Friday, February 20, 2015

Visible-Light-Driven CO2 Reduction with Carbon Nitride: Enhancing the Activity of Ruthenium Catalysts #chempaperaday 195

A carbon nitride and ruthenium complex system with 4 different Ru complexes are reported in this article. The authors state that these results are "the best values that have been reported for heterogeneous photocatalysts for CO2 reduction under visible-light irradiation to date." I am trying to design and synthesize homogeneous catalysts, but I always have great interest in heterogeneous systems.

Below you can see their CO2 reduction abilities. 

The German Chemical Society (GDCh) and Nazi Germany #chempaperaday 194

For those interested in history of science and chemistry, this is a short and a good article.

"all sciences and engineering were involved in the planning of the war, but chemistry played a central role; hardly any area of the war effort was able to do without the help of chemistry, for example in the synthesis of gasoline, new polymeric materials, or the availability of explosives.

A simplified summary is that the DChG was a society for (inter)national researchers in academia, whereas the VDCh represented predominantly the German industrial chemists. The leading scientific
journal of the DChG was the Berichteder deutschen Chemischen Gesellschaft, whereas the top-tier journal of the VDCh was Angewandte Chemie."

I am glad to learn that a new book is coming very soon:

Chemiker im “Dritten Reich” Die Deutsche Chemische Gesellschaft und der Verein Deutscher Chemiker im NS-Herrschaftsapparat


Sunday, February 15, 2015

One Hundred Years of the Fritz Haber Institute #chempaperaday 192

Fritz Haber Institute is one of the "sub" institutes of Max Planck Institute. Unless you are interested what they do, you probably have not heard of the institute. Since, I follow some of their research areas, I can say I know a some about the institute and in fact it would be an honor for me to work there one day in the future.

So I was really happy when I came across this paper about a month ago. It's a short history of the institute and the research within covering one hundred years. I am glad I read it because I was able to learn much more than I know about FHI. I did not know FHI had seven Nobel laureates for example.

                                                                   Photo: Wikipedia
If you read the paper, you will learn how much the institute contributed to modern science especially in surface chemistry, heterogeneous catalysis and electron microscopy. I would like to highlight a few titles that were also related to FHI: gas masks, methane detector, allotropes of hydrogen, symmetry. 

The fields of research explained by the paper are:

Gas-Phase Kinetics and Dynamics
Methane Detector
Haber-Born Cycle
Sttatistical Mechanics
The Franck-Hertz and the Compton Effects
Theoretical Chemistry
Molecular Beams
Colloid Chemistry
Electron Microscopy
Surface Science

[The] science research project of today is the temporary culmination of a very long, hard- fought struggle by a largely invisible community of our ancestors. Each of us may be standing on the shoulders of giants; more often we stand on the graves of our predecessors.

"In the words of the historian Fritz Stern, Haber' s Institute during the First World War became “ kind of forerunner of the Manhattan Project."

Gallium-Iron multiple bond controversy #chempaperaday 189-191

I have three papers starting with a report claiming that there is evidence for a Ga-Fe triple bond and they named it "ferrogallyne."

As you can see the evidence for this so-called multiple bond was not so convincing. So, being an expert in multiple bonds, F.A. Cotton wrote his comments and concerns about this assignment. He explained his reasoning and suggested that there is also a dative bond between Ga and Fe.

There was no reply from the original authors. So, this is unfortunate. I was able to find a computational paper on the issue. But, it's not the best paper to read on the subject. The authors simply say that the triple bond is a "pseudo-conflict" in this case because our bonding model is not "appropriate." Personally, I agree with Cotton and I think there should only be a Ga->Fe bond.

Sunday, February 8, 2015

Lewis Acidity of Organofluorophosphonium Salts #chempaperaday 187-188

The paper I read was "Lewis Acidity of Organofluorophosphonium Salts: Hydrodefluorination by a Saturated Acceptor that was published in Science. The second one is the "perspective" by F.Gabbai in the same issue. 

Caputo, C. B.; Hounjet, L. J.; Dobrovetsky, R.; Stephan, D. W., Lewis Acidity of Organofluorophosphonium Salts: Hydrodefluorination by a Saturated Acceptor. Science 2013, 341 (6152), 1374-1377.

Gabbaï, F. P., Lewis Acids with a Difference. Science 2013, 341 (6152), 1348-1349.

I pretty much knew nothing about hydrodefluorination until I read these papers. Now I know some. Really difficult research but it's not very popular yet. So, there is a lot of opportunities in this area of research.

Whittlesey, M. K.; Peris, E., Catalytic Hydrodefluorination with Late Transition Metal Complexes. ACS Catalysis 2014, 4 (9), 3152-3159

"Synthesis, Characterization, and Structures of a Persistent Aniline Radical Cation" and the controversy #chempaperaday 183-186

The recent controversy and discussion starts with the publication of the report of a stabilized aninile radical cation.

Here the authors claim that they were able to stabilize the radical cation and report x-ray structures, electrochemical studies and some EPR data.

Shortly after this paper, two comments appear:

Comment on “Synthesis, Characterization, and Structures of Persistent Aniline Radical Cation”: It Is a Protonated Aniline and Not an Aniline Radical Cation


Comment on “Synthesis, Characterization, and Structures of a Persistent Aniline Radical Cation”: A New Interpretation Is Necessary

The commenters try to replicate the experiments and they basically say that it is not an aniline radical. They have some detailed studies and explanations.

Finally, the original authors publish a reply to those two comments here:

Reply to Comments on “Synthesis, Characterization, and Structures of Persistent Aniline Radical Cation”

The problem with the "reply" is that they accept some of their "mistakes" and claim that they obtained the aniline radical cation. But, they can't really clarify some of the other concerns that the commenters pointed out.

Really interesting read.