What is the difference between COSY and Tocsy?
Whereas COSY typically establishes correlations between protons over two to three chemical bonds, TOCSY can provide correlations between all the protons that make up a “spin system”. This ability of TOCSY helps identify discrete building blocks within a molecule, or distinguish spin systems from different molecules.
What does a COSY NMR tell you?
COSY (Correlated Spectroscopy) was one of the first multidimensional experiments. Cross peaks in COSY are between protons that are coupled. COSY tells you “what proton is coupled to what proton.” Protons that are two, three, or sometimes four bonds apart may show cross peaks.
What is the difference between COSY and no ESY?
For example, the presence of a cross peak (a correlation off the diagonal) on a COSY dataset is a result of nuclei coupling through a bond(s) whereas a NOESY dataset measures NOE’s (Nuclear Overhauser Effect) through space regardless of the number of bonds separating the nuclei.
What is Tocsy NMR?
TOCSY (Total Correlation Spectroscopy) creates correlations between all protons within a given spin system, not just between geminal or vicinal protons as in COSY. Correlations are seen between distant protons as long as there are couplings between every intervening proton.
What information is available from the Tocsy experiment?
The total correlation spectroscopy (TOCSY) experiment allows the generation of cross peaks between virtually all spins in the same spin system. A spin system is a group of spins that couples to one or more other members of the group. A molecule may contain one spin system, or it may contain a hundred spin systems.
How do you read HSQC-Tocsy?
To interpret the HSQC-TOCSY spectrum, one should start with the direct correlation HSQC peaks. For example, in the HSQC the 1 (anomeric) proton and carbon are at 5.42 ppm and 92 ppm, respectively. TOCSY then transfers proton signal to coupled protons such as the 2, 3, 4, and 5 protons.
How do you interpret COSY data?
¹H-¹H Correlation Spectroscopy (COSY) shows the correlation between hydrogens which are coupled to each other in the ¹H NMR spectrum. The ¹H spectrum is plotted on both 2D axes….Step 2: ¹H-¹H COSY.
| Chemical Shift (ppm) | COSY correlations | Assignment |
|---|---|---|
| 1.770 | 3-4 | 3 |
What is Hmbc technique?
The HMBC (Heteronuclear Multiple Bond Correlation) experiment gives correlations between carbons and protons that are separated by two, three, and, sometimes in conjugated systems, four bonds. Direct one-bond correlations are suppressed. This gives connectivity information much like a proton-proton COSY.
What is COSY technique?
COSY is a technique for determining correlations through the chemical bond. In it’s most used form this allows us to see which proton resonances are mutually coupled. As described in the section on 1H spectra, coupling of protons through 2,3 or 4 bonds has a significant impact on the appearance of a proton spectrum.
What is the total number of peaks in the Tocsy?
At a glance, the TOCSY spectrum tells us we have a two-carbon chain because we see two peaks in a row (or, really, a two by two array). It also tells us we have a chain of three peaks because we can see three peaks in a row (or a three by three array).
What is Hsqc Tocsy?
An HSQC-TOCSY experiment stands for Heteronuclear Single Quantum Coherence-Total Correlation Spectroscopy and other variants include HMQC-TOCSY, HSQC-COSY, etc. Depending on the mixing time, the hybrid experiment generally offers information on both short-range and long-range coupled nuclei.