A series of novel chiral tetrahedral heterometal clusters have firstly been separated on cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase by high performance liquid chrom-atography, using hexane as the mo...A series of novel chiral tetrahedral heterometal clusters have firstly been separated on cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase by high performance liquid chrom-atography, using hexane as the mobile phase with various alcohols as modifiers.展开更多
Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-...Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP) is the best and most-widely-used CSP in chiral separations, but experimental data of enantiomeric separation of dipeptides on this CSP is lacking. Simulation studies were conducted to determine the order of elution and the chiral recognition mechanism of didpetides on this CSP. Results indicated that the docking energy of SR-enantiomers were higher than SS-antipodes. The range of docking energies for SR-enantiomers was -7.44 to -5.92 kcal/mol with CSP, but -7.15 to -5.87 kcal/mol for SS-stereoisomers. Therefore it is predicted that SS-enantiomer will elute first, followed by SR-antipode. Furthermore, hydrogen bondings, van der Waal's interactions and electrostatic interactions were observed among SR- and SSenantiomers and chiral grooves of CSP. The number of hydrogen bonds was one in each enantiomer binding except S-Ala-R-Tyr, which contained two hydrogen bonds. No hydrogen bond was found in S-Ala-R-Trp, S-Leu-S-Trp, and S-Leu-S-Tyr dipeptides bindings. The chiral recognition mechanisms dictate different strengths of stereoselective bindings of the enantiomers on CSP.展开更多
A new method to prepare polysaccharide-coating type chiral stationary phases （CSPs） was developed in this work. As a typical example, naked silica gel was coated by cellulose, which was then derivatized with 3,5-dim...A new method to prepare polysaccharide-coating type chiral stationary phases （CSPs） was developed in this work. As a typical example, naked silica gel was coated by cellulose, which was then derivatized with 3,5-dimethylbenzoyl chloride to afford cellulose tris（3,5-dimethylbenzoate）-silica gel （CTDBS） complex. The silanols on CTDBS were end-capped with 3- aminopropyltriethoxysilane to obtain CSP 1. The amino groups on CSP 1 were further end-capped with 3,5-dimethylbenzoyl chloride to give CSP 2. The silanols on CTDBS were end-capped with methyltrimethoxysilane to yield CSP 3. CSPs 1-3 were characterized by FTIR, solid-state 13C-NMR and elemental analysis. The enantioseparation abilities of CSPs 1-3 were evaluated with structurally various chiral analytes. The enantioseparation results demonstrated that the end-capping moieties on CSPs 1 and 2 significantly affected enantioseparation. In addition, the effect of the structures of chiral analytes and end- capping moieties on the retention factors and the resolutions was discussed.展开更多
Amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) coated on a kind of small particle silica gel was pre-pared. On this ADMPC chiral stationary phase (CSP), the direct enantiomeric separation of six novel chiral transi...Amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) coated on a kind of small particle silica gel was pre-pared. On this ADMPC chiral stationary phase (CSP), the direct enantiomeric separation of six novel chiral transi-tion metal tetrahedral clusters has firstly been achieved using n-hexane as the mobile phase containing various al-cohols as modifiers. The effect of mobile phase modifiers and the structural variation of the solutes on their reten-tion factors (k) and resolutions (Rs) were investigated. The result suggests that not only the structure and concentra-tion of alcohol in mobile phase, but also the structural differences in racemates can have a pronounced effect on enantiomeric separation. ADMPC-CSP is a suitable CSP for the optical resolution of chiral tetrahedral cluster by HPLC.展开更多
Amylose tris(3,5 dimethphenylcarbamate) was synthesized and used as the chiral stationary phase upon adsorption over silica gel. This stationary phase offered a practically useful chiral column with a high enantiomer ...Amylose tris(3,5 dimethphenylcarbamate) was synthesized and used as the chiral stationary phase upon adsorption over silica gel. This stationary phase offered a practically useful chiral column with a high enantiomer separability. Amylose was allowed to react with an excess of 3,5 dimethphenylcarbamate in pyridine for 48h. The obtained carbamate was dissolved and adsorbed on silica gel which has been treated with 3 aminopropyltriethoxysilane. The weight ratio of the carbamate to the silica gel was 0.45/2.55. The quizalofop was resoluted on amylose tris(3,5 dimethphenylcarbamate) chiral stationary phase. Separation was carried out with a hexane/2 propanol mixture at a flow rate of 0.5 mL·min -1 at room temperature. The effects of 2 propanol concentration on the retention and resolution had been investigated.展开更多
基金supported by the Chinese Academy of Sciences under a‘Hundreds of Talents program’to Yonmnin Li.
文摘A series of novel chiral tetrahedral heterometal clusters have firstly been separated on cellulose tris-(3,5-dimethylphenylcarbamate) stationary phase by high performance liquid chrom-atography, using hexane as the mobile phase with various alcohols as modifiers.
基金the Department of Science and Technology, New Delhi, India (DST/INT/RFBR/P-147)the Russian Foundation of Basic Research, Russia (RFBR 13-03-92692) for financial assistance
文摘Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP) is the best and most-widely-used CSP in chiral separations, but experimental data of enantiomeric separation of dipeptides on this CSP is lacking. Simulation studies were conducted to determine the order of elution and the chiral recognition mechanism of didpetides on this CSP. Results indicated that the docking energy of SR-enantiomers were higher than SS-antipodes. The range of docking energies for SR-enantiomers was -7.44 to -5.92 kcal/mol with CSP, but -7.15 to -5.87 kcal/mol for SS-stereoisomers. Therefore it is predicted that SS-enantiomer will elute first, followed by SR-antipode. Furthermore, hydrogen bondings, van der Waal's interactions and electrostatic interactions were observed among SR- and SSenantiomers and chiral grooves of CSP. The number of hydrogen bonds was one in each enantiomer binding except S-Ala-R-Tyr, which contained two hydrogen bonds. No hydrogen bond was found in S-Ala-R-Trp, S-Leu-S-Trp, and S-Leu-S-Tyr dipeptides bindings. The chiral recognition mechanisms dictate different strengths of stereoselective bindings of the enantiomers on CSP.
基金financially supported by the National Natural Science Foundation of China(No.50973086)Hubei Provincial Department of Education of China(Z 20081501)
文摘A new method to prepare polysaccharide-coating type chiral stationary phases （CSPs） was developed in this work. As a typical example, naked silica gel was coated by cellulose, which was then derivatized with 3,5-dimethylbenzoyl chloride to afford cellulose tris（3,5-dimethylbenzoate）-silica gel （CTDBS） complex. The silanols on CTDBS were end-capped with 3- aminopropyltriethoxysilane to obtain CSP 1. The amino groups on CSP 1 were further end-capped with 3,5-dimethylbenzoyl chloride to give CSP 2. The silanols on CTDBS were end-capped with methyltrimethoxysilane to yield CSP 3. CSPs 1-3 were characterized by FTIR, solid-state 13C-NMR and elemental analysis. The enantioseparation abilities of CSPs 1-3 were evaluated with structurally various chiral analytes. The enantioseparation results demonstrated that the end-capping moieties on CSPs 1 and 2 significantly affected enantioseparation. In addition, the effect of the structures of chiral analytes and end- capping moieties on the retention factors and the resolutions was discussed.
基金Project supported by Chinese Academy of Science (No. KY95-S1-205).
文摘Amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) coated on a kind of small particle silica gel was pre-pared. On this ADMPC chiral stationary phase (CSP), the direct enantiomeric separation of six novel chiral transi-tion metal tetrahedral clusters has firstly been achieved using n-hexane as the mobile phase containing various al-cohols as modifiers. The effect of mobile phase modifiers and the structural variation of the solutes on their reten-tion factors (k) and resolutions (Rs) were investigated. The result suggests that not only the structure and concentra-tion of alcohol in mobile phase, but also the structural differences in racemates can have a pronounced effect on enantiomeric separation. ADMPC-CSP is a suitable CSP for the optical resolution of chiral tetrahedral cluster by HPLC.
文摘Amylose tris(3,5 dimethphenylcarbamate) was synthesized and used as the chiral stationary phase upon adsorption over silica gel. This stationary phase offered a practically useful chiral column with a high enantiomer separability. Amylose was allowed to react with an excess of 3,5 dimethphenylcarbamate in pyridine for 48h. The obtained carbamate was dissolved and adsorbed on silica gel which has been treated with 3 aminopropyltriethoxysilane. The weight ratio of the carbamate to the silica gel was 0.45/2.55. The quizalofop was resoluted on amylose tris(3,5 dimethphenylcarbamate) chiral stationary phase. Separation was carried out with a hexane/2 propanol mixture at a flow rate of 0.5 mL·min -1 at room temperature. The effects of 2 propanol concentration on the retention and resolution had been investigated.
