This preview shows page 1. Sign up to view the full content.
Unformatted text preview: d
JAX.
• Four frequencies are detected by the receiver:
A2 = νA (Xα)
A1 = νA (Xβ)
X2 = νX (Aα)
X1 = νX (Aβ)
B) Magnitude Spectrum
• FT with respect to t2 yields four signals at A1, A2, X1, and X2.
These signals are modulated in t1 with these same four frequencies.
• FT with respect to t1 gives a 2D NMR spectrum with four groups of
signals, each containing four signals.
♦ Groups centered at (νA, νA) and (νX, νX) are diagonal peaks.
♦ Groups centered at (νA, νX) and (νX, νA) are cross peaks.
♦ Within each group, separation in F1 and F2 is JAX. 9 C) PhaseSensitive Spectrum  10  5. TwoDimensional Homonuclear (H,H)Correlated NMR
Spectroscopy. COSY45:
Same as COSY90, but second 1H pulse is 45˚x' instead of 90˚x'.
Reduces the intensity of the signal, but simplifies the spectrum.
COSY90 COSY45 H3 H2 H1 H2 H1 COOH
Br
H3 Br
Crosssection of COSY45  11  6. TwoDimensional Homonuclear (H,H)Correlated NMR
Spectroscopy. Longrange COSY:
A fixed delay ∆ (0.1 to 0.4 s) is added before and after the second 1H
90˚x' pulse: Allows development of correlation effects for very weakly coupled 1H. h LongRange COSY COSY90
CH(2) CH2(4) CH2(3) CH(2) CH2(3) CH2(3) CH2(3) CH2(4) CH2(4) CH2(4) F1
(ppm) CH(2) F1
(ppm) CH(2) F2 (ppm) F2 (ppm)  12 ...
View
Full
Document
This note was uploaded on 11/13/2011 for the course CHEM 4190 taught by Professor Staff during the Fall '08 term at University of Georgia Athens.
 Fall '08
 Staff
 Equilibrium

Click to edit the document details