D-block chromophore

When one metal ion is used as a donor for sensitizing the emission of a second accepting metal ion, the characteristic lifetimes r of their excited states, which are related to their deactivation rates by r = k l, are affected by the metal-to-metal communication process. This situation can be simply modeled for the special case of an isolated d-f pair, in which the d-block chromophore (M) sensitizes the neighboring lanthanide ion (Ln) thanks to an energy transfer process described by the rate constant k 1 ". In absence of energy transfer, excited states of the two isolated chromophores decay with their intrinsic deactivation rates kxl and kLn, respectively, which provides eqs. (32) and (33) yielding eqs. (34) and (35) after integration ... 

The use of strongly absorbing d-block chromophores as sensitizers for the NIR emissions from lanthanide ions has attracted increasing attention since the first report by van Veggel and coworkers on the Nd + and Yb + luminescence sensitized by Ru(bpy)j+ and ferrocene in 2000. Subsequently, many d-block chromophores, based on related transition metals, such as R +, Ru +, Re+, Os +, Pd, Zn +, Cr +, and Co +, have been extensively studied in sensitizing the NIR emissions of lanthanide ions (i.e., Nd +,... 

Figure 12.12 Building blocks of an artificial photosynthesis system for hydrogen production using a chromophore (C), an electron acceptor (A) and a sacrificial donor(D)...

For some examples, see e.g. (a) Hogan CF, Harris AR, Bond AM et al (2006) Electrochemical studies of porphyrin-appended dendrimers. PhysChemChemPhys 8 2058-2065 (b) Jang W-D, Nishiyama N, Zhang G-D et al (2005) Supramolecular nanocarrier of anionic dendrimer porphyrins with cationic block copolymers modified with polyethylene glycol to enhance intracellular photodynamic efficacy. Angew Chem Int Ed 44 419 -23 (c) Loiseau F, Campagna S, Hameurlaine A et al (2005) Dendrimers made of porphyrin cores and carbazole chromophores as peripheral units. Absorption spectra, luminescence properties, and oxidation... 

For polysaccharides with an accessible u.v. chromophore, circular dichroism (c.d.) provides a sensitive index of structure, conformation, and interactions. This is illustrated by the very different c.d. spectra shown (28,29) by the three block types present in alginate, and, as shown below, by the large spectral changes on chelation of calcium ions on specific binding sites around the carboxy chromophore (l4,15) ... 

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