Energy donors

AG and AH can be expressed as a multiplicative function of hydrogen bonding in different polar and nonpolar solvents by means of enthalpy acceptor factors E - enthalpy donor factors free energy acceptor factors Q, and free energy donor factors Q (Eqs. (32) and (33), where kj, 2- 3 [kcal/mol] are regression coefficients). 

Substitution of Asn or Glu for Asp707 inhibited Ca transport both with ATP or acetylphosphate as energy donors the formation of E P from ATP in the presence of 0.1 mM Ca or from Pi in the absence of Ca was also inhibited [103]. This data is consistent with a requirement for Asp707 in the phosphorylation of the enzyme by ATP, acetylphosphate and inorganic phosphate. 

WEEDSA van der Waals free energy donor surface area... 

These reactions, while not very important for high-energy donors in the absence of azulene, do help define what the potential energy diagrams should look like, that is, the fram-stilbene triplet is a discrete intermediate while the cij-stilbene triplet is a high vibrational form of the phantom triplet. Herkstroeter and McClure(13> have been able to observe the fro/w-stilbene triplet via flash photolysis using low-temperature glasses however, no similar triplet was observed for cfr-stilbene. Only when they studied cfr-stilbene-like... 

Since energy transfer from high triplet energy donors to both s-tram and s-cis conformations should be diffusion controlled, and the piperylene is more than 95% in the s-trans conformation at room temperature, the role of the c-T and c-C isomers can be neglected to a first approximation. 

The cyan emitting form obtained by the mutation Y66W [10] deserves special attention, as it has led to the ECFP form (absorption at 437 nm, emission at 474 nm), whose variants are still intensively used as excitation energy donors in FRET imaging experiments for monitoring molecular associations in the living cell... 

Lanthanides also have potential as DEFRET energy donors. Selvin et al. have reported the use of carbostyril-124 complexes (53) with europium and terbium as sensitizers for cyanine dyes (e.g., (54)) in a variety of immunoassays and DNA hybridization assays.138-140 The advantage of this is that the long lifetime of the lanthanide excited state means than it can transfer its excitation energy to the acceptor over a long distance (up to 100 A) sensitized emission from the acceptor, which occurs at a wavelength where there is minimal interference from residual lanthanide emission, is then measured. 

A FRET pair is constituted by two chromophores, one acting as energy donor and the other as acceptor. The efficiency of the energy transfer process is described as ... 

There are so many different examples of photochemical dimerizations and cross-cycloadditions 8-11,13-17) 0f olefinic compounds that one is not surprised to find several variations of mechanistic patterns. Simple olefins, including dienes and strained small ring, bicyclic olefins and styrene derivatives form a class of compounds that undergo such reactions sensitized by triplet energy donors. Some examples axe given in Eqs. 19—23, where only cyclobutane products are depicted. Theory... 

Energy transfer entails the excitation of a molecule that during the lifetime of the excited state passes its excitation energy to another molecule. The loss of excitation energy from the initial excited species (the donor) results in quenching of the luminescence of the energy donor and may result in luminescence from the energy recipient (acceptor), which becomes excited in the process. 

Understand that in photoinduced electron transfer, the excited state can be an electron donor or an electron acceptor, whereas in energy transfer the excited state is exclusively an energy donor. 

Sensitisation by a high-energy donor, such as triplet xanthone, can populate both the Qi and the D, states by energy transfer (Figure 10.4). This results in both the photosolvation reaction and phosphorescence emission. 

Sensitisation with lower-energy donors, such as triplet Ru(bpy)3+, on the other hand, means that energy transfer is only possible to the Di state (Figure 10.4). This results in phosphorescence emission, but the photosolvation reaction does not occur. This shows that the Qi state must be responsible for the photosolvation reaction. 

On the basis of Scheme 5, we recently realized label-free sequence-specific DNA detection with SNP selectivity with the aid of SI nuclease [59]. In this assay, IBr and TO are chosen as the energy donor and acceptor, respectively. 

As a separate issue, the ring-opening reaction of the spirooxazine and the spiropy-ran can be sensitized by triplet energy donors[73,113-115]. A typical absorption rise for a benzophenone-sensitized ring-opening reaction is compared to that of the unsensitized fast absorption rise for NOSI3 in Fig. 13 [73,113]. In this case, both solutions were optically matched at the excitation wavelength. 

FORSTER FORMALISM AND QUANTUM DOTS AS ENERGY DONORS 287... 

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