Chemicals and Related Substances
This is my Chemicals page. Its purpose is to describe the various chemicals I deal with in the lab so that the rest of my site won't confuse you. I've included a couple illustrations to clarify what I'm talking about in a few situations.
While not really a 'chemical' per se, these are the fundamental substance I deal with. When I use the term 'Gold Nanoparticles', sometimes abbreviated AuNPs, I'm referring to individual clusters of gold atoms about 5.5nm across. These are spherical groups comprised of around 4000 individual gold atoms and 'ligated' with a substance known as 1-dodecanethiol. I'll describe this compound separately in a moment, but for now just think of a few hundred little filaments sticking off of the surface which help to maintain a uniform size distribution of nanoparticles. My group has a process called 'Digestive Ripening' which produces these nanoparticles in the form I'm given with a very narrow size distribution. I don't really know all the steps to this process, and my group still doesn't fully understand why it works the way it does, so I won't go into the details.
All the Gold Nanoparticles I work with (and as far as I can tell from my reading, all Gold Nanoparticles) are in various solutions. While ordinary macroscopic amounts of gold are, of course, gold in color, the colloids I deal with are a deep purple shade. If diluted, this color will of course lighten, and sometimes looks a little more pinkish than purple. The use of the word colloid now implies some sort of solvent. There are two different solvents that I'm dealing with, 4-tert Butyltoluene and 2-butanone. These will be addressed after 1-dodecanethiol.
This term can be broken up into four components: thiol, dodeca, ane, and 1-. These four terms combined lead to a compound comprised of a carbon chain ('ane') twelve units in length ('dodeca'), with a Sulfur and a Hydrogen ('thiol') on the end (in the 1-position). Each of the twelve carbons in the chain are single bonded to one another, leaving space for 2 hydrogens off of all the central ones and 3 off the end carbon. The net result is C12H25SH and is pictured below first in its full glory and secondly in a shorthand where the lines simply assume carbons at the ends with hydrogens filling them out. This compound is of interest because the sulfur atom has two free electron pairs. When it comes into contact with the gold nanoparticles the electrons are pulled right in by the gold. Since gold also happens to be the most electronegative metal, this results in a fairly strong bond. It is possible to vary these ligands in two key ways. One of these is by changing the length of the carbon chain. My group has investigated 8, 10, and 16 length chains in the past, but for now I am only using the 12. The other way to vary them is by changing the thiol to something like a phosphine (P instead of S) or an amine (N instead of S), but because these have different outer shells, the same double electron pair is not produced, and neither of these configurations sticks to the gold quite as strongly.
This term can also be broken into several components: Toluene, tert Butyl, and 4-. The first of these, Toluene, is a chemical made up of a ring of six carbons with alternating single and double bonds with five of these carbons attached to a hyrdogen and one attached to a CH3 group via the C. The tert Butyl portion of the name means another of the carbons in the ring is attached to yet another carbon which is in turn bonded to three CH3 groups, also via the C's. The 4- indicates that this structure is attached to the ring directly opposite the CH3 from the Toluene. This final resulting structure is again indicated in two forms below, and will be abbreviated as tBT from now on.