N-Heterocylic Carbenes (NHC) in Surface Chemistry and Transition Metal Catalysis
N-Heterocyclic carbenes (NHCs) are a unique class of molecules that have attracted significant attention due to their versatile properties and wide applications. In simple terms, NHCs can accelerate chemical reactions, which is beneficial in chemical synthesis and the pharmaceutical industry. They also play an important role in surface chemistry, where their strong bonding ability can modify surfaces to make them more effective in sensors and microelectronics applications.
Carbenes are neutral organic compounds characterized by a carbon atom with one pair of free electrons. They have been a subject of scientific interest for centuries due to their high reactivity and instability. The quest to synthesize stable carbenes dates back to 1835, and it was a significant milestone when, in 1991, a stable NHC was successfully isolated. This breakthrough marked an important advancement in the field of chemistry, opening up new possibilities for the use of NHCs in various applications. In NHC, the carbene carbon is situated between a nitrogen and a hetero atom which stabilize the electron-deficient carbon through electronic and steric effects.
NHCs are widely used as building blocks in organometallic chemistry. One primary application is the ruthenium-based Grubb’s Catalyst, which produces propene (a precursor to plastic), detergents, and polymers via ring-opening cyclo-olefin polymerization. NHC-Palladium complexes are used as catalysts in the pharmaceutical industries, specifically Ag(I)-NHC complexes which have been used in biological applications.
In addition to forming stable transition metal complexes, NHCs also have the unique ability to form robust monolayers on crystalline gold surfaces. These monolayers exhibit remarkable resilience to extreme pHs and harsh chemical conditions, surpassing the performance of traditionally used sulfur-based molecules. This exceptional resilience of NHC functionalized gold surfaces and gold nanoparticles paves the way for their wide-ranging applications in biological sensing, biomedicine, and catalysis, instilling a sense of confidence in their robustness and reliability.
Recently, at the Ascensus Newburyport site, we developed scalable routes to synthesize five NHC precursors and 1 free NHC—carbene with high purity (see below).
These compounds are extensively used in surface chemistry, metal passivation, and as ALD precursors in the microelectronics and pharmaceutical industries. You can now find these commercially available compounds recently added to in our catalog product line on The Strem Catalog Website.
