Synthesis of New Dendritic Macromolecules as Potential Optical Limiting Materials
Abstract
We have synthesized two new chromophore series whose bipolaron absorptions are in the spectral region 600-900 nm, an area of extreme interest for eye protection from laser attack. These chromophore series were derivatized for attachment to 3,5 dihydroxybenzyl alcohol to form dendrons, which were then attached to a core molecule, bis-phenol A, to form G-O dendrimers. We were also successful in preparing several dendrimers based on bis-(diphenylamino)stilbene repeat units by divergent methodology. These new dendrimers not only form highly absorbing charge states, but also display very large two photon absorption cross-sections. When the dendrimers are irradiated in the presence of strong electron acceptors, such as fullerene, photoinduced absorption occurs, and highly absorbing transient species are formed. In solution these photoinduced species appear to be polaronic rather than bipolaronic. These results offer the possibility that either polaronic radical-cations or bipolaronic dications might be accessible by photoinduced electron transfer processes. When these reverse saturable absorption processes occur in the same chromophores that have large two photon absorption, optical power limiting can observed from either or both mechanisms, depending on the excitation wavelength. Thus these new materials may be considered to be bimechanistic in an optical limiting sense.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 06, 2000
- Accession Number
- ADA384070
Entities
People
- Charles W. Spangler
- Lee H. Spangler
Organizations
- Montana State University