title: Interactions of helquats with chiral acidic aromatic analytes investigated by partial-filling affinity capillary electrophoresis.
abstract: Noncovalent molecular interactions between helquats, a new class of dicationic helical extended diquats, and several chiral acidic aromatic drugs and catalysts have been investigated using partial-filling affinity capillary electrophoresis (PF-ACE). Helquats dissolved at 1mM concentration in the aqueous background electrolyte (40mM Tris, 20mM acetic acid, pH 8.1) were introduced as ligand zones of variable length (0-130mm) into the hydroxypropylcellulose coated fused silica capillary whereas 0.1mM solutions of negatively charged chiral drugs or catalysts (warfarin, ibuprofen, mandelic acid, etodolac, binaphthyl phosphate and 11 other acidic aromatic compounds) were applied as a short analyte zone at the injection capillary end. After application of electric field, analyte and ligand migrated against each other and in case of their interactions, migration time of the analyte was increasing with increasing length of the ligand zone. From the tested compounds, only isomers of those exhibiting helical chirality and/or possessing conjugated aromatic systems were enantioselectively separated through their differential interactions with helquats. Some compounds with conjugated aromatic groups interacted with helquats moderately strongly but non-enantiospecifically. Small compounds with single benzene ring exhibited no or very weak non-enantiospecific interactions. PF-ACE method allowed to determine binding constants of the analyte-helquat complexes from the changes of migration times of the analytes. Binding constants of the weakest complexes of the analytes with helquats were less than 50L/mol, whereas binding constants of the strongest complexes were in the range 1 000-1 400L/mol.
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic; Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic.
authors: Martin
authors: M
authors: Růžička
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic.
authors: Dušan
authors: D
authors: Koval
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic.
authors: Jan
authors: J
authors: Vávra
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic.
authors: Paul E
authors: PE
authors: Reyes-Gutiérrez
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic.
authors: Filip
authors: F
authors: Teplý
authors: Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám., 542/2, 166 10 Prague 6, Czech Republic. Electronic address: kasicka@uochb.cas.cz.
authors: Václav
authors: V
authors: Kašička
mesh_terms: D000465:Algorithms; D002482:Cellulose / Q000031:analogs & derivatives; D004396:Coloring Agents; D019075:Electrophoresis, Capillary / Q000379:methods*; D006841:Hydrocarbons, Aromatic / Q000032:analysis*; D007202:Indicators and Reagents; D008024:Ligands; D004364:Pharmaceutical Preparations / Q000032:analysis; D013237:Stereoisomerism
chemical_list: D004396:Coloring Agents; D006841:Hydrocarbons, Aromatic; D007202:Indicators and Reagents; D008024:Ligands; D004364:Pharmaceutical Preparations; D002482:Cellulose; C008079:hydroxypropylcellulose
keywords: Affinity capillary electrophoresis; Binding constant; Chiral separation; Helquats; Noncovalent interactions; Partial filling