Construction of fluorescent hyperbranched polysiloxane‐based clusteroluminogens with enhanced quantum yield and efficient cellular lighting

Bai, Tian; Zhang, Yunsheng; Wang, Lan; Yan, Hongxia; Zhou, Wenhao

doi:10.1002/agt2.267

Cited by 17 publications

(17 citation statements)

References 34 publications

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“…These confinement/immobilization strategies mainly include aggregation/clustering (i.e., supramolecular type), 31 chemical cross-linking (i.e., chemical type), 32,33 mechanical compression (i.e., physical type), 16 and dendrimer/dendritic confinement (i.e., architectural type). 34,35 Such strategies to achieve "molecular confinement, immobilization, or rigidification" have been applied to create novel, active molecular states with through-space electronic communication/interactions that are presumed to be new molecular quantum states. 16 In addition, Feng et al reported that Si coordination with heteroatoms causes silicone-induced aggregation and endows silicone/siloxane-based polymers with NTIL properties.…”

Section: ■ Introductionmentioning

confidence: 99%

Unraveling the Influence of the Carbon Skeleton Structure and Substituent Electronic Effects on the Nontraditional Intrinsic Luminescence Properties of Nonconjugated Polyolefins

Bai,

Han,

2024

Macromolecules

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Through-space conjugation (TSC) has gradually been proven to be a vital interaction in photophysical processes, especially with the recent observation of nontraditional intrinsic luminescence (NTIL) arising from cluster/aggregation-induced molecular-scale confinement. However, although the effect of the spatial distance between molecular chains has been understood, it is not clear how the distance between adjacent conjugated structures in a single chain affects the NTIL properties of polymers, and this has become a significant research focus. Herein, four nonconjugated polyolefins with different carbon skeletons (C5/C6/C7/C8, in which the repeat units contained 5, 6, 7, and 8 carbon atoms, respectively) were synthesized, and their photophysical properties were systematically studied. The experimental and theoretical results showed that although the carbon skeleton of the C5 polymer contained only one less carbon atom than that of the C6 polymer (but possessed the same conjugated structure in the chain), the C5 polymer (QY = 23.4%) exhibited a much greater luminescence efficiency than the C6 polymer (QY = 3.3%). Moreover, the distance to the neighboring conjugated structure in the C7/C8 polymer chains was the same as that in the C5/C6 polymers, whereas the conjugated structure in the C7/C8 polymers had a longer π conjugation region and more rigid polymer chains than the C5/C6 polymers; thus, the C7/C8 polymer had longer fluorescence emission wavelengths than the C5/C6 polymers. Moreover, simple and nonconjugated polymers of CPBB (PCPBB-C4) derivatives with electron-donating (methoxy) and electron-withdrawing (alkynyl) groups were also prepared, and the fluorescence spectra showed that both the electron-donating (increased electron density and stabilized TSC) and electronwithdrawing (increased through space electronic interactions) groups in PCPBB-C4 resulted in red-shifted luminescence and increased luminescence efficiency. Above all, these insights reveal that the carbon skeleton structure and substituent electronic effects strongly influence the NTIL properties and provide valuable strategies for optimizing the NTIL efficiency and tuning the emission colors of nonconjugated polymers.

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Section: ■ Introductionmentioning

confidence: 99%

Unraveling the Influence of the Carbon Skeleton Structure and Substituent Electronic Effects on the Nontraditional Intrinsic Luminescence Properties of Nonconjugated Polyolefins

Bai,

Han,

2024

Macromolecules

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“…The key point of these two mechanisms is the intra-and/or intermolecular through-space conjugation (TSC) through the overlap or sharing of electron clouds of NCCs, [13] which leads to the formation of extended n-n, n-π and π-π conjugation and hence lowered energy levels, promoting electron transitions and photoluminescence emissions. Adjusting the chemical structures like the type of NCCs, [14] rigidity or flexibility of polymer chains [15,16] and intra-and/or intermolecular interactions are effective in promoting TSC and hence PL of NTLs.…”

Section: Introductionmentioning

confidence: 99%

Effects of nonaromatic through-bond conjugation and through-space conjugation on the photoluminescence of nontraditional luminogens

Zhang¹,

Bai²,

Deng³

et al. 2023

Preprint

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Photoluminescence (PL) mechanisms of nontraditional luminogens (NTLs) have attracted great interests, and they are generally explained with intra/intermolecular through-space conjugation (TSC) of nonconventional chromophores (NCCs). Here we propose a new concept of nonaromatic through-bond conjugation (TBC) and proved that it plays an important role in the PL of NTLs. The PL behaviors of cyclohexanedione (CHD), dimethyl-1,3-cyclohexanedione (DMCHD) and their three respective isomers are studied and correlated with their chemical structures and aggregate structures. These compounds show different fluorescence emissions from blue to yellow region, and they also show different concentration-dependent emission (CDE) and excitation-dependent emission (EDE) characteristics. The position of ketone groups and the steric hindrance of methyl groups in the compounds determine the occurrence of keto-enol tautomerism or not. The compounds with conjugated keto-enol structure (i.e., nonaromatic TBC) show red-shifted emissions with comparison to the compounds with only isolated diketone structures. Theoretical calculations show that TBC effect reduces the HOMO-LUMO energy gaps of single molecules, and it facilitates the formation of stronger TSC in the aggregate state. The cooperative effect of nonaromatic TBC and TSC leads to more significantly red-shifted emissions. This work provides a novel and deeper understanding of the PL mechanisms of NTLs and is of great importance for directing the design and synthesis of NTLs with enhanced and red-shifted emissions.

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“…24 Moreover, the Si O Si bond in the HBPSi structure has a large bond angle, and the vacant orbital on each Si atom is favorable for accepting electrons and forming coordination bonds, which prompts HBPSi to emit bright fluorescence. 25 Therefore, it can be predicted that the electronabsorbing effect of Cl or Br atoms can greatly change the electron delocalization of the entire HBPSi molecular system after the introduction of Cl or Br atoms into its structure, and affecting the AIE performance of HBPSi. Halogen atoms acting as electron-absorbing groups can not only strengthen the electrostatic force between molecules, which is conducive to intermolecular aggregation, but also broaden the fluorescence emission peak of the polymer due to its electron-donating conjugate effect.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with F atoms, Cl atoms and Br atoms are rarely studied, which possess larger atomic radius and more balanced electron effects, such as electron‐attracting induction effect and electron‐donating conjugation effect 24 . Moreover, the SiOSi bond in the HBPSi structure has a large bond angle, and the vacant orbital on each Si atom is favorable for accepting electrons and forming coordination bonds, which prompts HBPSi to emit bright fluorescence 25 . Therefore, it can be predicted that the electron‐absorbing effect of Cl or Br atoms can greatly change the electron delocalization of the entire HBPSi molecular system after the introduction of Cl or Br atoms into its structure, and affecting the AIE performance of HBPSi.…”

Section: Introductionmentioning

confidence: 99%

The blue fluorescence luminescence properties of hyperbranched polysiloxane containing halogen atom

Jia

Yang

et al. 2023

Polymer International

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In order to obtain a new class of aggregation‐induced emission (AIE) polymers without common conjugated chromophores in their structures, hyperbranched polysiloxanes (HBPSi) containing halogen elements were obtained by introducing chlorine and bromine atoms into HBPSi (Cl‐HBPSi, Br‐HBPSi) through one‐step polycondensation reaction. The relationship between the chemical structure and fluorescence properties of the two types of HBPSi was studied. The results show that both Cl‐HBPSi and Br‐HBPSi prepared in this study can emit bright blue light under a UV lamp of 365 nm wavelength, and appropriate ratio of raw materials can endow the halogenated HBPSi with moderate degree of polymerization, and give it strong excitation intensity and emission intensity. Meanwhile, Br‐HBPSi exhibits a higher fluorescence intensity, which is due to the ‘heavy atom effect’ of halogen atoms. In addition, for different concentrations of tetrahydrofuran (THF) solutions with the same addition of HBPSi, the luminescence intensity increases gradually with the decrease of THF concentration. These results indicate that the emission intensity is affected by the molecular weight and concentration of polymers, and that the AIE properties of halogenated HBPSi are related to the ‘impurity atomic clusters’ formed by halogenated atoms and the hydroxyl groups formed by the heterogeneity of HBPSi. © 2023 Society of Industrial Chemistry.

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Construction of fluorescent hyperbranched polysiloxane‐based clusteroluminogens with enhanced quantum yield and efficient cellular lighting

Cited by 17 publications

References 34 publications

Unraveling the Influence of the Carbon Skeleton Structure and Substituent Electronic Effects on the Nontraditional Intrinsic Luminescence Properties of Nonconjugated Polyolefins

Unraveling the Influence of the Carbon Skeleton Structure and Substituent Electronic Effects on the Nontraditional Intrinsic Luminescence Properties of Nonconjugated Polyolefins

Effects of nonaromatic through-bond conjugation and through-space conjugation on the photoluminescence of nontraditional luminogens

The blue fluorescence luminescence properties of hyperbranched polysiloxane containing halogen atom

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