Photochemical trigger

Collier JH, Hu BH, Ruberti JW et al (2001) Thermally and photochemically triggered self-assembly of peptide hydrogels. J Am Chem Soc 123 9463-9464... 

Photochemically Triggered Physical Amplification of Photoresponsiveness in Molecular Aggregate Systems... 

Figure 1. Examples of photochemically triggered physical amplification.

Photochemically Triggered Induced Circular Dichroism in Liposomes When an optically inactive chromophore is subject to the effect of optically active environment, optical activity may be induced at the absorption wavelength of the optically inactive chromophore. This phenomenon of induced circular dichroism(ICD) is often observed in polypeptides bearing various achiral chromophores on the side chain( ). The strong chiral environment caused by the peptide helix structure is responsible for this. Distance from, and orientation to, the chiral field decide the degree of ICD appearing on the achiral chromophore. 

We have demonstrated that a chiral vesicle composed of di-palmitoyl-L- a-phosphatidylcholine(l-DPPC) doped with the azobenzene containing amphiphiles shown in Scheme 2 is a subject to photochemically triggered phase transition and exhibits a non-linear photoresponse in terms of ICD appearing at the absorption band of azobenzene. 

Image Amplification by Means of Photochemically Triggered Phase Transition in Liquid Crystal... 

A photochemically triggered phase transition is again clearly demonstrated. The apparent increase of the transmittance before its sharp decline is seemingly due to a subtle change in interference of... 

Figure 8. Photochemically triggered phase transition in solid polymer film.

Wender PA, Zercher CK, Beckham S, Haubold EM (1993) A photochemically triggered DNA-cleaving agent - synthesis, mechanistic and DNA cleavage studies on a new analog of the antitumor antibiotic dynemicin. J Org Chem 58 5867-5869... 

Molecular Recognition Events Controllable by Photochemical Triggers or Readable by Photochemical Outputs... 

In this chapter, we introduce molecular recognition events controllable by photochemical triggers or readable by photochemical outputs, particularly focusing on our own recent research achievements. 

The two most important methods of both probing and stimulating supramolecular devices are photochemical and electrochemical techniques. The most prevalent events to occur in such devices are electron, energy and proton transfer, as well as molecular rearrangement. Any of these events can provide the basis for forms of transducable output on which molecular electronic devices may be based. Therefore, the theories most commonly applied to such electrochemically and photochemically triggered events are outlined in this chapter. In addition, an overview of the mechanisms by which such events occur is provided, identifying the molecular or physical parameters required to make such events feasible in a supramolecular structure. 

Ru-modified cytochrome bs and photochemical triggering methods were used to examine the kinetics of ET in cytochrome bs/c complexes. Rapid intraprotein reduction (<100 ns) of Fe(III)-cytochrome bs by excited Ru(bpy)3 + made it possible to probe bs c ET kinetics. Two concentration-independent ET rates (4 x 10 s, 3.4 x 10" s ) were observed, suggesting that two cytochrome bs/c species are present in solution. Studies of ionic-strength dependences and the effects of mutations suggest that the slower Fe(ni)-cytochrome c reduction phase may be limited by conformational changes within one of the complexes. ... 

Table 18). This compensates for the shorter excited state lifetime of the ro-taxane, and allows its photooxidation to occur in a relatively short time when a sufficiently high concentration of /7-N02C6H4CH2Br is present in the solution. The principle of the photochemically triggerred rearrangement of the rotaxane Cu.31 is shown in Figure 45. 

S. Tazuke, S. Kurihara, and T. Ikeda, Amplified image recording in liquid crystal media by means of photochemically triggered phase transition, Chem. Lett. 1987, 911-914. 

Banfi, L. Guanti, G. Rasparini, M. Intramolecular opening of [l-lactams with amines as a strategy toward enzymatically or photochemically triggered activation of lactenediyne prodrugs. Eur. J. Org. Chem. 2003, 1319-1336. 

Photochemical triggers irreversibly release free target molecules and also photoproduct(s) formed by the transformation of photoremovable groups (Scheme 6.189). Their design must fulfil several requirements for example, the side-products should be chemically and photochemically stable and nontoxic (in biological applications) and the photoremovable moiety should absorb at wavelengths... 

Explain the following concepts and keywords photochromism photoswitching photoinitiator photoaffinity labelling photo-Wolff rearrangement photoactivatable compound Barton reaction photochemical trigger photolabile linker photoamination redox photosensitization. 

Fig. 1. Examples of photochemically triggered physical amplification. a) Spherical micelle, read-out by change in surface tension, b) Plate-like micelle, read-out by light scattering, c) Vesicle, read-out by circular dichroism. d) Liquid crystals, read-out by polarized light.

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