Browse Prior Art Database

Molecular Electronic Circuit Device

IP.com Disclosure Number: IPCOM000034465D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 6 page(s) / 96K

Publishing Venue

IBM

Related People

Aviram, A: AUTHOR

Abstract

A technique is described whereby a molecular circuit device functions as a flip-flop, an inverter, an OR logic gate, and as an AND logic gate. Discussed are the molecular considerations needed to construct the functional circuit configurations. (Image Omitted) Molecular conductors and semiconductors have been known for some time [1]. More recent compounds, such as polypyrrol, polyacetylene and polythiophene, have their conductivity rival that of metals, such as copper. It has been found that, invariably, the valence bands of these compounds are partially filled. Depleting the valence band is usually accomplished by charge complexation, or by oxydation. Therefore, one basic requirement for conduction in organic compounds is the presence of an unfilled electronic band.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 32% of the total text.

Page 1 of 6

Molecular Electronic Circuit Device

A technique is described whereby a molecular circuit device functions as a flip-flop, an inverter, an OR logic gate, and as an AND logic gate. Discussed are the molecular considerations needed to construct the functional circuit configurations.

(Image Omitted)

Molecular conductors and semiconductors have been known for some time [1]. More recent compounds, such as polypyrrol, polyacetylene and polythiophene, have their conductivity rival that of metals, such as copper. It has been found that, invariably, the valence bands of these compounds are partially filled. Depleting the valence band is usually accomplished by charge complexation, or by oxydation. Therefore, one basic requirement for conduction in organic compounds is the presence of an unfilled electronic band. In the case of electron tunneling, the use of sigma pi separation [2] has been explored. Due to the difference in relative bond energies, sigma bonds can function as tunneling barriers for the electron transfer between donor and acceptor groups located in the same molecule [3]. It has been shown that electrons can tunnel in a field gradient across the sigma bonds, either through space, or through the bond [4]. The concept described herein explores the use of the 90-degree twist barrier, whereby a barrier can be constructed by means of an allen bond or preferably by a spiro sigma carbon bond. An organic molecule that contains a spiro bond, as shown in Fig. 1, has a 90- degree twist and is quite rigid so as to serve as a spacer between two pi-type moieties that would be structurally at ninety degrees to each other, as shown in Fig. 2. In the event each of the pi-system moieties would be known to be potential organic conductors, namely if an electron were to be removed, or added, then they would qualify for the proposed switch.

(Image Omitted)

In the event a molecular switch, as shown in Fig. 2, had one electron removed from either pi-group, then that particular segment would become electrically conductive. The other pi-system would still be insulating. Due to the imposed geometry, there would be little overlap between the two pi-systems. The conductive part would remain conductive for longer periods of time, than it would have been in a molecule that enabled the two pi-systems to be situated in the same plane. This is primarily due to the fact that the electron exchange could have occurred by means of internal tunneling. In the case of the spiro compound, the matrix element for electron transfer may in itself be cylindrically invariant along the molecular axis. However, symmetry considerations prevent proper overlap between the wave functions of the two pi-groups, since they are at 90 degrees to each other and the overlap integral should be zero. Although in practice, some minute overlap may exist. If the

1

Page 2 of 6

molecule were to be placed between two electrodes, so that the axis, that is normal to the electrodes, passes through...