Switches, molecular electronic materials

Molecular electronics currently is defined as the use of organic molecular materials to perform an active function in the processing of information and its transmission and storage. An alternative definition has been suggested, namely, the achievement of switching on a molecular scale. As observed by G.G. Roberts (University of Oxford), It is interesting to note that only a modest diminution in the size of electronic circuit components is required before the scale of individual molecules is reached in fact many existing ciicuit elements could alieady be accommodated within the aiea occupied by a leukemia virus. ... 

Theoretical chemistry at York University was strengthened in the 1990s with the appointments of Bill Pietro in 1991 and Rene Fournier in 1996. Pietro wrote part of the Gaussian code as a graduate student and several modules of SPARTAN while an assistant professor at the University of Wisconsin. While he was in Madison he developed a research program based on molecular electronic devices.236 He expanded his interests to several facets of molecular electronics, including molecular electroluminescent materials, molecular electronic devices (diodes, switches, and sensors), and functionalized semiconductor nanoclusters.237 These new materials not only are scientifically very exciting, but they offer the possibility of revolutionary impact on the future of the electronics industry. 

There has been a resurgence of interest in proton-coupled redox reactions because of their importance in catalysis, molecular electronics and biological systems. For example, thin films of materials that undergo coupled electron and proton transfer reactions are attractive model systems for developing catalysts that function by hydrogen atom and hydride transfer mechanisms [4]. In the field of molecular electronics, protonation provides the possibility that electrons may be trapped in a particular redox site, thus giving rise to molecular switches [5]. In biological systems, the kinetics and thermodynamics of redox reactions are often controlled by enzyme-mediated acid-base reactions. 

Rotaxanes were proposed as challenging materials in areas covering molecular electronics like for example switches [66], molecular wires [14], and finally, logic gates [14], These molecules are already known for their binary reversible states arising from shuttling of the macrocycle along the thread. 

Early efforts to incorporate this electronic molecular switch into framework materials were driven primarily by an interest in elucidating the nature of cooperativity in SCO lattices, with the ultimate goal of controlling the switching properties to deliver bistable systems at ambient temperature. Classical examples of such systems are mem-... 

Molecular electronics (ME) is so named because it uses molecules to function as switches and wires . ME is a term that refers both to the use of molecular materials in electronics and to electronics at molecular level. It is as yet not very clear how molecular electronic devices will operate, but it is conjectured that active molecules are needed, either in isolation or becoming active by association with other molecules. It is thought that electronics is likely to imitate some of the basic functions of macroscopic devices such as memories, sensors and logic circuits. 

Metallophthalocyanine polymers offer good stability in thermal, chemical, hydrolytic and photochemical environments. The reversible redox property and cycle stability of phthalocyanine compounds and their polymers make them useful as active components in sensors, switches, diodes, memory devices, NLO materials, etc. different types of phthalocyanine polymers are available and they are amenable to chemical modifications to suit the devices requirements. It is possible to exercise chemical control of the properties of the phthalocyanine polymers as well as functionalize other conducting polymers with the characteristics of phthalocyanines. Hence phthalocyanine polymers have become potential candidates for producing useful and viable materials for electronic, optoelectronic and molecular electronic applications. 

New natural polymers based on synthesis from renewable resources, improved recyclability based on retrosynthesis to reusable precursors, and molecular suicide switches to initiate biodegradation on demand are the exciting areas in polymer science. In the area of biomolecular materials, new materials for implants with improved durability and biocompatibility, light-harvesting materials based on biomimicry of photosynthetic systems, and biosensors for analysis and artificial enzymes for bioremediation will present the breakthrough opportunities. Finally, in the field of electronics and photonics, the new challenges are molecular switches, transistors, and other electronic components molecular photoad-dressable memory devices and ferroelectrics and ferromagnets based on nonmetals. 

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