High-contrast mechanochromism and polymorphism-dependent fluorescence of difluoroboron β-diketonate complexes based on the effects of AIEE and halogen

Qi, Yunpeng; Wang, Yongtao; Yu, Yiping; Liu, Zhiyong; Zhang, Yan; Du, Gangjun; Qi, Yu

doi:10.1039/c5ra27819h

Cited by 53 publications

(13 citation statements)

References 58 publications

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“…Although aggregation enhanced emission (AEE) phenomena, opposite to aggregation caused fluorescence quenching of π‐conjugated molecules, provides strategy to develop organic solid state fluorescent materials, only limited class of molecules showed stimuli induced fluorescence changes . For example, organic solid state fluorescent materials generated using non‐planar propeller core often exhibit mechanical stimuli responsive fluorescence switching due to planarization of core or phase change . Temperature controlled molecular packing in an excited state intramolecular proton transfer (ESIPT) and terpyridine based compound lead to reversible fluorescence switching ,.…”

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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“…[33] In this work, we show our efforts to construct outstanding MFC activities based on this kind of fluorophore. Firstly, considering that halogen atom can be used to regulate the intermolecular interactions, [39] packing modes, [40] and crystallinity [41,42] of organic molecules due to strong electron-withdrawing ability, which might be helpful for the generation of MFC phenomenon, bromine atom is first introduced into 4-position. Although the introduction of bromine weakens the crystallization ability of the obtained derivatives BIC-1-BIC-3 (Scheme 1) and leads to changes in their morphologies upon grinding, no fluorescence color changes are observed.…”

Section: Introductionmentioning

confidence: 99%

Construction of Mechanofluorochromic and Aggregation‐Induced Emission Materials Based on 4‐Substituted Isoquinoline Derivatives

Wang

Chen

Zhu

et al. 2022

Chemistry An Asian Journal

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Although many organic mechanofluorochromic (MFC) materials have been reported, the design strategy and formation mechanism are still unclear, and thus some of their discoveries are based on chance or a result of blind screening of some compounds. Herein, we show a strategy for constructing MFC materials from a multisubstituted isoquinoline compound with excellent crystallinity. The introduction of bromine atom at 4‐position realizes the morphological change from crystalline state to amorphous state under the stimulation of external pressure, but it is not enough to generate MFC phenomenon. Similarly, although naphthalene, benzofuran, and benzothiophene endow the resultant isoquinolines with twisted molecular conformations and aggregation‐induced emission (AIE) activities, no obvious solid‐state emission color changes are observed. However, the introduction of 2‐benzylidenemalononitrile and (E)‐2‐cyano‐3‐phenylacrylate leads not only to the AIE activities of IQ‐M and IQ‐A, but also to their outstanding and reversible MFC properties. The MFC activities of these two derivatives are demonstrated to come from more twisted molecular conformations, larger deformation spaces, and stronger intramolecular charge transfer compared with the other isoquinolines. This work offers important reference value for the construction of MFC and AIE materials from traditional fluorophores.

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“…12−25 To realize the high-contrast mechanochromic phenomenon before and after stimulating, strong solid-state emission is highly desired. 26,27 However, emissions of a majority of luminophors are weakened or even quenched when they are in solid or aggregation states, which is caused by the aggregation-caused quenching (ACQ) effect. 28 Such a notorious and thorny ACQ problem has greatly limited the effective application of mechanochromic materials.…”

Section: Introductionmentioning

confidence: 99%

1,8-Naphthalimide-Based Highly Emissive Luminophors with Various Mechanofluorochromism and Aggregation-Induced Characteristics

et al. 2019

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Six 1,8-naphthalimide-based tetraphenylethene derivatives were reported. These highly solid-state emissive compounds showed aggregation-induced emission enhancement or aggregate fluorescence change characteristics. Furthermore, these aggregation-induced green light-emitting or aggregation-induced yellow light-emitting luminophors also exhibited various mechanofluorochromism behaviors involving different fluorescent color changes. To determine the mechanochromic mechanism of these six mechanical stimulus-responsive luminogens, the powder X-ray diffraction (XRD) and X-ray single-crystal measurements were carried out. The powder XRD test results indicated that their interesting mechanofluorochromic behaviors were attributed to the interconversion between crystalline and amorphous states. Meanwhile, the X-ray single-crystal analyses results implied that the twisted molecular conformation and the absence of an intense intermolecular acting force led to a loose packing motif, and the alteration of molecular packing was responsible for the observed mechanofluorochromic effect.

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High-contrast mechanochromism and polymorphism-dependent fluorescence of difluoroboron β-diketonate complexes based on the effects of AIEE and halogen

Abstract: A series of AIEE-active difluoroboron β-diketonate complexes derivatives exhibit high-contrast mechanochromism, polymorphism-dependent fluorescence, and extremely high fluorescent quantum yields which could be as promising stimuli-responsive materials.

Cited by 53 publications

References 58 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

Construction of Mechanofluorochromic and Aggregation‐Induced Emission Materials Based on 4‐Substituted Isoquinoline Derivatives

1,8-Naphthalimide-Based Highly Emissive Luminophors with Various Mechanofluorochromism and Aggregation-Induced Characteristics

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