WATOC 2014 – Virtual edition


I had a blast last week at WATOC2014 in Santiago de Chile! It was a wonderful opportunity to find old friends, meet new ones and listen to some exciting research done around the world, as well as some of the classics such as Pekka Pyykkö, who was awarded the Schrödinger medal. I decided to share my talk on SlideShare.com but also here because I found at WATOC that many many people seem to like this little space of mine! I was shocked, flattered but mostly happy to know that this little blog of mine is well regarded.

So, without further ado, here is my presentation at WATOC2014, please read the captions on each image for context. Feel free to make any comments, sharing or liking. Thanks for clicking!

Self explanatory :)

Self explanatory :)

Administration of a drug follows one of these two extreme pharmacokinetic pathways. Either way, drugs accumulate in non-target tissues, are wasted and cause undesired secondary effects.

Administration of a drug follows one of these two extreme pharmacokinetic pathways. Either way, drugs accumulate in non-target tissues, are wasted and cause undesired secondary effects.

Ideally, a drug should arrive to the target tissue. Several polymolecular drug carriers have been developed.

Ideally, a drug should arrive to the target tissue. Several polymolecular drug carriers have been developed.

In terms of monomolecular carriers, cyclodextrines have shown moderate success.

In terms of monomolecular carriers, cyclodextrines have shown moderate success.

Calixarenes offer a more chemically-tunable alternative.

Calixarenes offer a more chemically-tunable alternative.

We decided to go with drugs for the treatment of chronic myeloid leukemia

We decided to go with drugs for the treatment of chronic myeloid leukemia

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Interaction energies were calculated with the NBODel approach, in which elements of the Fock Matrix common to two molecular fragments are deleted

Interaction energies were calculated with the NBODel approach, in which elements of the Fock Matrix common to two molecular fragments are deleted

This deletion yields a new Fock matrix which is re-diagonalized; the increase in energy is ascribed to the interaction between both fragments.

This deletion yields a new Fock matrix which is re-diagonalized; the increase in energy is ascribed to the interaction between both fragments.

GTP was a small place to start (chemical space blocked due to animation lost in translation)

GTP was a small place to start (chemical space blocked due to animation lost in translation)

Interaction energies obtained

Interaction energies obtained

Hydrogen bonds and pi - pi interactions account for the large interaction energies

Hydrogen bonds and pi – pi interactions account for the large interaction energies

Diapositiva13

Detail of the interactions in some of the obtained geometries

 

 

MD simulations show the progress of the "release" process.

MD simulations show the progress of the “release” process.

So we moved to a larger drug with more degrees of freedom (and a comercial one too)

So we moved to a larger drug with more degrees of freedom (and a comercial one too)

Chemical space increased regard to the one used with GTP.

Chemical space increased regard to the one used with GTP.

In both cases, two insertion modes were considered.

In both cases, two insertion modes were considered.

Some results...

Some results…

100ns of MD show three kinds of structures (inserted, partially released and totally released)

100ns of MD show three kinds of structures (inserted, partially released and totally released)

PMF US - the profile of release tells us if the carrier is way too strong to be a carrier at all.

PMF US – the profile of release tells us if the carrier is way too strong to be a carrier at all.

Where do we go from here?

Where do we go from here?

Second generation CML drugs; however Bosutinib poses a funny challenge

Second generation CML drugs; however Bosutinib poses a funny challenge

A comercial error has released two isomers to the market, only one of them actually works. CAN WE GENERATE A RECOGNITION AGENT??

A comercial error has released two isomers to the market, only one of them actually works. CAN WE GENERATE A RECOGNITION AGENT??

I know, some results need  some attention, I know, trust me.

I know, some results need some attention, I know, trust me.

Also, Imatinib is cardiotoxic. We research now the competence between allegedly affected enzymes and the carriers to at least delay the toxic effect.

Also, Imatinib is cardiotoxic. We research now the competence between allegedly affected enzymes and the carriers to at least delay the toxic effect.

Diapositiva26

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Diapositiva27

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Thanks to all of these wonderful guys who made all publications possible (and also those who gave the money)

Thanks to all of these wonderful guys who made all publications possible (and also those who gave the money)

(The view from my office in Toluca) Any questions?

(The view from my office in Toluca, Mexico) ANY QUESTIONS? Write it in the comments section!

 

If you made it this far, let me tell you that this is also available at Slideshare.com :)

Thanks for reading, commenting and sharing!

WATOC 2014


I inexcusably forgot to write about my visit to WATOC2014 but as they say it’s better late than never. I’ve been here in Santiago de Chile for a day and a half now attending mostly to session 5 “applications to compelling problems”. WATOC (World Association of Theoretical and Computational Chemists) is probably the largest conference in our speciality and some of the big names are here which makes me very nervous to present my talk!

My talk will be very similar to the one presented in the last ACS meeting in San Francisco, in silico design of monomolecular drug delivery agents based on calix[n]arene macrocycles.

I wont try to report from WATOC, I’m not any good at that but will for sure be available if anyone wants to contact me.

248th ACS meeting – San Francisco 2014


This is my first time giving a talk at the ACS meeting so I’m a tad nervous but also excited about the possibility to listen to so many great researchers and hopefully interact with some of them, although such a massive event is hardly the best place to build a network.
My talk will deal with our recently published work on calixarene based drug carriers and the new results we are currently getting, and will take place on Tuesday 12th at 16:15 at the session regarding the use of small macrocycles in drug discovery. Feedback is very important to us so we look forward to some heavy criticism of our results.
If you are there, download the free app which will show you around the different presentations and stands.

IMG_2816-0.PNG
I will also make use of twitter to move from one lecture to another. See you there!

New paper in JACS


Well, I only contributed with the theoretical section by doing electronic structure calculations, so it isn’t really a paper we can ascribe to this particular lab, however it is really nice to see my name in JACS along such a prominent researcher as Prof. Chad Mirkin from Northwestern University, in a work closely related to my area of research interest as macrocyclic recognition agents.

In this manuscript, a calix[4]arene is allosterically opened and closed reversibly by coordinating different kinds of ligands to a platinum center linked to the macrocycle. (This approach has been referred to as the weak link approach.) I recently visited Northwestern and had a great time with José Mendez-Arroyo, the first author, who showed me around and opened the possibility for further work between our research groups.

(Ligands: Green = Chloride; Blue = Cyanide)

Closed, semi-open and fully open conformations; selectivity is modulated through cavity size. (Ligands: Green = Chloride; Blue = Cyanide)

Here at UNAM we calculated the interaction energies for the two guests that were successfully inserted into the cavity: N-methyl-pyridinium (Eint = 57.4 kcal/mol) and Pyridine-N-oxide (Eint = +200.0 kcal/mol). Below you can see the electrostatic potential mapped onto the electron density isosurface for one of the adducts. Relative orientation of the hosts within the cavity follows the expected (anti-) alignment of mutual dipole moments. At this level of theory, we could easily be inclined to assert that the most stable interaction is indeed the one from the semi-open compound and that this in turn is due to the fact that host and guest are packed closer together but there is also an orbital issue: Pyridine Oxide is a better electron acceptor than N-Me-pyridinium and when we take a closer look to the (Natural Bonding) orbitals interacting it becomes evident that a closer location does not necessarily yields a stronger interaction when the electron accepting power of the ligand is weaker (which is, in my opinion, both logic and at the same time a bit counterintuitive, yet fascinating, nonetheless).

Electrostatic potential mapped onto the electron density surface of one of the aducts under study

Electrostatic potential mapped onto the electron density surface of one of the adducts under study

All calculations were performed at the B97D/LANL2DZ level of theory with the use of Gaussian09 and NBO3.1 as provided within the former. Computing time at UNAM’s supercomputer known as ‘Miztli‘ is fully acknowledged.

The full citation follows:

A Multi-State, Allosterically-Regulated Molecular Receptor With Switchable Selectivity
Jose Mendez-Arroyo Joaquín Barroso-Flores §,Alejo M. Lifschitz Amy A. Sarjeant Charlotte L. Stern , and Chad A. Mirkin *

J. Am. Chem. Soc., Article ASAP
DOI: 10.1021/ja503506a
Publication Date (Web): July 9, 2014

 Thanks to José Mendez-Arroyo for contacting me and giving me the opportunity to collaborate with his research; I’m sure this is the first of many joint projects that will mutually benefit our groups. 

 

Science in the World Cup


So the World Cup is once again on top of us. I’m not a Football (Soccer) enthusiast but I’ve got to admit that the expectation of such a large and widely covered event is pretty contagious. This year, however, I’m very excited about the inaugural kick-off ceremony because a paraplegic teen will be the one to set the ball in motion, thanks to the use of an exoskeleton developed by the illustrious Brazilian researcher, Dr. Miguel Nicolelis, this patient will not only walk again but also perform a feat of equilibrium: kicking a football. More impressive than the exoskeleton itself is the brain-computer-machine interface since the patient will control the entire process by himself. Miguel Nicolelis is widely known and highly regarded in the scientific community; I’m not sure if he is that famous outside academia, but if he isn’t, he should be. The natural question about Dr. Nicolelis is what is he? Is he a robotics engineer? a neurologist? a programmer? a physician? The answer could be no other than ‘all of the above‘.

And even more impressive than all that, if that’s even possible, is the fact that this huge achievement of technology is presented at one of the most viewed sporting events on the planet. Brazilian organizers could have selected many things to kick-off this event: From Adriana Lima to Pelé; from a Samba line to aboriginal Amazonian people, but instead they chose to go with a scientific and technological breakthrough achieved by one of their own. I wonder if this is a way to tell the world they are interested in investing in science and technology as a way to pave the way of their economical and social development. Brazil is currently regarded as a fast growing nation economically although the social disparity seems to be still quite large. The message I’m getting, at least in principle, is that Brazil is a modern nation with high regard for scientific development on which they will rely their future.

Kudos to the Brazilian organizers who thought of placing this large scientific breakthrough in a sporting event, proving that this world should become boundless and the way to do it is through science.

Some .fchk files wont open in GaussView5.0 (Update)


A couple of weeks ago I posted a solution for a common error regarding .fchk files that will display the error below when opened with GaussView5.0. As I expected, this error has to do with the use of diffuse functions in the basis set and is related to a change of format between Gaussian versions.

CConnectionGFCHK::Parse_GFCHK()
Missing or bad data: Alpha Orbital Energies
Line Number 1234

Although the method described in the previous post works just fine, the following update is a better approach. Due to a change of spelling between G03 and G09 (which has been corrected for G09 but not available for GV versions prior to 5.0.9) one must change “independent” for “independant

To make the change directly from the terminal the following command is needed:

sed -i 's/independent/independant/g' file.fchk

Alternatively you can redirect the output to a new file

sed -e 's/independent/independant/g' file.fchk > newfile.fchk

if you want to keep the old version and work with a new one.

Of course this edition can be performed manually with any text editor available (for example if you work in Windows) but solutions from the terminal always seem easier and a lot more fun to me.

Thanks to Dr. Fernando Cortés for sharing his insight into this issue.

If a .fchk file wont open in GaussView5.0


I’ve found the following error regarding the opening of .fchk files in GaussView5.0.

CConnectionGFCHK::Parse_GFCHK()
Missing or bad data: Alpha Orbital Energies
Line Number 1234

The error is prevented to a first approximation (i.e. it at least will allow GV to open and visualize the file but other issues may arise) by opening the file and modifying the number of basis functions to equal the number of independent functions (which is lower)

FILE HEADER 
FOpt RM062X 6-311++G(d,p) 
Number of atoms I 75
Info1-9 I N= 9
 163 163 0 0 0 110
 2 18 -502
Charge I 0
Multiplicity I 1
Number of electrons I 314
Number of alpha electrons I 157
Number of beta electrons I 157
Number of basis functions I 1199
Number of independent functions I 1199
Number of point charges in /Mol/ I 0
Number of translation vectors I 0
Atomic numbers I N= 75
... ...
... ...

Once both numbers match you can open the file normally and work with it. My guess is this will continue to happen with highly polarized basis sets but I need to run some tests.

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