Molecular switches as motors of molecular machines
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| License | CC Attribution - NoDerivatives 4.0 International: You are free to use, copy, distribute and transmit the work or content in unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
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00:00
MoleculeComputer animation
00:09
Materials scienceMoleculePolymerSurface scienceWalkingChemistryFunctional groupSea levelMolecularityCancerMeeting/Interview
01:07
Meeting/Interview
01:23
BenzeneMoleculeUltraviolettspektrumIsomerMeeting/Interview
01:40
Separation processMoleculeMachinabilityTool steelFunctional groupMolecularityChemical compoundMolecular geometryMeeting/Interview
01:52
Phenyl groupOptische AktivitätMoleculeChemical experimentMolecular geometry
02:00
Optische AktivitätPhenyl groupSystemic therapyChemical propertyFunctional groupMeeting/Interview
02:25
MoleculeChemical propertyChemical compoundMolecular geometryMeeting/Interview
02:36
Chemical propertyComputer animation
02:47
ConflagrationWursthülleMoleculeMeeting/Interview
02:59
Carcinoma in situComputer animation
03:07
Operon
03:14
MoleculeMeeting/Interview
03:24
DyeingBenzeneRiver sourceAgeingSubstitutionsreaktionGeneAusgangsgesteinChemical compoundSystemic therapyWursthülleReducing agentEthyleneAzofarbstoffNitroverbindungenBiosynthesisChemical experimentMeeting/Interview
03:59
Functional groupWine tasting descriptorsReducing agentDeathSubstituentAzofarbstoff
04:30
Functional groupSubstituentBiosynthesisChemical experiment
04:50
EthanolSolutionSodium hydroxideZincDiagramMeeting/Interview
05:05
NitroverbindungenEthanolChemical experiment
05:17
Chemical experiment
05:26
SolutionStarvation responseSodium hydroxideSuspension (chemistry)EthanolMolar volumeChemical experiment
05:42
Potenz <Homöopathie>ElektronentransferPowdered milkZincQuartzSolventWater purificationChemical experiment
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Chemical experiment
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SauceLamb and muttonElimination reactionPotenz <Homöopathie>Chemical experimentMeeting/Interview
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Chemical compoundAgricultureMicrobial cystColourantChemical experiment
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SeleniteCarcinoma in situThermoformingChemical experimentMeeting/Interview
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MoleculePhosphateBinding energyChemical reactionTiermodellSubstitutionsreaktionIonenbindungRadioactive decayThermoformingWine tasting descriptorsActive siteSynthaseSubstituentPhenyl groupChemical experiment
Transcript: English(auto-generated)
00:09
My name is Reiner Herges. I'm a chemistry professor at the University of Kiel. Our research interests are centered in the field of molecular nanosciences.
00:20
Practically every engineering task that we know from our macroscopic world, like motors, pumps, information storage, is already realized at the molecular level in nature. And we think that the elementary step in these more sophisticated functions is a switching event. So in order to perform more sophisticated functions, we need switching molecules.
00:48
And these switching molecules have to be put on the surface or implemented into functional materials. In order to give you an example, I'm presenting a polymer film here in which we have implemented one of our switching molecules.
01:27
The most frequently used and well-investigated switching molecule is asobenzene. It is most stable in its trans configuration and upon irradiation with UV light it would undergo cis-trans isomerization.
01:42
But there are several disadvantages of asobenzene. It's a very flexible molecule. It can flap to either this or the other side. And there's free rotation around the phenyl groups. So to construct molecular machines, motors, we need more rigid molecules.
02:03
In order to achieve that, we have bridged the two ortho positions of asobenzene and end up with a bicyclic system. This diastocene has improved properties. There is no free rotation of the phenyl groups anymore.
02:21
We have higher switching efficiencies and we can switch with visible light. But before we go to the laboratory to make these molecules, we are calculating them in the computer. Here we have 20 candidates of conceivable switching molecules which are optimized using a density functional theory method.
02:45
We know the properties and now we set up a ranking list of the best candidates. And of course we would try to synthesize the best molecules with the optimized parameters. In this case, this was the diastocene as we can see here.
03:03
This is most stable in the cis configuration and less stable in the trans configuration. And we can switch it using visible light. And now we are going to the laboratory to visit my PhD student, Hanno Zell, who is actually making this molecule.
03:25
Hello, my name is Hanno Zell. I'm a PhD student in the Herges Grüd and I am dealing with the synthesis of diazosines. Diazosine is a modified optimized asobenzene. And as you know, there are many ways to prepare asobenzines.
03:41
But we found that in case of diazosine, the most suitable synthesis is the reduction of the corresponding nitro compound to the azo compound. So in case of our parent system, the diazosine without any further substituents, we start from the dinitro divenzyl with the nitro groups in the auto position of the ethylene bridge.
04:14
And after reduction, this leads to our azo compound, the diazosine without any further substituents.
04:27
We now try to make substituted diazosines. And this makes the synthesis a bit more complicated because the reducing agent
04:41
has to be compatible with the introduced substituents and the functional groups therein. It turned out that the best reducing agent for this purpose is zinc with sodium hydroxide in an ethanol solution.
05:02
Now I demonstrate how we do it in practice. The starting material is a nitro compound. And at first, we suspended in ethanol.
05:29
To this 90 milliliters of an ethanol suspension, we now add 50 milliliters of a 12 molar sodium hydroxide solution.
05:48
Finally, we add the zinc powder and reflux for 30 minutes. And after work up and purification, we obtain our product as yellow crystals which dissolve in organic solvents.
06:15
Hello, my name is Benjamin Salmon and I'm a PhD student in the workgroup of Professor Herges. I build the light sources and in contrast of using traditional macro lamps for illumination, we use commercially available high power LEDs.
06:30
So this is our compound in the cis form. And if we eliminate it, it isomerizes to the transform which is red colored.
06:45
Upon irradiation with green light, it isomerizes back to the cis form which is yellow.
07:00
So this is actually the molecule my PhD student made in the laboratory. It is able to grab another molecule and to release it, but we are more ambitious. We want to make molecules that are able to make other molecules. In order to achieve that, we have to attach more sophisticated substituents at the both phenyl rings.
07:27
Imagine we have two substituents. Each of them is able to bind a monomeric molecule, two phosphate molecules for instance, at the two binding sites.
07:42
And upon irradiation, we can now bring these two molecules in close proximity, form a bond, and upon irradiation with visible light, we can release the product. So if we would achieve that, we would have a very simple model of the ATP synthase which is able to make ATP from phosphate and ADP.
08:07
So we can drive chemical reactions away from the thermodynamic equilibrium. This would be our final goal.
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