Dyes included in channels: effects of the confinement on the photoexcited triplets

Maniero, Anna Lisa; Barbon, Antonio; Bortolus, Marco; Brustolon, Marina

doi:10.1016/j.synthmet.2004.05.026

Cited by 5 publications

(7 citation statements)

References 16 publications

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“…2 Moreover, compared to their shorter oligomer analogues, polymers neither offer large inter-chain exciton couplings. 3 Therefore, within the last years, special attention has been paid to supramolecular, nanostructured host-guest compounds (HGCs), [4][5][6][7] especially based on channel-forming organic [7][8][9][10][11][12][13][14] or inorganic host materials like nanoporous silica 15,16 or zeolites. 4,6,17 The interest in such materials is twofold.…”

Section: Introductionmentioning

confidence: 99%

“…Applied research benefits from the control of the geometry by the supramolecular organization in a variety of cavity sizes and shapes, as well as from high fluorescence efficiencies and exciton diffusion by the suppression of emission quenching (as often induced by aggregation) despite the high chromophore concentration in the HGCs, 4,6,8,12,[17][18][19][20] allowing for bright color-tuned materials. 4,12 Inorganic hosts demonstrated superior chemical and mechanical stability, and tunability of crystal size and aspect ratio, as well as the possibility of optically or electrically addressing such materials via the 'stopcock principle' introduced by G. Calzaferri et al 4,6 Basic research on the other hand finds in such materials an ideal system to investigate the impact of spatial confinement on chromophore properties, 9,14,[21][22][23][24] but especially to study the 'ingredients' of three-dimensional exciton transport through a radical reduction of parameters, that is the use of weakly coupled, well-defined oligomers in a highly ordered system. 8,18,19 From such studies also traditional active layers of (polymeric) conjugated materials might benefit by learning how to achieve high exciton diffusion lengths.…”

Section: Introductionmentioning

confidence: 99%

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Directional exciton transport in supramolecular nanostructured assemblies

Gierschner

2012

Phys. Chem. Chem. Phys.

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Supramolecular nanostructured host-guest compounds provide an intriguing strategy for improved materials in optoelectronic devices. Here, conjugated organic guest molecules are embedded in channel-forming organic or inorganic hosts, like perhydrotriphenylene (PHTP) and zeolites, leading to weakly coupled, highly ordered, and brightly emissive materials. In-depth material characterization allows for a full understanding of the exciton transport mechanism in the weak coupling regime through steady-state time-resolved fluorescence studies combined with quantum-chemical based Monte-Carlo simulations without adjustable parameters. Despite weak chromophore coupling and dilution by the host, the exciton diffusion length exceeds 50 nm similar to molecular crystals, and might be tuned to the μm range by the proper choice of host and guest materials.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Directional exciton transport in supramolecular nanostructured assemblies

Gierschner

2012

Phys. Chem. Chem. Phys.

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“…They show spectral changes and efficient energy transfer processes when included as guests in one-dimensional supramolecular architectures, as in perhydrotriphenylene crystals (PHTP). 11 This characteristic can be exploited for energy conversion or in detectors of short-wavelength radiation. Recently, we have reported conformational de-tails of the PHTP:T3 inclusion compound.…”

Section: Introductionmentioning

confidence: 99%

Endohedral terthiophene in zigzag carbon nanotubes: Density functional calculations

Orellana

Vásquez

2006

Phys. Rev. B

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The inclusion and encapsulation of terthiophene ͑T3͒ molecules inside zigzag single-walled carbon nanotubes ͑CNT's͒ is addressed by density functional calculations. We consider the T3 molecule inside six semiconducting CNT's with diameters ranging approximately from 8 to 13 Å. Our results show that the T3 inclusion process is exothermic for CNT's with diameters larger than 9 Å. The highest energy gain is found to be of 2 eV, decreasing as the CNT diameter increases. This notable effect of stabilization is attributed to the positively charged CNT inner space, as induced by its curvature, which is able to accommodate the neutral T3 molecule. The band structure of the T3@CNT system shows that T3 preserves its electronic identity inside the CNT's, superimposing their molecular orbitals onto the empty CNT band structure without hybridization. Our results predict that the electronic states added by the T3 molecules would give rise to optical effects and nonradiative relaxation from excited states.

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“…The much higher resolution of these techniques with respect to optical spectroscopies give clear cut information on the molecular structure in the excited state by comparing experimental and calculated principal values of the fine dipolar tensor [zero-field splitting (ZFS) parameters]. 12,13 Moreover, the three triplet sublevels are generated with non Boltzmann populations, and consequently the time resolved EPR spectra are spin polarized. The values of non equilibrium populations are the fingerprint of the photophysical path of triplet formation.…”

Section: Introductionmentioning

confidence: 99%

“…Oligothiophenes with rod-like shape have been also included in nanostructured channel-like cavities of organic hosts. 13,16,17 In the present paper we report the TR-EPR and Echo-EPR spectra of the photoexcited a-oligothiophenes 4-T 2 (4,4 0 -dipentoxy-2,2 0 -dithiophene), 3-T 2 (3,3 0 -dipentoxy-2,2 0 -dithiophene) and 4-T 4 (4,4 0 0 0 -dipentoxy-2,2 0 :5 0 ,2 00 :5 00 ,2 0 0 0 -tetrathiophene), in an oriented glass of a liquid crystalline (LC) phase, and in a disorderd glassy phase for 3-T 2 .…”

Section: Introductionmentioning

confidence: 99%

Structure and dynamics of the triplet state of oligothiophenes in isotropic and partially oriented matrices

Barbon

Bortolus

Maniero

et al. 2005

Phys. Chem. Chem. Phys.

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The photoexcited triplet states of 4,4'-dipentoxy-2,2'-dithiophene (4-T2), 3,3'-dipentoxy-2,2'-dithiophene (3-T2), and 4,4'''-dipentoxy-2,2':5',2'':5'',2'''-tetrathiophene (4-T4) have been investigated by time-resolved electron paramagnetic resonance in glassy toluene and in a frozen oriented liquid crystal, which provides a partially ordered medium. The preferential orientation of the rod-like 4-T2 and 4-T4 is compared to that of the disk-like 3-T2. The use of an oriented matrix coupled to simple semiempirical calculations allowed us to determine the orientation of the principal axes of the fine interaction with respect to the molecular axes. The motional behavior of the molecules in the isotropic and anisotropic matrices has been studied by comparing the spectral profiles of the Echo detected EPR (Echo-EPR) spectra with those of the continuous wave time resolved EPR (TR-EPR). A model considering the modulation of the zero-field splitting (ZFS) by molecular libration accounts for the Echo-EPR lineshape, on the basis of motions around preferential axes depending on the embedding matrix. The differences in the ZFS parameters of the two isomers 4-T2 and 3-T2 are attributed to a mesomeric effect due to the substituents.

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Dyes included in channels: effects of the confinement on the photoexcited triplets

Cited by 5 publications

References 16 publications

Directional exciton transport in supramolecular nanostructured assemblies

Directional exciton transport in supramolecular nanostructured assemblies

Endohedral terthiophene in zigzag carbon nanotubes: Density functional calculations

Structure and dynamics of the triplet state of oligothiophenes in isotropic and partially oriented matrices

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