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Europium confined cyclen dendrimers with photophysically active triazoles
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-9200-8004
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
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2008 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 18, no 22, 2545-2554 p.Article in journal (Refereed) Published
Abstract [en]

Dendrimers up to the fourth generation (G1-G4) were successfully synthesized via the efficient copper catalyzed 1,3-dipolar cycloaddition between primary alkynes and azides (CuAAC), also referred to as a click reaction. The synthetic protocol involved the preparation of presynthesized dendron wedges that subsequently were attached to a tetra-valent alkyne functional cyclen core. These constructed structures integrated stable triazole groups "intra-locked'' between the cyclen and dendron wedges. The incorporation of a lanthanide metal ion, europium, into the interior of all cyclen dendrimers was monitored by FT-IR. Interestingly, the photophysical results showed that the proximate triazole not only acts as a stable linker but also as a sensitizers, transferring its singlet-singlet excitation in the ultraviolet region (270-290 nm) to the partially filled luminescent lanthanide 4f shell. An increase of luminescence decay time from the lanthanide D-5(0) -> F-7(2) emission was observed with increasing dendrimer size, indicating that the shielding effect of the dendron wedges is important for the relaxation of the photo-excitation and energy transfer. To the best of our knowledge, this is the first time a set of dendron wedges have successfully been attached to a cyclen metal ion cage via the versatile click reaction. Furthermore, the produced triazoles intra-locked in close proximity to the macrocycle core elucidated an interesting photophysical function.

Place, publisher, year, edition, pages
2008. Vol. 18, no 22, 2545-2554 p.
Keyword [en]
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-8693DOI: 10.1039/b802197jISI: 000256073500004ScopusID: 2-s2.0-44149087379OAI: diva2:14080
QC 20100621Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2010-06-28Bibliographically approved
In thesis
1. Functional Dendritic Materials using Click Chemistry: Synthesis, Characterizations and Applications
Open this publication in new window or tab >>Functional Dendritic Materials using Click Chemistry: Synthesis, Characterizations and Applications
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [sv]

Förfrågan efter nya och mer avancerade applikationer är en pågående process vilket leder till en konstant utveckling av nya material. För att förstå relationen mellan en applikations egenskaper och dess sammansättning krävs full förståelse och kontroll över materialets uppbyggnad. En sådan kontroll över uppbyggnaden hos material hittas i en undergrupp till dendritiska polymerer som kallas dendrimerer. I den här doktorsavhandlingen belyses nya metoder för att framställa dendrimer med hjälp av selektiva kemiska reaktioner. Sådana selektiva reaktioner kan hittas inom konceptet klickkemi och har i detta arbete kombinerats med traditionell anhydrid- och karbodiimidmedierad kemi.

Denna avhandling diskuterar en accelererad tillväxtmetod, dendrimerer med inre och yttre reaktiva grupper, simultana reaktioner och applikationer baserade på dessa dendritiska material.

En accelererad tillväxtmetod har utvecklats baserad på AB2- och CD2-monomerer. Dessa monomerer tillåter tillväxt av dendrimerer utan att använda sig av skyddsgruppkemi eller aktivering av ändgrupper. Detta gjordes genom att kombinera kemoselektiviteten hos klickkemi tillsammans med traditionell syraklorid kopplingar.

Dendrimerer med inre alkyn- eller azidfunktionalitet syntetiserades genom att använda AB2C-monomerer. Den dendritiska tillväxten skedde med hjälp av karbodiimidmedierad kemi. Monomererna som användes bär på en C-funktionalitet, alkyn eller azid, och på så sätt byggs får interiören i de syntetiserade dendrimeren en inneburen aktiv funktionell grupp.

Ortogonaliteten hos klickkemi användes för att sammanfoga monomerer till en dendritisk struktur. Traditionell anhydridkemi- och klickemireaktioner utfördes samtidigt och på så sätt kunde dendritiska strukturer erhållas med färre antal uppreningssteg.

En ljusemitterande dendrimer syntetiserades genom att koppla azidfunktionella dendroner till en alkynfunktionell cyclenkärna. Europiumjoner inkorporerades i kärnan varpå dendrimerens fotofysiska egenskaper analyserades. Mätningarna visade att den bildade triazolen hade en sensibiliserande effekt på europiumjonen. Termiska studier på några av de syntetiserade dendrimerer utfördes för att se om några av dem kunde fungera som templat vid framställning av isoporösa filmer.

Abstract [en]

The need for new improved materials in cutting edge applications is constantly inspiring researchers to developing novel advanced macromolecular structures. A research area within advanced and complex macromolecular structures is dendrimers and their synthesis. Dendrimers consist of highly dense and branched structures that have promising properties suitable for biomedical and electrical applications and as templating materials. Dendrimers provide full control over the structure and property relationship since they are synthesized with unprecedented control over each reaction step. In this doctoral thesis, new methodologies for dendrimer synthesis are based on the concept of click chemistry in combination with traditional chemical reactions for dendrimer synthesis.

This thesis discusses an accelerated growth approach, dendrimers with internal functionality, concurrent reactions and their applications.

An accelerated growth approach for dendrimers was developed based on AB2- and CD2-monomers. These allow dendritic growth without the use of activation or deprotection of the peripheral end-groups. This was achieved by combining the chemoselective nature of click chemistry and traditional acid chloride reactions.

Dendrimers with internal azide/alkyne functionality were prepared by adding AB2C monomers to a multifunctional core. Dendritic growth was obtained by employing carbodiimide mediated chemistry. The monomers carry a pendant C-functionality (alkyne or azide) that remains available in the dendritic interior resulting in dendrimers with internal and peripheral functionalities.

The orthogonal nature of click chemistry was utilized for the simultaneous assembly of monomers into dendritic structures. Traditional anhydride chemistry and click chemistry were carried out concurrently to obtain dendritic structures. This procedure allows synthesis of dendritic structures using fewer purification steps.

Thermal analyses on selected dendrimers were carried out to verify their use as templates for the formation of honeycomb membranes. Additionally, a light emitting dendrimer was prepared by coupling of azide functional dendrons to an alkyne functional cyclen core. A Europium ion was incorporated into the dendrimer core, and photophysical measurements on the metal containing dendrimer revealed that the formed triazole linkage possesses a sensitizing effect.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 77 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2008:47
Dendrimer, Dendron, Dendritic, Hyperbranched, Click, Chemistry, CuAAc, One-Pot, Multi-functional, Simultaneous, Honeycomb, Isoporous, MALDI, NMR, GPC, TGA, DSC
National Category
Polymer Chemistry
urn:nbn:se:kth:diva-4808 (URN)978-91-7415-017-9 (ISBN)
Public defence
2008-06-13, F3, Lindstedtsvägen 26, KTH, Stockholm, 14:00
QC 20100629Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2010-09-13Bibliographically approved

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