Light controlled switching

Figure 10.9. The light-controlled switching of the [2]pseudorotaxane [l ran.v-14] 4PF6 and the partial H-NMR spectra [400 MHz, CD3CN, 25°C] of an equimolar mixture of 1 4PF6 and 14 (a) after complexation, (b) after irradiation (A = 360 nm, 1 h) and decomplexation, and (c) after irradiation (A = 440 nm, 1 h) and complexation. The bipyridinium hydrogen atoms (HJ in the a-positions with respect to the nitrogen atoms were used as the probe protons and (co) and (un) stand for complexed and...

Figure 10.20. The light-controlled switching of the [2]rotaxane 28 4C104.

Between these two extremes arc encompassed a Pandora s Box of myriad contrivances such as counters, light-controlled switches, moisture sensors, heat and cold sensors, capacitively operated relays, and uncountable combination.s of all of these and many more. 

Electrical switches, e.g., light control switches, turn signal switches Gears, e.g., helical gears for window lifts Gear shift forks Heater plates... 

Electrical. The plant electrical system is sometimes more important than the steam system. The electrical system consists of the utihty company s entry substation, any ia-plant generating equipment, primary distribution feeders, secondary substations and transformers, final distribution cables, and various items of switch-gear, protective relays, motor starters, motors, lighting control panels, and capacitors to adjust power factor. 

Mativetsky JM, Pace G, Elbing M, Rampi MA, Mayor M, Samori P (2008) Azobenzenes as light-controlled molecular electronic switches in nanoscale metal-molecule-metal junctions. J Am Chem Soc 130 9192-9193... 

The front panel of the controller has two four-digit thumbwheel switches and two lighted pushbutton switches. The thumbwheels determine flow rate (ml/min) and volume to be delivered (ml). One pushbutton switch initiates the pump-refill operation. The other starts the injection, or stops an injection in progress. After power-up or reset, the microprocessor initializes itself and sets up the timing module and serial ports. It then jumps into a looping program that scans the two pushbutton switches and the... 

Light is switched off at +0.5 V vs. SCE for the cathodic sweep. In (a) there is no added reductant (b), (c), and (d) contain 0.5mM ferrocene, 1, l -dimethylferrocene, and acetyl-ferrocene, respectively. Acetylferrocene does not attenuate the surface ferricenium surface ferrocene wave since it is not a sufficiently powerful reductant. Ferrocene and 1, l -dimelhylferrocene both attenuate the surface ferricenium - surface ferrocene wave. But l,l -dimethylferrocene is more effective under identical conditions despite the fact that the same, mass transport-limited, steady-state photocurrent is found for these two reductants. These data suggest that after the light is switched off the reduction of surface ferricenium is controlled partially by mass transport and partly by the electron transfer rate (see text). 

Ang L-H, Chattopadhyay S, Wei N, Oyama T, Okada K, Batschauer A, Deng X. 1998. Molecular interaction between COP1 and HY5 defines a regulatory switch for light control of Arabidopsis development. Mol Cell 1 213-22. 

So far, several example of the chemically and electrochemically controlled switching of bistable linear molecular machines have been presented. The final section of this chapter will be dedicated to illustrating how such molecular switches and motors, when designed ingenuously, can also be powered by nature s most abundant and powerful energy source - light. 

Fig. 9 General mechanism for light-controlled ion switching in the /ac-[Re (CO)3(bpy)L3] complex...

Recently, Stauffer el al. have studied 6-hydroxy-substituted 2//-1-benzopyrans and combined electrochemistry with photochemistry in an approach to exerting control over the light-induced switching capability of these molecules (Scheme 17). 

Another method sometimes employed to indicate catalyst levels, particularly in storage hoppers, makes use of a series of lights controlled by switches attached to diaphragms in the walls of the vessel (185). Pressure actuates the switch when the diaphragm is covered by catalyst. 

Furukawa H, Misu M, Ando K, et al. (2008) Light-controlled on-off switch of a fluorescent nanoparticle. Macromol Rapid Commun 29 547-551... 

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