Updates on Application of Silver Nanoparticles - Progress in Organic and Physical Chemistry: Structures and Mechanisms - page 113

9

Updates on Application of
Silver Nanoparticles

N. I. Naumkina, O. V. Mikhailov,
and T. Z. Lygina

CONTENTS

9.1 Introduction ..................................................................................................... 113
9.2 Experimental.................................................................................................... 114
9.3 Discussion and Results .................................................................................... 114
9.4 Conclusion ....................................................................................................... 119
Keywords ................................................................................................................. 119
Acknowledgment ..................................................................................................... 119
References ................................................................................................................ 119

9.1 INTRODUCTION
Many medical and biological processes consist of photosensitive redox stages that
occur with the participation of metal porphyrins and hydrogen peroxide. For instance
photosynthesis consists of a large number of redox reactions, some of them are photo-
catalyzed by chlorophyll (Chl). During photosynthesis the interaction of electron do-
nor and carbon dioxide leads to the formation of energy intensive organic compounds
and generation of oxygen [1]. At present time it is proposed that water molecules are
oxidized to Ɉ 2 , and hydrogen peroxide is an intermediate of water oxidation [2, 3].
Moreover it is assumed that probably ɇ 2 Ɉ 2 is a source of photosynthetic oxygen [2]. It
is important that ɇ 2 Ɉ 2 oxidation is less endothermic than water [4]. In photodynamic
therapy metal porphyrins produce singlet oxygen, which is converted into hydrogen
peroxide in water media [3]. Thus, the pharmacologically active porphyrin photosen-
sitizers contact with the H 2 O 2 also.
Creation of arti¿ cial photosensitive systems is useful for the study of coordination
and photochemical interaction of metal complexes of porphyrins and reactive oxygen
species. It is known that some metal complexes with porphyrins and phthlocyanines
are effective catalysts of ɇ 2 Ɉ 2 decomposition in dark [5]. In this work, a photocatalytic
activity of Chl and metal (Cr, Cu, Sn, Zn, Cd, Mg) are complexes of tetraphenylpor-
phyrin (TPP) in the reaction of ɇ 2 Ɉ 2 decomposition was studied. Special attention is
paid to the coordination of metal porphyrins and hydrogen peroxide. In addition