High Luminescence Quantum Yield Research Articles

Reviewing the effect of aggregates in Rhodamine 6G aqueous solution on fluorescence quantum efficiency

Rhodamines constitute a class of dyes extensively investigated and applied in various contexts, primarily attributed to their high luminescence quantum yield. This study delves into the impact of aggregation on the thermal and optical properties of Rhodamine 6G (R-6G) solutions in distilled water. Examined properties encompass thermal diffusivity (D), temperature coefficient of the refractive index (dn/dT), fluorescence quantum efficiency (η), and energy transfer (ET). These parameters were assessed through thermal lens (TL) and conventional absorption and emission spectroscopic techniques. The dimerization of R-6G solutions was revisited, revealing that an increase in R-6G concentration alters the features of absorption and emission spectra due to dimer formation, resulting in unexpected behavior of η. Consequently, we introduce a novel model for the fraction of absorbed energy converted into heat (φ), which accounts for emissions from both monomers and dimers. Employing this model, we investigate and discuss the concentration-dependent behaviors of η for monomers (ηm) and dimers (ηd). Notably, our findings demonstrate that ηm values necessitate ηd = 0.2, a relatively substantial value that cannot be disregarded. Additionally, applying the Förster theory for dipole–dipole electric ET, we calculate microparameters for ET between monomers (CDD) and monomer–dimer (CDA). Critical ranges for ET in each case are quantified. Microparameter analysis indicates that ET between monomer–monomer and monomer–dimer species of R-6G dissolved in distilled water holds significance, particularly in determining ηm. These results bear significance, especially in scenarios involving high dye concentrations. While applicable to R-6G in water, similar assessments in other media featuring aggregates are encouraged.

Cation vacancy-boosted BaZnB4O8:xEu3+ phosphors with high quantum yield and thermal stability for pc-WLEDs.

Achieving high luminescent quantum yield and thermal stability of phosphors simultaneously remains challenging, yet it is critical for facilitating high-power white light emitting diodes (WLEDs). Herein, we report the design and preparation of the layered structure BaZnB4O8:xEu3+ (0.10 ≤ x ≤ 0.60) red phosphors with high quantum yield (QY = 76.5%) and thermal stability (82.8%@150 °C) by the traditional solid-state reaction method. The results of XRD and Rietveld refinement show that the presence of Eu3+ ions at Ba2+ sites causes the formation of cation (Zn2+/Ba2+) vacancies in the lattice. The PL and PL decay results reveal that the quenching concentration of BZBO:xEu3+ phosphors is as high as 50%, and the lifetime remains unchanged with Eu3+ concentration due to the unique structure of the host and the cation vacancies generated by the heterovalent substitution. Furthermore, on a 395 nm near-UV chip, a pc-WLED device with exceptional optical performance (CCT = 4415 K, CRI = 92.1) was realized using the prepared BZBO:0.50Eu3+ as a red phosphor. Simple synthesis and excellent performance parameters suggest that the reported BaZnB4O8:xEu3+ phosphors have promising applications in high-power pc-WLEDs. At the same time, it also indicates that cationic vacancy engineering based on heterovalent ion substitution is a potential strategy for improving luminescence quantum yield and thermal quenching performance.

A facile fluorescence imprinted strategy based on boronic acid functionalized MOF and Mg/N-CDs for discrimination of transferrin: Expansion for boronic acid functionalized MOF application

In this research, we proposed a novel fluorescence imprinted sensor (FIS@MIP) for rapid and sensitive detection of transferrin (TrF) based on the boronic acid functionalized Zr-MOF (Zr-UiO-66-B(OH)2) and high fluorescence quantum yield of Mg/N co-doped carbon dots (Mg/N-CDs). The boronic acid moieties of Zr-UiO-66-B(OH)2 could significantly covalently bind TrF and load more Mg/N-CDs to avoid fluorescence quenching caused by self-aggregation of Mg/N-CDs. Additionally, Zr-UiO-66-B(OH)2 was prepared though linker fragmentation approach, which eliminated the complex post modification process and could provide sufficient boric acid groups. High luminescent and fluorescence quantum yield endowed Mg/N-CDs remarkable fluorescence response to TrF. Under the optimal conditions, the fluorescence intensity of FIS@MIP at 438 nm was quenched by Trf within 1 min. Based on specific recognition sites, a good linear relationship was obtained in the linear range of 0.1 µM–20 µM, and the low detection limit was determined as 0.067 µM. In order to explore portable detection application, a home-made device based on smartphone was designed for on-site detection of TrF with a detection limit of 0.38 µM. Significantly, this smartphone platform was successfully applied for detection of TrF in simulated actual samples (i.e., human urine and human serum) with satisfactory results, which provided a new promising strategy for on-site and sensitive discrimination of TrF in actual samples. This research will promote the development of the application of boronic-acid functionalized Zr-MOF in molecularly imprinted sensing of glycoproteins..

Recyclable soft photonic crystal film with overall improved circularly polarized luminescence

Existing circularly polarized luminescence materials can hardly satisfy the requirements of both large luminescence dissymmetry factor and high luminescent quantum yield, which hinders their practical applications. Here, we present a soft photonic crystal film embedded with chiral nanopores that possesses excellent circularly polarized luminescence performance with a high luminescence dissymmetry factor as well as a large luminescent quantum yield when loaded with various luminescent dyes. Benefitting from the retention of chiral nanopores imprinted from a chiral liquid crystal arrangement, the chiral soft photonic crystal film can not only endow dyes with chiral properties, but also effectively avoid severe aggregation of guest dye molecules. More importantly, the soft photonic crystal film can be recycled many times by loading and eluting guest dye molecules while retaining good stability as well as circularly polarized luminescence performance, enabling various applications, including smart windows, multi-color circularly polarized luminescence and anticounterfeiting.

Heterobimetallic lanthanide tetrahedral cages: Synthesis, design and application for potential multimodal imaging contrast agent

The construction and functionalization of lanthanide-organic cages have been a research hotspot in coordination chemistry. Benefiting from the unique luminescent and magnetic properties of lanthanide ions, the potential applications of lanthanide-organic cages in biological imaging applications are promising, but only a few corresponding explorations have been reported. Herein, we introduced a series of lanthanide tetrahedral cages, (EunGd4–nL4) (sol)8 (n = 0, 1, 2, 3 and 4, where L = (4,4′,4″-tris(4,4,4-trifluoro-1,3-dioxobutyl)-triphenylamine, and sol = dimethyl sulfoxide and methanol), with potential applications in biological imaging. Given the good luminescent and magnetic properties of Eu3+ and Gd3+ ions, Eu4L4 and Gd4L4 complexes show a high luminescence quantum yield of 29% in DMSO and large longitudinal relaxivity (r1) of 11.4 (mmol/L)−1/s at 0.5 T in water containing 1 vol% DMSO, respectively. The heterobimetallic Eu–Gd complexes achieve a dual imaging mode by combining luminescent and magnetic centers in one cage. When the Gd:Eu ratio increases from 1:3 to 3:1, the r1 values increases from 5.33 to 8.64 (mmol/L)−1/s, higher than that of commercial contrast agent Gd-DOTA (3.23 (mmol/L)−1/s). Owing to their low toxicity and good cell imaging ability toward ECA 109 cells, the self-assembled Eu–Gd heterobimetallic tetrahedral cages could be potential candidates for the multimodal imaging contrast agent.

Cyclic Voltammetry as an Activation Method of TiO2 Nanotube Arrays for Improvement of Photoelectrochemical Water Splitting Performance

AbstractA facile and eco‐friendly method for activating anodic TiO2 nanotubes (TNTs) by cyclic voltammetry (CV) is proposed, and photoelectrochemical properties of CV‐activated TNTs are compared with those of non‐activated TNTs and of TNTs activated by hydrogen‐thermal reduction. EPR and luminescence studies show that the pristine samples demonstrate rather large content of paramagnetic and luminescing defects, while hydrogenation and CV‐activation lead to the different type of rearrangement of defects. TNTs activated by CV‐Na2SO4 demonstrate significantly improved photocurrent density (2.25 mA cm−2) in comparison with that of the hydrogen treated and pristine ones (0.93 mA cm−2 and 0.31 mA cm−2) under NUV‐irradiation at 0.2 V (RHE). Enhanced photoactivity of Na2SO4‐activated TNTs correlates with higher luminescence quantum yield, lowest paramagnetic defects content and larger decay time of the luminescence. Thus, a decrease in the content of defects is an important factor that reduces the non‐radiative recombination of charge carriers. The activation‐induced redistribution of surface and bulk defects in nanotubes explains the increased photoelectrochemical activity of TiO2‐based anodes. Cyclic voltammetry has been proved to be a reliable method to increase the efficiency of TNTs in PEC water splitting.

Ultrahigh porosity photoluminescent silicon aerocrystals with greater than 50% nanocrystal ensemble quantum yields

Three types of mesoporous silicon flakes were fabricated by anodization in methanoic hydrofluoric acid from the same substrates (heavily doped p-type). Even though anodization current density, rinsing, drying method, and storage condition were the same for all three wafers, the resulting porous silicon (PSi) structures had very different properties. They had very different colors. Two of them showed quite high luminescence quantum yields (QYs), confirmed by very long luminescence lifetimes. The highest QY exceeded 50% for a peak photoluminescence wavelength of ∼750 nm. To date, this QY is the highest obtained for PSi and very importantly for silicon with large mesopores, which is typically not highly efficient (as opposed to silicon with small mesopores and microporous silicon). Large mesopores (>15 nm diameter) facilitate impregnation of various substances into luminescent material, such as metals for plasmonics and drugs for theranostics. The differing luminescent properties were correlated to electrolyte temperature during anodization, and evolution of the electrolyte batch (lowering of active fluoride content and buildup of hexafluorosilicate) used to anodize several wafers, whose effects are often overlooked when mass-producing PSi. Supercritical drying and completion of the slow growth of native oxide passivation in the dark leading to different final partially oxidized PSi structures are also important factors for the high QYs obtained. The highest QY was obtained with the structure having the most isolated Si nanocrystals in an amorphous Si oxide tissue.

New anilido-pyridine boron difluorides with high Stokes shift and intrinsic electrofluorochromism

New boron-locked substituted anilido-pyridines were obtained. The compounds exhibit high Stokes shift (up to 147 nm) and practical luminescence quantum yield (up to 62%), both in solution and in a solid state. The compounds demonstrate reversible electrochemical behavior and intrinsic electrofluorochromism. The possibility to modulate the fluorescence by direct electrochemical repetitive on/off switching was demonstrated by the spectroelectrochemical measurements, opening up prospects for creating fluorescent redox-switches based on these compounds.

Construction of High Quantum Yield Lanthanide Luminescent MOF Platform by In Situ Doping and Its Temperature Sensing Performance.

Lanthanide luminescent MOF materials show excellent luminescent properties. However, obtaining lanthanide luminescent MOFs with high quantum yield is a challenging research. A novel bismuth-based metal-organic framework [Bi(SIP)(DMF)2] was constructed by solvothermal method, utilizing 5-sulfoisophthalic acid monosodium salt (NaH2SIP) and Bi(NO3)3·5H2O. Thereafter, doped MOFs (Ln-Bi-SIP, Ln = Eu, Tb, Sm, Dy, Yb, Nd, Er) with different luminescent properties have been obtained by in situ doping with different lanthanide metal ions, among which Eu-Bi-SIP, Tb-Bi-SIP, Sm-Bi-SIP, and Dy-Bi-SIP have high quantum yield. What is special is that the doping amount of Ln3+ ions is very low, and the doped MOF can achieve high luminescence quantum yields. EuTb-Bi-SIP obtained by Eu3+/Tb3+ codoping and Dy-Bi-SIP exhibit good temperature sensing performance over a wide temperature range with the maximum sensitivity Sr of 1.6%·K-1 (433 K) and 2.6%·K-1, respectively (133 K), while the cycling experiments also show good repeatability in the assay temperature range. Finally, considering the practical application value, EuTb-Bi-SIP was blended with an organic polymer poly(methyl methacrylate) (PMMA) to produce a thin film, which shows different color changes at different temperatures.

Electrooptical switching and photopatterning of luminescence in nematic liquid crystals doped with mesogenic europium complex

Stimuli-responsive self-organized soft matter such as liquid crystals, polymers, gels attracts great attention due to a variety of possible applications in modern technologies. Electroinduced hydrodynamic (EHD) instability in liquid crystals is one of long-discovered effects that shows a great potential for future applications. However, this effect is insufficiently studied and its practical implementation has yet to be found. In the present paper, we applied an EHD instability to tuning luminescent properties of nematic mixtures doped with a highly emissive europium complex, which has good solubility in a liquid crystalline (LC) matrix and high quantum yield of luminescence. Nematic mixtures studied in this work possess negative anisotropy of dielectric constant and positive anisotropy of conductivity that allow for observing convective EHD patterns induced by ionic conductivity. The influence of field frequency on the threshold voltage was studied and optimal conditions for induction of EHD patterns were determined. The luminescence intensity was found to substantially decrease or increase under an applied electric field depending on the alignment behavior of LC molecules inside the cells and the angle of observation. In a tilted cell (60°), the emission intensity gradually increases under applied electric field and reaches values ca. 2.5 times higher than in zero field conditions. This phenomenon is associated with alignment of the europium complex molecules along electric field direction (cooperatively with LC molecules) and EHD-induced light scattering. Kinetics of electrooptic switching was studied and different approaches to luminescence photopatterning of the studied nematic mixture with polymerizable monoacrylate and diacrylate were demonstrated.

Binuclear Lanthanide Complexes Based on 4-Picoline-N-oxide: From Sensitized Luminescence to Single-Molecule Magnet Characteristics

Lanthanide complexes featuring luminescent and/or single-molecule magnet (SMM) characteristic(s) are proposed candidates to develop molecule-based spintronics, memory, and quantum information processing (QIP) device architectures. Herein, we report on the luminescent and/or SMM characteristic(s) of charge-neutral binuclear lanthanide complexes─[Ln2Cl6(4-picNO)4(μ2-4-picNO)2]·2H2O (Ln3+ = Tb3+ ([Tb2]) or Dy3+ ([Dy2]); 4-picNO = 4-picoline-N-oxide). The Dy and Tb complexes show 4-picNO-sensitized luminescence with quantum yields in the solid state of 0.14% and 88%, respectively. The luminescent Dy complex is an SMM with a magnetization reversal barrier (Ueff) = 20.6(4) cm–1 under zero applied magnetic field, whereas the Tb complex is not an SMM. The facile preparation of [Ln2Cl6(4-picNO)4(μ2-4-picNO)2]·2H2O complexes showing high luminescence quantum yield (Tb3+) and SMM characteristics (Dy3+) might prove useful toward the designing of analogue luminescent-SMM hybrids suitable for technological applications.

Fluorescent boron difluoride curcuminoides as perspective materials for bio-visualization

Curcuminoids of boron difluoride, 1-aryl(hetaryl)-5-phenylpenta-2,4-dien-1-onates of boron difluoride, have been synthesized. A comparative study of the electronic structure, luminescent properties and their potential for applications in bio-imaging has been carried out. The influence of the electronic structure of α-substituents on the luminescence of compounds was studied by the methods of stationary and time-resolved luminescence spectroscopy and DFT modeling. The introduction of π-donor substituents leads to a noticeable bathochromic shift and an increase in the Stokes shift in the luminescence spectra. On going from σ-donor substituents in the phenyl ring to π-donor substituents, the luminescence quantum yield increases from 0.03 to 0.22. The maximum Stokes shift and high quantum yield of luminescence is exhibited by the complex with a stilbene substituent, which has the longest π-system and the maximum efficiency of charge transfer. Dyes are able to penetrate into the cells of the model cell line and accumulate, moreover, accumulation occurs mainly in the cytoplasm of cells. The compounds penetrate into the cells by 12 h of incubation without damaging it’s structure and without causing rapid cell death. The submicromolar range of non-toxic concentrations during long-term incubation for a model cell line was determined, which is a characteristic of fluorescent imaging. Due to uniform distribution in the cytoplasm of cells dye with naphtyl substituent is promising for visualization of the cell cytoplasm. This leader compound has the lowest cytotoxicity for cells from the synthesized series of dyes, which makes it promising for further studies as a fluorescent imaging agent.The leader compound has the lowest cytotoxicity for cells from the synthesized series of dyes, which makes it promising for further studies as a fluorescent imaging agent.

Solvent-Type Passivation Strategy Controls Solid-State Self-Quenching-Resistant Behavior in Sulfur Dots.

Treatment of sulfur dots with polyethylene glycol (PEG) has been an efficient way to achieve a high luminescence quantum yield, and such a PEG-related quantum dot (QD)-synthesis strategy has been well documented. However, the polymeric insulating capping layer acting as the "thick shell" will significantly slow down the electron-transfer efficiency and severely hamper its practical application in an optoelectric field. Especially, the employment of synthetic polymers with long alkyl chains or large molecular weights may lead to structural complexity or even unexpected changes of physical characteristics for QDs. Therefore, in sulfur dot preparation, it is a breakthrough to use short-chain molecular species to replace PEG for better control and reproducibility. In this article, a solvent-type passivation (STP) strategy has been reported, and no PEG or any other capping agent is required. The main role of the solvent, ethanol, is to directly react with NaOH, and the generated sodium ethoxide passivates the surface defects. The afforded STP-enhanced emission sulfur dots (STPEE-SDs) possess not only the self-quenching-resistant feature in the solid state but also the extension of fluorescence band toward the wavelength as long as 645 nm. The realization of sulfur dot emission in the deep-red region with a decent yield (8.7%) has never been reported. Moreover, a super large Stokes shift (300 nm, λex = 345 nm, λem = 645 nm) and a much longer decay lifetime (109 μs) have been found, and such values can facilitate to suppress the negative influence from background signals. Density functional theory demonstrates that the surface passivation via sodium ethoxide is dynamically favorable, and the spectroscopic insights into emission behavior could be derived from the passivation effect of the sulfur vacancy as well as the charge-transfer process dominated by the highly electronegative ethoxide layer.

Portable and luminescent fiber based sensing device for antibiotics in human urine and real water samples

A new lanthanide complex is designed and obtained based on the ligand of 2,4,5,6-tetrafluoroisophthalic acid (H2TFPA) and 1,10-phenanthroline (phen) under mild hydro(solvo)thermal conditions. The new complex has the molecular formula of [Tb2(TFBA)3(phen)2(H2O)2]n (TbMOF) and it is characterized in detail. It is confirmed that TbMOF shows high water stability, thermal stability, acid and alkali resistance. The experimental results show that TbMOF solid state sample shows a luminescence decay lifetime of 0.448 ms, and a high luminescence quantum yield (QY) of 38.15%. Interestingly, studies showed that TbMOF is an excellent sensor for detecting antibiotics of ciprofloxacin (CIP). In addition, the limit of detection (LOD) for CIP is an extremely high sensitivity value of 0.17 ppm. In the concentration range of 1.0 × 10−7-1.0 × 10−6 M, CIP shows an excellent linear relationship with the luminescence intensity of TbMOF. Most importantly, test paper based on TbMOF and fiber material of filter paper is fabricated, which is a strongly anti-interference, selective, sensitive, portable and visible to the naked eyes sensing device towards CIP in real samples of human urine, tap water, and lake water.

Conversion of the non-luminous lead-free inorganic halide perovskite variant CsNiCl3 nanocrystals into photoluminescent materials by Cu+ and In3+ doping

All-inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) as promising optoelectronic materials have attracted tremendous research interest because of their intense photoluminescence, broad absorption, and tunable bandgap. Even with these fascinating characteristics, their practical applications are still suffering from the presence of toxic lead and inadequate stability. Herein, we successfully synthesize CsNiCl3 NCs in a comparatively low-temperature route for the first time. By Cu+ and In3+ doping, CsNiCl3 NCs can be converted from non-luminous into photoluminescent materials. The broad green fluorescence emission at 530 nm of CsNiCl3 NCs with high luminescence intensity and quantum yield (42.2%) is achieved. Broad band emission with a large Stokes shift can be attributed to the recombination process of self-trapped excitons (STEs). The transient fluorescence spectra of the doped CsNiCl3 NCs show two ultra-long lifetimes of about 50 and 120 µs, which are assigned to the STE recombination, indicating that the nonradiative recombination process is suppressed after doping. Our research provides an innovative method for developing environmentally friendly lead-free metal halide NCs.

Octahedral Molybdenum Cluster-Based Nanomaterials for Potential Photodynamic Therapy.

Photo/radiosensitizers, such as octahedral molybdenum clusters (Mo6), have been intensively studied for photodynamic applications to treat various diseases. However, their delivery to the desired target can be hampered by its limited solubility, low stability in physiological conditions, and inappropriate biodistribution, thus limiting the therapeutic effect and increasing the side effects of the therapy. To overcome such obstacles and to prepare photofunctional nanomaterials, we employed biocompatible and water-soluble copolymers based on N-(2-hydroxypropyl)methacrylamide (pHPMA) as carriers of Mo6 clusters. Several strategies based on electrostatic, hydrophobic, or covalent interactions were employed for the formation of polymer-cluster constructs. Importantly, the luminescent properties of the Mo6 clusters were preserved upon association with the polymers: all polymer-cluster constructs exhibited an effective quenching of their excited states, suggesting a production of singlet oxygen (O2(1Δg)) species which is a major factor for a successful photodynamic treatment. Even though the colloidal stability of all polymer-cluster constructs was satisfactory in deionized water, the complexes prepared by electrostatic and hydrophobic interactions underwent severe aggregation in phosphate buffer saline (PBS) accompanied by the disruption of the cohesive forces between the cluster and polymer molecules. On the contrary, the conjugates prepared by covalent interactions notably displayed colloidal stability in PBS in addition to high luminescence quantum yields, suggesting that pHPMA is a suitable nanocarrier for molybdenum cluster-based photosensitizers intended for photodynamic applications.

Novel Approach for Detecting Vapors of Acids and Bases with Proton-Transfer Luminescent Dyes Encapsulated within Metal–Organic Frameworks

Luminescent metal-organic frameworks (LMOFs) are one of the most promising materials for being implemented as active layers in the fabrication of photonic devices such as luminescent sensors of harmful chemicals. It is highly desirable that these materials undergo quantifiable spectroscopic (absorption or emission) changes in the presence of vapors of those analytes, as in many industrial processes, these toxic compounds are in the gas phase. Although great progresses have been achieved in the field, in most of the examples reported hitherto, the detection of chemicals by LMOFs is attained in solution. Herein, we present a novel approach consisting of the encapsulation of proton transfer dyes (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt, HPTS, and 3-hydroxyflavone, 3-HF) within the pores of two distinct MOFs. The trapped proton transfer dyes (PT-dyes) may exist as different structures (enol, anion, or zwitterion), each of these exhibiting unique optical properties. Indeed, our findings reveal that the dyes can be encapsulated as anionic or enol species. Remarkably, the PT-dye@MOF composites exhibit a high luminescence quantum yield (up to 30%), which is sensitive (showing shifting in the emission wavelengths with a concomitant quenching/enhancement of the intensity) in the presence of vapors of an acid (HCl) and a base (triethylamine). These results open a novel avenue for the development of smarter vapoluminescent MOF-based materials.

Engineering high-emissive silicon-doped carbon nanodots towards efficient large-area luminescent solar concentrators

Luminescent solar concentrators (LSCs) are devices that can collect sunlight from a large area, concentrating it at the borders of the slab, to achieve efficient photovoltaic conversion when small area solar cells are placed at their edges, realizing building-integrated photovoltaics. Efficient luminophores in terms of high luminescence quantum yield are needed to obtain high-performance LSCs. A key point is the ability to engineer the Stokes shift (i.e. the difference between the maximum of the absorption and emission spectra), to minimize reabsorption processes. In this work, we report novel silicon-doped carbon nanodots (Si-CDs) with an ultrahigh quantum yield (QY) up to 92.3% by a simple hydrothermal method. Thin-film structured LSCs (5 × 5 × 0.2 cm3) with different concentrations of Si-CDs are prepared by dispersing the Si-CDs into polyvinyl pyrrolidone (PVP) matrix, and the optimal power conversion efficiency (PCE) of LSCs can be as high as 4.36%, which is nearly 2.5 times higher than that prepared with silicon-undoped CDs. This Si-CDs/PVP film LSC has a high QY of 80.5%. A large-area LSC (15 × 15 cm2) is also successfully fabricated, which possesses a PCE of 2.06% under natural sunlight irradiation (35 mW·cm−2), one of the best reported values for similar size LSCs. The efficient Si-CDs as luminescent substances for high-efficiency large-area LSCs will further give an impetus to the practical exploitation of LSCs.

Thiapillar[6]arene: Synthesis, Functionalization, and Properties

AbstractThe design and synthesis of new macrocycles with well-defined cavities represent a promising avenue for the development of new supramolecular hosts. Moreover, the ability to diversify a macrocycle through chemical manipulations enables the fine-tuning and tailoring of properties. In this report, the synthesis and functionalization of thiapillar[6]arene, a pillar[6]arene analogue in which the bridging methylene groups are replaced by sulfurs, are described. First, we demonstrate the scalable synthesis of the parent thiapillar[6]arene. Next, the diversification of thiapillar[6]arene is demonstrated via functionalization of the phenols and oxidation of the sulfur atoms. The solid-state structures of two thiapillar[6]arene derivatives are reported, and the effect of sulfur oxidation state on the macrocyclic conformation is discussed. All sulfone derivatives described were found to demonstrate high luminescence quantum yields (ΦF = 0.43–0.66) in CH2Cl2 with emission maxima between λ = 404 and 462 nm. Lastly, assessment of the electrochemical properties of the sulfone derivatives by square-wave voltammetry revealed electron-accepting ability owing to the oxidation of the sulfur atoms, with four reduction events observed for the analogues surveyed. Overall, this work implicates thiapillar[6]arene as a modular scaffold amenable for further applications in host–guest chemistry and sensing.

Highly luminescent air-stable AgInS2/ZnS core/shell nanocrystals for grow lights

Plants need lights in the blue (400–500 nm) and red (600–700 nm) spectral regions for the photosynthesis to grow. Lights to match the mentioned spectral ranges can be provided from a blue LED and red luminescence materials. This article presents the high yield solvothermal syntheses of AgInS2 (AIS) core nanocrystals (NCs) and AIS/ZnS core/shell NCs that emit stably strong luminescence peaking around 665 nm under the excitation of a blue LED. The solvothermal syntheses of AIS core NCs were performed in oleylamine solvent added with 1,3-dimethylthiourea at 200 °C for a relatively short time of 20 min, in a closed Teflon vessel. Then, the ZnS shells with different thicknesses of 1, 3, 5, and 7 monolayers were coated on the same AIS core NCs at 150 °C for 60 min under open air. The synthesised AIS core and AIS/ZnS core/shell NCs were characterised by using X-ray diffraction (XRD), transmission electron microscopy (TEM), and optical spectroscopies (UV–Vis absorption and photoluminescence (PL), including steady state and time-resolved PL). With increasing the thickness of the ZnS shell, AIS/ZnS core/shell NCs become more stable under open air to emit the strong luminescence in the 600–700 nm range, peaking at ∼650 nm with the high luminescence quantum yield (QY) up to ∼60%. The blue-shift of the emission and increase of the QY after shelling AIS core NCs with ZnS are rationalized by the formation of the partially alloyed structure and passivation of surface states. In addition, time-resolved PL spectra exhibit to be red-shifted with the delay time after the excitation that is evident for the nature of donor–acceptor pairs recombination in AIS/ZnS core/shell NCs. Coating of layers of AIS/ZnS core/shell NCs dispersed in transparent epoxy on the 460-nm LED as assays for the grow light sources are also illustrated.