Rotational strength sign and normal modes description: A theoretical and experimental comparative study in bicyclic terpenes

Ureña, Francisco Partal; Avilés–Moreno, Juan Ramón; González, Juan Jesús López

doi:10.1002/chir.20899

Cited by 6 publications

(1 citation statement)

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“…Infrared vibrational circular dichroism spectroscopy constitutes a powerful tool for studying the chirality of molecular species and supramolecular organizations, both in solution − and in the solid phase. − In the present work, the application of IR and VCD spectroscopies is extended to the investigation of the complexes formed by S -18c6H 4 with the enantiomers of a primary amine (the amino acid serine in protonated form). Some of the fundamental issues to be addressed are the following: (i) the overall ability of the VCD technique to discern between the complexes formed by the two enantiomers, (ii) the predominant interactions and conformations of the crown–serine complexes, and (iii) the selective binding of the crown ether to any one of the enantiomers of serine, leading to chiral recognition.…”

Section: Introductionmentioning

confidence: 99%

Chiral Recognition of Amino Acid Enantiomers by a Crown Ether: Chiroptical IR-VCD Response and Computational Study

et al. 2013

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We report on a combined experimental and computational study of the chiral recognition of the amino acid serine in protonated form (L/D-SerH(+)), by the crown ether (all-S)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (S-18c6H4). Infrared and vibrational circular dichroism spectroscopies (IR-VCD) are employed to characterize the chiroptical response of the complexes formed by S-18c6H4 with the L-SerH(+) and D-SerH(+) enantiomers in dried thin films obtained from aqueous solutions. The study focuses on vibrational modes directly related to the intermolecular hydrogen bonds between the crown ether derivative and serine, responsible for crown-serine binding, namely, the C═O and C-O stretching modes, and on the C-O-H bending mode, which yield intense IR and VCD signals in the range of wavenumbers 900-2000 cm(-1). The experimental spectra are analyzed in combination with a computational structural survey and optimization at different levels of density functional theory. The conformational landscape of the complexes is found to be primarily governed by a bowl-like structure of the crown ether host and a tripodal coordination of the protonated R-NH3(+) group of serine with the oxygen atoms of the central ether ring. Additionally, one or two of the carboxylic side groups of the crown ether interact with the -COH and -COOH groups of serine. Chiral selectivity is probed by recording the IR and VCD spectra of dried thin films obtained from aqueous solutions with equimolar concentrations of the two serine enantiomers and the macrocycle. The results demonstrate a marked chiral recognition of L-SerH(+) relative to D-SerH(+) by the S-18c6H4 substrate, which arises from the favorable host-guest coordination through H-bonds at optimum distances and collinear orientations, also involving a limited distortion of the crown ether backbone.

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Section: Introductionmentioning

confidence: 99%

Chiral Recognition of Amino Acid Enantiomers by a Crown Ether: Chiroptical IR-VCD Response and Computational Study

et al. 2013

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Self‐Assembly Structures of 1H‐Indazoles in the Solution and Solid Phases: A Vibrational (IR, FIR, Raman, and VCD) Spectroscopy and Computational Study

et al. 2013

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Interleukin‐2 is an immunotherapeutic agent for the treatment of metastatic tumors. Administration of recombinant human IL‐2 (rhIL‐2) in vivo activates lymphocytes and cell‐mediated immune responses. In mice, we have recently observed a dramatic increase of serum IFN‐γ levels in response to in vivo administration of rhIL‐2, which was necessary for the observed protective effects of IL‐2 against the development of collagen‐induced arthritis. To explore further the basis of this phenomenon, the kinetics and source of IFN‐γ in response to IL‐2 was investigated. Highest serum levels of IFN‐γ were observed within 3 h of IL‐2 administration, with levels decreasing over time. Anti‐IL‐2 receptor β antibody blocked this IFN‐γ induction. Multiple doses of rhIL‐2 resulted in corresponding increases in circulating IFN‐γ. IFN‐γ induction was dose‐dependent between doses of 240 to 30,000 U of rhIL‐2. Analysis of the cellular source of IFN‐γ secretion using NK‐ and T cell‐deficient mice demonstrated that NK cells are the likely source of IFN‐γ. Furthermore, IFN‐γ secretion in response to IL‐2 administration was not affected bythe absence of IL‐12, the pivotal cytokine for determination of Th1 responses. These results suggest that effects of IL‐2 on immune responses in vivo may be mediated by IFN‐γ.

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A Spectroscopic Study of Colchicine in the Solid State and in Solution by Multinuclear Magnetic Resonance and Vibrational Circular Dichroism

Virgili¹,

Quesada‐Moreno²,

Avilés–Moreno³

et al. 2014

Helvetica Chimica Acta

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Although almost 200‐years‐old, several unknown aspects remain to be explored of colchicine, the unique available drug for acute flares of gout. In this article, we report density‐functional theory (DFT) studies of geometry, energy, and NMR; 1H‐, 13C‐, and 15N‐NMR chemical shifts and some spin‐spin coupling constants, including the complete analysis of the saturated part (ring B); the assignment of both enantiomers by NMR using a chiral solvating agent; solid‐state NMR experiments of the different forms of natural and racemic colchicine, and IR and vibrational circular dichroism (VCD) studies of these same forms.

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Rotational strength sign and normal modes description: A theoretical and experimental comparative study in bicyclic terpenes

Cited by 6 publications

References 35 publications

Chiral Recognition of Amino Acid Enantiomers by a Crown Ether: Chiroptical IR-VCD Response and Computational Study

Chiral Recognition of Amino Acid Enantiomers by a Crown Ether: Chiroptical IR-VCD Response and Computational Study

Self‐Assembly Structures of 1H‐Indazoles in the Solution and Solid Phases: A Vibrational (IR, FIR, Raman, and VCD) Spectroscopy and Computational Study

A Spectroscopic Study of Colchicine in the Solid State and in Solution by Multinuclear Magnetic Resonance and Vibrational Circular Dichroism

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