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现在不仅有机化学家,而且生物化学家和生物学家对单重态氧化学都感到兴趣。因为单重态氧与有机物的反应能力很强,而且还与有机材料受光和氧的破坏作用、以及动植物的生命过程等~([1,2])有一定联系. 单重态分子氧氧原子在组成氧分子时,按分子轨道理论的解释,应该有一对电子填入能量相同的两个简并反键轨道π~*2p_v和π~*2p_z上。根据洪特规则,这两个电子尽可能分占不同轨道,且自旋平行。氧分子的这种电子状态,即是三重态。由于具有g对称性,所以是~3∑_g态。在激发态时,氧分子的两个π~*电子可同时占据一个π~*轨道,其自旋相反,这便是氧分子的第一激发单重态,它也具有g对称性,故电子态是~1△_g。如果两个电子分占不同的π~*轨道,且自旋相反,这是氧分子的第二激发单重态(~1∑_g)。激发态氧分子虽有各种单重态,但一般用的单重态氧为其最低激发态,即~1△_g状态(~1O_2)~([2,3])。
Not only organic chemists now, but also biochemists and biologists are interested in singlet oxygen chemistry. Because of the strong ability of singlet oxygen to react with organic matter, it is also related to the damage of organic materials by light and oxygen, as well as the life processes of animals and plants [1,2]. The singlet oxygen Atoms in the composition of oxygen molecules, according to the theory of molecular orbital theory, there should be a pair of electrons filled into the energy of the same two degenerate anti-bond orbit π ~ * 2p_v and π ~ * 2p_z on. According to Hunt’s rule, the two electrons share different orbits as much as possible and the spins are parallel. This electronic state of the oxygen molecule is triplet. Since it has g symmetry, it is ~ 3Σ_g state. In the excited state, two π ~ * electrons of oxygen molecules occupy a π ~ * orbit at the same time. Their spin is the opposite. This is the first excited singlet state of oxygen molecules. State is ~ 1 △ _g. If two electrons share different π ~ * orbitals and the spin is opposite, this is the second excited singlet (~ 1Σ_g) of the oxygen molecule. Although the excited state oxygen molecules have various kinds of singlet states, the singlet oxygen generally used is the lowest excited state, ie ~ 1 △ _g state (~ 1O_2) ~ ([2,3]).