Chemistry as a Prism: A Review of Light‐Emitting Materials Having Tunable Emission Wavelengths

Kim, Eunha; Park, Seung Bum

doi:10.1002/asia.200900102

Cited by 132 publications

(71 citation statements)

References 175 publications

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“…Smart fluorescent organic materials that exhibit external stimuli responsive reversible fluorescence are considered as potential candidates for advancement of modern technologies such as optoelectronics, optical recording, security inks and fluorescent sensors . The solid state fluorescence of organic materials are strongly influence by the molecular conformation, packing and intermolecular interactions . Subtle alteration of conformation and molecular arrangement by external stimuli can substantially modulate the excitonic interactions and fluorescent response in the solid state ,.…”

Section: Introductionmentioning

confidence: 99%

Tunable and Switchable Solid State Fluorescence: Alkyl Chain Length‐Dependent Molecular Conformation and Self‐Reversible Thermochromism

et al. 2017

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Flexible alkyl chain has been used to control the molecular conformation, packing and intermolecular interactions of aggregation enhanced emissive (AEE) triphenylamine fluorophore, and tune the fluorescence maxima and mechano/thermochromism. 2‐(4‐(diphenylamino)‐2‐ethoxybenzylidene)malononitrile (DPABM‐2), 2‐(4‐(diphenylamino)‐2‐propoxybenzylidene)malononitrile (DPABM‐3), 2‐(4‐(diphenylamino)‐2‐butoxybenzylidene)malononitrile (DPA‐BM‐4), 2‐(4‐(diphenylamino)‐2‐pentyloxybenzylidene) malono‐nitrile (DPABM‐5), 2‐(4‐(diphenylamino)‐2‐hexyloxybenzylidene) malonon‐itrile (DPABM‐6) and 2‐(4‐(diphenylamino)‐2‐heptyloxybenzylidene) malononitrile (DPABM‐7) exhibited weak to strong solid state fluorescence (absolute quantum yield (Φf)=4 to 26%). DPABM‐2 did not show significant fluorescence changes to external stimuli, however, DPABM‐3 and DPABM‐4 exhibited off‐on fluorescence switching. DPABM‐3 also showed tunable fluorescence via polymorphism. Interestingly, DPABM‐5‐7 showed alkyl chain orientation dependent self‐reversible thermochromism. DPABM‐5 and DPABM‐7 exhibited decrease of fluorescence intensity with temperature whereas DPABM‐6 showed increase of fluorescence intensity. Solid state structural analysis revealed the influence of alkyl chain length on the molecular conformations and packing. Powder X‐ray diffraction (PXRD) studies indicate that phase change of materials from crystalline to amorphous and vice‐versa was responsible for fluorescence switching with external stimuli. Further, AEE of DPABM derivatives and the reactive ethylene‐malononitrile has also been exploited for fabricating hydrazine sensing polymer composite film. Thus simple change of alkyl chain lengths lead to the generation of polymorphism, mechanochromism and temperature dependent self‐reversible fluorescence switching materials.

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Section: Introductionmentioning

confidence: 99%

Tunable and Switchable Solid State Fluorescence: Alkyl Chain Length‐Dependent Molecular Conformation and Self‐Reversible Thermochromism

et al. 2017

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“…Furthermore, many studies have focused on discovering novel fluorescent small molecules as well as tuning their photophysical properties, such as quantum yield F F , Stokes shift, absorption, excitation, and emission wavelength [2]. Despite the high demand for fluorophores, however, there are only a limited number of fluorescent organic core skeletons with sufficient flexibility in their synthetic strategies.…”

Section: Introductionmentioning

confidence: 99%

Discovery of New Fluorescent Dyes: Targeted Synthesis or Combinatorial Approach?

Kim

Park

2010

Springer Series on Fluorescence

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Because of their advantageous properties, fluorescent organic molecules have been used extensively in various applications. Despite the high demand for fluorophores, there are only a limited number of fluorescent organic core skeletons with sufficient flexibility in their synthetic strategies. The rational design of fluorescent probes having desirable photophysical properties is still far from being achieved because of the complexity of underlying photophysical phenomena of fluorescent small molecules. To study and improve the photophysical properties of fluorescent core skeletons, many efforts have been pursued. Traditionally, targeted approach had been used to rationally study the photophysical properties of known fluorescent core skeleton. On the other hand, recent studies showed that combinatorial approach can act as a powerful tool to discover or develop novel fluorescent probes. Through a comparison between targeted synthesis and combinatorial approach in the study of fluorescent organic compounds, we can conclude that the targeted synthesis with rational design and systematic modification using combinatorial approach are complementary to each other for the discovery of novel, small molecules with desired photophysical properties.

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“…In contrast, conventional π‐conjugated organic molecules showed strong fluorescence in the solution and become weak or non‐fluorescence due to aggregation caused quenching in the solid state. Special approaches such as aggregation enhanced emission (AEE) and supramolecular interactions have often been employed to generate strong solid state fluorescent materials . The enol‐keto photocycle (E−E*‐K*‐K−E) provided distinct four‐level laser scheme to achieve population inversion; hence, ESIPT materials have been utilized as laser dyes ,.…”

Section: Introductionmentioning

confidence: 99%

Molecular Conformation‐ and Packing‐Controlled Excited State Intramolecular Proton Transfer Induced Solid‐State Fluorescence and Reversible Mechanofluorochromism

Kundu

Karthikeyan²,

Moon

et al. 2018

ChemistrySelect

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Excited state intramolecular proton transfer (ESIPT) materials are highly desirable because of their unique solid state fluorescence. Schiff base molecules with appropriate hydrogen donor functional group forms intramolecular H‐bonding, a basis for ESIPT, however, only few molecules show solid state fluorescence. Herein, carbazole based Schiff base molecules 1 (2‐((E)‐(4‐(9H‐carbazol‐9‐yl)phenyl‐mino)methyl)phenol), 2 (2‐((E)‐(4‐(9H‐carbazol‐9‐yl)phenylimino) methyl)‐5‐methoxyphenol), 3 (2‐((E)‐(4‐(9H‐carbazol‐9‐yl)phenyl‐imino)methyl)‐5‐(diethylamino)phenol) and 4 (1‐((E)‐(4‐(9H‐carbazol‐9‐yl)phenylimino)methyl)naphthalen‐2‐ol)) were synthesized and ESIPT induced solid state fluorescence were correlated with solid state structural conformation and molecular packing. 2 and 4 exhibited solid state fluorescence whereas 1 and 3 did not show any fluorescence even though both 1 and 3 showed strong intramolecular H‐bonding. Further structural comparison revealed that not only the intramolecular H‐bonding facilitated ESIPT, the molecular conformation and resulting molecular packing also plays important role on the solid state fluorescence. Computational studies have also been performed to get the insight on the role of molecular conformation and organization. The non‐planar twisted molecular conformation of 2 and 4 showed reversible mechanofluorochromism (MFC). Powder X‐ray diffraction indicates that hard crushing converted crystalline to amorphous/partial amorphous phase whereas heating converts amorphous to crystalline. Thus the present study provides a structural insight for developing ESIPT based new Schiff base materials.

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Chemistry as a Prism: A Review of Light‐Emitting Materials Having Tunable Emission Wavelengths

Cited by 132 publications

References 175 publications

Tunable and Switchable Solid State Fluorescence: Alkyl Chain Length‐Dependent Molecular Conformation and Self‐Reversible Thermochromism

Tunable and Switchable Solid State Fluorescence: Alkyl Chain Length‐Dependent Molecular Conformation and Self‐Reversible Thermochromism

Discovery of New Fluorescent Dyes: Targeted Synthesis or Combinatorial Approach?

Molecular Conformation‐ and Packing‐Controlled Excited State Intramolecular Proton Transfer Induced Solid‐State Fluorescence and Reversible Mechanofluorochromism

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