Click here to visit the University of Bristol home page

 
Click here to return to home page
Click here to discover the properties of cubane
Click here to look further into the synthesis of cubane
Click here to find out about the potential uses if cubane
Click here to see more examples of other strained ring systems
Click here find out about this site
Click here to see a list of material referenced on this site
Click here to see a list of other chemistry based websites

Until recently, cubane was considered as just an academic curiosity, a novelty with no actual use within modern day chemistry. Yet further research found that serveral possible applications in industry, materials science and medicine could exist, giving cubane a new future of which Philip E. Eaton had once visualised:

    "There is something for these compounds that are being made, and they do, I think, have a very interesting future - both in the explosives area and potentially in the pharmaceutical area." - Philip E. Eaton

The main areas of interest are:

  • Explosives and Propellants
  • Material Science
  • Pharmaceuticals

  • Explosives and Propellants

    There are several factors which dictate how good an explosive a compound would make. Major factors are the number of moles and molecular weights of the gaseous products and the energetics of decompostion. Density is also an important factor as the more moles of an explosive that can be packed into a smaller volume the better due to the fact that the explosion pressure is proportional to the density of the material, squared.

    Cubane is amongst the dozen densest saturated hydrocarbon molecules that exist, with a density of 1.29 g cm-3. It is thermodynamically unstable with a heat of formation of 144 kcal mol-1. These two factors alone led the US Army Armament Reseacrh and Development Centre (ARDEC) towards a proposal for a brand new, powerful explosive - Octanitrocubane, (ONC) where all of the hydrogens are replaced by nitro groups, bound to each carbon through nitrogen:

    Octanitrocubane C8(NO2)8

    Octanitrocubane contains enough oxygen to oxidise all carbon atoms to CO2 and, along with dinitrogen, explodes into 12 gaseous molecules producing the desired effect for either explosives or propellants:

    Predictions are that ONC has the potential to become one of the most powerful explosives, the estimates for some of it's properties are shown here against other military standards:

     

    Like cubane, ONC was once thought impossible to make and keep however when finally synthesised, it was found to be fairly stable with decomposition taking place at over 220 ºC and it was very dense. It was fairly shock resistant, meaning that it has the potential to become a useful explosive. The only problem is that cubane derivatives are still far too expensive to be considered as the starting material of an explosive that may be required in thousand-pound quantities for defense projects or major demolition work, limiting it's use for the time being.

    In terms of propellants, cubane derivatives such as ONC fit the specification perfectly. Releasing the explosive burst of enegy required, yet with no hydrogen atoms present, no water is produced during the burning and so produce little or no visible smoke (steam) in the plume behind the rocket; such 'low-signature' rockets are very hard to track.

    Return to the top of the page


    Material Science

    Cubanes have a very defined geometry, rigid and of regular shape and dimensions. This could allow them to act as building blocks in the developing world of nanoarchitecture, in the form of oligomeric compounds.Polycubanes, alkylated [n]cubylcubanes, can already be synthesised:

    A possible application of this would be to synthesise liquid crystals with new, exceptional properties such as UV transparency.

    Return to the top of the page


    Pharmaceuticals

    Cubanes are not inherently toxic. They are considered as biologically stable, lipophilic platforms on which a wide choice of substituents in a variety of well defined spatial relationships can be installed.

    The distance across the cube (diagonally) is very similar to that of the ipso-para distance across a benzene ring; meaning that functional groups can be not only added within the 'benzene-plane' but above and below it. This creates a huge opening for research in the field of substituted cubanes as replacements for bezyl groups within drug development as they would offer similar behaviour yet more options and maybe new solutions as they would provide more sites for substitution.

    It has already been discovered that dipivaloylcubane -a cubane derivatized with keto, cyano, and amide groups (shown below) exhibits moderate activity against human immunodeficiency virus (HIV) without causing any damage to healthy cells within the body.

    Also, a phenylcubane derivative has been known to show some anti-cancer properties just showing the versatility and maybe the pharmaceutical basis for further applications of cubane and its derivatives.