Abstract:Solid‐state materials with efficient room‐temperature phosphorescence (RTP) emissions have found widespread applications in materials science, while liquid or solution‐phase pure organic RTP emission systems has been rarely reported, because of the nonradiative decay and quenchers from the liquid medium. Reported here is the first example of visible‐light‐excited pure organic RTP in aqueous solution by using a supramolecular host‐guest assembly strategy. The unique cucurbit[8]uril‐mediated quaternary stacking … Show more
“…This mechanism has four important features: first, in aqueous solution, CBs provide a hydrophobic environment that protects the triplet state from the collision of the triplet oxygen and other molecules. Second, the strong host-guest interactions As a result, the combination of the host-guest interaction, π-π/Br-π interaction, halogen bonding, and multiple hydrogen bonding jointly contribute to the long RTP of CB [8]/HA-BrBP in aqueous solution probably by restricting the molecular motion, promoting the ISC and reducing the non-radiative decay 14,17,[31][32][33][34]37,[42][43][44][45] .…”
Section: Resultsmentioning
confidence: 99%
“…Fourth, the formation of halogen bonding between the C-Br of BrBP and the N atom of the adjacent BrBP (C-Br···N angle of 159.6°, Br···N distance 3.09 Å) increase the Mulliken charge on the Br atom and thus affected the heavy effect. As a result, the combination of the host–guest interaction, π–π/Br–π interaction, halogen bonding, and multiple hydrogen bonding jointly contribute to the long RTP of CB[8]/HA–BrBP in aqueous solution probably by restricting the molecular motion, promoting the ISC and reducing the non-radiative decay 14 , 17 , 31 – 34 , 37 , 42 – 45 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Macrocyclic compounds (i.e., cyclodextrin, cucurbituril) have become a research hotspot for realizing purely organic phosphorescence in aqueous solution due to their special properties of internal hydrophobicity/external hydrophilicity and host-guest interactions 12,[26][27][28][29][30][31][32] . Up to now, although the phosphorescence in water has made great progress through the host-guest interactions, the purely organic phosphorescence with long lifetime and function in water is rarely reported and still faces great opportunities and challenges.…”
Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature phosphorescent supramolecular polymer by combining cucurbit[n]uril (CB[7], CB[8]) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB[7] mediated pseudorotaxane polymer CB[7]/HA–BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB[8] results in biaxial pseudorotaxane polymer CB[8]/HA–BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB[8] and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.
“…This mechanism has four important features: first, in aqueous solution, CBs provide a hydrophobic environment that protects the triplet state from the collision of the triplet oxygen and other molecules. Second, the strong host-guest interactions As a result, the combination of the host-guest interaction, π-π/Br-π interaction, halogen bonding, and multiple hydrogen bonding jointly contribute to the long RTP of CB [8]/HA-BrBP in aqueous solution probably by restricting the molecular motion, promoting the ISC and reducing the non-radiative decay 14,17,[31][32][33][34]37,[42][43][44][45] .…”
Section: Resultsmentioning
confidence: 99%
“…Fourth, the formation of halogen bonding between the C-Br of BrBP and the N atom of the adjacent BrBP (C-Br···N angle of 159.6°, Br···N distance 3.09 Å) increase the Mulliken charge on the Br atom and thus affected the heavy effect. As a result, the combination of the host–guest interaction, π–π/Br–π interaction, halogen bonding, and multiple hydrogen bonding jointly contribute to the long RTP of CB[8]/HA–BrBP in aqueous solution probably by restricting the molecular motion, promoting the ISC and reducing the non-radiative decay 14 , 17 , 31 – 34 , 37 , 42 – 45 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Macrocyclic compounds (i.e., cyclodextrin, cucurbituril) have become a research hotspot for realizing purely organic phosphorescence in aqueous solution due to their special properties of internal hydrophobicity/external hydrophilicity and host-guest interactions 12,[26][27][28][29][30][31][32] . Up to now, although the phosphorescence in water has made great progress through the host-guest interactions, the purely organic phosphorescence with long lifetime and function in water is rarely reported and still faces great opportunities and challenges.…”
Purely organic room-temperature phosphorescence has attracted attention for bioimaging but can be quenched in aqueous systems. Here we report a water-soluble ultralong organic room-temperature phosphorescent supramolecular polymer by combining cucurbit[n]uril (CB[7], CB[8]) and hyaluronic acid (HA) as a tumor-targeting ligand conjugated to a 4-(4-bromophenyl)pyridin-1-ium bromide (BrBP) phosphor. The result shows that CB[7] mediated pseudorotaxane polymer CB[7]/HA–BrBP changes from small spherical aggregates to a linear array, whereas complexation with CB[8] results in biaxial pseudorotaxane polymer CB[8]/HA–BrBP which transforms to relatively large aggregates. Owing to the more stable 1:2 inclusion complex between CB[8] and BrBP and the multiple hydrogen bonds, this supramolecular polymer has ultralong purely organic RTP lifetime in water up to 4.33 ms with a quantum yield of 7.58%. Benefiting from the targeting property of HA, this supramolecular polymer is successfully applied for cancer cell targeted phosphorescence imaging of mitochondria.
“…reported another RTPsystem based on CB[8] and atriazine derivative TBP,which is the first visiblelight-excited purely organic RTPi na queous solution (Figure 2e). [20] A2:2 quaternary complex was formed by CB[8] and TBP.T he confinement of the complex could effectively suppress the nonradiative relaxation and protect the guest molecules from oxygen, resulting in ay ellow RTPe mission originating from the charge-transfer state of the TBP dimer. This material was successfully utilized in fabricating multicolor hydrogels and cell imaging.…”
Materials displaying room‐temperature phosphorescence (RTP) have been attracting wide attention in recent years due to their distinctive characteristics including long emissive lifetime and large Stokes shift, and their various applications. Most synthesized RTP materials are metal complexes that display enhanced intersystem crossing and crystallization is a common way to restrict nonradiative transition. Amorphous metal‐free RTP materials, which do not rely on expensive and toxic metals and can be prepared in a straightforward fashion, have become an important branch of the field. This Minireview summarizes recent progress in amorphous RTP materials according to the approaches used to immobilize phosphors: host–guest interactions, molecule doping, copolymers, and small‐molecule self‐assembly. Some existing challenges and insightful perspectives are given at the end of the Minireview, which should benefit the future design and development of amorphous metal‐free RTP materials.
“…In the traditional photoluminescence process, RTP is generated by the radiative transition of triplet state which is generated from excited singlet state through intersystem crossing (ISC). Crystal packing (22), polymerization (23) and host-guest interaction (24)(25)(26) are analyzed to suppress the molecular vibration and oxygen quenching which competed with the radiative transition.…”
Section: Mechanism Of Trace-ingredient-mediated Bicomponent Rtpmentioning
<p>The trace impurities in
pure organic phosphors were always ignored because the ultra-low content
impurities were considered to hardly affect the luminescent properties. Evidences
from corresponding reports and research have shown that impurities may greatly affect
room temperature phosphorescence (RTP) in some crystalline compounds. To date, very
few literatures have clearly study the role of impurities in RTP because of the
difficulty in the separation and structure identification of impurities. Also no
reports have focused on utilizing trace impurities to form new strategies for efficient
RTP.</p>
<p>For the
first time, an impurity was isolated from 1-(4-bromophenyl)-1<i>H</i>-imidazole (1BBI) and
structural identified, which was proved to be the key to RTP in 1BBI crystal. Neither
purified impurity nor 1BBI matrix shown any detectable RTP. The impurity could light
up the unusual ultralong RTP in matrix even at <b>0.01 mol%</b> content. Inspired
by impurity/matrix phosphorescence, a trace-ingredient-mediated bicomponent strategy
was introduced for high phosphorescence quantum yield (QY, up to 74.2%) and extralong
lifetime (up to 430 ms).</p><p><b>Research Highlights of this work are including</b></p><p><b>1. </b><b>The study of impurities in organic luminescent materials, including
phosphorescent materials, is rarely reported due to the great difficulty of
separation, purification</b><b> and structure characterization. This work not only separated, purified
and structure identified the trace impurity in the system but also confirmed
the fact that the impurity engenders the RTP. And the corresponding mechanism
was proposed as well.</b></p><p><b>2. </b><b>Inspired by
the role of impurities in RTP, this work proposed an effective strategy for the
design and preparation of persistent organic RTP based on active ingredient incorporation.
Seven compounds were screened out to conduct the bicomponent RTP system and
achieved bright RTP with high QY (up to 74.2%) and extra-long lifetime (up to
430 ms)) RTP with tunable colors.</b></p><p><b>3. </b><b>Combining
the dual emission of blue fluorescence and yellow phosphorescence, a bicomponent
system achieved a bright white-light emission, which shows its outstanding application
potential.</b></p><p>
The design concept and
strategy of this work supplies an efficient approach to develop RTP by simply
mixing the matrix with a trace amount
of active ingredients. And the trace-ingredient-mediated bicomponent system is preferred
for its high efficiency, color-tunable, low cost and easy to prepare properties,
which will make important sense for facilely developing organic persistent RTP
materials. This work will not only lead to a new understanding of persistent
organic RTP but also develop a facile and effective strategy for RTP afterglow
materials.<br></p>
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