Quantum Mechanical Calculations of Conformationally Relevant <sup>1</sup>H and <sup>13</sup>C NMR Chemical Shifts of Calixarene Systems

Bifulco, Giuseppe; Gomez‐Paloma, Luigi; Riccio, Raffaele; Gaeta, Carmine; Troisi, Francesco; Neri, Placido

doi:10.1021/ol052166g

Cited by 44 publications

(30 citation statements)

References 21 publications

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“…As shown in Figure 1, the Scheme 1. [9] Moreover, we also found that only four signals due to the aliphatic carbons were observed in the 13 C NMR spectra of 4 b and 5 b. Scheme 2.…”

Section: Resultsmentioning

confidence: 71%

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Tian

Chen

2010

Chemistry A European J

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Two pairs of novel triptycene-derived calix[6]arenes 4a,b and 5a,b have been efficiently synthesized through both one-pot and two-step fragment-coupling strategies starting from 2,7-bis(hydroxymethyl)-1,8-dimethoxytriptycene 1. Subsequent demethylation of 4a,b and 5a,b with BBr(3) in dry dichloromethane gave the macrocyclic compounds 6a,b and 7a,b. Treatment of either 4a or 6a with AlCl(3) resulted in the same debutylated product 8, while 9 was similarly obtained from either 5a or 7a. Structural studies revealed that all of the macrocycles have well-defined structures with fixed conformations both in solution and in the solid state owing to the introduction of the triptycene moiety with a rigid three-dimensional (3D) structure, making them very different from their classical calix[6]arene counterparts. As a consequence, it was found that all of these the triptycene-derived calix[6]arenes could encapsulate small neutral molecules in their cavities in the solid state. Moreover, it was also found that the macrocycles 4b and 5b showed highly efficient complexation abilities toward fullerenes C(60) and C(70), forming 1:1 complexes with association constants ranging from (5.22+/-0.20) x 10(4) to (8.68+/-0.30) x 10(4) M(-1).

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“…As shown in Figure 1, the Scheme 1. [9] Moreover, we also found that only four signals due to the aliphatic carbons were observed in the 13 C NMR spectra of 4 b and 5 b. Scheme 2.…”

Section: Resultsmentioning

confidence: 71%

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Tian

Chen

2010

Chemistry A European J

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“…In particular, an approach based on integrated NMR experimental data with GIAO 1 H NMR DFT calculated values was proposed to study ligand-macromolecule interactions, going well over the successful application of 1 H and 13 C NMR chemical shift calculations in the structure elucidation of organic molecules, [8a,9b,28] in the interpretation of polymer spectra [28d] and in the conformational analysis of peptides, [91][92][93] oligosaccharides, [94] and calixarenes. [95] Thus, two 3D models were built where 36 was covalently bound to A5 or A6 (model A or B, respectively; Figure 11a,b), and starting from the NMR structure of duocarmycin SA covalently linked to the DNA duplex (PDB [96] archive code 1DSA) [97] 36 was built and docked in the minor groove. [24] In order to perform quantum mechanical calculations in a reasonable computation time and with a reliable model, only six base pairs of the DNA were considered (Figure 11).…”

Section: Quantum Mechanical Calculation Of Nmr Parameters As a Tool Fmentioning

confidence: 99%

Quantum Mechanical Calculation of NMR Parameters in the Stereostructural Determination of Natural Products

et al. 2010

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The present microreview highlights the recent goals reached by the application of a combined approach of NMR spectroscopy and quantum chemical methods in the structural studies of natural products. In particular, different case studies are reported, showing the comparison of calculated NMR parameters at the quantum mechanical (QM) theory level with experimental data for the configurational assignment of organic compounds. Moreover, it is shown that the QM-NMR

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“…These properties make DFT more practical and feasible for the computations of large molecules and databases containing a sizable number of molecules. Accordingly, DFT methods are employed in most cases, and the methods unarguably provide the best compromise between computational cost and reliability among all quantum chemical methods . Moreover, there are different kinds of functionals for solving problems in different situations (molecular groups).…”

Section: Introductionmentioning

confidence: 99%

Density functional theory study of ¹³C NMR chemical shift of chlorinated compounds

Zhou

Gao

et al. 2012

Magnetic Reson in Chemistry

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The use of the standard density functional theory (DFT) leads to an overestimation of the paramagnetic contribution and underestimation of the shielding constants, especially for chlorinated carbon nuclei. For that reason, the predictions of chlorinated compounds often yield too high chemical shift values. In this study, the WC04 functional is shown to be capable of reducing the overestimation of the chemical shift of Cl-bonded carbons in standard DFT functionals and to show a good performance in the prediction of (13)C NMR chemical shifts of chlorinated organic compounds. The capability is attributed to the minimization of the contributions that intensively increase the chemical shift in the WC04. Extensive computations and analyses were performed to search for the optimal procedure for WC04. The B3LYP and mPW1PW91 standard functionals were also used to evaluate the performance. Through detailed comparisons between the basis set effects and the solvent effects on the results, the gas-phase GIAO/WC04/6-311+G(2d,p)//B3LYP/6-31+G(d,p) was found to be specifically suitable for the prediction of (13)C NMR chemical shifts of chlorides in both chlorinated and non-chlorinated carbons. Further tests with eight molecules in the probe set sufficiently confirmed that WC04 was undoubtedly effective for accurately predicting (13) C NMR chemical shifts of chlorinated organic compounds.

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Quantum Mechanical Calculations of Conformationally Relevant ¹H and ¹³C NMR Chemical Shifts of Calixarene Systems

Cited by 44 publications

References 21 publications

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Quantum Mechanical Calculation of NMR Parameters in the Stereostructural Determination of Natural Products

Density functional theory study of ¹³C NMR chemical shift of chlorinated compounds

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Quantum Mechanical Calculations of Conformationally Relevant 1H and 13C NMR Chemical Shifts of Calixarene Systems

Cited by 44 publications

References 21 publications

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C60 and C70

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C60 and C70

Quantum Mechanical Calculation of NMR Parameters in the Stereostructural Determination of Natural Products

Density functional theory study of 13C NMR chemical shift of chlorinated compounds

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Quantum Mechanical Calculations of Conformationally Relevant ¹H and ¹³C NMR Chemical Shifts of Calixarene Systems

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C₆₀ and C₇₀

Density functional theory study of ¹³C NMR chemical shift of chlorinated compounds