Synthesis of Giant Rigid π-Conjugated Dendrimers

Jiang, Yang; Lü, Yi-Xuan; Cui, Yuxin; Zhou, Qifeng; Ma, Yuguo; Pei, Jian

doi:10.1021/ol702063e

Cited by 36 publications

(19 citation statements)

References 24 publications

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“…Keywords: conformational change · cycloaddition · energy transfer · porphyrinoids · rotaxanes functions as the energy donors due to its high fluorescence quantum efficiency. [12] [3]Rotaxane A was synthesized utilizing a "threading-followed-by-stoppering" strategy among various template-directed protocols. [13] The well-known interaction between dibenzo [24]crown-8 (DB24C8) and dibenzyl ammonium (DBA) was chosen for the mechanical assembly, [14] and the Cu I -catalyzed azide-alkyne cycloaddition (CuAAC) was applied for the stoppering due to its good functional-group tolerance and high efficiency.…”

Section: Design and Synthesismentioning

confidence: 99%

Energy Transfer and Concentration‐Dependent Conformational Modulation: A Porphyrin‐Containing [3]Rotaxane

Han

Pei

2012

Chemistry An Asian Journal

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A zinc porphyrin-containing [3]rotaxane A was synthesized through a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Energy donors and acceptor porphyrin were introduced to dibenzo[24]crown-8 (DB24C8) and dibenzyl ammonium (DBA) units of [3]rotaxane A to understand the intramolecular energy transfer process. Investigations of the photophysical properties of [3]rotaxane A demonstrated that the intramolecular efficient energy transfer readily occurred from the donors on the wheels to the porphyrin center on the axis. The fluorescence of energy donors in the region of 400 to 450 nm was efficiently absorbed by the porphyrin acceptor under irradiation at 345 nm, and finally a red light emission at about 600 nm was achieved. Further investigation indicated that the conformation of [3]rotaxane A was self-modulated by changing its concentration in CH(2)Cl(2). The triazole groups on the wheel coordinated or uncoordinated to Zn(2+) through intramolecular self-coordination with the change in the concentration of [3]rotaxane A in CH(2)Cl(2). Therefore, this conformational change was reversible in a non-coordinating solvent such as CH(2)Cl(2) but inhibited in a coordinating solvent such as THF. Such interesting behaviors were rarely observed in porphyrin derivatives. This self-modulation feature opens up the possibility of controlling molecular conformation by varying concentration.

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Section: Design and Synthesismentioning

confidence: 99%

Energy Transfer and Concentration‐Dependent Conformational Modulation: A Porphyrin‐Containing [3]Rotaxane

Han

Pei

2012

Chemistry An Asian Journal

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“…Another π‐conjugated dendrimer 12 constructed solely with one central truxene decorated by three truxenyl units has also been used as EML in SL‐OLEDs. [ 23 ] The solid state PL spectrum of 12 [ 23b ] is similar to that recorded in toluene solution [ 23a ] indicating that formation of aggregates in the solid state is prevented because of the rigid and bulky structure of 12 . However and despite a blue emission is reached (430/460 nm), SP‐SL 12 [ 20 ] displays low performance (CE max of 0.07 cd A −1 ).…”

Section: Blue Single‐layer Oleds Using Pure Hydrocarbon Oscsmentioning

confidence: 88%

Blue Single‐Layer Organic Light‐Emitting Diodes Using Fluorescent Materials: A Molecular Design View Point

Poriel

Rault‐Berthelot

2020

Adv Funct Materials

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technology is mastered, it suffers from a real complexity, a high cost, and is time-consuming. Simplifying the multilayer structure with the so-called single-layer OLEDs (SL-OLEDs), the simplest device only made of the electrodes and the EML has hence rapidly appeared as a promising and appealing solution in this technology (Scheme 2, left).However, removing the functional organic layers of an OLED stack often leads to a dramatic decrease of the performance and reaching high efficiency blue SL-OLEDs has required intense researches and especially in term of materials design. Indeed, if one removes all the organic layers surrounding the EML, the efficient injection, transport, and recombination of charges within the device, should be insured by the EML itself and therefore the fluorophore. However, this appears to be a real obstacle to cross for blue emitting materials. Indeed, blue fluorophores usually possess a high HOMO and a low LUMO energy rendering the injection of charges in such materials very difficult. This has been one of the main issue to address in this field. Common properties required for high-performance blue emitting materials can be summarized as follows: 1) blue light emission between 380 and 500 nm with maximum wavelength around 450 nm; 2) a narrow full width at half maximum less than 60 nm; which produces low Commission Internationale de l'Eclairage (CIE) y-coordinate of less than 0.10 for TVs and cell phones; 3) thermal and morphological stability for stable device operation and a long device lifetime; 4) balance charge transport between electrons and holes flow and 5) adequate HOMO/LUMO energy levels for charge recombination and injection.Gathering all these properties in a single molecule is far from being an easy task and requires very precise designs. Indeed, as soon as one tries to adjust the HOMO/ LUMO energy levels of an organic semiconductor (OSC) with the Fermi levels of OLED electrodes, its gap is contracted and the emission wavelength is bathochromically shifted. This design strategy can hence lead to a material in which the charges can be more easily injected (the gap is contracted) but with an emission wavelength no more in the blue region. Trying to find the best compromise between adequate HOMO/LUMO energy and a blue emission has been the main challenge to address in the molecular design of efficient fluorophores for blue SL-OLEDs. This particularity has strongly restrained the development of such materials. However, for the last 30 years, research groups have developed many different molecular design strategies, which have led in some cases to high performance blue SL-OLEDs. Reaching high performance SL-OLEDs by molecular engineering of the fluorophore and Cyril Poriel is

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“…We have successfully synthesized dendrimers comprised solely of truxene units, up to the second generation ( Figure 10) [34]. The dendrimer's rigid scaffold results in strong steric repulsion in the solid state, giving this molecule an almost identical photoluminescence spectrum in the solid state as in solution.…”

Section: Fully Conjugated Dendrimers For Sensorsmentioning

confidence: 99%