Molecular logic gates design

Fig. 15 A molecular OR gate, whose chemical structure maps the electrical circuit diagram shown in Fig. 20a. Two Aviram-Ratner molecular rectifier chemical groups have been bonded to a central chemical node. This intramolecular circuit with one simple node can be easily designed, because the node Kirchoff node law is valid here. Note that the molecular orbital of each partner can be still identified on the 2 T(E) because of their weak interactions through the CH2 bridge. This is not always the case. The obtained logic surface demonstrates an OR function for well-selected values of the input voltage, but with two logical level 1 outputs which would have to be corrected using an additional output circuit...

Another very good example of the mapping procedure, which can be practiced to design a semiclassical intramolecular logic gate molecular circuit, is the nontrivial... 

S. Tuchman, S. Sideman, S. Kenig, and N. Lotan, Enzyme based logic gates controlled by outside signals principles and design, in Molecular Electronics and Molecular Electronic Devices, K. Sienicki, Ed., Vol. HI, CRC Press, Boca Raton, FL, 1994, pp. 223-238. 

Figure 9. (a) Schematic representation of the five-module format of a photoactive triad which is switchable only by the simultaneous presence of a pair of ions. This design involves the multiple application of the ideas in Figure 1. The four distinct situations are shown. Note that the presence of each guest ion in its selective receptor only suppresses that particular electron transfer path. The mutually exclusive selectivity of each receptor is symbolized by the different hole sizes. All electron transfer activity ceases when both guest ions have been received by the appropriate receptors. The case is an AND logic gate at the molecular scale. While this uses only two ionic inputs, the principle established here should be extensible to accommodate three inputs or more, (b) An example illustrating the principles of part (a) from an extension of the aminomethyl aromatic family. The case shown applies to the situation (iv) in part (a) where both receptors are occupied. It is only then that luminescence is switched "on". Protons and sodium ions are the relevant ionic inputs.

One of the most promising bottom-up approaches in nanoelectronics is to assemble 7i-conjugated molecules to build nano-sized electronic and opto-electronic devices in the 5-100 nm length scale. This field of research, called supramolecular electronics, bridges the gap between molecular electronics and bulk plastic electronics. In this contest, the design and preparation of nanowires are of considerable interest for the development of nano-electronic devices such as nanosized transistors, sensors, logic gates, LEDs, and photovoltaic devices. 

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