Krasnovsky A A, Rodgers M A, Galpern M G, Rihter B, Kenney M E, Lukjanetz E A
Center for Photochemical Sciences, Bowling Green State University, OH 43403.
Photochem Photobiol. 1992 May;55(5):691-6. doi: 10.1111/j.1751-1097.1992.tb08512.x.
Using the direct measurement of the photosensitized luminescence of singlet molecular oxygen (1O2) the rate constants (kq) have been determined for 1O2 quenching by the monomeric molecules of the following phthalocyanines and naphthalocyanines in chloroform: tetra-(4-tert-butyl) phthalocyanine (I); octa-(3,6-butoxy) phthalocyanine (II), tetra-(6-tert-butyl)-2,3 naphthalocyanine (III), aluminium tetra-(1-tert-phenyl)-2,3 naphthalocyanine (IV), tri-(n-hexyl-siloxy) derivatives of silicon- (V), tin- (VI), aluminium- (VII) and gallium- (VIII) 2,3 naphthalocyanine. The following kq values were obtained (kq x 10(-8) M-1 s-1): 2.9 (I), 59 (II), 100 (III), 20 (IV), 3.9 (V), 53 (VI), 33 (VII), 110 (VIII). As most of the quenchers have the low-lying triplet levels, a contribution of the quenching mechanism based on the energy transfer from 1O2 to these levels has been analysed. A formula is proposed describing the relation between kq values caused by this mechanism, and photophysical constants of the quencher triplet state. This formula was applied to phthalocyanines, naphthalocyanines, beta-carotene and bacterochlorophyll a. The data suggest that the energy transfer can fully explain the activity of V and strongly contributes into the activities of II, III and VI-VIII. A charge transfer interaction might be an additional mechanism involved in 1O2 quenching by compounds studied. As some phthalocyanines and naphthalocyanines are strong physical quenchers of singlet oxygen they can be used as efficient inhibitors for photodestructive processes in photochemical systems.
通过直接测量单线态分子氧（¹O₂）的光敏发光，已测定了以下酞菁和萘酞菁的单体分子在氯仿中对¹O₂猝灭的速率常数（kq）：四 -（4 - 叔丁基）酞菁（I）；八 -（3,6 - 丁氧基）酞菁（II），四 -（6 - 叔丁基）-2,3萘酞菁（III），铝四 -（1 - 叔苯基）-2,3萘酞菁（IV），硅 -（V）、锡 -（VI）、铝 -（VII）和镓 -（VIII）2,3萘酞菁的三 -（正己基 - 硅氧基）衍生物。获得了以下kq值（kq×10⁻⁸ M⁻¹ s⁻¹）：2.9（I），59（II），100（III），20（IV），3.9（V），53（VI），33（VII），110（VIII）。由于大多数猝灭剂具有低三重态能级，已分析了基于从¹O₂到这些能级的能量转移的猝灭机制的贡献。提出了一个公式，描述了由该机制引起的kq值与猝灭剂三重态的光物理常数之间的关系。该公式应用于酞菁、萘酞菁、β - 胡萝卜素和细菌叶绿素a。数据表明，能量转移可以充分解释V的活性，并对II、III和VI - VIII的活性有很大贡献。电荷转移相互作用可能是所研究化合物对¹O₂猝灭的另一种机制。由于一些酞菁和萘酞菁是单线态氧的强物理猝灭剂，它们可用作光化学系统中光破坏过程的有效抑制剂。
