Chiral Recognition Properties Research Articles

New macromolecular ionophore: enantioselective membrane transport of racemic amino acid by [formula omitted

The chiral recognition property of poly[(1 → 6)-2,5- anhydro-3,4- di-O- methyl- d-glucitol ] ( 2b) towards racemic RCH(CO 2CH 3)NH + 3·X − (3·HX) has been studied using a transport system involving an aqueous source and receiving phases separated by a chloroform phase containing 2b. For HPF 6, HClO 4 and HCl salts of 3a (R = Ph), the amount of 3a transported into the receiving phase decreased in the order of PF − 6 > ClO − 4 > Cl −, but the optical purities changed only slightly from 9.3 to 10.9%. The transport rates for aromatic guests, 3a and 3b (R = CH 2Ph, were faster than those for aliphatic ones, 3c (R = CH(CH 3) 2) and 3d (CH 2CH(CH 3) 2), using PF − 6 as the counterion. The optical purity was 10.9% for 3a as a maximum value and decreased in the order of 3a > 3c > 3b and 3d. The formationof a complex between 2b and 3a·HX was confirmed by 1H and 13C n.m.r. spectral measurements.

Chiral separation of β-blockers by high-performance capillary electrophoresis based on non-immobilized cellulase as enantioselective protein

Optical isomers of some basic parmaceutical drugs (β-blockers) were separated by means of high-performance capillary electrophoresis in a carrier-free solution, using the chiral recognition properties of a cellulase (cellobiohydrolase I). High resolution of the isomers and peaks with satisfactory symmetry were obtained only when the enzyme was dissolved at a high concentration (40 mg/ml; total 10 μg) in a buffer of high ionic strength (0.4 M sodium phosphate) supplemented with 2-propanol. Surprisingly, the isomer selectivity was lost when the electrophoresis was carried out in the buffers used for chromatographic separation of the isomers on a bed derivatized with cellulase. At pH 5.1 (the experimental pH), the enantiomers are positively charged and the enzyme is negatively charged. With the cathode at the detection end of the capillary the enzyme accordingly migrated away from the detection point and the enantiomers toward it. Disturbances in the UV detection of the enantiomers otherwise caused by the presence of the enzyme were thus avoided. As the runs are performed in the absence of a supporting medium the analyses can be automated easily, which also facilitates the screening of different proteins for their chiral recognition properties and studies to establish the optimum experimental conditions.

Investigation of enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an ovomucoid-bonded column

The enantioselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl, -propionyl, -butyryl and -valeryl) on an ovomucoid (OVM)-bonded silica column were investigated with respect to eluent pH (from 3 to 7) and organic modifier (2-propanol, ethanol, methanol and acetonitrile). The enantioselectivity was dependent on the eluent pH and organic modifier used. Reversal of the enantiomeric elution order of racemic PP and its ester derivatives occurred around eluent pH 5–7 and/or by variation of the organic modifier used. The results reveal that chiral recognition or binding properties may be altered by a change in eluent pH and/or addition of orgnaic solvents. Reversal of the enantiomeric elution order suggests that there may be more than one binding site on the OVM-bonded column, and/or that at least two chiral recognition mechanisms may operate on the OVM-bonded column with regard to PP and its ester derivatives. Also, a conformational change of the OVM bonded structure might be caused by a change in eluent pH and/or addition of organic modifier.

Retention, enantioselectivity and enantiomeric elution order of propranolol and its ester derivatives on an alpha1-acid glycoprotein-bonded column

The retention, enantionselectivity and enantiomeric elution order of racemic propranolol (PP) and its ester derivatives (O-acetyl,-propionyl,-butyrul and-valeryl PP) on an α1-acid glycoprotein (AGP)-bonded column have been investigated by changing eluent composition (eluent pH, buffer concentration, type and content of organic modifier). The retention of these cationic solutes, PP and its ester derivatives, was influenced by eluent pH, ionic strength and organic modifier content. The enantioselectivity was dependent on eluent pH and type of organic modifier. Reversal of the enantiomeric elution order of ester derivatives of PP (O-propionyl-butyryl) and-valeryl PP) occurred around eluent pH 6–7. These results suggst that chiral recognition or binding properties may be altered by the change in eluent composition, espeically eluent pH and type of organic modifier.

Synthesis and enantioselective coloration of optically active azophenolic acerands incorporating two 1,1′-binaphthyl moieties as the chiral centre

Two chiral azophenolic acerands 2 and 3 with two 1,1′-binaphthyl moieties as the chiral centre have been prepared, and their chiral recognition properties based on enantiomeric amine-selective coloration have been examined; the host 3 shows a higher enantioselective coloration than the host 2 with a variety of primary amines.

Synthesis and chiral recognition of optically active crown ethers incorporating a helicene moiety as the chiral centre

The synthesis of optically active crown ethers (8), (14), and (18) incorporating helicene molecular frameworks is reported. Their chiral recognition properties have been examined and show that (M)-(–)-(14), although of the same helicity as (M)-(–)-(8) and (M)-(–)-(18), exhibits opposite chiral recognition for the transport of methyl phenylglycinate, 1-phenylethylamine, and 1,2-diphenylethylamine, and that the pentahelicene crown (8) has a higher enantiomer selectivity than the hexahelicene crown (14) and hexa[7]circulene crown (18) towards these substrates. At 6.0–6.2% transport using (8), the optical purity of methyl phenylglycinate and 1,2-diphenylethylamine was as high as 77–82%.

Characteristics of ovomucoid-conjugated columns in the direct liquid chromatographic resolution of racemic compounds

The chiral recognition properties of ovomucoid-conjugated columns were investigated. Trypsin slightly affected the chiral recognition characteristics of the column. Neuraminidase treatment of ovomucoid columns altered their acidic solute retention properties. Deglycosylated ovomucoid-conjugated columns dit not resolve racemic chlorpheniramine or ketoprofen. A sugra chain is essential for the exhibition of chiral recognition ability for ovomucoid.

Synthesis and Chiral Recognition of Optically Active Crown Ethers Incorporating a 9,9′-Biphenanthryl Moiety as the Chiral Center

Abstract Two chiral crown ethers incorporating a 9,9′-biphenanthryl moiety as the chiral center have been prepared, and their chiral recognition properties in transport of methyl (±)-phenylglycinate hydrochloride, (±)-1-phenylethylamine hydrochloride, and (±)-1,2-diphenylethylamine hydrochloride were examined.

Chromatographic Optical Resolution on Polysaccharides and Their Derivatives

Abstract Cellulose and other polysaccharides have been known to exhibit chiral recognition properties for along time. Microcrystalline cellulose triacetate, cellulose triacetate with a particular morphology, was found to have excellent chiral properties over ten years ago. Recently, a new kind of packing material, utilizing cellulose esters has been developed, to resulting in numerous examples of optical resolution. The history of utilizing polysaccharides for the purpose of optical resolution will be briefly described and the typical examples of successful optical resolutions will be summarized. Though the mechanism of chiral recognition by polysaccharide derivatives is not known, much interesting information was obtained, the participation of crystalline lattice, the morphology and the ability of chiral recognition, the nature of the adsorptive interaction, etc. will be discussed.

SYNTHESIS OF NOVEL CROWN ETHER INCORPORATING THE (−)-(5S,6R,13S,14R)-5,6,13,14-TETRAHYDRO-5,13-METHANOCYCLOOCTA[1,2-a:5,6-a′]DINAPHTHALENE-6,14-DIOL SUBUNIT AS THE C2-SYMMETRIC CHIRAL CENTER

Abstract (−)-5,6,13,14-Tetrahydro-5,13-methanocycloocta[1,2-a:5,6-a′]dinaphthalene-6,14-diol was synthesized and its absolute configuration was established. Optically active crown ether was prepared by using this glycol as a source of chirality and its chiral recognition property was examined.

ChemInform Abstract: SYNTHESIS OF CHIRAL CROWN ETHERS DERIVED FROM TRANS,TRANS‐ AND CIS,TRANS‐2,2′‐SPIROBIINDAN‐1,1′‐DIOLS. THEIR CHIRAL RECOGNITION AND COMPLEXATION PROPERTIES

AbstractDurch Umsetzung der chiralen Spirobiindan‐Derivate (I) mit den entsprechenden (V) werden die Kronenether (VI) und der offenkettige Polyether (VII) dargestellt [Bestimmung der absoluten Rotation von (Ia) durch Synthese des optisch reinen Diols über den Ester (III) (Ausb‐Angabe in g) und Oxidation zum Diketon (II), dessen optische Drehung aus der Literatur bekannt ist].

Synthesis of Chiral Crown Ethers Derived from trans, trans- and cis, trans-2,2′-Spirobiindan-1,1′-diols. Their Chiral Recognition and Complexation Properties

Abstract trans,trans-2,2′-Spirobiindan-1,1′-diol (1) was resolved as its (−)-ω-camphanic ester and the absolute rotation of the glycol 1 was determined. Two crown ethers and the acyclic analog were derived from (+)-1. Two crown ethers incorporating (+)-cis,trans-2,2′-spirobiindan-1,1′-diol were also prepared. Their chiral recognition properties in transport of methyl (±)-phenylglycinate hydrochloride and abilities to extract alkali metal picrates were investigated.

Synthesis and chiral recognition of optically active crown ethers incorporating a 4,4′-biphenanthryl; moiety as the chiral centre

Two chiral crown ethers (+)-(S)-(4) and (–)-(R,R)-(5) with a 4,4′-biphenanthryl moiety as the chiral centre have been prepared, and their chiral recognition properties were examined to show that (+)-(S)-(4) has a high enantiomer selectivity for 2-aminotetralin and 1,2-diphenylethylamine.

Chiral recognition properties of chiral 18-crown-6 ethers with aromatic substituents

Chiral recognition properties of chiral 18-crown-6 ethers with aromatic substituents

Synthesis and chiral recognition of novel crown ethers incorporating helicene chiral centres

Two novel optically active crown ethers (7) and (14) incorporating helicene molecular frameworks were prepared, and their chiral recognition properties were examined to show that (M)-(–)-(7) and (M)-(–)-(14) had opposite chiral recognition for the transport of methyl phenylglycinate or 1-phenylethylamine.