Nowadays, high-performance liquid chromatography (HPLC) on chiral stationary phase (CSP) is the most versatile technique for the enantioseparation of chiral compounds. The basic requirement for distinction of enantiomers is the creation of a diastereomeric relationship between the enantiomers pair of a chiral analyte and an enantiopure chiral selector. In HPLC environment, multiple and well balanced noncovalent interactions underlie the enantiodiscrimination process.[1] In particular, the strength of secondary short-type interactions such as hydrogen bonds, pai-pai and dipole-dipole interactions can be significantly influenced by mobile phase (MP) polarity. In the last decades, sigma- and pai-hole bonds have been recognized as new families of noncovalent interactions. In particular, halogen and chalcogen bonds, involving atoms of group VII and VI, respectively, have found applications in several fields.[2] Despite the importance of noncovalent interactions in LC environment, sigma-hole bonds were unexplored in this field until we pointed out the contribution of halogen bond for stereorecognition of analytes by polysaccharide-based CSPs, thus expanding the range of interactions available for LC enantiodiscrimination.[3] Interestingly, we observed that halogens can switch their behaviour from sigma-hole donor to hydrophobic centre depending on sigma-hole depth and MP polarity. Currently, on the basis of a computational-guided study, we are investigating chalcogen and pai-hole bonds, so far unexplored in LC, by means of the enantioseparations of pentafluorophenyl (pai-hole) substituted analytes as probes, which contain sulphur[4] and selenium atoms as chalcogen sites. References [1] Scriba, G. K. E., J. Chromatogr. A 2016, 1467, 56-78. [2] (a) Cavallo, G., Metrangolo, P., Milani, R., Pilati, T., Priimagi, A., Resnati, G., Terraneo, G., Chem. Rev. 2016, 116, 2478-2601; (b) Bauzá, A., Mooibroek, T. J., Frontera, A., ChemPhysChem 2015, 16, 2496-2517. [3] (a) Peluso, P., Mamane, V., Aubert, E., Cossu, S., J. Chromatogr. A 2014, 1345, 182-192; (b) Peluso, P., Mamane, V., Aubert, E., Dessì, A., Dallocchio, R., Dore, A., Pale, P., Cossu, S., J. Chromatogr. A 2016, 1467, 228-238; (c) Dallocchio, R., Dessì, A., Solinas, M., Arras, A., Cossu, S., Aubert, E., Mamane, V., Peluso, P., J. Chromatogr. A 2018, 1563, 71-81. [4] Peluso, P., Gatti, C., Dessì, A., Dallocchio, R., Weiss, R., Aubert, E., Pale, P., Cossu, S., Mamane, V., J. Chromatogr. A 2018, 1567, 119-129. Acknowledgement: This work has been supported by Università Ca' Foscari di Venezia, Italy (DSMN, ADIR funds). V. M. thanks the International Center Frontier Research in Chemistry (icFRC) and the Laboratory of Excellence for Complex System Chemistry (LabEx CSC). C. G. acknowledges funding from Danmarks Grundforskningsfond (award No. DNRF93).
sigma- and pai-hole bonds: emergent noncovalent interactions in liquid-chromatography enantiodiscrimination
Paola Peluso;
2019
Abstract
Nowadays, high-performance liquid chromatography (HPLC) on chiral stationary phase (CSP) is the most versatile technique for the enantioseparation of chiral compounds. The basic requirement for distinction of enantiomers is the creation of a diastereomeric relationship between the enantiomers pair of a chiral analyte and an enantiopure chiral selector. In HPLC environment, multiple and well balanced noncovalent interactions underlie the enantiodiscrimination process.[1] In particular, the strength of secondary short-type interactions such as hydrogen bonds, pai-pai and dipole-dipole interactions can be significantly influenced by mobile phase (MP) polarity. In the last decades, sigma- and pai-hole bonds have been recognized as new families of noncovalent interactions. In particular, halogen and chalcogen bonds, involving atoms of group VII and VI, respectively, have found applications in several fields.[2] Despite the importance of noncovalent interactions in LC environment, sigma-hole bonds were unexplored in this field until we pointed out the contribution of halogen bond for stereorecognition of analytes by polysaccharide-based CSPs, thus expanding the range of interactions available for LC enantiodiscrimination.[3] Interestingly, we observed that halogens can switch their behaviour from sigma-hole donor to hydrophobic centre depending on sigma-hole depth and MP polarity. Currently, on the basis of a computational-guided study, we are investigating chalcogen and pai-hole bonds, so far unexplored in LC, by means of the enantioseparations of pentafluorophenyl (pai-hole) substituted analytes as probes, which contain sulphur[4] and selenium atoms as chalcogen sites. References [1] Scriba, G. K. E., J. Chromatogr. A 2016, 1467, 56-78. [2] (a) Cavallo, G., Metrangolo, P., Milani, R., Pilati, T., Priimagi, A., Resnati, G., Terraneo, G., Chem. Rev. 2016, 116, 2478-2601; (b) Bauzá, A., Mooibroek, T. J., Frontera, A., ChemPhysChem 2015, 16, 2496-2517. [3] (a) Peluso, P., Mamane, V., Aubert, E., Cossu, S., J. Chromatogr. A 2014, 1345, 182-192; (b) Peluso, P., Mamane, V., Aubert, E., Dessì, A., Dallocchio, R., Dore, A., Pale, P., Cossu, S., J. Chromatogr. A 2016, 1467, 228-238; (c) Dallocchio, R., Dessì, A., Solinas, M., Arras, A., Cossu, S., Aubert, E., Mamane, V., Peluso, P., J. Chromatogr. A 2018, 1563, 71-81. [4] Peluso, P., Gatti, C., Dessì, A., Dallocchio, R., Weiss, R., Aubert, E., Pale, P., Cossu, S., Mamane, V., J. Chromatogr. A 2018, 1567, 119-129. Acknowledgement: This work has been supported by Università Ca' Foscari di Venezia, Italy (DSMN, ADIR funds). V. M. thanks the International Center Frontier Research in Chemistry (icFRC) and the Laboratory of Excellence for Complex System Chemistry (LabEx CSC). C. G. acknowledges funding from Danmarks Grundforskningsfond (award No. DNRF93).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
