tag:blogger.com,1999:blog-3300702123878659843.post4344839306194477879..comments2024-03-26T05:25:50.831-04:00Comments on University of Ottawa NMR Facility Blog: E.COSY and the Relative Signs of Coupling ConstantsGlenn Faceyhttp://www.blogger.com/profile/05146575170575279335noreply@blogger.comBlogger20125tag:blogger.com,1999:blog-3300702123878659843.post-52550563330868281202023-07-21T20:45:43.435-04:002023-07-21T20:45:43.435-04:00Anonymous,
These data were processed with QSIN = 2...Anonymous,<br />These data were processed with QSIN = 2 apodization. <br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-39465578053104087852023-07-21T20:40:36.130-04:002023-07-21T20:40:36.130-04:00Hellow Sir. Can you specify the processing paramet...Hellow Sir. Can you specify the processing parameters for ecosygpph pulse program? "edp" parameterAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-46868568359501294452020-02-19T08:29:46.815-05:002020-02-19T08:29:46.815-05:00Rajendra,
I do not know why the slopes are all the...Rajendra,<br />I do not know why the slopes are all the same. I don't think it has anything to do with which optical isomer of Phenylalanine used.<br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-37101998373531200852020-02-19T03:56:26.904-05:002020-02-19T03:56:26.904-05:00Hi Glenn,
I completed PhD in solid state NMR with...Hi Glenn,<br /><br />I completed PhD in solid state NMR with Dr PK Madhu, TIFR, Mumbai, India in 2009.<br />I was working with YK Nalli to obtain ECosy spectra of phenylalanine. After optimising parameters with jeol engineers we got a reasonable spectra but all the slopes are of one sign. We used L-phenylalanine as sample.<br />Do you think using D-phenylalanine can help? Should be try L-phenylalanine.HCl as a sample.<br />I can run the same experiment on a Bruker spectrometer.<br />Please let me know if there is another trick I am missing.Rajendra Thakurhttps://www.blogger.com/profile/08485229725717918141noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-61354787958600280232020-01-08T09:15:20.976-05:002020-01-08T09:15:20.976-05:00Y.K. Nalli,
I am not familiar with the JEOL softwa...Y.K. Nalli,<br />I am not familiar with the JEOL software or parameters so not in a position to offer advice. I suggest that you contact one of the JEOL application chemists. They are very knowledgeable.<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-11750792722896701702020-01-07T19:56:40.329-05:002020-01-07T19:56:40.329-05:00Dear Glenn Facey!
We recorded E-COSY spectra of a ...Dear Glenn Facey!<br />We recorded E-COSY spectra of a compound on Jeol-600 MHZ using default pulse sequence (ecosy_phase.jxp).<br /><br />My purpose is to calculate J-values to fix the stereochemistry of compound, but, in the spectra all the signals (Off-diagonal peaks) are simmetrical with same J value for all protons. Could you please suggest me if any parameters below to be corrected.<br /><br />Details:<br /><br />x_domainn : Proton<br /><br />x_offset : 5[ppm]<br /><br />x_sweep :15[ppm]<br /><br />x_points : 1024<br /><br />x_prescans : 4<br /><br />mod_return : 1<br /><br />y_points : 256<br /><br />x_acq_time : 0.11375[s]<br /><br />x_resolution : 8.79159[Hz]<br /><br />y_acq_time : 28.43628[ms]<br /><br />y_resolution :35.16635[Hz] <br /> YK Nallihttps://www.blogger.com/profile/07671834422522980522noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-31246479266957362072016-05-25T12:34:18.774-04:002016-05-25T12:34:18.774-04:00AMAN,
I think you should be able to use this metho...AMAN,<br />I think you should be able to use this method to determine relative signs of 19F-19F coupling constants however I think you will have to use 1H decoupling for the entire sequence (except the recycyle delay).<br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-42723884802358972552016-05-25T03:55:11.231-04:002016-05-25T03:55:11.231-04:00Hello sir, I am working with a molecule having fiv...Hello sir, I am working with a molecule having five coupled nuclei (four 19F and one 1H). Do you think I can use E.COSY to find out the relative signs of only 19F nuclei while 1H is decoupled during acquisition?<br /><br />Thanks,<br />Amanddep. AMAN SIDHUhttps://www.blogger.com/profile/04322647743860558339noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-1851323686996633192014-04-14T14:28:42.953-04:002014-04-14T14:28:42.953-04:00Dear AJAY,
Thank you for your question. Although ...Dear AJAY,<br />Thank you for your question. Although I have not looked into the matter in any depth, I suspect the ECOSY method can be used to measure the relative signs of coupling constants for strongly coupled spins - at least to a point. If the coupling is much larger than the chemical shift difference then I suspect the analysis would be non-trivial.<br /><br />Glenn Glenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-23892289302838718872014-04-11T00:35:42.789-04:002014-04-11T00:35:42.789-04:00Hello sir,E.COSY is applied for strong coupling al...Hello sir,E.COSY is applied for strong coupling also..or notAJAYhttps://www.blogger.com/profile/10330065734804621754noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-29189094053439736322013-03-05T11:28:03.868-05:002013-03-05T11:28:03.868-05:00Anonymous,
I don't think this E-COSY experime...Anonymous,<br /><br />I don't think this E-COSY experiment will allow you to make such an assignment. I would suggest a NOESY measurement if there are enough protons in the system.<br /><br />Glenn Glenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-11608741617747721252013-03-04T17:53:33.464-05:002013-03-04T17:53:33.464-05:00Thanks Glenn, it's very helpful. Do you know i...Thanks Glenn, it's very helpful. Do you know if there's a way to assign spins A and B stereospecifically for a similar molecule?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-28336502134095853842011-08-29T13:09:26.581-04:002011-08-29T13:09:26.581-04:00Rajesh,
Pl1 = 0
pl10 = 9.63
p1 = 11.88u
p2 = 23.7...Rajesh,<br /><br />Pl1 = 0<br />pl10 = 9.63<br />p1 = 11.88u<br />p2 = 23.76u<br />p16 = 1000u<br />p17 = 2500u<br />nd0 = 1<br />ns = 4<br />ds = 16<br />td0 = 2k<br />td1 = 256<br />Fnmode = TPPI<br />gpz1 = 40 %<br />gpnam1 = SINE.100<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-61987751098331843792011-08-27T23:58:05.135-04:002011-08-27T23:58:05.135-04:00can you specify the experimental parameters for ec...can you specify the experimental parameters for ecosygpph bruker pulse program .. i am not able to reproduce the spectra using PHE in D2O..<br /><br /><br />regards,<br />rajeshAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-9153043887565090512011-03-22T08:58:19.197-04:002011-03-22T08:58:19.197-04:00Anonymous,
I do not know the answer to your questi...Anonymous,<br />I do not know the answer to your question.<br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-24454367951878729142011-03-22T07:31:10.273-04:002011-03-22T07:31:10.273-04:00Hi! Can we use gDQFCOSY (from Varian pulse sequenc...Hi! Can we use gDQFCOSY (from Varian pulse sequence library) for the same purpose?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-5469466561638010322010-07-14T14:57:15.873-04:002010-07-14T14:57:15.873-04:00Bhaswati,
In the COSY spectrum, the active coupli...Bhaswati,<br /><br />In the COSY spectrum, the active coupling is the coupling giving rise to the COSY cross peak being considered and the passive coupling is not. For a example in an ABX spin system, if one is considering the cross peaks between A and B then the active coupling is JAB and the passive couplings are JAX and JBX.<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-62759874874317821052010-07-14T04:18:20.054-04:002010-07-14T04:18:20.054-04:00What is active and passive coupling???I searched b...What is active and passive coupling???I searched but didn't find a good definition.Bhaswatinoreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-2879480141018539522010-06-07T14:06:04.015-04:002010-06-07T14:06:04.015-04:00Hi John,
Thank you for your comment and question....Hi John,<br /><br />Thank you for your comment and question. The sign of the coupling constant can indeed provide information about a molecule. It is known ,for example that three-bond vicinal proton coupling constants are positive whereas two-bond geminal proton coupling constants are negative. If one was trying to identify an unknown sample and found that a particular coupling constant was negative then one might have reason to believe that the protons were geminal to one another rather than vicinal.<br /><br />GlennGlenn Faceyhttps://www.blogger.com/profile/05146575170575279335noreply@blogger.comtag:blogger.com,1999:blog-3300702123878659843.post-20139389792181077172010-06-07T06:44:44.827-04:002010-06-07T06:44:44.827-04:00Interesting, but what information does the sign of...Interesting, but what information does the sign of the coupling constant provide about the molecule?John Tranthttps://www.blogger.com/profile/04430439798008327969noreply@blogger.com