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Molecular and Supramolecular Electronic Devices

Molecular and Supramolecular Electronic and Mechanic Devices and Building Blocks... [Pg.519]

Molecular devices have been defined as structurally organized and functionally integrated chemical systems they are based on specific components arranged in a suitable manner, and may be built into supramolecular architectures [1.7,1.9]. The function performed by a device results from the integration of the elementary operations executed by the components. One may speak of photonic, electronic or ionic devices depending on whether the components are respectively photoactive electroactive or ionoactive, i.e., whether they operate with (accept or donate) photons, electrons, or ions. This defines fields of molecular and supramolecular photonics, electronics and ionics. [Pg.89]

Two basic types of components may be distinguished active components, that perform a given operation (accept, donate, transfer) on photons, electrons, ions, etc. structural components, that participate in the build-up of the supramolecular architecture and in the positioning of the active components, in particular through recognition processes in addition, ancillary components may be introduced to modify or perturb the properties of the other two types of components. A basic feature is that the components and the devices that they constitute should perform their function ) at the molecular and supramolecular levels as distinct from the bulk material. Incorporation of molecular devices into supramolecular architectures yields functional supermolecules or assemblies (such as layers, films, membranes, etc.). [Pg.89]

The photochemical and photophysical processes discussed above provide illustrations and incentives for further studies of photoeffects brought about by the formation of supramolecular species. Such investigations may lead to the development of photoactive molecular and supramolecular devices, based on photoinduced energy migration, electron transfer, substrate release, or chemical transformation. Coupling to recognition processes may allow the transduction of molecular infor-... [Pg.103]

Switching also implies molecular and supramolecular bistability since it resides in the reversible interconversion of a molecular species or supramolecular system between two thermally stable states by sweeping a given external stimulus or field. Bistability in isolated molecules or supermolecules is, for instance, found in optical systems such as photochromic [8.229] or thermochromic substances or devices, in electron transfer or magnetic processes [8.239], in the internal transfer of a bound substrate between the two binding sites of a ditopic receptor (see Section 4.1 see also Fig. 33) [6.77]. Bistability of polymolecular systems is of a supramolecular nature as in a phase transition or a spin transition, both of which involve an assembly of interacting species. [Pg.124]

Fig. 50. Chemionics as the chemistry of recognition-directed and self-organised photonic, electronic and ionic molecular and supramolecular devices generated by means of functional programmed chemical systems. Fig. 50. Chemionics as the chemistry of recognition-directed and self-organised photonic, electronic and ionic molecular and supramolecular devices generated by means of functional programmed chemical systems.
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. [Pg.250]

The field of molecular electronics is in its embryonic stage. Although many molecular and supramolecular systems have been designed (and synthesized) to work in a solution-phase context, their successful incorporation into functioning devices is hugely dependent not only on the design of the chemical computing element, but also on the nature of the device itself. [Pg.229]

The prospective applications ofmolecular assemblies seem so wide that their limits are difficult to set. The sizes of electronic devices in the computer industry are close to their lower limits. One simply cannot fit many more electronic elements into a cell since the walls between the elements in the cell would become too thin to insulate them effectively. Thus further miniaturization of today s devices will soon be virtually impossible. Therefore, another approach from bottom up was proposed. It consists in the creation of electronic devices of the size of a single molecule or of a well-defined molecular aggregate. This is an enormous technological task and only the first steps in this direction have been taken. In the future, organic compounds and supramolecular complexes will serve as conductors, as well as semi- and superconductors, since they can be easily obtained with sufficient, controllable purity and their properties can be fine tuned by minor adjustments of their structures. For instance, the charge-transfer complex of tetrathiafulvalene 21 with tetramethylquinodimethane 22 exhibits room- temperature conductivity [30] close to that of metals. Therefore it could be called an organic metal. Several systems which could serve as molecular devices have been proposed. One example of such a system which can also act as a sensor consists of a basic solution of phenolophthalein dye 10b with P-cyciodextrin 11. The purple solution of the dye not only loses its colour upon the complexation but the colour comes back when the solution is heated [31]. [Pg.14]


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