Lecture 23. Using TOCSY to Elucidate Spin Systems. ROESY

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Lecture 23. Using TOCSY to Elucidate Spin Systems. ROESY
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This is a graduate course in organic spectroscopy, focusing on modern methods used in structure determination of organic molecules. Topics include mass spectrometry; ultraviolet, chiroptical, infrared, and nuclear magnetic resonance spectroscopy.
Ionenbindung Chain (unit) Chemische Verschiebung Peptide Resonance (chemistry) Plant breeding Wursthülle Methylgruppe Molecule Electron Abbruchreaktion Protein Amino acid Beta sheet Process (computing) Urea Setzen <Verfahrenstechnik> Metal Atom probe Singulettzustand Amyl alcohol Peptide Stockfish Electronic cigarette Toxicity Systemic therapy Emission spectrum Taxis Spectroscopy Simulation Functional group Azo coupling Mixing (process engineering) Cobaltoxide Biomolecular structure Biopolymer
Ionenbindung Kohlenstoff-14 Kohlenhydratstoffwechsel Chain (unit) Chemische Verschiebung Reaction mechanism Peptide Resonance (chemistry) Plant breeding Wursthülle Titanium carbide DNS-Synthese Molecule Polymorphism (biology) Altbier Phenylalanine Ale Municipality Amino acid Inclusion (mineral) Nucleic acid Setzen <Verfahrenstechnik> Area DNS-Synthese Minimale Hemmkonzentration Lysine Carbon (fiber) Protonation Electronic cigarette Wine tasting descriptors Dispersion Systemic therapy Toxicity Vietnamese people Taxis Hydrogen Azo coupling RNA Chemical structure Base (chemistry) Mixing (process engineering) Messenger RNA S-Adenosyl methionine Isotopenmarkierung Biopolymer
Sense District Chemische Verschiebung Resonance (chemistry) Methylgruppe Ammonium Alpha particle Molecule Electron Ageing Hydroxybuttersäure <gamma-> Protein Phenylalanine Naphthalin Amino acid Beta sheet Benzene Indium Laxative Stickstoffatom Proline PEEK Lysine Carbon (fiber) Protonation Systemic therapy Emission spectrum Hydrogen Taxis Vancomycin Functional group Chemical compound Chemical structure Stuffing
River delta Residue (chemistry) Resonance (chemistry) Plant breeding Hydroxyl Gene cluster Methylgruppe Alpha particle Sulfide Mast cell Ageing Electron Hydroxybuttersäure <gamma-> Phenylalanine Beta sheet Metal Setzen <Verfahrenstechnik> Potenz <Homöopathie> Topicity Protonation Wine tasting descriptors Water Emission spectrum Systemic therapy Taxis Hydrogen Functional group Azo coupling Chemical compound Medical history Isotopenmarkierung
River delta Residue (chemistry) Proline Plant breeding Radioactive decay Muscle relaxant Trace element Alpha particle Ammonium Sample (material) Ageing Phenylalanine Amino acid Mass spectrometry Beta sheet Toxin Process (computing) Potenz <Homöopathie> Lysine Protonation Electronic cigarette Water Taxis Functional group Stuffing
Methyl iodide Residue (chemistry) Candy Dimethylsulfoxid Tar Resonance (chemistry) Surface finishing Plant breeding Bis (band) Aromaticity Calcium hydroxide Chemistry Methylgruppe Alpha particle Molecule Hydroxybuttersäure <gamma-> Ageing Phenylalanine Naphthalin Beta sheet Sea level Side chain Body weight Conformational isomerism Setzen <Verfahrenstechnik> Potenz <Homöopathie> Heterodimere Protonation Solution Anomalie <Medizin> Emission spectrum Systemic therapy Vietnamese people Hydrogen Taxis Azo coupling Chemical structure Mixing (process engineering) Biomolecular structure
Toxicity Systemic therapy Hydrogen Resonance (chemistry) Protonation
right now I think maybe it will begin even if the last few people coming so I Wanna talk about 2 related techniques today and the related and pulse sequence they're completely different what they do 1 of them is this toxicity and 1 of them is is Rosene said taxi is a correlation experiment at Stanford total correlation spectroscopy I'll put total in quotes because 1 doesn't get an infinite number of cross peaks this sad technique was co-developed by developed at the same time with another technique that's the same sequence called wholehearted which always sounds good police announced that it Christmastime it stands for homer nuclear Hartman Hinds spectroscopy and they're the same same technique but that Taxi taxi has has taken over so the idea is that you get cross peaks where all and again I'm going to put this in quotes because there are limits on their spins and spin system nude so what this is what this technique is like is it's like a super cozy and give you a really simple example here of we have probe and all and that was sort of the of the stature of the molecule when I did the 1st encouraged to specter if you have probe in all cozy Bowling you methyl group central methylene and link the central methylene into the next methylene and assuming the wages exchanging rapidly that won't be linked in there what toxic will do since all of these groups are in the same spin system is Tuxedo will also link the methyl groups to the terminal methylene and were Toxey really really shines there sort of 2 different situations that Toxey really shines In the small molecules realm where taxi really shines is in situations of overlap In pretty good about giving inspector where there's not too much overlap and you can walk away through cozy but sometimes you'll end up with peaks overlapping and other peaks and he simply stopped being able to walk their way through and so you look and you say Hey what's going on here I can't figure out my my way all the way through South just give you a couple of hypothetical examples that there may be illustrate my thinking on this of a case where you might have overlapped so like if you take a molecule pentanol and we think about where things typically show up at its wits plain-vanilla Mathilde . 4 a methylene that's next to an oxygen say is at 3 . 5 parts per million in methylene that's abated to an oxygen that's going to be added as somewhere around 1 . 9 parts per million but by the time we get down to this methylene chain bless you you're going to have your methylene sp pretty much it unperturbed boasted about 1 . 4 4 ppm in other words if you go into the cozy spectrum you're going to get into a quagmire right here where you have trouble tracing your way through the cozy spectrum and so those types of issues if you've got multiple spin systems in the molecule and you're really trying to figure out what your fragments are those types of issues can be problematic and so again let me give you in a molecule and just sort of talk about typical chemical shifts so we'd say write Esther methylene next to an Ernesta I usually think 4 . 1 ppm plain-vanilla methylene sigh think about .period knowing metals I think about . 9 parts per million Americans group that Bader To work Carbondale I think about said about 1 . 1 parts per million in other words it's beta to an electron withdrawing groups so it's at the point position shifted down by a couple of tenths of a him but then if you think about a month following that say data to an oxygen normally I think about Imus assigned maybe at 1 . 9 ppm but being baited to an oxygen maybe it'll be about 2 . 4 ppm and normally I'll think of summer methyl group as next to an Astor as being about 2 parts per million but if it's a methylene group it'll go down by another about .period were part of William so you can easily see how a molecule like this might have to spend systems where when you try to trace your way through you get caught up and so if everything overlap the 2 . 4 it would be really hard in a cozy of a molecule like this to distinguish this spin system from this 1 in other words to try to walk your way through and see if this methyl was part of a different spin system then this manifold over here and talks he's extremely good at doing this the other thing that taxi is good is that there is a parameter that's very important in Toxey called the spin like mixing time and so when I say all other spins and spin system were typically talking about within a limit maybe maybe through about 7 bonds if you vary the spin mixing time and you can use Toxey is sort of a super cozy experiment where if you have a very short time you basically get just 1 job just like from here to here but if you go a little longer to jump starts to appear if you go longer during your spin like mixing time more and more goes you can do a series of talks experiments that'll basically walk your way from 1 spin to the next to the next and what's good is if you have a region where there is overlap and in a region where there isn't overlap so like the the overlap might be a 2 . 4 this molecule and the region that doesn't have overlapped might be it's a 1 . 1 . 9 you can go ahead and walk along those stocks he tracks and see who the coupling partner is for each and then do longer and longer mixing times to pick them all out so that's 1 really good use for for a taxi is overlap the other really good use is of college biopolymers which sounds like like something intimidating but any sort of molecule that has unit of it's spin systems better units within it so there are many types of of macro while macro like Tamsin many types of an entire batik cycle Acosta's that have unnatural amino acids that have a series of spin systems of show you some biopolymers so for example peptides and proteins and so if you think about it each amino acid in a peptide or protein is its own spin system and so forth where each you know comprises a spin system and so you can pick out of all of the spin systems and basically very quickly a sign all of the resonances in a polypeptide will do an example of this with the
psychic peptide shelters are another example we just saw Professor Peng Wu's a seminar and he was working with various types of Lagos after rides in so Interlagos Zackariah each Monroe center-right unit it is an isolated at you know it and they're often very heavily overlapped and so just giving sort of a generic cartoon of the Milingo Sakharov's structure and so each Sugar unit is its own spin system in Toxey they're very crowded together they all end up having similar chemical shifts and Toxey really shines and working with always a sackful rides In the other area that works out very well with
with toxicity is nucleic acids the NRA and ordinary where again the basic unit is sugars and bases and each sugar it is its own spin systems so you have a nuclear bases depending on the DNA or RNA you'll have a knowledge of these positions soldiers with this and in brackets so again all of these are representing kind of pieces of art of a biopolymer structure that might be might be useful for elucidating so as I was hinting at before 1 of the limits of toxicity is it doesn't go on forever and so the limits are you just say I always hate to put a hard number about 7 bonds so for example waterway I mean let's say we look at the molecule why saying so lysine is an amino acid with the 4 carbon chain put this is but this is part of a biopolymer so if you're talking about tracing your way From the Absalon carbon to the nth through you're going from 1 2 3 4 5 6 7 bonds that's about as far as you would go and so in other words you'll end up having this hydrogen if you do it right crossing with all of them are Filene's along the way giving cross speaks as well as if you do it right the NH replies to do the experiment due to low in which case the NH from people will have exchanged so as I said the parameter is the key parameter is a mixing time but in typical this is 1 of the experiments the the experiments downstairs that like a cozy experiment were and HM QC experiment during a gym BC experiment the parameters Jon Greaves gives you a few take this sort of default hurts and h NBC experiment that's going to be once I started fits all In the case of a taxi experiment you actually have to think intelligently about the experiment typical values are about 75 to 100 milliseconds spin market mixing time and you obviously want to go to the high end to pick up longer correlations you might go up to say 200 milliseconds If you go shorter particularly if you're down and sort of in the let's say 25 to 75 range you'll be using the experiment as kind of a super cozy but 1 where you can walk away from 1 by 1 to the next and the next know what are the implications for your own project is that I'm with strict line is because strict 9 has some really extended spin systems you may not be able to trace your way through all of the spin systems but you'll be able to get part way the other limitations so obviously so 1 limit is the number of bonds the other limit is your coupling basically proceeds are directly depending on how strongly things are coupled in other words if you have a very small J. that can lead to an absence of cross peaks so it's not so much an issue with a flexible chain but if you come down to strict meaning your tracing your way through a spin system were 1 died role as close to 90 degrees year coupling constant is very small you know Hirtzer 2 or 0 hurts if you a really small coupling constant taxi may not take you through basically you need to have some reasonably large couplings you may see things behaving as if the isolated spin systems were nearly nearly isolated spin systems so at the end now the nice thing about Toxey as a citizen to Burry good at dealing with overlap and all show you in just a moment an example where you just would be struggling like crazy by cozying were assigned you know a zillion different protons in 1 fell swoop there is an alternative that's extremely powerful will talk about it in the last week of classes and that's the HM QC toxicity so toxic it works as long as you can find some regions where there aren't overlap and you can get like 1 resonance that isn't overlapping but if you've got really bad overlap you may even have trouble tracing their way through the taxi HM QC taxi is a variant that's like taxi but it has other dispersion of the 13 dimensional members see 13 residences because you have to 200 ppm end up having very little overlap and the dispersion can be very very powerful that's too much for us to assimilate at this point so let me just dumb let me just say I'll I'll show you that in the future alright what I'd like to do now is to talk about give us an example of 1 molecule we're going to assign every resonance in this molecule In the molecule is Grandma side yes sedated In it's a non ribosome 0 peptide with that means is it's not synthesized by the traditional tiara and a DNA .period messenger RNA to urinate mechanism and its structure consists of 5 amino acids that are repeated tries and some going to draw broader structure of the molecule all draw kind of in a stylized fashion because I think that's that's actually useful for reflecting the confirmation of the molecule so the molecules starts with a probably In and we next continue with that of failing it is and we next it's a non non Rivasseau polypeptides so we next have an unnatural colored unnatural amino acid but it would be better as saying on fruitiness generic known ribosome amino acid and so the next 1 label this is failing the next 1 is on a thing Warner seems like lysine except instead of having a for carving chain and has a 3 carbon chain so 1 2 3 the next amino acids in the molecule is Lucine In the final amino acid before we feed ourselves it is the unnatural and and anti Amir of phenylalanine so that's D phenylalanine and so that's half the molecule and then the molecule repeats itself slightly right
loosening up here then the molecule repeats itself and so now we're going to continue around With Colleen In next amino acid is failing and then we come to on the thing once again and then we come to Lucena I just try if you know if you know what a drawdown that's that's fine too but it this is still have anything better to be doing right now after all as you've been as you can see there are a lot there are lots of different hydrogen is In this molecule and 1 thing to keep in mind is there's actually some sense that all of this in other words you work in a molecule like this and you'd say Oh well OK alpha proton sets the proton that's directly next to the nitrogen in next to the carbon and you're going to say 0 wait that's next to an electron withdrawing group its tertiary and it's invaded its Alpha to Aqaba Neil and say it's a OK well you know tertiary brings you down field next to a carbon meals sits you down field next to an electron withdrawing group shifted downfield and you end up in the fortified part per million rand or you look after beta protons say family that's 1 over and he'd say all all OK now that's data to an electron withdrawing groups so that's going to go downfield a little bit it's tertiary so that's going to go downfield Wilbert so it's going to be a little downfield of 2 parts per million were you look at the gamma protons the ones on the methyl groups and you're gonna say OK OK those are methyl groups that are really to anything so those of you like .period minor maybe maybe 1 ppm and so several English again have powerful they die Gamma Delta for this 1 the union will have Alpha Beta Gamma Delta for the Lucien an alpha and beta then all the finals which if you wanted to you could call them that affects all etc. and then some relief for the pros rolling data and so we start to make some sense of now 1 thing that's nice even if you're not an expert in this series even if you don't do this stuff a lot what's nice is OK you can always sort of worked out where things typical lady show up in so I I will start with it will hand out for you and basically what what these data that I'm passing out are really just what we've we've enjoyed it when I started to go through the valley in there with an example 3rd just typical chemical shifts of unstructured amino acids in the water by unstructured I mean not part of any sort of alpha-helix she and so pretty much just as I went through and said Hey we can into that you're alpha proton on your Bailey is going to be somewhere in the fortified parts per million region in your data protons in the somewhere a little down field of 2 parts per million and your damn of protons are going to be somewhere around .period knowing parts from here and you can go ahead and look that up and you can do the same thing for Lucine and said this basically provides you with good guidance for things you might might already be really really know I'm in other words you work say 1 of the main and you'd say OK well in a worship the Delta protons it on a thing show up well you got this ammonium group next to them nitrogen isn't as electron withdrawing seat sale about 3 parts per million but you can look and say OK at lysine word is it safe for the Epsilon protons and lysine and you'd say Oh OK about 3 parts per million by intuition is correct so this can be a nice helped the flip side gives you all 20 of the protein eugenic amino acids so you don't have to what don't have to go ahead and know exactly what they are alright so we're gonna use these to help us sign a residences but of course ultimately because things will vary this compound has some structured to it it happens to adopt the beta-sheet structure things may not show up at exactly these positions plus every amino acids neighbor was shifted around but you can look and say OK we're what I expect say the beta protons of phenylalanine to shopping you can say well it's a naphthalene it's going it's next to a benzene ring it's faded to a nitrogen in say somewhere around 3 ppm or you could go ahead and say what were what I see for phenylalanine only I'd seen somewhere around 3 . 4 million or what I would like to do at this point is for us To look at the actual Toxey spectrum of grammar side and as so to answer your question yes the structure is written out so if you're drawing really did look like a disaster there you have it here but then you'll have to to keep have to keep flipping and flipping over and over again today to keep a labeling our resonances are so what's wanted out it's only good for 1 will have written evidence to rule out on the floor you and it's not even Christmas time so whenever I'm dealing with a heavily overlapping spectrum and I want want to help my eyes out I like to slap agreed on the thing just held helped me see things line up from you can also use a ruler but it's very very nice and very gentle 1 your eyes to be able to say trace across peek over and interest across the right up over here so I I like to do that I what's because taxi is like a Super Cosi you basically can trace entire attract off of taxi and get everything in a spin system now remember spin system isn't always the whole amino acids so for example in phenylalanine the benzene ring is 1 spin system that separates for all intents and purposes not coupled to the alpha proton the debate Proton and the age Proton will grow and grow and you might enrage so this happens to be a spectrum indium ourselves that this is India Moselle and this particular 1 happens to have they 70 8
ms been locked it's been mixing time now 1 thing about molecules with NH is in no choose those generally exchange rapidly so if I took a spectrum in G 2
0 we would just C H O D people like we did in our cycle comedian in around hydroxy probably problem we just C H the but DMS OG 6 the protons don't exchange you're going to have an H is and so forth there if you wanna see Iran ages in water you can actually do and expect an experiment where you use 15 where you use 90 per cent H 2 0 and 10 per cent D 204 locking so most of your protons 90 per cent of the proton stay as in ages and then use water suppression because you're working with no moles of compound in 100 Moeller watering at 55 50 Moeller H 2 0 the 100 Moeller alright so let us start and let's look at the anatomy of the spectrum so the anatomy of our spectrum and I'll show you along this axis your alpha protons are over here your math are over here your in ages moreover here this is your fennel groups so I'll label it will put all of our labels here so this is our fennel group from the phenylalanine and let's see you've got some some bidders in Damazin and Delta's Over here itself so that that kind of gives us our starting anatomy right arm baffles are kind of at the . 9 ppm range you're Alpha's added directly next electron withdrawing groups are down here shoes that are attached to the search for here or what we're going to do now is used to assign every resident so I want to show you the power of the toxic technique in will just take a single track in the taxi so I'll
start off of this peak here that's a tight little double-edged and I'll draw a line just to help my trace along with and you look at it you say OK so what sort of residue has an alpha proton ended a couple of protons at about 3 parts per million Is it the failing Was the have it's been system b and what types of protons do we get in there veiling were what residues what you have haven't daily that you don't have in say on Athena phenylalanine were probably method so we would expect cross peaks somewhere up here so it's not availing it's not only same so we have Alphaproteobacteria 1 other sort of protons in that rests in that residents of what is that residents and this protons are right around 3 parts per million so phenylalanine because we just have 2 other protons the 2 a stereotype that they'd approach times so you trace your way up here and in this cluster of 3 which we could expand upon his year the alpha and you trace your way up here and here a year to die history a topic the status and you can kind of see the ABX patter of 1 of the few data tempting to the that basically assigns 1 of our resident alright let's go on to another 1 but me take this taxi track so I'm gonna label this guy as well he Zerphey and 8 so we are going to sign all the resonances here so let me take this next taxi track so what is this crossed the method solicited failing a Lucien and what I say about the gamma Proton of the bitter protons availing must Marcelline typical it's baited to an electron withdrawing groups it's typically about 2 we will further downfield into this is so this is our Hussein itself this is the NH This is our Lu it's all just trace that up to here on the diagonal so there's our Lou In H so Ahlu math souls are hiding right in this cluster here so that is our Delta and then Ahlu bathers and gamblers are lumped together over here where surveillance hiding I'm 1 just below it look at that meeting the Devil sneaky devil at Vail in NIH is hiding right under the fennel group and you wouldn't have known it except that Dornfeld it is not part of a spin system With methyl groups and here we see the crossed speak for our Valionis they are gamma protons the metals and here's the cross Pete for where are availing beta proton and look at that that billing data Proton has a nice pattern because it's a hydrogen that splits by the math foals and also displayed by the McKnight it actually ends up being the double-edged of Sept Texas the one-day a wanted technical analysis and hiding under here is our alpha proton exciting I meant to mark I marked our betas Indiana as I mark their Lou H and sulfide trace out here that as the loo althought son got a label him because we're going to victoriously a sign every resonance here so OK we got our Alpher now let's go on and we'll do our Valionis taxi track so sneakily hiding under here is our Vail NH underneath this group here Is there a veil Alfonse right close to the fennel phenylalanine Alpha here's our veiled data In underneath the methyl cluster a little bit often decide if
you trace your tracks is your veil Dennis Our so we've got are available this is our fennel aren't so what we have left left to trace out so we've got we've got 1 more this is the whole NH Region here so we've got 1 more age but something's funny something's funny about this what's left for Inter 1 of the sprawling doesn't have a mandate to the 1 amino acid that doesn't have a mandate to this has to be this has to be on a thin and yet you look at this guy and you say Wait a 2nd OK so we've got our Alpha here we have this has to be 1 we've got our Alpha that's the alpha over here we've got a bunch of stuff over here but remember what I said the delta of 1 of the like the delta of lysine it's like the epsilon of license right it's next to an ammonium group should be at about 3 parts per million we don't see a track now we're doing 78 Ms spend a lot of time remember I said the longer the spin what time the more jobs you can make but forces the big caveat if you go to a long you've got relaxation you also putting a lot of power into the spectrometry for the spin locked mixing she can't go to longer and returning your sample into to cooked the eggs is going to be heating it up with all the radiofrequency radiation so you have to go 6 hops to go from the ALF approach from the NH of on a thing To the Delta protons of 1 the and were not quite going there and 78 Ms been locked mixing time so normally if you go there you see the same tracks repeated again and again so for example you get a toxin track for the phenylalanine Alpha's where you can see see here you get that the I'm on the phenylalanine you get the betas and you'll get the alpha proton here and in the NHL for here but here were not getting all Oliver cross speaks of regaining our order seeing you getting your 115 betas in their right under here but not new on the scene epsilon but look what happens now if we haven't gone all the way through I can just pick a different Toxey track so instead of starting at the on scene NHI started the on alpha proton now look you get 1 more cross speaks you still have this cross here but now we get 1 more and there's are missing on that 1 Delta Proton and so the on Delta if you trace it up traces out right underneath Over here so it's right I we have only 1 residue left to assign at this point all we have left to assign is this by the way is our ammonium so this is a N H 3 plus and so all I need to do is pick an unclaimed residue and work my way through so we haven't played this guy right he kind of stands out and he's got to be something associated with the probably in his too far upfield to be a probably an alpha proton so he's are probably not dealt the proton right Alpha Beta Gamma Delta so there will start with our prowling Delta proton and I'll just draw my taxi track of course doesn't have an innate so we have nothing out NH regions and I can just Tracy all of my crusty so we have our Pearline Delta Over here and then I can trace these guys up here so here's my probably in Alpha it's slumped right under here looks like it's a little bit downfield so it's that guy right at the edge there's a pro Alford there's pro Delta right over there just groups and then these guys over here are probably invaders and Gamez so I can just trace them trace them right up and it's basically 1 of them's lumped under our water peak and then 1 of them over here In the end the last 1 is kind of right over here and so these guys Our are Kroll data modem and so the point and this is in very short order we've gone ahead and been able to get all of our
residents assignments for I don't even know how many different protons but fun show different protons in it was a lot less painful lot were quick in trying to trace our way through cozy and the cozy in that region with Obadias in gamblers were things overlapped heavily we would have been completely stumped we would have traced our math falls into the beta and gamma region and never been able to trace our way over to the Lucina LFO or the Lucien NH from time we would have been lost since this is a very nice example of how Hoxie deals with overlaps are the last experiment I wanted to is rosy we've already presented nosy knows the user to Indiana we experiment the big problem with no solution is that you go from having positive and always To having negative and always as you go from small molecules to very big molecules in that intermediate range molecules of say molecular weight of let's say about a thousand to 15 hundred you often have 0 I know ladies In what role as saying it is and always in the rotating frame rotating frame over house effect so it's basically like nosy but for intermediate weight it's actually the same pulse sequences of taxi it uses a different level of power in the spin lock mixing and so it's good when you have molecules that have 0 and always so I wanna go ahead and show us the nosy spent the rosy spectrum for grammar Seidman Esq and Rosie is particularly good for for dealing with Styria chemistry and conformational analysis just as we used and all ways to deal with stereo chemistry and conformational analysis in proximity you can use rosy for the same thing so I'll show you an example and I'll show you 1 little highlight so here is our old and I should give you your next out in exhaled give us to handouts striking finishes up so this is the 1 I'm handing out right now is the rosy spectrum of grammar side Aston I just want to show you what it's showing about the confirmation of the molecule In what I'll do is just give us a little hint of the upcoming homework said were will use use Roseann taxi a few more days if there aren't enough sweep them sweep them over I made I made enough of these odds of actually I've actually draw on the molecule of drawing grammar Sidon as in a realistic confirmation it's actually this extended conformation and what's cool about this extended beta-strand confirmation is you can basically trace your own way From residue To residue so each of your alpha proton pointing basically your side chain is pointing out at the blackboard and back into your blackboard the hydrogen here is pointing like this the hydrogen here is pointing like this the alpha hydrogen years pointing like this for the billing side chains pointing out and so this ends up doing is it puts the inter-residue distance as very short and actually gives you a much further intro residue NHL distance so let me show you how this manifests itself in the rosy spectrum of the molecules so this
region here and of course this region here Is the cross peaks between the NHS and the Alpha's right because we've got our NHS here in the ppm Range in the office in the fortified ppm range so we've just blown this out over here this is actually from Nakanishi books and candy she blew this up so let's go ahead and look at saying this crossed speak here this is a cross peak between phenylalanine NIH and while Fla and you notice that that crossed speak is very very strong right here our free and years our luau far and then if you look at the other causes the the of the age it's much weaker this is our this 1 here is our Lu Lu of Lou Alpha this is our our I'm sorry our fee the Alpha the NH to the Alford much weaker because they're not staring at each other in the face we see that same behavior over here this 1 here is our Luanne H To on alfalfa then again these guys staring at each other in the face years the Luening furiously on Alpha and you'll notice the crossed the with the aim of the aged and the luau much weaker remember and always across speaks very as distance the inverse 6 so if you have 2 hydrogen that are close to each other like 2 and a half systems you get a much stronger in a week that if you have hydrogen so further apart like three-and-a-half Frank Stronach member that table I put out of relative intensities were recited tenfold difference in intensity of Anallese finally here you have the worn and aged avail Althoff and so that that this 1 right over here so you can see this sort of extended beta-strand confirmation of molecules OK you're going to use this exact same type of analysis in your homework to design all the residues in this molecule which forms a hydrogen bonded dimer and I want to give you a couple of little hints on at 1 of the little hands is in assigning your resonances you'll be able to identify these methylene this methyl and naphthalene you'll be able to use we used to walk your way over you'll be able to use Posey and Toxey to walk your way through the aromatic rings systems you'll be able to look for hydrogen is that are close to each other across the ring and see evidence of dimerization in your structure if you have to hydrogen is that a symmetrical you won't see across peak between them
because they're they're 1 resonance anyway go ahead and have fun with this you will actually be able to apply the same skills that basically work your way through the spin systems do the toxicity to get all of your assignments and then do the rosy to go ahead and figure out which I regions are close to each other you can't you can't see a proton with itself because if you have 1 hydrogen at 4 ppm and it's the same hydrogen at 4 ppm you can't get across speaks so those 2 were symmetrical are so that'll be something you'll be doing doing I guess over the over the weekend


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