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 Rate Thread Display Modes
  #1  
Unread 12-24-2002, 12:07 PM
Junior Member
 
Join Date: Dec 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: Please help!! NMR of Naphthalene: why are the alpha-protons more downfield than the beta- protons?

Hi, can you please help me explain why the alpha-protons of naphthalene are further downfield? I know that the protons at the alpha position must be more deshielded, but I don't know how to explain why they have less electron density compared to the beta protons. Does this have to do with the number of double bonds that can be drawn in different resonance structures? Thanks for your help!Thanks so much!
Reply With Quote


Did you find this post helpful? Yes | No
Best Answer - Posted by Cubbi5362
In aromatics, the protons are deshielded due to ring currents. The alpha protons in naphthalene are close enough to the other ring to feel BOTH ring currents. The beta protons only feel one ring's current. Look at anthracene, where the protons on the central ring are even further deshielded (into 8.4 ppm), under the combined effect of three rings.Here's a recent publication on this topic: http://www.biomedsearch.com/nih/Understanding-ring-current-effects-magnetic/18711723.html

Content provided by Yahoo Answers.

  #2  
Unread 12-24-2002, 12:07 PM
Junior Member
 
Join Date: Dec 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 Please help!! NMR of Naphthalene: why are the alpha-protons more downfield than the beta- protons?

In aromatics, the protons are deshielded due to ring currents. The alpha protons in naphthalene are close enough to the other ring to feel BOTH ring currents. The beta protons only feel one ring's current. Look at anthracene, where the protons on the central ring are even further deshielded (into 8.4 ppm), under the combined effect of three rings.Here's a recent publication on this topic: http://www.biomedsearch.com/nih/Understanding-ring-current-effects-magnetic/18711723.html

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
[KPWU blog] add protons (hydrogens) to structure
add protons (hydrogens) to structure A list of online servers or programs as I know which can add hydrogens on the structures (most likely determined by X-ray crystallography). WHATIF server (http://swift.cmbi.ru.nl/servers/html/index.html) –> check “Hydrogen (bonds)” in the left frame Molprobity server (http://molprobity.biochem.duke.edu/) –> after uploading a PDB file, you will see “add hydrogen” in the online interface. HAAD: (a computer http://stats.wordpress.com/b.gif?host=kpwu.wordpress.com&blog=76132&post=662&subd=kpwu&ref=&feed=1 Go to KPWU blog to read complete post.
nmrlearner News from NMR blogs 0 02-25-2012 12:16 AM
[NMR paper] Assignment of the nonexchanging protons of the alpha-spectrin SH3 domain by two- and
Assignment of the nonexchanging protons of the alpha-spectrin SH3 domain by two- and three-dimensional 1H-13C solid-state magic-angle spinning NMR and comparison of solution and solid-state proton chemical shifts. Related Articles Assignment of the nonexchanging protons of the alpha-spectrin SH3 domain by two- and three-dimensional 1H-13C solid-state magic-angle spinning NMR and comparison of solution and solid-state proton chemical shifts. Chembiochem. 2001 Dec 3;2(12):906-14 Authors: van Rossum BJ, Castellani F, Rehbein K, Pauli J, Oschkinat H ...
nmrlearner Journal club 0 11-19-2010 08:44 PM
[Stan NMR blog] Chemical shifts of naked and dressed protons
Chemical shifts of naked and dressed protons Did you know that the full proton NMR window is actually 90 ppm wide and not just 12? More...
nmrlearner News from NMR blogs 0 08-21-2010 05:42 PM
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
Does NMR coupling happens between equivalent protons?
for example, in 1,4 dioxane, do the HNMR signals show up as singlets or triplets?
Justin T NMR Questions and Answers 2 05-28-2003 11:40 PM


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 - 2017, 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 10:20 PM.


Map