymeric architectures hinges on the use of a norbornene‐based α‐bromo ester that can act as an ATRP initiator and ROMP monomer (a so‐called inimer), as well as a thio‐bromo click partner. This allows for the use of a “grafting‐through” ROMP approach of ATRP‐based macromonomers that can undergo a post‐polymerization thio‐bromo click modification. Additionally, this material can undergo further modifications using archetypal copper‐catalyzed azide/alkyne click reaction as well as metal‐free strain‐promoted azide/alkyne click reactions.