Temperature-induced phase switch

A temperature-induced phase switch of the smart pNIPAM tail of these novel bioconjugates was demonstrated to alter the substrate activity towards enzymatic hydrolysis of the pNIPAM-peptide conjugates (Fig. 13.10) (Molawi and Studer, 2007). 

Fig. 4 Molecular mechanism of the thermally-induced SME. Ttrans is the thermal transition temperature of the switching phase (adapted from [40] Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission)...

Photoinduced spin-related phenomena are a particularly important field of the solid-state photophysics, because fast spin switching is a prospective basis for applications in the field of spintronics. An illustrative example is the production of the metastable state of the iron propyltetrazole (ptz) complex [Fe(ptz)6](BF4)2 by laser light-induced excited spin-state trapping (LIESST) and the determination of the resulting structure by steady-state X-ray photodiffraction [68]. In another example, steady-state X-ray photodiffraction at cryogenic temperatures was successfully utilized to study photoinduced phase transition due to spin crossover in the tris(a-picolylamine)iron(II) complex [69]. The phase transition is accompanied by... 

Erasing of the image can be achieved by switching the photoirradiation to 525 nm to induce cis - trans isomerization of azobenzene. Since the absorbance of the cis isomer at 525 nm is weak, it takes a longer period than the image recording process. Also there seems to be a certain time delay between photoreaction and complete recovery of the nematic phase. This problem is relevant to molecular mobility in liquid crystals as a function of temperature. 

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