Solvent‐free luminous molecular liquids (LMLs) are a new generation of soft matter which exhibit uncharged, nonvolatile, and fluidic nature and emit intense and homogeneous luminescence in the ...condensed state. They can be produced readily on the gram scale by modifying luminophores with bulky, flexible, and low‐melting side chains. Their performance can be facilely enriched by blending them with commercially available functional substances. Therefore, since their active optoelectronic properties were perceived a decade ago, LMLs have been regarded as promising contributing components in the burgeoning field of flexible and wearable light‐emitting devices. Recently, richer insights into LMLs have triggered various new applications. Additionally, unexpected phase behavior and photophysical properties have been discovered coincidentally. Therefore, the sensible and sophisticated molecular design principles of LMLs are still being augmented to guarantee predictable, steady, and consistent end‐use performance. This review summarizes the latest developments in LMLs, including molecular design principles, regulation and enrichment of their photophysical properties, and their versatile applications. Additionally, a prediction of the perspectives of LMLs in the near future is presented at the end.
The history, molecular design principles, function enrichment, and versatile applications of luminous molecular liquids are reviewed. As a newly emerging nonvolatile soft luminescent material, luminous molecular liquids are uncharged, nonvolatile, fluidic, and highly luminescent. Their effortless preparation, superior stability, high processability, facile refillability, and unlimited deformability facilitate wide applications in various research fields, in particular, the burgeoning flexible light‐emitting devices.
A novel and easily accessible luminescent iridium(iii) complex Ir(tpy)2(N^N)PF6 (, tpy = 2-(p-tolyl)pyridine, N^N = 4-(4-amino-3-nitrophenoxy)-methylene-4'-methyl-2,2'-bipyridine) for the sensing of ...HOCl has been designed and synthesized. The detection strategy is based on the HOCl-promoted cleavage of the PET quenching 4-amino-3-nitrophenyloxy moiety of the weakly emissive complex , which gives rise to a highly luminescent complex Ir(tpy)2(N^N')PF6 (, N^N' = 4-hydroxymethyl-4'-methyl-2,2'-bipyridine). Comparisons of the absorption, emission and mass spectra of in the absence and presence of HOCl have all confirmed the transformation of to . Titration and competition experiments have revealed high sensitivity and high selectivity of for HOCl, respectively. Significantly, the feasibility of the sensor under physiological conditions enables the successful luminescent imaging of HOCl in HeLa cells.
In recent years, high-power white light-emitting diode (wLED)/laser diode (wLD) lighting sources based on transparent phosphor ceramic (TPC) materials have attracted increasing application interest ...in automotive headlights, projection displays, and space navigation lighting due to their superior brightness, lighting distance, compactness, lifespan, and environmental resistance compared with the widely used phosphor-converted wLEDs. However, preparing TPC-converted wLEDs/wLDs with high color rendering index (CRI) remains a huge challenge, which limits their widespread application. In this review, we summarize the recently adopted strategies for constructing TPCs to develop high-power wLEDs/wLDs with high CRI values (>75). The construction protocols were categorized into four groups: host regulation, red-emitter doping, host regulation/red-emitter doping combination, and composite structure design. A comprehensive discussion was conducted on the design principles, photoluminescent properties, and device performances for each strategy. The challenges and future trends of high-power and high-CRI wLEDs/wLDs based on TPCs are also discussed toward the end of this review.
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•A novel synthetic method based on vapor-phase catalytic methylation was presented.•Environmental friendly 1,1,1,3,3,3-hexafluoroisopropylmethyl ether was synthesized.•The synthetic ...process is continuous and pollution-free.•The reaction is catalyzed by alkaline earth metal fluorides, with MgF2 most active.•A mechanism for the catalytic methylation was proposed.
1,1,1,3,3,3-Hexafluoroisopropylmethyl ether (HFE-356mmz) is an important substitute for chlorofluorocarbons and hydrochlorofluorocarbons due to its zero ozone depletion potential and low global warming potential. However, mass production of HFE-356mmz remains a long-standing challenge. Herein, we applied metal fluorides as catalysts in the methylation of 1,1,1,3,3,3-hexafluoroisopropanol to produce HFE-356mmz for the first time.
The catalyst not only improves the synthetic efficiency, but also makes the reaction solvent-free.
The pollution-free, recyclable, and continuous synthetic process enables industrial production of HFE-356mmz. To optimize the synthetic efficiency, a series of metal fluorides (AlF3, MgF2, CaF2, SrF2, and BaF2) was used, among which MgF2 exhibited the highest activity. Through careful examination of each metal fluoride, it was found that the activity of the catalyst was determined by co-operative action of the surface acid–base properties and the total amount of surface acid sites. Based on these results, a rational mechanism for the vapor-phase methylation was proposed.
Organic π-conjugated molecules with extremely rich and tailorable electronic and optical properties are frequently utilized for the fabrication of optoelectronic devices. To achieve high solubility ...for facile solution processing and desirable softness for flexible device fabrication, the rigid π units were in most cases attached by alkyl chains through chemical modification. Considerable numbers of alkylated-π molecular systems with versatile applications have been reported. However, a profound understanding of the molecular state control through proper alkyl chain substitution is still highly demanded because effective applications of these molecules are closely related to their physical states. To explore the underlying rule, we review a large number of alkylated-π molecules with emphasis on the interplay of van der Waals interactions (vdW) of the alkyl chains and π-π interactions of the π moieties. Based on our comprehensive investigations of the two interactions' impacts on the physical states of the molecules, a clear guidance for state control by alkyl-π engineering is proposed. Specifically, either with proper alkyl chain substitution or favorable additives, the vdW and π-π interactions can be adjusted, resulting in modulation of the physical states and optoelectronic properties of the molecules. We believe the strategy summarized here will significantly benefit the alkyl-π chemistry toward wide-spread applications in optoelectronic devices.
A novel luminescent biscyclometalated iridium(III) complex Ir(C^N)2bpyPF6 (Ir-S, bpy = 2,2'-bipyridine) containing two 2-phenylpyridine (ppy) cyclometalating ligands (C^N) functionalized with ...1,3-dithiane for the detection of Hg(2+) ions has been synthesized and characterized by spectroscopic and photophysical measurements. The luminescence of Ir-S exhibits a ratiometric response upon the addition of Hg(2+) ions. The absorption, emission, (1)H NMR and ESI mass spectral changes of Ir-S in the absence and presence of Hg(2+) ions have all demonstrated the Hg(2+)-promoted thioacetal deprotection reaction of Ir-S and the generation of a complex Ir(pba)2bpyPF6 (Ir-CHO, Hpba = 4-(pyridin-2-yl)benzaldehyde). DFT calculation studies suggest that the dominant participation of the 1,3-dithiane group in the HOMO of Ir-S leads to different excited states and distinct excited energies of Ir-S and Ir-CHO and consequently results in their different emission properties. The titration and competition experiments significantly reveal the highly sensitive and selective properties of Ir-S as a promising indicator for Hg(2+) ions over other metal cations.
Solvent-free, nonvolatile, room-temperature alkylated-π functional molecular liquids (FMLs) are rapidly emerging as a new generation of fluid matter. However, precision design to tune their ...physicochemical properties remains a serious challenge because the properties are governed by subtle π-π interactions among functional π-units, which are very hard to control and characterize. Herein, we address the issue by probing π-π interactions with highly sensitive pyrene-fluorescence. A series of alkylated pyrene FMLs were synthesized. The photophysical properties were artfully engineered with rational modulation of the number, length, and substituent motif of alkyl chains attached to the pyrene unit. The different emission from the excimer to uncommon intermediate to the monomer scaled the pyrene-pyrene interactions in a clear trend, from stronger to weaker to negligible. Synchronously, the physical nature of these FMLs was regulated from inhomogeneous to isotropic. The inhomogeneity, unexplored before, was thoroughly investigated by ultrafast time-resolved spectroscopy techniques. The result provides a clearer image of liquid matter. Our methodology demonstrates a potential to unambiguously determine local molecular organizations of amorphous materials, which cannot be achieved by conventional structural analysis. Therefore this study provides a guide to design alkylated-π FMLs with tailorable physicochemical properties.
In present study, we discovered unusual solvent-mediated aggregation-enhanced emission (AEE) character of 11-mercaptoundecanoic acid capped gold nanoclusters (MUA-Au NCs). When aggregated in aqueous ...media, the MUA-Au NCs showed strong emission, which was weakened by adding ethanol. Interestingly, the suppressed emission was selectively enhanced in the presence of hydrogen sulfide (H
2
S) because H
2
S was absorbed onto Au NCs through the strong sulfur-gold bonding affinity. The hydrolyzed H
2
S, namely, HS
−
, made the Au NCs negatively charged, which aggregated again due to decreased solubility. The H
2
S-mediated fluorescence enhancement can be further amplified by introducing a hydrophilic thiolate (glutathione, GSH) onto the surface of Au NCs (GSH/MUA-Au NCs), which enabled sensitive determination of H
2
S. Under the optimized condition, a detection limit of 35 nM was achieved. The determination was not interfered by other anions such as F
−
, Cl
−
, Br
−
, I
−
, OAc
−
, N
3
−
, NO
3
−
, HCO
3
−
, SCN
−
, SO
3
2−
, and SO
4
2−
. This excellent sensing performance allowed practical application of the GSH/MUA-Au NC-based sensing platform to accurate determination of H
2
S in human serum samples.
Graphical abstract
Unusual aggregation-enhanced emission character of 11-mercaptoundecanoic acid capped gold nanoclusters is discovered and has been applied for fluorometric hydrogen sulfide detection.
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•One-pot and top-down synthesis of Au8 NCs was represented.•Characterizations of the prepared Au8 NCs and formation mechanism were discussed.•A sensitive and selective fluorescence ...probe for hemoglobin was proposed.•The capability of the present probe was validated by analyzing hemoglobin in blood samples.
Gold nanoclusters (Au NCs) with atomic precision have huge application potentials in chemo/bio sensing, catalysis, and energy conversion. However, a precise atomic control of Au NCs still remains a great challenge. Herein, we developed a facile one-pot and top-down strategy to synthesize eight-atom numbered Au NCs (Au8 NCs), aiming to understand their fundamental physicochemical properties and explore their potential applications. The etching of gold nanoparticles by their encapsulated hyperbranched polyethyleneimine was significantly promoted by a newly proposed catalyst, hydrogen peroxide, which gave rise to brightly blue-emitting Au8 NCs (quantum yield = 28.8%). The as-prepared Au8 NCs could sense hemoglobin with a detection limit of 5.0 nM through the combination of Fenton reaction and fluorescence resonance energy transfer. And the sensing behaviour is unaffected by the presence of various interferents such as proteins, small molecules, anions, and metal ions. In addition, a hemoglobin evaluation in blood samples with small relative standard deviations and satisfied recoveries was achieved using the proposed Au8 NC nanoprobes.
The exploitation of selective and sensitive dopamine (DA) sensors is essential to more deeply understand its biological function and diagnosis of related diseases. In this study, gold ...nanocluster-encapsulated hyperbranched polyethyleneimine (hPEI-Au NCs) has been explored as the specific and ratiometric DA nanoprobe through hPEI-assisted DA self-polymerization reactions. The Au NCs encapsulation not only provides a fluorescent internal reference but also enhances the DA self-polymerization by weakening the proton sponge effect of the hPEI layer. Rapid and sensitive DA detection is realized through the proposed hPEI-Au NC nanoprobe with a limit of detection of 10 nM. The favorable selectivity over other possible interferents including amino acids, sugars, and salts is due to the specific self-polymerization reaction. The DA analysis in urine samples with small relative standard deviations has been accomplished with an hPEI-Au NC nanoprobe.
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