Saturday, October 5, 2013

Cooperative Catalysis

Cooperative catalysis occurs when the synergic catalytic effect of at least two different entities act together, increasing the rate of a chemical reaction beyond what is possible when either of the two entities is used independently. The idea of “Cooperative Catalysis” has inspired synthetic chemists to create artificial dual activation catalysts. Such a Cooperative Catalytic pathway is often used in enzymatic catalysis. Enzymes are continue to be a source of inspiration for (designing and) developing new catalytic reactions that are high in efficiency & selectivity, and minimal waste.

Urease is a dinuclear metalloenzyme which catalyzes the hydrolysis of urea into carbon-di-oxide and ammonia. The dimeric nickel center of this enzyme is (the active site) responsible for cooperative catalysis. Urea co-ordinates with one Ni-center, thus activate the electrophile (act as Lewis Acid), whereas water coordinates with the second Ni. It is thus acidified and can be deprotonated by histidine to generate hydroxide as a nucleophile (generate nucleophile), which is, now in close to the electrophile, and, can attack in an intramolecular fashion.

A similar cooperative catalytic activity with Bronsted and Lewis acidities can be generated by simultaneous incorporation of multiple elements in the silica framework is quite interesting and holds promises of unprecedented catalytic performances.

We recently prepared a similar natural mimic, a bimetallic nano-porous catalystic system, which would be able to perform cooperative catalysis for the selective synthesis of ortho-prenylated phenols and 2,2-dimethyl chroman, starting from phenol and allylic alcohol. Prenylated phenols are widely distributed in nature and are known to be an important structural unit of the pharmaceutical compounds. Similarly, 2,2-dimethylchroman derivatives also exhibit broad range of interesting physiological properties, we are able to synthesis the important structural motif by using the new cooperative catalytic systems.

The amount of aluminum present in the frame work dictates the acidity of the catalyst, and by fine tuning the aluminum content, we can develop the catalyst with desired catalytic property. Catalyst developed in such a manner was found to be highly active and selective.. The products obtained were good and satisfactory. Additionally, the synergistic effect of the bimetals (Cu and Al) in the nanoporous catalysts controls the selectivity of the final products.

Thursday, October 3, 2013

Nobel Advice

Are you a Nobel aspirant, young researcher, or want to be part of good science? Here is an advice from Prof. Avram Hershko ( Winner of 2004 Nobel Prize -for the discovery of ubiquitin-mediated protein degradation)

Here is a lesson from his life in science that he presented at the Lindau Nobel Meeting 2013."
  • It is very important to have good mentors- you cant learn how to do good science just from reading the literature 
  • Find an important subject that is not yet interesting to others the big guys will get there before you! Do not go with the mainstream. 
  • Accidental observations may be the most important one. Grab your Luck. 
  • Use what ever experimental approach is needed for your objective. It may not necessarily be the most fashionable (“state-of- the- art”) technology. Of course, biochemistry will always be needed. 
  • Science should be curious driven adventure. You should have a lot of excitement and fun. 
  • Never leave bench work, and shall continues to get a lot of excitement and fun.