A joint theoretical and experimental investigation on the 13C and 1H NMR chemical shifts of coumarin derivatives

d’Antuono, Philippe; Botek, Edith; Champagne, Benoı̂t; Maton, Laetitia; Taziaux, Dorothée; Habib‐Jiwan, Jean‐Louis

doi:10.1007/s00214-009-0625-x

Cited by 6 publications

(11 citation statements)

References 42 publications

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“…They differ by the orientations of the amide function and of the flexible ethyl branches on the N atom and, as a consequence, several conformers present very similar energies. 19 The MB distribution is modified when accounting for the effects of the solvent. When complexing a cation, the geometry of C343-dea changes.…”

Section: C343-deamentioning

confidence: 99%

“…With respect to C343-dea, a slightly smaller electronic conjugation between the coumarin ring and the amide function, characterized by a larger bond length alternation, has been noticed. 19 For the four complexes, several general trends can be observed: (i) the number of stable conformers contributing to the MB distribution at room temperature is at most three, being a consequence of the higher coordination of the metal with the crown ligand than in the case of the diethylamide group, which allows less geometrical flexibility to the ligand (Table S3 of the ESIw), (ii) complexing the monovalent cations leads to a single dominant conformation whereas there are two for the divalent cations, (iii) the complexation is mostly done by the O atoms of the lactone-corresponding to the smallest M n+ -O distance-and those of the crown-ether so that the O atom of the amide function points outside (Fig. 1), then (iv) contrary to the C343-dea complexes, the N atom of the amide participates to the complexation-though the M n+ -N distances are larger than the M n+ -O distances-in particular in the case of the divalent cations, and (v) the geometrical modifications on the coumarin moiety are similar to those found in the complexes of C343-dea, though of slightly smaller amplitudes (Fig.…”

Section: C343-crownmentioning

confidence: 99%

“…Indeed, the effect of the solvent is not always systematic and better agreement with experiment are obtained with IEFPCM data than with data calculated for the isolated molecules. 19…”

Section: Nmr Spectramentioning

confidence: 99%

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Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

Botek

d’Antuono

Jacques

et al. 2010

Phys. Chem. Chem. Phys.

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A joint theoretical-experimental investigation has been carried out to unravel the details of the complexation of cations by fluoroionophores based on coumarin 343 and to interpret the modifications in the ligand and also in the coumarin structural, electronic, magnetic, and vibrational properties. It is confirmed that C343-dea (1) complexes the cations by both the lactone and the amide oxygen atoms whereas for C343-crown (2) and C343-dibenzocrown (3), the cations are complexed by the oxygen atoms of the lactone as well as those of the crown ligand. These complexations induce geometric modifications, which are delocalized over the coumarin backbone and are related to electronic reorganizations that modify the spectroscopic signatures. This paper analyzes these signatures and shows how they are related as well as how they can be used to monitor the complexation process. Upon complexation, the UV-visible absorption spectra display a bathochromic shift of the most intense electronic transition; this shift is generally larger for the most flexible compound 1 as well as when complexing divalent cations. NMR spectra bear many signatures of the complexation, of which the most remarkable ones are the large shielding of C(1) and the large deshieldings of C(9) and C(16). Additional makers of complexation are highlighted in the IR vibrational spectra, in particular the bands associated with the lactone and amide CO vibrations, which are downshifted when the corresponding CO is involved in the complexation mode and, otherwise, upshifted. A high degree of consistency characterizes the different geometrical, electronic, magnetic, and vibrational signatures, which substantiates the assignment of the modes of complexation in 1-3. In addition, the agreement between the experimental data and the theoretical values is rather satisfactory, in that it at least enables us to interpret the spectral signatures.

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Section: C343-deamentioning

confidence: 99%

Section: C343-crownmentioning

confidence: 99%

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Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

Botek

d’Antuono

Jacques

et al. 2010

Phys. Chem. Chem. Phys.

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“…Departures from polarizable continuum model (PCM) results for the 1 H and 13 C shifts of cyclic ketones in a large number of solvents have been analysed in terms of solvatochromic parameters . Finally, in keeping with the generally accepted practice of refining computational results by means of linear (or nonlinear) scaling, multi‐standard approaches and fragment referencing, scaling factors have been proposed for common NMR solvents …”

Section: Introductionmentioning

confidence: 99%

¹H NMR spectra of alcohols in hydrogen bonding solvents: DFT/GIAO calculations of chemical shifts

Lomas

2015

Magnetic Reson in Chemistry

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Proton nuclear magnetic resonance (NMR) shifts of aliphatic alcohols in hydrogen bonding solvents have been computed on the basis of density functional theory by applying the gauge-including atomic orbital method to geometry-optimized alcohol/solvent complexes. The OH proton shifts and hydrogen bond distances for methanol or ethanol complexed with pyridine depend very much on the functional employed and very little on the basis set, provided it is sufficiently large to give the correct quasi-linear hydrogen bond geometry. The CH proton shifts are insensitive to both the functional and the basis set. NMR shifts for all protons in several alcohol/pyridine complexes are calculated at the Perdew, Burke and Ernzerhof PBE0/cc-pVTZ//PBE0/6-311 + G(d,p) level in the gas phase. The results correlate with the shifts for the pyridine-complexed alcohols, determined by analysing data from the NMR titration of alcohols against pyridine. More pragmatically, computed shifts for a wider range of alcohols correlate with experimental shifts in neat pyridine. Shifts for alcohols in dimethylsulfoxide, based on the corresponding complexes in the gas phase, correlate well with the experimental values, but the overall root mean square difference is high (0.23 ppm), shifts for the OH, CHOH and other CH protons being systematically overestimated, by averages of 0.42, 0.21 and 0.06 ppm, respectively. If the computed shifts are corrected accordingly, a very good correlation is obtained with a gradient of 1.00 ± 0.01, an intercept of 0.00 ± 0.02 ppm and a root mean square difference of 0.09 ppm. This is a modest improvement on the result of applying the CHARGE programme to a slightly different set of alcohols. Some alcohol complexes with acetone and acetonitrile were investigated both in the gas phase and in a continuum of the relevant solvent.

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“…Indeed, straightforward regioselective mono‐glycopyranosylation37 and etherification38 have been reported at the 7‐hydroxyl group of 3,4‐cyclohexenoesculetin ( 1 ). 13 C and 1 H NMR chemical shifts of coumarin derivatives (δ C‐7 > δ C‐5 > δ C‐6 > δ C‐8 )39 also suggested that the relative electron deficiency of C‐7, C‐6, and C‐8 would result in the relative reactivity: 7‐hydroxyl > 6‐hydroxyl > 8‐hydroxyl. Hydroxyl p K a values in coumarins 1 – 5 corresponding to their positions (Table 1) suggested that phase‐transfer catalysis at pH 8–9 could provide regio‐ and stereoselective synthesis of β‐ D ‐galactopyranosides, as we also exploited previously for 19 F NMR β‐gal reporters 40.…”

Section: Resultsmentioning

confidence: 79%

Novel Fe³⁺‐Based ¹H MRI β‐Galactosidase Reporter Molecules

et al. 2012

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There is increasing interest in the development of reporter agents to reveal enzyme activity in vivo using small animal imaging. We have previously demonstrated the feasibility of detecting lacZ gene activity using the commercially available 3,4-cyclohexenoesculetin-β-D-galactopyranoside (S-Gal™) as a 1H MRI reporter. Specifically, β-galactosidase (β-gal) releases the aglycone, which forms an MR contrast-inducing paramagnetic precipitate in the presence of Fe3+. Contrast was primarily T2-weighted signal loss, but T1 effects were also observed. Since T1-contrast generally provides signal enhancement as opposed to loss, it appeared attractive to explore whether analogues could be generated with enhanced characteristics. We now report the design and successful synthesis of novel analogues together with characterization of 1H MRI contrast based on both T1 and T2 response to β-gal activity in vitro for the lead agent.

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A joint theoretical and experimental investigation on the 13C and 1H NMR chemical shifts of coumarin derivatives

Cited by 6 publications

References 42 publications

Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

¹H NMR spectra of alcohols in hydrogen bonding solvents: DFT/GIAO calculations of chemical shifts

Novel Fe³⁺‐Based ¹H MRI β‐Galactosidase Reporter Molecules

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A joint theoretical and experimental investigation on the 13C and 1H NMR chemical shifts of coumarin derivatives

Cited by 6 publications

References 42 publications

Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

Theoretical and experimental investigation of the structural and spectroscopic properties of coumarin 343 fluoroionophores

1H NMR spectra of alcohols in hydrogen bonding solvents: DFT/GIAO calculations of chemical shifts

Novel Fe3+‐Based 1H MRI β‐Galactosidase Reporter Molecules

Contact Info

Product

Resources

About

¹H NMR spectra of alcohols in hydrogen bonding solvents: DFT/GIAO calculations of chemical shifts

Novel Fe³⁺‐Based ¹H MRI β‐Galactosidase Reporter Molecules