Triple state

Fig. 2. PT diagram for a pure substance that expands on melting (not to scale). For a substance that contracts on melting, eg, water, the fusion curve. A, has a negative slope point / is a triple state point c is the gas—Hquid critical state (—) are phase boundaries representing states of two-phase equiUbrium ...

Both types of processes, 7r -assisted y, -bond cleavage and P -bonding, have been invoked to operate in the phototransformations of the aldehyde-ketone (153) to products (155), (156) and (158). The conversions have been observed at room temperature in dioxane, t-butanol, ethanol and benzene using light of wavelengths 2537 A or above 3100 A or sensitization by acetophenone. The phosphorescing excited triple state of (153) is very similar to that of testosterone acetate (114), but its reactions are too rapid... 

Singlet and Triple States Benzene and Simple Aromatic Compounds... 

Thus, the sign of the observed polarization of the Me protons of the product 22 (absorption) is unambiguous evidence of the formation of an intermediate triplet 1,3-biradical 23T, and this fact, in turn, means that 16 enters the reaction with 21 in the excited triplet state. The end product 22 is formed after the triplet-singlet conversion of the triplet biradical 23t followed by cyclization of the singlet biradical 23s (Scheme 11), while the triplet biradical 23T also reverts to the initial reagents. Only this reverse reaction could explain the negative polarization (emission) of the Me protons of the initial thiacycloheptyne 21. It should be noted that the process described in Scheme 11 is the first example of a reaction of the excited triple state of germylene 1676. 

Different activity of 5-[2-(dimethylamino)ethyl]-9-phenyl-47/-benzo[,y) ]thiazolo[5,4-g]isoquinoline-4,6(5/f)-dione derivatives as photonucleases may arise from the impact of substituents on the 2-phenyl ring of thiazole on the electron population of the excited triple state according to AMI semi-empirical calculations <2004TL1247>. 

A new family of photonucleases, 5-[2-(dimethylamino)ethyl]-9-phenyl-4//-benzo[rA]thiazolo[5,4-g]isoquinoline-4,6(57/)-dione derivatives, 544, was synthesized and evaluated. These compounds intercalated into DNA efficiently and damaged DNA photochemically at concentrations as low as 5pM. Mechanistic studies suggested that a novel naphthalimide-thiazole radical produced via an excited triple state might be involved in the DNA photodamage <2004TL1247>. 

Thus in the case of the coupled fermions when the singlet and tripled states belong to the same molecular species, the corresponding scattering functions are... 

Biacetyl diffused onto the pre-wetted fiber initially. Then, as monomer vapors were introduced and the surface was irradiated with ultraviolet-visible light, the excited biacetyl dissociated to yield acetyl radicals or decayed to its more stable triple state through intersystem crossing. These radical species abstract accessible hydrogens from the substrate or near the surface of the fiber substrate, which in turn react with monomer in the proximity or possibly within the solvent wetting the substrate. Growing pol)rmer chains were terminated in a manner whereby only limited initiation of homopol3nnerization occurred. 

Besides the excited singlet states some excited tripled states Ti, T2, etc. exist, which cannot be reached directly by absorption of radiation starting from the ground state Sq. This direct transition is forbidden [3]. In the case of radiationless transition this limitation is not valid. For this reason the molecule A can radiationlessly deactivate to the first triplet state A" (Tj) (see Jablonski s diagram in Fig. 1.1)... 

Fig. 8.30. Sequence of reactions involved in the development of sunlight flavor ( 3 indicates that the oxidized riboflavin reacts in triple state.)...

Livingstone and Owens have shown that the triplet state is an essential intermediate in chlorophyll-sensitized photochemical reactions occurring in homogeneous solutions (17). It has not yet been satisfactorily proven whether or not the triple state participates in in viw chlorophyll reactions, but nevertheless there is considerable evidence that the sequence of biochemical reactions in photosynthesis is initiated by a chlorophyll molecule in its triplet state (5). 

In convenhonal systems, the excited state is the singlet state. However, there are systems, in which from both singlet and triple state electroluminescence is observed. These systems are superior to the convenhonal ones. 

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