UV-Photolyse von 5-Joduracil / UV Photolysis of 5-Iodouracil

Abstract

Religious giving has been argued to be different compared to non-religious giving, because it influences after-life consumption while contributions to non-religious organizations are irrelevant to after-life consumption. The study herein examines this theoretical argument by investigating the relationships between age and religious and non-religious giving using the data of the Survey of Social Development Trends from Taiwan. From categorized contributions, this study estimates the effects of age, income, and price of giving on religious, charitable, academic, medical, and political contributions, as well as on the probability of providing volunteer work and the frequency of religious participation. The findings suggest that the positive relationships between age and the level of giving are stronger for religious and charitable giving while the positive effects of age on academic and medical giving are much weaker, and there is no significant relationship between age and political giving. That is, religious giving and charitable giving are closely related to afterlife consumption, but the effects of age on academic giving and medical giving are considerably different. Moreover, older people are more likely to provide volunteer work and attend more religious activities than younger individuals. Contributions to religious and charitable groups are positively related to contributions to academic, medical, and political organizations.

Generation of Thiyl Radicals by the Photolysis of 5-Iodo-4-thiouridine

“…3,22,23 However, to the best of our knowledge, there are no reports in the literature on the photochemistry of iodinesubstituted aromatic thiones. Photoinduced homolysis of C( 5)-I in 3, in analogy to the photochemistry of its oxygen congener 2, 3,4,[7][8][9][11][12][13][14][15][16] should lead to the formation the C(5)-centered radical 4-thiouridine-5-yl radical 7 (Chart 2) and an iodine atom. However, attempts to trap radical 7 by suitable reagents were unsuccessful.…”

“…5,6 The main photoreactions of 1 are photocycloaddition (forming thiethane) and H-abstraction. The results of photochemical studies of the nucleoside 2, 3,4 5-iodouracil, [7][8][9][10][11][12] and other derivatives of pyrimidine 13,14 indicate that the primary photochemical event, following electronic excitation of the chromophore, is C-I bond homolysis leading to the 5-uracilyl radical. 3,13,14 Subsequent reactions of this radical and eventually the structures of isolated, stable photoproducts depend on the presence of various reactive agents such as H atom donors, radical scavengers, and olefinic or aromatic compounds present in the irradiated systems.…”

“…In the absence of reactive addends in deoxygenated aqueous or acetonitrile-water solutions, the major product obtained from 2 or 5-iodouracil was uridine or uracil, respectively. 3,4,12 Irradiation of 2′,3′-O-isopropylidene-5-iodouridine 15 or 1,3-dimethyl-5-iodouracil 16 in the presence of benzene, pyrene, or phenantrene gave uracil derivatives with an appropriate aromatic substituent at the C-5 position of the uracil ring in addition to the dehalogenated pyrimidine or its nucleoside. The (C-5)-uridinyl radical is trapped by bis(2-amino-1-thioethane) to give 5-(2-aminoethylthio)-uracil 9,11,17 upon irradiation of 5-iodouracil in the presence of the disulfide.…”

“…The results of photochemical studies of the nucleoside 2 , , 5-iodouracil, − and other derivatives of pyrimidine , indicate that the primary photochemical event, following electronic excitation of the chromophore, is C−I bond homolysis leading to the 5-uracilyl radical. ,, Subsequent reactions of this radical and eventually the structures of isolated, stable photoproducts depend on the presence of various reactive agents such as H atom donors, radical scavengers, and olefinic or aromatic compounds present in the irradiated systems. In the absence of reactive addends in deoxygenated aqueous or acetonitrile−water solutions, the major product obtained from 2 or 5-iodouracil was uridine or uracil, respectively. ,, Irradiation of 2‘,3‘- O -isopropylidene-5-iodouridine or 1,3-dimethyl-5-iodouracil in the presence of benzene, pyrene, or phenantrene gave uracil derivatives with an appropriate aromatic substituent at the C-5 position of the uracil ring in addition to the dehalogenated pyrimidine or its nucleoside. The (C-5)-uridinyl radical is trapped by bis(2-amino-1-thioethane) to give 5-(2-aminoethylthio)-uracil ,, upon irradiation of 5-iodouracil in the presence of the disulfide.…”

Mechanistic Studies of the 5-Iodouracil Chromophore Relevant to Its Use in Nucleoprotein Photo-Cross-Linking

“…The high nucleoprotein photo-cross-linking yields achieved with 5-iodouracil substituted nucleic acids suggested that the primary photochemical process with excitation at the long-wavelength tail of the absorption band was also photoelectron transfer, possibly with the 5-iodouracil chromophore in the triplet state. However, a number of studies with 5-iodouracil, − 5-iodouridine, and even oligonucleotides and nucleic acids , bearing 5-iodouracil have concluded that the primary photochemical process of this chromophore is carbon−iodine bond homolysis. Indeed, carbon−iodine bond homolysis is a general photoreaction of organic iodides, , including vinyl iodides .…”