Charge photoisomerization

Under UV light irradiation, cis-trans photoisomerization of the ionophore in the membrane occurs. We assume that the cis and trans isomers are both present in the membrane and the cis isomer forms a 1 1 (ionophore-cation) complex with a stability constant, Am.cb- In this case, the surface charge density, and the phase boundary... 

The effect was explained on the basis that the change in geometry of the azo moieties, caused by their trans-ds photoisomerization, might produce an increase in the local charge density of the environment around the helical backbone, thus destabilizing the ordered structure. 25 Unfortunately, the photoinduced conformational change was not reversible and the original structure could be not restored by irradiation at X > 390 nm or upon dark-adaptation. 

It has been recently reported that the E-form of bis(ferrocenylethynyl)-ethane, 97a, can undergo photoisomerization to the Z-form, 97b, by excitation of a charge transfer band with visible light [82]. This structural change affords a decrease in the through bond mixed-valence interaction between two ferrocenes. 

Photoisomerization of charge-transfer (CT) complexes of (E)- and (Z)-l,2-fe-(l-methyl-4-pyridinio)ethenes 99 with iodine can be effected by irradiating at the CT band in acetonitrile (Sch. 41). The CT excitation of the... 

The photochemical transformations after the radial MC charge shift are effective in weakening of the M-L bond between the central atom and ligand, which usually results in the photodissociation, photosubstitution, or photoisomerization mode (Figure 6.6). 

Coordination compounds are known for their photochemical properties, which may result in photodissociation, photosubstitution, photoisomerization, photoreduction, or photooxidation, for example (3). In addition to inner-sphere rearrangements, the complexes in excited states are susceptible to transfer their energy or charges into other species, such as solvent molecules, ion-pair partners, and other nonbonded quenchers. 

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