Light-activated switch

FIGURE 7-18 The Photovoltaic Effect, (a) As a light-activated switch, (b) Generating electricity. Light promotes electrons into the conduction band in the junction. 

Fig. 7 Light-driven switch represented by dihydroindolizine 12, betaine 13, and protonated betaine 14 (A = thermal activation).

We would like to acknowledge support from Science Foundation Ireland under the CLARITY grant (07/CE/I1147) and Light Activated Molecular Switches (07/RFP/MASF812) awards. 

Substantial progress has been accomplished in the fabrication of molecular and biomolecular optoelectronic devices. Light-activated molecular and bio-molecular systems have been integrated with electronic transducers, and the optical switching of the systems has been electronically transduced to the macroscopic environment. In particular, the photonic switching of an electron-transfer cascade has allowed the amplified electronic transduction of an input... 

The molecular analysis of recombinant switch regions also sheds light on switch induction and isotype commitment. Such studies reveal that, upon activation, class switching is induced in some cells but not others. Otherwise, recombinations on the excluded IgH allele would have been found in late IgM expressing cells this... 

Recent x-ray crystallographic studies reveal how the subunits of Gt protein Interact with each other and with light-activated rhodopsln and provide clues about how binding of GTP leads to dissociation of G from Gp (Figure 13-25). Two surfaces of Gta Interact with Gp an N-termlnal region near the membrane surface and the two adjacent switch 1 and switch 11 regions, which are found in all G j proteins. Although Gp and G, also contact each other, G does not contact Gt . 

Security lighting installed on the outside of the home may be activated by external detectors. These detectors sense the presence of a person outside the protected property and additional lighting is switched on. This will deter most potential intruders while also acting as courtesy lighting for visitors (Fig. 14.51). 

Several examples that may be considered mechanical molecular devices have been reported including die rotaxane based molecular shuttle [16], the chir-optical molecular switch [17], light-activated bianthrone molecules [18], mole-eular brakes [19], molecular ratchets [20], molecular propellers [21], and eonformationally invertable columnar mesophases [22]. 

---