Towards octupolar ruthenium acetylide complexes for nonlinear optical materials : synthesis, characterization and linear and nonlinear optical properties
Creators: name: Schwich, Torsten
Publisher: name: The Australian National University
Year: 2012
Subjects: subject: QC446.2.S34 2012
subject: Nonlinear optics Materials
subject: Optical materials
subject: Ruthenium compounds

description: When nonlinear optical (NLO) effects were first observed experimentally in the early 1960s, the door to a new field of research was opened. Over the last 50 years, this area has expanded rapidly, supported by applications and devices that are based on nonlinear effects. The search for small, and yet fast and highly efficient devices for, e.g., data processing, data storage, or logic gates, is ongoing. Materials with nonlinear optical properties, and in particular organometallic complexes and coordination compounds, have been found to be strong candidates in this area for a number of reasons. An overview of the results that have been published by research groups in this field over the last decade is given in the opening Chapter. Understanding the highly complex physical processes of nonlinear optics, and maximizing these effects to make practical use of them, is a challenge for theoreticians, physicists and chemists. The overlap of these fields enables us to develop models to derive strategies towards building efficient NLO materials. The focus of the present work is on two aspects of ruthenium acetylide complexes incorporating pi-conjugated systems. The first part considers the effects on NLO properties, resulting from lengthening the pi-delocalized system in unbranched octupolar (star-shaped) ruthenium acetylide complexes. Acetylide complexes of bis(bidentate)-ligated Ru have proven to provide desired physical and optical properties; the star-shaped design of the complexes allows access to mono-disperse macromolecular entities that combine large pi-conjugated systems, while incorporating the desired metal centers. In this part of the work, a number of systematically varied octupolar ruthenium acetylide complexes were synthesized and characterized. Their optical and physical properties are discussed, and their nonlinear optical properties were explored by frequency-dependent Z-scan measurements. A variety of new NLO scaling factors are suggested and were applied to NLO data, and the applicability of the new NLO scaling factors was explored. Linear, oligo(phenylethynyl)-bridged ruthenium acetylide complex analogues of the star-shaped complexes were also synthesized, in order to establish the different NLO properties of linear (dipolar) vs. star-shaped (octupolar) arrangements. The second part of this work presents a group of systematically varied mono-disperse, branched ruthenium acetylide complexes (dendrimers). The main interest was the variation of the core unit. Six first-generation organometallic dendrimers with nitrogen, boron, and phenyl cores were synthesized and characterized. The NLO properties of two nitrogen-cored zero-generation dendrimers and an analogous nitrogen-cored first-generation dendrimer were explored; comparison to analogous organic zero-, first- and second-generation dendrimers revealed a drastic enhancement of the NLO properties on incorporation of the metal centers. A number of star-shaped and dendritic mixed-metal osmium-ruthenium acetylide complexes were also synthesized. --provided by Candidate.