Dendritic sidegroups as three-dimensional barriers to aggregation quenching of conjugated polymer fluorescence

Jakubiak, Rachel; Bao, Zhenan; Rothberg, Lewis J.

doi:10.1016/s0379-6779(00)00225-3

Cited by 140 publications

(77 citation statements)

References 20 publications

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“…16 The main argument in favor of excimer formation is the strong redshift of the PL of films as compared to solutions. 13,22 However, alternative interpretations of the photophysics of PPV systems suggested instead that there are indeed ground state interactions. 55 Nguyen et al concluded that for MEH-PPV films, a red edge in the absorption spectrum is related to an interchain aggregate.…”

Section: Discussionmentioning

confidence: 99%

“…The best example here is the PPV system for which the solubility was improved significantly by the addition of side chains/functional groups. 2,13,14 The key objective has therefore been to enable the control of the interactions, but in this context it is of utmost importance prior to this to first understand the character of the interactions. There are several different proposals regarding the nature of the interactions in the solid state, i.e., thin films.…”

Section: Introductionmentioning

confidence: 99%

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Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Pålsson

Vaughan

Monkman

2006

The Journal of Chemical Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Two related poly͑phenylene-vinylene͒ ͑PPV͒ light-emitting polymers have been investigated by means of polarized optical spectroscopy. The purpose of the investigation was to investigate the nature of the interactions in thin films and to examine what impact the difference in side chain structure and molecular weight in poly͑2Ј-methoxy-5-2-ethyl-hexoxy͒-1,4-phenylene vinylene ͑MEH-PPV͒ and poly͑2-͑3Ј ,7Ј-dimethyloctyloxy͒-5-methoxy-1,4-phenylene-vinylene͒ ͑OC 1 C 10 -PPV͒ has on the electronic and optical properties of the two polymers. Aligning the polymers by dispersing them in anisotropic solvents and stretched films shows that the side chains have an impact on the relative orientations of the transition dipole moments. In anisotropic solvents the linear dichroism is larger for MEH-PPV than for the related polymer OC 1 C 10 -PPV, while in stretched films the opposite situation prevails. A lower polarization of the luminescence from OC 1 C 10 -PPV, relative to MEH-PPV, was also obtained independent of alignment medium used. The data therefore suggest that while mechanical stretching may align the OC 1 C 10 -PPV to a greater degree, the emitting species is distinct from the absorbing species. The circular dichroism ͑CD͒ spectra of both polymers undergo dramatic changes when the liquid phase and the solid state ͑film͒ are compared. The solution CD spectra shows no evidence of interchain interactions; instead the spectra of both systems indicate a helical conformation of the polymers. The CD spectra of films are dramatically different with the strong Cotton effect being observed. This points to the formation of an aggregate in the film, with an associated ground state interaction, an interchain species such as a physical dimer, or a more complex higher aggregate.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Pålsson

Vaughan

Monkman

2006

The Journal of Chemical Physics

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“…[4,5] Complexity results from photophysical processes, which in dilute solution include solvent and/or conformational relaxation [3,[6][7][8][9][10] and intrachain energy transfer, [11][12][13] while in concentrated solution or in films they may also involve interchain energy transfer, [2] excimer formation [14] and formation of H or J aggregates. [15][16][17] The correct interpretation of this information is important for detecting, understanding and resolving problems such as imbalance of electron and hole injection currents, [18][19][20][21][22][23] decreased luminescence yields, which result from aggregation quenching that is dependent on the polymer concentration, [15][16][17] and chemical stability of the films.…”

Section: Introductionmentioning

confidence: 99%

Photodynamics of a PV Trimer in High‐Viscosity Solvents and in PMMA Films: A New Insight into Energy Transfer versus Conformational Relaxation in Conjugated Polymers

Paolo¹,

Morgado

Maçanita³

2009

ChemPhysChem

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Non-Stokes-Einstein relaxation: The rate constant of conformational relaxation of a phenylenevinylene trimer (see picture) in different solvents is proportional to eta(-alpha), with alpha values decreasing from close to unity (low viscosity) to zero at sufficiently high solvent viscosity. This behaviour is attributed to the flexible methylbutyl side chains of the trimer, which partially screen the solvent friction. The p-phenylenevinylene (PV) trimer (MBOPV3) was used to probe the effect of conformational relaxation on fluorescence decays of PV-based polymers in the high solvent viscosity regime, from n-hexadecane (3.45 cP at 293 K) to liquid paraffin (123 cP at 293 K), and in dilute poly(methyl methacrylate) (PMMA) solid films. The effect of intermolecular energy transfer and radiative transport on the fluorescence decays was also analysed by increasing the concentration of MBOPV3 in the PMMA films up to a pure MBOPV3 film. The rate constant of conformational relaxation was found to decrease with increasing solvent viscosity up to about 23 cP, but then becomes viscosity independent. The non-Stokes-Einstein behaviour of k(CR) versus eta over the whole viscosity range apparently results from the presence of the flexible methylbutyl side chains of MBOPV3, which partially screens the solvent friction. Conformational relaxation is not observed in very dilute PMMA solid films, where the fluorescence decay becomes single exponential. The decays become multi-exponential again with an increase of MBOPV3 concentration in the PMMA films, but in this case it is due to intermolecular (interchain) energy transfer from less planar to more planar conformations of MBOPV3. In the pure MBOPV3 film, interchain energy transfer (radiative and non-radiative) is the major process responsible for the observed (tetra-exponential) decays.

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“…Because of their unique structure and size, potential applications are manifold and include their use for light harvesting/energy fueling purposes [56][57][58], gene delivery [59], the bottom-up approach to nanoscience [60], and as catalyst supports [61]. Thus, the study of molecules and macromolecules with multiple branched structures and a high concentration of functional terminal groups is rapidly growing.…”

Section: Advantages and Applications Of Dendronized Polymersmentioning

confidence: 99%

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

et al. 2012

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Dendronization is a synthetic methodology that offers important advantages.The resulting products, which are called dendronized materials, present new and specific properties. This review shows numerous examples in which individual dendrons are used as building blocks to prepare more complex arrays via covalent or non-covalent interactions. In particular, it points out how the structural information programmed into the dendritic architecture can be used in the dendronization process to generate nanostructures with specific tailored properties. We emphasize the use of different dendrons, with diverse chemical structure and size, to functionalize diverse substrates like linear polymers, and plane and curved inorganic surfaces. Apart from this, the review also demonstrates that self-assembly represents an ideal approach to create well-defined hyperbranched surfaces and it includes some discussion about the ability of both organic and inorganic building blocks to direct this process.

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Dendritic sidegroups as three-dimensional barriers to aggregation quenching of conjugated polymer fluorescence

Cited by 140 publications

References 20 publications

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Polarized optical spectroscopy applied to investigate two poly(phenylene-vinylene) polymers with different side chain structures

Photodynamics of a PV Trimer in High‐Viscosity Solvents and in PMMA Films: A New Insight into Energy Transfer versus Conformational Relaxation in Conjugated Polymers

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

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