Module „NMR“ (MSc): Practical exercises Sheet 09 Courtesy Prof. G. Jansen & Dr. T. Schaller, Univ. Duisburg-Essen 9.1 C14H16N2 (in CDCl3)

500 MHz 1H NMR Spektrum

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125 MHz 13C NMR Spektren(in CDCl3)

unten: 1H entkoppelt; oben : DEPT-135

500 MHz 1H-13C HSQC Spektrum

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500 MHz 1H-13C HMBC Spektrum + Ausschnitt

H1 - CD,E,F

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9.2 C5H12O in CDCl3

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9.3

The 1H NMR spectrum of trans-anethole (C10H12O) recorded in CDCl3 solution at 298 K and 400 MHz is given below.

The 1H NMR spectrum has signals at δ 1.82 (dd, J = 6.6, 1.7 Hz, 3H, H1), 3.71 (s, 3H, H8), 6.04 (dq, J = 15.8, 6.6 Hz, 1H, H2), 6.30 (dq, J = 15.8, 1.7 Hz, 1H, H3), 6.78 (m, 2H, H6), and 7.21 (m, 2H, H5) ppm.

Use this information to produce schematic diagrams of the COSY and NOESY spectra, showing where all of the cross peaks and diagonal peaks would be.

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9.4 Read the following publication and explain the relevance of the following NMR data: R. Gupta, G. Hou, R. Renirie, R. Wever, and T. Polenova (2015) 51V NMR crystallography of

vanadium chloroperoxidase and its directed evolution P395D/L241V/T343A mutant:

Protonation environments of the active site. J. Am. Chem. Soc. 137, 5618–5628.

• Vanadium (V) has two NMR-active nuclei (half-integer), 50V (n.a. 0.25 %) and 51V

(99.75%). 51V preferred as an NMR nucleus over 50V because it is much more

sensitive and yields relatively shaper signals. 51V yields somewhat broad lines in small

symmetric molecules but its signals become wider with increasing size of the

complex. 51V has to date found very limited use as a spectroscopic NMR probe of

biological systems. In this paper, the authors reported a 51V solid-state NMR study of

a 67.5-kDa vanadium chloroperoxidase.

Q1: Why the quadrupolar coupling constant CQ and chemical shift anisotropy δσ are sensitive

reporters of the geometric and electronic structure of the diamagnetic vanadium center?

Q2: How the quadrupolar and chemical shift anisotropy tensors were determined?

Q3: How were the authors certain about which peak(s) is(are) the isotropic one(s) from such

spectra (e.g., shown in Figure 3) with many spinning sidebands?

Q4: What does the so-called “51V-based NMR crystallography” mean? Besides MAS NMR,

what is the other method involved in this technique? And how it works in this paper towards

structural elucidation?