Digital processing and communication with molecular switches
TL;DR: In this paper, the three basic logic operations (AND, NOT, and OR) and more complex logic functions (EOR, INH, NOR, XNOR, and XOR) have been reproduced already at the molecular level.
Abstract: The tremendous pace in the development of information technology is rapidly approaching a limit. Alternative materials and operating princlples for the elaboration and communication of data in electronic circults and optical networks must be identified. Organic molecules are promising candidates for the realization of future digital processors. Their attractive features are the miniaturized dimensions and the high degree of control on molecular design possible in chemical synthesis. Indeed, nanostructures with engineered properties and specific functions can be assembled relying on the power of organic synthesis. In particular, certain molecales can be designed to switch from one state to another, when addressed with chemical, electrical, or optical stimulations, and to produce a detectable signal in response to these transformations. Binary data can be enceded on the input stimulations and output signals employing logic conventions and assumptions similar to those ruting digital electronics. Thus, binary inputs can be transduced into binary outputs relying on molecular switches. Following these design principles, the three basic logic operations (AND, NOT, and OR) and more complex logic functions (EOR, INH, NOR, XNOR, and XOR) have been reproduced already at the molecular level. Presently, these simple "molecular processors" are far from any practical application. However, these encouraging results demonstrate already that chemical systems can process binary data with designed logic protocols. Further fundamental studies on the various facets of this emerging area will reveal if and how molecular switches can become the basic components of furture logic devices. After all, chemical computers are available atready. We all carry one in our head!
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TL;DR: The exciting successes in taming molecular-level movement thus far are outlined, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion are highlighted.
Abstract: The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.
2,301 citations
TL;DR: In this article, a review article focuses primarily on the work carried in our laboratories over the last few years using luminescent and colorimetric sensors, where the anion recognition occurs through hydrogen bonding in organic or aqueous solvents.
1,165 citations
TL;DR: In this paper, the authors present a review of recent advances in assembly techniques for forming ultrathin carbon nanotubes, modeling and experimental work that reveals their collective properties, and engineering aspects of implementation in sensors and in electronic devices and circuits with various levels of complexity.
Abstract: Ultrathin films of single-walled carbon nanotubes (SWNTs) represent an attractive, emerging class of material, with properties that can approach the exceptional electrical, mechanical, and optical characteristics of individual SWNTs, in a format that, unlike isolated tubes, is readily suitable for scalable integration into devices. These features suggest the potential for realistic applications as conducting or semiconducting layers in diverse types of electronic, optoelectronic and sensor systems. This article reviews recent advances in assembly techniques for forming such films, modeling and experimental work that reveals their collective properties, and engineering aspects of implementation in sensors and in electronic devices and circuits with various levels of complexity. A concluding discussion provides some perspectives on possibilities for future work in fundamental and applied aspects.
1,060 citations
TL;DR: The ideas and experimental results within 350 references are marshalled to illustrate the design bases and application potential of molecular luminescent sensing and switching devices that have appeared since the turn of the century as mentioned in this paper.
1,032 citations
TL;DR: This review provides a summary of the widely reported electrical switching phenomena in polymers and the corresponding polymer electronic memories.
902 citations
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TL;DR: This experiment demonstrates the feasibility of carrying out computations at the molecular level by solving an instance of the directed Hamiltonian path problem with standard protocols and enzymes.
Abstract: The tools of molecular biology were used to solve an instance of the directed Hamiltonian path problem. A small graph was encoded in molecules of DNA, and the "operations" of the computation were performed with standard protocols and enzymes. This experiment demonstrates the feasibility of carrying out computations at the molecular level.
4,266 citations
3,623 citations
TL;DR: In this paper, benzene-1,4-dithiol molecules were self-assembled onto the two facing gold electrodes of a mechanically controllable break junction to form a statically stable gold-sulfur-aryl-solfur-gold system, allowing for direct observation of charge transport through the molecules.
Abstract: Molecules of benzene-1,4-dithiol were self-assembled onto the two facing gold electrodes of a mechanically controllable break junction to form a statically stable gold-sulfur-aryl-sulfur-gold system, allowing for direct observation of charge transport through the molecules. Current-voltage measurements at room temperature demonstrated a highly reproducible apparent gap at about 0.7 volt, and the conductance-voltage curve showed two steps in both bias directions. This study provides a quantative measure of the conductance of a junction containing a single molecule, which is a fundamental step in the emerging area of molecular-scale electronics.
3,114 citations
TL;DR: ‘mono-molecular’ electronics, in which a single molecule will integrate the elementary functions and interconnections required for computation, is proposed.
Abstract: The semiconductor industry has seen a remarkable miniaturization trend, driven by many scientific and technological innovations. But if this trend is to continue, and provide ever faster and cheaper computers, the size of microelectronic circuit components will soon need to reach the scale of atoms or molecules—a goal that will require conceptually new device structures. The idea that a few molecules, or even a single molecule, could be embedded between electrodes and perform the basic functions of digital electronics—rectification, amplification and storage—was first put forward in the mid-1970s. The concept is now realized for individual components, but the economic fabrication of complete circuits at the molecular level remains challenging because of the difficulty of connecting molecules to one another. A possible solution to this problem is ‘mono-molecular’ electronics, in which a single molecule will integrate the elementary functions and interconnections required for computation.
2,853 citations
TL;DR: This work demonstrates logic circuits with field-effect transistors based on single carbon nanotubes that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
Abstract: We demonstrate logic circuits with field-effect transistors based on single carbon nanotubes. Our device layout features local gates that provide excellent capacitive coupling between the gate and nanotube, enabling strong electrostatic doping of the nanotube from p-doping to n-doping and the study of the nonconventional long-range screening of charge along the one-dimensional nanotubes. The transistors show favorable device characteristics such as high gain (>10), a large on-off ratio (>10(5)), and room-temperature operation. Importantly, the local-gate layout allows for integration of multiple devices on a single chip. Indeed, we demonstrate one-, two-, and three-transistor circuits that exhibit a range of digital logic operations, such as an inverter, a logic NOR, a static random-access memory cell, and an ac ring oscillator.
2,642 citations