BioNMR
NMR aggregator & online community since 2003
BioNMR    
Learn or help to learn NMR - get free NMR books!
 

Go Back   BioNMR > Educational resources > NMR Questions and Answers
Advanced Search



Jobs Groups Conferences Literature Pulse sequences Software forums Programs Sample preps Web resources BioNMR issues


Webservers
NMR processing:
MDD
NMR assignment:
Backbone:
Autoassign
MARS
UNIO Match
PINE
Side-chains:
UNIO ATNOS-Ascan
NOEs:
UNIO ATNOS-Candid
UNIO Candid
ASDP
Structure from NMR restraints:
Ab initio:
GeNMR
Cyana
XPLOR-NIH
ASDP
UNIO ATNOS-Candid
UNIO Candid
Fragment-based:
BMRB CS-Rosetta
Rosetta-NMR (Robetta)
Template-based:
GeNMR
I-TASSER
Refinement:
Amber
Structure from chemical shifts:
Fragment-based:
WeNMR CS-Rosetta
BMRB CS-Rosetta
Homology-based:
CS23D
Simshift
Torsion angles from chemical shifts:
Preditor
TALOS
Promega- Proline
Secondary structure from chemical shifts:
CSI (via RCI server)
TALOS
MICS caps, β-turns
d2D
PECAN
Flexibility from chemical shifts:
RCI
Interactions from chemical shifts:
HADDOCK
Chemical shifts re-referencing:
Shiftcor
UNIO Shiftinspector
LACS
CheckShift
RefDB
NMR model quality:
NOEs, other restraints:
PROSESS
PSVS
RPF scores
iCing
Chemical shifts:
PROSESS
CheShift2
Vasco
iCing
RDCs:
DC
Anisofit
Pseudocontact shifts:
Anisofit
Protein geomtery:
Resolution-by-Proxy
PROSESS
What-If
iCing
PSVS
MolProbity
SAVES2 or SAVES4
Vadar
Prosa
ProQ
MetaMQAPII
PSQS
Eval123D
STAN
Ramachandran Plot
Rampage
ERRAT
Verify_3D
Harmony
Quality Control Check
NMR spectrum prediction:
FANDAS
MestReS
V-NMR
Flexibility from structure:
Backbone S2
Methyl S2
B-factor
Molecular dynamics:
Gromacs
Amber
Antechamber
Chemical shifts prediction:
From structure:
Shiftx2
Sparta+
Camshift
CH3shift- Methyl
ArShift- Aromatic
ShiftS
Proshift
PPM
CheShift-2- Cα
From sequence:
Shifty
Camcoil
Poulsen_rc_CS
Disordered proteins:
MAXOCC
Format conversion & validation:
CCPN
From NMR-STAR 3.1
Validate NMR-STAR 3.1
NMR sample preparation:
Protein disorder:
DisMeta
Protein solubility:
camLILA
ccSOL
Camfold
camGroEL
Zyggregator
Isotope labeling:
UPLABEL
Solid-state NMR:
sedNMR


Reply
Thread Tools Search this Thread Rating: Thread Rating: 1 votes, 5.00 average. Display Modes
  #1  
Unread 01-01-2002, 06:47 PM
Junior Member
 
Join Date: Jan 2002
Posts: 1
Points: 12, Level: 1
Points: 12, Level: 1 Points: 12, Level: 1 Points: 12, Level: 1
Level up: 23%, 38 Points needed
Level up: 23% Level up: 23% Level up: 23%
Activity: 0%
Activity: 0% Activity: 0% Activity: 0%
NMR Credits: 0
NMR Points: 12
Downloads: 0
Uploads: 0
Default Answered: what is/ how do you calculate the chemical shift in an NMR?

I have read the technical definitions but I still do not understand what the chemical shift means and how you calculate it given an NMR peak. If someone could kind of dumb it down for me but still give me the important things to know/ how it helps you determine the structure of a molecule with the NMR I would appreciate it.
Reply With Quote


Did you find this post helpful? Yes | No
Best Answer - Posted by SuperNashwan
If you are mainly interested in structure determination then I wouldn't worry too much about how chemical shifts are calclulated and concentrate on how you can apply the data. The best way of learning NMR is to get examples and practice. Eventually you will see familiar patterns and use this information.You really want to consider 3/4 pieces of information. One, the chemical shift will tell you the kind of connectivity your protons have, for example methyl protons generally have chem shifts around the 1ppm mark. Aromatics you can find around 6.5-7. Aldehydes around 10ppm. This indicates the type of C-H bonds you have.Secondly, look at the multiplicities. Are there any patterns? If you see a splitting pattern that is say 2 distinct even lines then you can use the n+1 rule which tells you that there is n=1 hydrogens on the adjacent atom. Coupling occurs in many different ways and you can refer to pascals triangle to help determine your multiplicities and you should learn these (IE singlets, doublets, triplets, doublet of doublets etc.)Thirdly look at the integration on the peaks. In modern NMR these will be given below the peaks, and tell you how many hydrogens are in that environment. Again using methyl protons as an example, you'd have a peak at about 1ppm, with 3 below. This 3 indicates 3H attached to your C atom, IE -CH3.Finally, coupling constants can be calulated from the difference between 2 peaks. This value (called the J value) can help you to assign the stereochemistry of your molecule. For example you have deduced from chemical shifts and you'd 13C nmr that you have a alkene group in your molecule with 2 subsitituents. Is it the E or Z alkene? Well you calculate your J value and its 16Hz. You know now its the E-alkene. Really this is a basic run through of what is a powerful technique in chemistry. Are you interested in organic synthesis? Well this technique has to be mastered. As an organic chemist I'd recommend not getting too bogged down in calculations (leave that to the phys guys), and just use the information you have in front of you to determine what you're lovely smelling molecule is! I always remember the first "unknown" NMR I figured out. Its a great feeling when you nail it.SO get some spectras, and get cracking!http://wwwchem.csustan.edu/Tutorials/NMRTABLE.HTM - se this as a guide to chemical shifts for protons in certain environments.http://www.wfu.edu/~ylwong/chem/nmr/h1/index.html - Guide to splitting patterns and some practice.

Content provided by Yahoo Answers.

  #2  
Unread 01-01-2002, 06:47 PM
Junior Member
 
Join Date: Jan 2002
Posts: 1
Points: 2, Level: 1
Points: 2, Level: 1 Points: 2, Level: 1 Points: 2, Level: 1
Level up: 3%, 48 Points needed
Level up: 3% Level up: 3% Level up: 3%
Activity: 0%
Activity: 0% Activity: 0% Activity: 0%
NMR Credits: 0
NMR Points: 2
Downloads: 0
Uploads: 0
Provided Answers: 1
Default what is/ how do you calculate the chemical shift in an NMR?

If you are mainly interested in structure determination then I wouldn't worry too much about how chemical shifts are calclulated and concentrate on how you can apply the data. The best way of learning NMR is to get examples and practice. Eventually you will see familiar patterns and use this information.You really want to consider 3/4 pieces of information. One, the chemical shift will tell you the kind of connectivity your protons have, for example methyl protons generally have chem shifts around the 1ppm mark. Aromatics you can find around 6.5-7. Aldehydes around 10ppm. This indicates the type of C-H bonds you have.Secondly, look at the multiplicities. Are there any patterns? If you see a splitting pattern that is say 2 distinct even lines then you can use the n+1 rule which tells you that there is n=1 hydrogens on the adjacent atom. Coupling occurs in many different ways and you can refer to pascals triangle to help determine your multiplicities and you should learn these (IE singlets, doublets, triplets, doublet of doublets etc.)Thirdly look at the integration on the peaks. In modern NMR these will be given below the peaks, and tell you how many hydrogens are in that environment. Again using methyl protons as an example, you'd have a peak at about 1ppm, with 3 below. This 3 indicates 3H attached to your C atom, IE -CH3.Finally, coupling constants can be calulated from the difference between 2 peaks. This value (called the J value) can help you to assign the stereochemistry of your molecule. For example you have deduced from chemical shifts and you'd 13C nmr that you have a alkene group in your molecule with 2 subsitituents. Is it the E or Z alkene? Well you calculate your J value and its 16Hz. You know now its the E-alkene. Really this is a basic run through of what is a powerful technique in chemistry. Are you interested in organic synthesis? Well this technique has to be mastered. As an organic chemist I'd recommend not getting too bogged down in calculations (leave that to the phys guys), and just use the information you have in front of you to determine what you're lovely smelling molecule is! I always remember the first "unknown" NMR I figured out. Its a great feeling when you nail it.SO get some spectras, and get cracking!http://wwwchem.csustan.edu/Tutorials/NMRTABLE.HTM - se this as a guide to chemical shifts for protons in certain environments.http://www.wfu.edu/~ylwong/chem/nmr/h1/index.html - Guide to splitting patterns and some practice.

Content provided by Yahoo Answers.
Reply With Quote


1 out of 1 members found this post helpful. Did you find this post helpful? Yes | No
Reply
Similar Threads
Thread Thread Starter Forum Replies Last Post
SHIFTX2: Chemical Shift Prediction
SHIFTX2 website SHIFTX2 is capable of rapidly and accurately calculating diamagnetic 1H, 13C and 15N chemical shifts from protein coordinate data. Compared to its predecessor (SHIFTX) and to other existing protein chemical shift prediction programs, SHIFTX2 is substantially more accurate (up to 26% better by correlation coefficient with an RMS error that is up to 3.3× smaller) than the next best performing program. It also provides significantly more coverage (up to 10% more), is significantly faster (up to 8.5×) and capable of calculating a wider variety of backbone and side chain...
gwnmr NMR software 0 01-10-2012 06:13 PM
[NMRwiki tweet] nmrwiki: How to "calculate" #nmr chemical shift perturbation using 13C and proton shi
nmrwiki: How to "calculate" #nmr chemical shift perturbation using 13C and proton shifts?http://qa.nmrwiki.org/question/181/ nmrwiki: How to "calculate" #nmr chemical shift perturbation using 13C and proton shifts?http://qa.nmrwiki.org/question/181/ Source: NMRWiki tweets
nmrlearner Twitter NMR 0 10-05-2010 02:04 AM
[NMR Geek blog] Chemical Shift Referencing Calculator
Chemical Shift Referencing Calculator Below is the protocol I follow for chemical shift referencing (direct for 1H, and indirect for 13C and 15N). Actually I always have to look back and forth for referencing, so thought why not make a small script and put it on web so that the access becomes handy. !!! The referencing should be done Full story can be found on the NMR geek blog
nmrlearner News from NMR blogs 0 08-22-2010 01:41 AM
Chapter 13 - NMR Chemical Shift
Chapter 13 - NMR Chemical Shift More...
nmrlearner NMR bookmarks 0 08-19-2010 02:34 PM
31P chemical shift value of phosphorus acid?
31P chemical shift value of phosphorus acid?
Ramyaa M NMR Questions and Answers 1 02-07-2005 04:32 AM
Chemical shift of protons?
Can someone give me the answers to the chemical shift of the protons in this compound: CH3CH2OCH2CH(CH3)COOH? Of if you can explain how to get the chemical shift it would be quite helpful as the info online does not really help me.
Tim Mrudande NMR Questions and Answers 1 01-16-2005 08:23 AM
HNMR chemical shift characteristic?
Hi, I'm trying to justify why that specific proton has such chemical shift characteristic.The molecule I'm working with is cyclopentadiene. I know that two protons attached on one of five carbon has 2.89ppm and the proton attached to the next carbon has 6.46ppm and the one on next carbon has 6.57ppm. I can't seem to justify the reason for that pattern.Another molecule is anisole. The methiyl group attached to the ester oxygen has 3.79ppm and the proton attached to carbon that is at ortho position with oxygen has 6.88ppm and the next proton(meta position) is 7.29ppm and the next one (para...
Filumena M NMR Questions and Answers 1 01-09-2005 01:40 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



BioNMR advertisements to pay for website hosting and domain registration. Nobody does it for us.



Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright, BioNMR.com, 2003-2013
Search Engine Friendly URLs by vBSEO 3.6.0

All times are GMT. The time now is 08:17 AM.


Map