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Nonlinear Absorbing platinum(II) Acetylides for Optical Power Limiting Applications
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

During the past few decades, laser technology has had a strong impact on our society, providing important contributions to materials processing, data storage, communications, medicine, and defense applications. However, the progress in laser technology has also brought about the development of harmful portable high‐power lasers and tactical laser weapons. As a result, the hazard of being blinded by lasers (accidentally or from hostile use) has increased significantly. Hence, the need for protection against lasers has emerged. In order to protect optical sensors against harmful laser radiation, materials that absorb high intensity light, such as nonlinear absorbing chromophores, are employed. The concept of controlling the intensity of an optical light beam is usually referred to as optical power limiting and can be used efficiently in sensor protection devices.In this thesis, various nonlinear absorbing platinum(II) acetylides have been synthesized and characterized regarding their photophysical and optical limiting properties. Dendronized platinum(II) acetylides were prepared in order to evaluate the site isolation effect offered by the dendritic surrounding. The photophysical measurements reveal that the dendritic encapsulation enhances the phosphorescence, increases the luminescence lifetimes, and improves the optical limiting performance due to reduced quenching of the excited states.Triazole‐containing chromophores were synthesized using click chemistry to achieve functionalized platinum(II) acetylides. It was found that the position of the triazole unit affects the photophysical properties of these chromophores. The most promising results were obtained for the chromophore with the triazole located at the end of the conjugation where it may act as an electron donor, thus contributing to improved two‐photon absorption.A branched platinum(II) acetylide was also prepared in order to investigate the effect of multiple conjugated arms as well as multiple heavy atoms within the same molecule on the optical limiting performance. The star shaped chromophore reached the lowest clamping level of all compounds included in this thesis and constitutes a highly suitable chromophore for optical power limiting applications.The nonlinear absorbing chromophores were also incorporated into novel solid state materials based on PMMA. The actual device fabrication of doped organic glasses as optical limiters for sensor protection is presented, and their optical limiting performance is reported. The obtained organic glasses can reduce the transmission of high intensity light by 97 %.

Place, publisher, year, edition, pages
Stockholm: KTH , 2008. , 73 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2008:59
Keyword [en]
optical power limiting
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-9169ISBN: 978-91-7415-102-2 (print)OAI: oai:DiVA.org:kth-9169DiVA: diva2:25521
Public defence
2008-10-03, F3, Lindstedtsvägen 26, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20100920Available from: 2008-09-30 Created: 2008-09-29 Last updated: 2010-09-20Bibliographically approved
List of papers
1. Dendron Decorated Platinum(II) Acetylides for Optical Power Limiting
Open this publication in new window or tab >>Dendron Decorated Platinum(II) Acetylides for Optical Power Limiting
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2006 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 39, no 6, 2238-2246 p.Article in journal (Refereed) Published
Abstract [en]

The effect of dendritic substituents on a nonlinear optical chromophore for optical power limiting (OPL) has been investigated. Synthesis and characterization of bis((4-(phenylethynyl)phenyl)ethynyl)bis-(tributylphosphine) platinum(II) with dendritic end groups are described. Polyester dendrimers up to the fourth generation were grown divergently using the anhydride of 2,2-bis(methylol)propionic acid (bis-MPA). The introduction of the dendritic moieties onto the NLO chromophore enables further processing of the materials using polymeric and related techniques. OPL measurements performed at 532, 580, and 630 nm show that the OPL properties improve with increasing size of the dendritic substituent. It is also shown that the addition of the dendrons increase the OPL as compared to the nondecorated bis((4-(phenylethynyl)phenyl) ethynyl)bis-(tributylphosphine)platinum(II). By use of femtosecond z-scan measurements carried out at different pulse-repetition frequencies, it is shown that the two-photon absorption cross section is ∼10 GM. Using pulse repetition frequencies (100 kHz-4.75 MHz) so that the time between the pulses is comparable with the triplet excited lifetime, the z-scans become dominated by excited-state absorption of excited triplet states.

Keyword
Absorption, Addition reactions, Nonlinear optics, Polyesters, Synthesis (chemical)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-9157 (URN)10.1021/ma0523670 (DOI)000236314800035 ()2-s2.0-33645809313 (Scopus ID)
Note
QC 20100907Available from: 2008-09-25 Created: 2008-09-25 Last updated: 2017-12-13Bibliographically approved
2. Electronic states and phosphorescence of dendron functionalized platinum(II) acetylides
Open this publication in new window or tab >>Electronic states and phosphorescence of dendron functionalized platinum(II) acetylides
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2007 (English)In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 124, no 2, 302-310 p.Article in journal (Refereed) Published
Abstract [en]

The photophysical properties of bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine) platinum(II) with 2,2-bis(methylo])propionic acid (bis-MPA) dendritic substituents were studied. The fluorescence emission decay upon excitation in the UV (typically 350-380 nm) was rapid, in the order of I ns or shorter. In oxygen-saturated tetrahydrofuran solvent, the phosphorescence decay time was in the order of 200 ns. Bright phosphorescence at 530 nm was found for dendrimers under certain conditions. The associated phosphorescence decay time considerably increased to above 100-200 mu s at higher concentrations (30-100 mu M), and in oxygen-evacuated samples. Thus, it was clarified that the strongest triplet quenching was caused by oxygen dissolved in the sample, since it was possible to reversibly go between the bright and quenched phosphorescent state by freeze-thaw pumping cycles. The bright phosphorescence formed spontaneously for the cases with the larger dendritic substituents is implying a chromophore protecting effect. From time-dependent density functional calculations, the electronic structure of a few low-lying singlet and triplet states are discussed. A new mechanism for efficient triplet state formation and phosphorescence of Pt-ethynyls is proposed. Here, a fast relaxation via internal conversion takes the excited population of the dominant pi -> pi*, excitation into a lower singlet state of ligand-to-metal charge transfer character of pi sigma* type. This allows an efficient inter system crossing to the triplet state manifold.

Keyword
optical power limiting, platinum(II)-complexes, triplet state, phosphorescence, electronic structure, inter-system crossing, 2, 2-bis(methylol)propionic acid dendrimers, nonlinear-optical properties, pt-ethynyl compound, site-isolation, dendritic encapsulation, core, absorption, porphyrin, molecules, metalloporphyrins
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-16335 (URN)10.1016/j.jlumin.2006.03.019 (DOI)000243674400021 ()2-s2.0-33751425887 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
3. Click Chemistry for Photonic Applications: Triazole-Functionalized Platinum(II) Acetylides for Optical Power Limiting
Open this publication in new window or tab >>Click Chemistry for Photonic Applications: Triazole-Functionalized Platinum(II) Acetylides for Optical Power Limiting
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2008 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 18, no 2, 166-175 p.Article in journal (Refereed) Published
Abstract [en]

Three different triazole-containing platinum(ii) acetylide compounds were synthesized by click chemistry and evaluated for their use in optical power limiting (OPL) applications. The triazole unit was incorporated at three different positions within, or at the end of, the conjugation path of the chromophore. The aim is to explore the possibilities of using click chemistry to prepare dendronized chromophores, and to evaluate how the triazole structure affects the photophysical properties and the optical power limiting abilities of these acetylide compounds. It is shown that the concept of click chemistry can be used to attach branched monomer units to ethynyl-phenyl arms by Huisgen 1,3-dipolar cycloaddition, forming triazole units within the chromophore. Photophysical characterization of these triazole-containing materials shows an absorption maximum within the UV-A region and emission through both fluorescence and phosphorescence. Bright phosphorescence was emitted from argon purged samples, and decay measurements thereof showed triplet lifetimes of up to 100 μs. The results from the photophysical characterization suggest that the triazole does break the conjugation path, and in order to gain maximum optical limiting the triazole needs to be placed at the end of the conjugation. All three investigated triazole-containing platinum(ii) acetylides show good optical power limiting at 532 nm (10 ns pulse, f/5 set-up, 2 mm cells). The most efficient compound, with the triazole positioned at the end of the conjugation, reaches a defined clamping level of 2.5 μJ for a sample with a concentration of 50 mM in THF and a linear transmission above 80% at 532 nm. These data can be compared to the OPL properties of Zn-based porphyrins or derivatized thiophenes, reaching clamping levels of 6-15 μJ.

Keyword
Chromophores, Molecular structure, Monomers, Photonic crystals, Physical optics, Platinum compounds
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-9159 (URN)10.1039/b711269f (DOI)000251770800004 ()2-s2.0-37249056570 (Scopus ID)
Note
QC 20100903Available from: 2008-09-25 Created: 2008-09-25 Last updated: 2017-12-13Bibliographically approved
4. Efficient Nonlinear Absorbing Platinum(II) Acetylide Chromophores in Solid PMMA Matrices
Open this publication in new window or tab >>Efficient Nonlinear Absorbing Platinum(II) Acetylide Chromophores in Solid PMMA Matrices
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2008 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 13, 1939-1948 p.Article in journal (Refereed) Published
Abstract [en]

Platinum(II) acetylides were incorporated into poly(methyl methacrylate) (PMMA) glasses to obtain solid-state nonlinear optical devices. We report on device fabrication, structural, chemical, and mechanical properties, as well as the optical limiting capabilities of the final solids. Two different guest-host systems are presented: 1) Dye molecules functionalized to be readily dispersed in methyl methacrylate (MMA) and subsequent in situ polymerization of the MMA yielding solid PMMA host matrices. 2) Dye molecules functionalized to copolymerize with MMA forming covalent bonds between the guest and the PMMA host matrix. A range of doped organic solids were prepared, reaching concentrations up to 13 wt% of the guest molecule. Raman spectra of the doped solid devices indicate that the chemical structure of the nonlinear dyes remains intact upon the polymerization of the solid matrix. Luminescence spectra confirm that the basic photophysical properties observed for the same solute molecules in THF are maintained also in the solid state. Optical power limiting (OPL) characterization reveal clamping levels for the dyes nonbonded to the solid host being less than 4 μJ at pulse energies up to 110 μJ at 532 nm (f/5 arrangement and 5 ns pulses), which is comparable to the performance of similar dyes in THF solutions. In contrast, the highly crosslinked solid possesses a higher clamping level (8 μj) at the same nominal concentration.

Keyword
Acrylic monomers, Chemical properties, Chemical reactions, Concentration (process), Covalent bonds, Crosslinking, Electron beam lithography, Esters, Light emission, Luminescence, Matrix algebra, Mechanical properties, Military seaplanes, Molecules, Monomers, Optical design, Optical instruments, Photoresists, Platinum, Polymer blends, Polymerization, Polymers, Seaplanes, Sulfur compounds
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-9156 (URN)10.1002/adfm.200800265 (DOI)000257808300010 ()2-s2.0-47949119549 (Scopus ID)
Note
QC 20100910Available from: 2008-09-25 Created: 2008-09-25 Last updated: 2017-12-13Bibliographically approved
5. Synthesis and Characterization of a 3-Arm Star Platinum(II) Acetylide Chromophore Targeted for Optical Limiting Applications
Open this publication in new window or tab >>Synthesis and Characterization of a 3-Arm Star Platinum(II) Acetylide Chromophore Targeted for Optical Limiting Applications
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(English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041Article in journal (Other academic) Submitted
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-9174 (URN)
Note
QS 20120328Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2017-12-13Bibliographically approved

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