Nuclear magnetic resonance studies for the chiral recognition of the novel chiral stationary phase derived from 18-crown-6 tetracarboxylic acid

Machida, Yoshio; Nishi, Hiroyuki; Nakamura, Kouji

doi:10.1016/s0021-9673(98)00207-6

Cited by 56 publications

(26 citation statements)

References 20 publications

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“…[7][8][9][10][11][12][13][14][15] The present results show that collaborative interaction between the deprotonated carboxyl group (À ÀCOO 2 ) of (1)-18C6H x and the protonated amino group (À ÀNH 3…”

Section: Guest-dependent Conformational Change Of (1)-18c6h Xmentioning

confidence: 85%

“…1] on silica gel. [7][8][9][10] In addition, (1)-18C6H 4 is also used as a chiral selector for amine compounds in capillary electrophoresis (CE) [11][12][13][14][15] or nuclear magnetic resonance (NMR). [16][17][18] To clarify the structural scaffold of (1)-18C6H 4 necessary for D/L-separation of racemic amino acids, we recently determined the crystal structures of (1)-18C6H 4 complexed with D-and L-isomers of tyrosine (Tyr), isoleucine (Ile), methionine (Met), phenylglycine (PheG), serine (Ser), and glutamic acid (Glu) by X-ray diffraction method, 19,20 and showed that all four carboxyl groups of (1)-18C6H 4 are deprotonatable and take the formula (1)-18C6H x , x 5 0-4, charge 5 24-0, depending on the interaction with the guest molecule.…”

Section: Introductionmentioning

confidence: 99%

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Guest‐dependent conformation of 18‐crown‐6 tetracarboxylic acid: Relation to chiral separation of racemic amino acids

Nagata¹,

Nishi²,

Kamigauchi

et al. 2008

Chirality

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(+)-18-crown-6 tetracarboxylic acid (18C6H(4)) has been used as a chiral selector for various amines and amino acids. To further clarify the structural scaffold of 18C6H(4) for chiral separation, single crystal X-ray analysis of its glycine(+) (1), H3O+ (2), H5O2+ (3), NH4+ (4), and 2CH3NH3+ (5) complexes was performed and the guest-dependent conformation of 18C6H(4) was investigated. The crown ether ring of 18C6H4 in 3, 4, and 5 took a symmetrical C2 or C2-like conformation, whereas that in 1 and 2 took an asymmetric C1 conformation, which is commonly observed in complexes with various optically active amino acids. The overall survey of the present and related complexes suggests that the molecular conformation of 18C6H4 is freely changeable within an allowable range, depending on the molecular shape and interaction mode with the cationic guest. On the basis of the present results, we propose the allowable conformational variation of 18C6H4 and a possible transition pathway from its primary conformation to the conformation suitable for chiral separation of racemic amines and amino acids.

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Section: Guest-dependent Conformational Change Of (1)-18c6h Xmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Guest‐dependent conformation of 18‐crown‐6 tetracarboxylic acid: Relation to chiral separation of racemic amino acids

Nagata¹,

Nishi²,

Kamigauchi

et al. 2008

Chirality

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“…A novel CSP derived from crown ether, which was prepared by immobilizing (ϩ)-18-crown-6 tetracarboxylic acid ((ϩ)-18C6H 4 ) on 3-aminopropylsilanized silica-gel, was reported by Machida et al 5) to show the effective enantiomer separation of amino compounds, and has been widely used as a chiral selector for the primary amines in capillary electrophoresis (CE) 6-9) and HPLC. [10][11][12] As for the enantiomer separation of D/L-amino acids by HPLC with (ϩ)-18C6H 4 immobilized CSP, it has been generally accepted that L-isomers are commonly eluted prior to D-amino acids, indicating that D-amino acids form more stable interactions with (ϩ)-18C6H 4 than L-amino acids. Because no systematic investigation was performed on the discrimination mechanism of (ϩ)-18C6H 4 between D-and Lisomers, we recently analyzed the crystal structures of the complexes of (ϩ)-18C6H 4 with D-and L-isomers of tyrosine, isoleucine, methionine and phenylglycine, and clarified the common structural scaffold of (ϩ)-18C6H 4 for D/L-separation of these chiral amino acids.…”

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confidence: 99%

Structural Scaffold of 18-Crown-6 Tetracarboxylic Acid for Optical Resolution of Chiral Amino Acid: X-Ray Crystal Analyses of Complexes of D- and L-Isomers of Serine and Glutamic Acid

Nagata¹,

Nishi²,

Kamigauchi

et al. 2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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The separation of enantiomers is a subject of great interest, because the biologically effective chiral drug is either of enantiomers and the antipode is regarded as the impurity showing sometime high toxicity. Recently, the HPLC with chiral stationary phases (CSPs) has been extensively used to achieve the direct enantiomer separation. Crown ether, first introduced by Pedersen in 1967, 1,2) was shown by Cram et al. 3,4) to resolve enantiomers by the host-guest complexation. Since then, the optically active crown ether derivatives have been widely used for the optical syntheses, resolutions and analyses of chiral amino compounds. A novel CSP derived from crown ether, which was prepared by immobilizing (ϩ)-18-crown-6 tetracarboxylic acid ((ϩ)-18C6H 4 ) on 3-aminopropylsilanized silica-gel, was reported by Machida et al. 5) to show the effective enantiomer separation of amino compounds, and has been widely used as a chiral selector for the primary amines in capillary electrophoresis (CE) 6-9) and HPLC. [10][11][12] As for the enantiomer separation of D/L-amino acids by HPLC with (ϩ)-18C6H 4 immobilized CSP, it has been generally accepted that L-isomers are commonly eluted prior to D-amino acids, indicating that D-amino acids form more stable interactions with (ϩ)-18C6H 4 than L-amino acids. Because no systematic investigation was performed on the discrimination mechanism of (ϩ)-18C6H 4 between D-and Lisomers, we recently analyzed the crystal structures of the complexes of (ϩ)-18C6H 4 with D-and L-isomers of tyrosine, isoleucine, methionine and phenylglycine, and clarified the common structural scaffold of (ϩ)-18C6H 4 for D/L-separation of these chiral amino acids. 13)On the other hand, concerning the first elution rule of Lamino acid in CE with (ϩ)-18C6H 4 , an exception was recently observed for the chiral separation of L/D-serine (Ser).14,15) To clarify why D-Ser is eluted prior to L-Ser, we investigated the chiral interactions of (ϩ)-18C6H 4 -L-Ser (L1) and (ϩ)-18C6H 4 -D-Ser (D1) complexes by the X-ray single crystal analyses. In addition, the crystal structures of (ϩ)-18C6H 4 -L-glutamic acid (L-Glu) (L2) and (ϩ)-18C6H 4 -DGlu (D2) complexes were also analyzed, as one of the examples according to the first elution rule of L-isomer. In this paper, we report the common as well as different interaction modes between the L-and D-isomers of these two amino acids. The atomic numberings of (ϩ)-18C6H 4 , Ser and Glu are given in Fig. 1. Results and DiscussionHPLC Analysis The separation data for D-/L-Ser and D-/L-Glu are given in Table 1. L-Glu was eluted prior to D-Glu, according to the first elution rule of L-amino acid in HPLC using (ϩ)-18C6H 4 column. 5) In the case of Ser, however, the elution order of D-and L-isomers was reversed, and D-isomer ; 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. Received September 6, 2005

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“…이 키랄 고정상은 아미노산을 포함한 1차 아미노기를 가지는 라세미 화합물의 광학분리에 매우 효과적으로 이용되었다 [1][2][3][4][5][6][7][8][9][10]. 비슷한 시 기에 일본의 Machida group에서도 (+)-18-C-6-TA를 공유 결합시킨 키랄 고정상을 제조하여 광학분리한 연구결과가 발표되었다 [11,12]. 동일한 키랄 선택자인 (+)-18-C-6-TA로 부터 출발하여 이를 공유결합시킨 크라운 에테르 형태의 키 랄 컬럼을 두 연구팀에서 독자적으로 각각 제조하였지만 이 를 위한 화학적 제조방법이 서로 달라 광학분리를 위한 실제 적인 키랄 고정상의 화학적 구조는 다르다.…”

Section: 서론unclassified

Comparative Enantiomer Separation on Chiral Stationary Phases Derived from Chiral Crown Ether by HPLC

황호¹,

전소희

김지연³

et al. 2012

KSBB Journal

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1) Comparative liquid chromatographic enantiomer separation of α-amino acids, their esters and primary amino compounds was performed using two chiral stationary phases (CSPs) prepared by covalently bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) of the same chiral selector. In general, the separation factors and resolution factors for these analytes on CSP 1 were greater than on CSP 2, while these capacity factors on CSP 2 were quite greater than on CSP 1. Except for leucine methyl ester and phenylalanine methyl ester, the elution orders of all analytes including α-amino α-alkyl acids and phenylglycine alkyl esters on CSP 1 are identical to those on CSP 2. This study showed that different connecting structures for these two CSPs might influence their ability to resolve the analytes depending on their structures related to the chiral recognition mechanism.

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Nuclear magnetic resonance studies for the chiral recognition of the novel chiral stationary phase derived from 18-crown-6 tetracarboxylic acid

Cited by 56 publications

References 20 publications

Guest‐dependent conformation of 18‐crown‐6 tetracarboxylic acid: Relation to chiral separation of racemic amino acids

Guest‐dependent conformation of 18‐crown‐6 tetracarboxylic acid: Relation to chiral separation of racemic amino acids

Structural Scaffold of 18-Crown-6 Tetracarboxylic Acid for Optical Resolution of Chiral Amino Acid: X-Ray Crystal Analyses of Complexes of D- and L-Isomers of Serine and Glutamic Acid

Comparative Enantiomer Separation on Chiral Stationary Phases Derived from Chiral Crown Ether by HPLC

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