Enantioseparations of chiral ruthenium(II) polypyridyl complexes using HPLC with macrocyclic glycopeptide chiral stationary phases (CSPs)

Abstract

A high performance liquid chromatographic method using macrocyclic glycopeptide chiral stationary phases (CSPs) was used to separate enantiomers of seven ruthenium(II) polypyridyl complexes. Among the five different CSPs, the Chirobiotic T2 was most effective and baseline separated all complexes. All complexes show the same elution order with the Δ-enantiomer being retained longer than the Λ-enantiomer. The mobile phase composition, including organic modifier type, organic modifier percent, salt type, and salt concentration, produced significant effects on the enantioresolution.

Enantiomeric Separations of Ruthenium (II) Polypyridyl Complexes Using HPLC With Cyclofructan Chiral Stationary Phases

“…21,22 Ammonium nitrate, tetramethylammonium nitrate, ammonium trifluroacetate, and tetramethylammonium acetate were tested as additives in a 70/30 methanol/acetonitrile mobile phase. Note that these ammonium and tetraalkylammonium additives can only be tested in their equimolar salt form due to the nonaqueous mobile phases being used.…”

“…Note that these ammonium and tetraalkylammonium additives can only be tested in their equimolar salt form due to the nonaqueous mobile phases being used. 21,22 However, for the CF-based CSPs used here, AA/TEA additives are most useful, so the tetramethylammonium nitrate was only used as a secondary option. 21,22 Ammonium nitrate, tetramethylammonium nitrate, ammonium trifluroacetate, and tetramethylammonium acetate were tested as additives in a 70/30 methanol/acetonitrile mobile phase.…”

“…[16][17][18][19][20][21][22] Capillary electrophoresis is not suitable for preparative-scale separations and, as such, highperformance liquid chromatography (HPLC) with chiral stationary phases (CSPs) has proven to be the best way to separate enantiomers of organometallic compounds due to the technique's broad selectivity, high efficiency, and ability to transition to preparative-scales. [16][17][18][19][20][21][22] Capillary electrophoresis is not suitable for preparative-scale separations and, as such, highperformance liquid chromatography (HPLC) with chiral stationary phases (CSPs) has proven to be the best way to separate enantiomers of organometallic compounds due to the technique's broad selectivity, high efficiency, and ability to transition to preparative-scales.…”

“…The separation of geometric isomers, diastereomers, and enantiomers of ruthenium complexes have been achieved by chromatographic methods and capillary electrophoresis using chiral selectors. [16][17][18][19][20][21][22] Capillary electrophoresis is not suitable for preparative-scale separations and, as such, highperformance liquid chromatography (HPLC) with chiral stationary phases (CSPs) has proven to be the best way to separate enantiomers of organometallic compounds due to the technique's broad selectivity, high efficiency, and ability to transition to preparative-scales. For example, the enantiomeric separation of ruthenium polypyridyl complexes has been obtained with macrocyclic glycopeptide CSPs and cyclodextrin (CD) CSPs.…”

Chiral Recognition Mechanism: Practical Considerations for Pharmaceutical Analysis of Chiral Compounds

“…In particular, CSPs based on derivatized polysaccharides, native and derivatized cyclodextrins, macrocyclic glycopeptides, and Pirkle-type chiral selectors operate quite well in four separation modes, i.e., RP, polar organic phase, NP, and super-or subcritical fluid chromatography (SFC) conditions. It is common that a chiral compound can be separated on the same CSP in more than one separation mode [58,160,166,[170][171][172][173][174][175][176]. For example, Nutlin-3, a small molecule antagonist of MDM2, has been baseline resolved from its enantiomer in all four mobile-phase conditions (Fig.…”