Page 24 - Photoreactive Organic Thin Films

I

PHOTOtSOM€RIZATION OF

AZOBENZENES

HERMANN RAU
Institut fiir Chemie, Universitdt Hohenheim, D-70593 Stuttgart, Germany

1.1 INTRODUCTION
1.2 THE AZO GROUP
1.2.1 Spectroscopic Properties
1.2.2 Isomerization
1.3 AZOAROMATICS OFTHEAZOBENZENETYPE
1.3.1 Spectroscopic Properties
1.3.2 Isomerization of Molecules of the Azobenzene Type
1.4 AZOAROMATICS OF THE AMINOAZOBENZENE TYPE
1.4.1 Spectroscopic Properties
1.4.2 Isomerization of Molecules of the Aminoazobenzene Type
1.5 AZOAROMATICS OF THE PSEUDO-STILBENETYPE
1.5.1 Spectroscopic Properties
1.5.2 Isomerization of Molecules of the Pseudo-StilbeneType
1.6 THE ISOMERIZATION MECHANISM
1.6.1 Azobenzene-Type Molecules
1.6.2 Pseudo-Stilbene-Type Molecules
1.7 CONCLUDING REMARKS

I.I INTRODUCTION

Most of the phenomena described in this monograph on photoreactive or-
ganic thin films are based on the isomerization of units deliberately built into
molecules, molecular assemblies, or polymers. Most especially, the Spectro-
scopic and isomerization behavior of these units determines the switching and
triggering properties of the photoreactive systems and devices. Information
storage and nonlinear optical properties, as well as photo-control of equilibria
and of polymer, membrane, and other properties are exploited in applications.
The majority of the systems outlined in this monograph contain the
azobenzene moiety as the photoswitchable unit. Therefore, the first chapter
of this monograph deals with the properties of this simple molecule and its
simple derivatives. Applications for various purposes are covered in some of
the following chapters.
Azobenzene 1 (Figure 1.1A) is particularly useful for these applications
for the following reasons:

Photoreactwe Organic Thin films
Copyright 2002, Elsevier Science (USA). All rights of reproduction in any form reserved.