Dynamic HPLC of stereolabile iron(II) complexes on chiral stationary phases

Abstract

A series of chiral tris-(1,10)-phenanthroline iron(II) complexes have been resolved by HPLC on chiral stationary phases based on either cellulose tris-(3,5-dimethylphenylcarbamate) or teicoplanin. At sub ambient temperatures, baseline separation of the enantiomers was observed for five different iron(II) complexes featuring substituted phenanthroline ligands. Dynamic HPLC profiles were observed near or above room temperature, indicating on-column Delta/Lambda enantiomerization. Rate constants for the Delta/Lambda interconversion in free solution and during chromatography were obtained by thermal racemization experiments and by computer simulation of the HPLC dynamic plots, respectively.

Determination of the Enantiomerization Barrier of the Residual Enantiomers of C3‐Symmetric Tris[3‐(1‐Methyl‐2‐Alkyl)Indolyl]Phosphane Oxides: Case Study of a Multitasking HPLC Investigation Based on an Immobilized Polysaccharide Stationary Phase

“…Simulations of experimental dynamic chromatograms were performed using the Auto‐DHPLC‐y2k lab‐made computer program, which implements both stochastic and theoretical plate models and can take into account all types of first‐order interconversion as well as tailing effects. In the present study, simulations of dynamic chromatograms of phosphanes 1 , 2 , 3 were carried out with a stochastic model.…”

Dynamic Behavior of Clobazam on High‐Performance Liquid Chromatography Chiral Stationary Phases

“…The accuracy of the dynamic HPLC method combined with computer simulation and comparison with other methods are described in detail in Refs. [30][31][32][33][34][35][36][37][38][39]. Closer inspection of the dynamic HPLC data reveals the presence of a small but sizeable retarding effect of the CSP on the on-column interconversion.…”

“…However, the much larger enantioselectivity observed on CSP2 results in a retarded elution of the most retained enantiomer, and this in turn has the effect of shifting the coalescence temperature to higher values: at T col = 40°C a broad peak with a bump in the front side is observed, and the complete coalescence requires further heating up to 60°C. Simulation of the dynamic HPLC plots [33][34][35][36][37][38][39] featuring a sizeable plateau gave the apparent rate constants for the on-column forward (k 12 rate constant for the conversion of the first into the second eluted enantiomer) and backward (k 21 ) enantiomerization processes ( Figs. 5 and 6).…”

Investigation of the enantiomerization barriers of the phthalimidone derivatives EM12 and lenalidomide by dynamic electrokinetic chromatography

“…In recent years, enantioselective dynamic chromatographic and electrophoretic techniques in combination with fast and efficient evaluation tools have proven to be highly precise in the determination of enantiomerization barriers of chiral drugs with enantiomerization barriers greater than 75 kJ/mol . The advantage of these techniques is that only minute amounts of the racemic sample are required and can be applied in combination with any separation technique that yields a separation of the desired enantiomeric species as dynamic HPLC (DHPLC) , dynamic GC (DGC) , and dynamic CE (DCE) . Separation of interconverting species yields characteristic elution profiles, characterized by plateau formation between the two interconverting species .…”