Our society is quickly changing as a result of the new information technologies that have become available in the last decennia. Nowadays, we produce and process enormous amounts of digital data (~220 exabytes per month; 1 exabyte is 10exp18 bytes), which is expected to become even larger in the coming years. This flood of information is increasingly affecting our environment. For instance, the world data centers currently consume more energy (~420 terawatt hours) than a country such as the UK (330 terawatt hours) and, as a further example, the amount of energy that is required for doing 300 Google searches is equivalent to that of boiling 1 liter of water. It is evident that new approaches are needed to tackle the energy consumption and the problems connected with it (e.g. not enough silicon can be produced in the future to handle all digital information that has to be stored). Nature has already solved this data and energy problem during the long period of its evolution. Our brains can easily store and process some 2.5 quadrillion (10exp15) bytes, while the energy consumption is only 20 watt/ day.
In our ERC Advanced grant project ENCOPOL we are following a new approach and aim at developing technologies to write and store digital data on the level of molecules. That is, not writing onto hard discs but onto synthetic polymers in the form of chemical functions, e.g. epoxide groups. The latter groups can occur in two forms, which are each other’s mirror images, each encoding for a digit: (R,R)-epoxide = digit 1 and (S,S)-epoxide = digit 0. Our source of inspiration is the class of naturally occurring DNA polymerases, which make copies of DNA, also an information storing polymer: combinations of its 4 base pairs encompass information for the synthesis of specific proteins. The DNA polymerases are machines that glide along a DNA chain and while doing so, copy the DNA strand. Just like in nature we intend to use molecular machines, but now completely synthetic ones for the writing of chemical information onto synthetic polymers. Also the theoretical machine proposed by the mathematician Alan Turing for the construction of a computer provides a useful blueprint for the encoding of information on the molecular level. This so-called Turing machine can write, read, erase, and store information. It is composed of a tape head that moves forwards and backwards along a tape while printing the digits 1 and 0.
Our molecular machine is composed of a molecular tape head constructed from a manganese porphyrin cage molecule that can bind to a long polymer chain containing alkene double bonds and while gliding along it convert these double bonds into (R,R)- or (S,S)-epoxide functions in a controlled fashion, i.e. with the help of light. To this end a light-switchable Feringa motor is attached to the cage and the state of this switch eventually determines whether a digit 1 or 0 is printed.
