Natural Pigments-Based Two-Component White Light Emitting Systems

In this paper, a new class of two component white light emitting systems viz, JaB (java plum + beetroot) {I}, and CaB (carrot + beetroot) {II} were developed through resonance energy transfer (RET) phenomenon by using a fruit (java plum) and two vegetable (carrot and beetroot) extracts. In these white light emitting systems, java plum and carrot are the donors while beetroot is the acceptor. The primary fluorescent pigments present in the natural extracts (i.e., anthocyanin in java plum, β-carotene in carrot, and betanin in beetroot) were responsible for the white light emission. The CIE (Commission Internationale d'Eclairage) coordinates for I and II were {0.32, 0.34} and {0.33, 0.33}, respectively, in solution phase. Interestingly, the white light emission (WLE) was also achieved in agar-agar gel medium. In gel medium, the CIE values were {0.31, 0.34} and {0.33, 0.32} for I and II, respectively. The donor-acceptor distance (r) for I and II were found to be 0.5 and 0.4 nm, respectively. Furthermore, the rate of energy transfer was also quantified with the values of 2.78 × 109 s-1 for JaB (I) and 1.02 × 108 s-1 for CaB (II) systems. The mechanistic investigation of the two white light systems was further supported by DFT studies.

Construction of an Artificial Light-Harvesting System with Photocatalytic Activity Based on Nor-seco-cucurbit[10]uril in Aqueous Solution

A supramolecular assembly was constructed based on the tetraphenylethylene derivatives (TPEs) and nor-seco-cucurbit[10]uril (ns-Q[10]). Upon introduction of the dye Rhodamine B (RB) into the TPEs@ns-Q[10] assembly, an energy transfer process can occur from the TPEs@ns-Q[10] assembly to RB. Moreover, after the addition of Nile Red (NiR), a two-step sequential energy transfer process from the TPEs@ns-Q[10] assembly to RB and then to NiR can occur. Additionally, the dye Eosin Y (ESY) was introduced into the TPEs@ns-Q[10] assembly and an energy transfer process can take place from the TPEs@ns-Q[10] assembly to ESY. To utilize the harvested energy from the TPEs@ns-Q[10]-RB-NiR and TPEs@ns-Q[10]-ESY system, we applied the TPEs@ns-Q[10] assembly-based light-harvesting systems (LHSs) as a catalyst for the advancement of the photocatalytic dehalogenation reaction in aqueous solution. When promoted with 0.5 mol % catalyst, the reaction yield reached 78 and 68%, demonstrating the promising potential of TPEs@ns-Q[10] assembly-based LHSs in the promotion of the photocatalytic dehalogenation reaction.

Ultrafast Dynamics of the Medicinal Pigment Curcumin inside the Imidazolium Surface Active Ionic Liquid Containing Giant Vesicles and White Light Generation via Triple-FRET Technique

The naturally occurring yellow polyphenolic medicinal pigment curcumin shows ultrafast dynamics in the excited states. These ultrafast dynamics are strongly influenced by the rigidity of the environments of the systems. The present investigation unveils the ultrafast excited-state intramolecular hydrogen atom transfer (ESIHT) (which is involved in the antioxidant mechanism) and the solvation dynamics of curcumin inside the imidazolium surface active ionic liquid (SAIL), 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl) micelle, and giant vesicles after introducing sorbitan monoesters (Span 20 and Span 80) in the aqueous medium. Interestingly, the short hydrocarbon chain containing Span 20 forms smaller, less rigid vesicles, and the long hydrocarbon chain containing Span 80 forms larger, more rigid giant vesicles after being assembled with [C16mim]Cl. The ESIHT and the solvation dynamics are slower in Span 80, containing rigid vesicles, than that in Span 20, comprising less rigid vesicles. Finally, we have established a three-component fluorescence resonance energy transfer (Triple-FRET) system to generate white light (WL) in the micelle and giant vesicles. Here the hydrophobic dye 1,6-diphenyl-1,3,5-hexatriene (DPH) acts as the donor, and the hydrophilic anticancer drug doxorubicin hydrochloride (DOX) serves as the acceptor along with the intermediate donor, curcumin. At a specific combination of the concentrations of these dyes in a particular self-assembled system, WL is generated due to the triple-FRET phenomena.

Water-soluble phosphate-pillar[5]arene (WPP5)-based artificial light-harvesting system for photocatalytic cross-coupling dehydrogenation

A novel water-soluble phosphate-pillar[5]arene (WPP5)-based artificial light-harvesting system (LHS) was successfully fabricated through the supramolecular assembly of phenyl-pyridyl-acrylonitrile derivative (PBT), WPP5, and organic pigment Eosin Y (ESY). Initially, after host-guest interaction, WPP5 could bind well with PBT and form WPP5 ⊃ PBT complexes in water, which further assembled into WPP5 ⊃ PBT nanoparticles. WPP5 ⊃ PBT nanoparticles performed an outstanding aggregation-induced emission (AIE) capability because of the J-aggregates of PBT in WPP5 ⊃ PBT nanoparticles, which were appropriate as fluorescence resonance energy transfer (FRET) donors for artificial light-harvesting. Moreover, due to the emission region of WPP5 ⊃ PBT overlapped well with the UV-Vis absorption of ESY, the energy of WPP5 ⊃ PBT (donor) could be significantly transferred to ESY (acceptor) via FRET process in WPP5 ⊃ PBT-ESY nanoparticles. Notably, the antenna effect (AE_{WPP5⊃PBT-ESY}) of WPP5 ⊃ PBT-ESY LHS was determined to be 30.3, which was much higher than that of recent artificial LHSs for photocatalytic cross-coupling dehydrogenation (CCD) reactions, suggesting a potential application in photocatalytic reaction. Furthermore, through the energy transfer from PBT to ESY, the absolute fluorescence quantum yields performed a remarkable increase from 14.4% (for WPP5 ⊃ PBT) to 35.7% (for WPP5 ⊃ PBT-ESY), further confirming their FRET processes in WPP5 ⊃ PBT-ESY LHS. Subsequently, in order to output the harvested energy for catalytic reactions, WPP5 ⊃ PBT-ESY LHSs were used as photosensitizers to catalyze the CCD reaction of benzothiazole and diphenylphosphine oxide. Compared to free ESY group (21%), a significant cross-coupling yield of 75% in WPP5 ⊃ PBT-ESY LHS was observed, because more UV region energy of PBT was transferred to ESY for CCD reaction, which suggested more potential in improving the catalytic activity of organic pigment photosensitizers in aqueous systems.

Photo-triggered full-color circularly polarized luminescence based on photonic capsules for multilevel information encryption

Materials with phototunable full-color circularly polarized luminescence (CPL) have a large storage density, high-security level, and enormous prospects in the field of information encryption and decryption. In this work, device-friendly solid films with color tunability are prepared by constructing Förster resonance energy transfer (FRET) platforms with chiral donors and achiral molecular switches in liquid crystal photonic capsules (LCPCs). These LCPCs exhibit photoswitchable CPL from initial blue emission to RGB trichromatic signals under UV irradiation due to the synergistic effect of energy and chirality transfer and show strong time dependence because of the different FRET efficiencies at each time node. Based on these phototunable CPL and time response characteristics, the concept of multilevel data encryption by using LCPC films is demonstrated.

Artificial supramolecular light-harvesting systems based on a pyrene derivative for photochemical catalysis

A supramolecular polymer based on NPyP and CB[8] was constructed via host–guest interactions with the AIE effect for artificial light-harvesting energy transfer and photocatalysis.

Supramolecular polymers based on host-guest interactions for the construction of artificial light-harvesting systems

In the present work, artificial light-harvesting systems with a fluorescence resonance energy transfer (FRET) process were successfully obtained in the aqueous solution. We designed and synthesized an amphiphilic pyrene derivative with two 4-vinylpyridium arms (Pmvb), which can interact with cucurbit[8]uril (CB[8]) to form supramolecular polymer through host-guest interactions in aqueous solution. The formation of supramolecular polymers results in a significant enhancement of fluorescence, which makes Pmvb-CB[8] an ideal energy donor to construct artificial light-harvesting systems in the aqueous solution. Subsequently, two different fluorescence dyes Rhodamine B (RhB) and Sulforhodamine 101 (SR101) were introduced as energy acceptors into the solution of Pmvb-CB[8] respectively, to fabricate two different artificial light-harvesting systems. The obtained artificial light-harvesting systems can achieve an efficient energy transfer process from Pmvb-CB[8] to RhB or SR101 with high energy transfer efficiency.

Novel Strategy of Constructing Artificial Light-Harvesting System with Two-Step Sequential Energy Transfer for Efficient Photocatalysis in Water

An efficient artificial light-harvesting system with a two-step sequential energy transfer was fabricated in the aqueous solution based on the host-guest interactions between cyano-substituted p-phenylenevinylene derivative (PPTA) and a water-soluble pillar[5]arene (WP5). PPTA-WP5 complex could self-assemble into nanoparticles, and two fluorescent dyes eosin Y (EY) and Nile Red (NIR) are employed as acceptors to realize sequential energy transfer. The PPTA-WP5-EY-NIR system could achieve efficient two-step sequential energy transfer process from PPTA-WP5 to EY and then to NIR (67% for the first step and 66% for the second step). Moreover, to make full use of the harvested energy, the hydrophobic microenvironment in the assembled nanoparticles is used to promote the aerobic cross-dehydrogenative coupling (CDC) reaction in aqueous medium with 88% yield after 12 h of irradiation. To our knowledge, this is the first example of artificial LHS with two-step energy transfer used to catalyze the CDC reaction in aqueous medium. This work directly mimics the function of photosynthesis in nature of converting solar energy into chemical energy in aqueous solution.

A facile way to construct sensor array library via supramolecular chemistry for discriminating complex systems

Differential sensing, which discriminates analytes via pattern recognition by sensor arrays, plays an important role in our understanding of many chemical and biological systems. However, it remains challenging to develop new methods to build a sensor unit library without incurring a high workload of synthesis. Herein, we propose a supramolecular approach to construct a sensor unit library by taking full advantage of recognition and assembly. Ten sensor arrays are developed by replacing the building block combinations, adjusting the ratio between system components, and changing the environment. Using proteins as model analytes, we examine the discriminative abilities of these supramolecular sensor arrays. Then the practical applicability for discriminating complex analytes is further demonstrated using honey as an example. This sensor array construction strategy is simple, tunable, and capable of developing many sensor units with as few syntheses as possible.

Monitoring Methionine Decarboxylase by Supramolecular Tandem Assay

Methionine is an essential amino acid involved in many physiological and pathological processes. Methionine starvation caused by methionine decarboxylase ( MetDC) degradation becomes a promising strategy for cancer treatment. Multistep colorimetric method, the present approach to monitor the MetDC activity, possesses drawbacks of the complicated process, low accuracy, and poor anti-interference due to indirect detecting. Herein, we report a facile and easy-to-use supramolecular tandem assay (STA) with cucurbit[7]uril and acridine orange reporter pair for the direct and real-time monitoring of MetDC activity. The applicability of this strategy for measuring enzyme-kinetic parameters and screening of inhibitors are also demonstrated. The STA for MetDC activity detection not only provides a feasible method for methionine-related disease diagnosing but also opens a perspective for cancer therapy.

Phenothiazine and triphenylamine-based fluorescent Schiff bases for the dual application of white light generation and H2O2 sensing

Two simple Schiff bases applied for white light emission in an ionic liquid medium and peroxide sensing with an exceptional LOD.

Supramolecular Bioimaging through Signal Amplification by Combining Indicator Displacement Assay with Förster Resonance Energy Transfer

Fluorescent chemosensors are powerful imaging tools in the fields of life sciences and engineering. Based on the principle of supramolecular chemistry, indicator displacement assay (IDA) provides an alternative approach for constructing and optimizing chemosensors, which has the advantages of simplicity, tunability, and modularity. However, the application of IDA in bioimaging continues to face a series of challenges, including interfering signals, background noise, and inconsistent spatial location. Accordingly, we herein report a supramolecular bioimaging strategy of Förster resonance energy transfer (FRET)-assisted IDA by employing macrocyclic amphiphiles as the operating platform. By merging FRET with IDA, the limitations of IDA in bioimaging were addressed. As a proof of concept, the study achieved mitochondria-targeted imaging of adenosine triphosphate in live cells with signal amplification. This study opens a non-covalent avenue for bioimaging with advancements in tunability, generality, and simplicity, apart from the covalent approach.

White light employing luminescent engineered large (mega) Stokes shift molecules: a review

Large (mega) Stokes shift molecules have shown great potential in white light emission for optoelectronic applications, such as flat panel display technology, light-emitting diodes, photosensitizers, molecular probes, cellular and bioimaging, and other applications. This review aims to summarize recent developments of white light generation that incorporate a large Stokes shift component, key approaches to designing large Stokes shift molecules, perspectives on future opportunities, and remaining challenges confronting this emerging research field. After a brief introduction of feasible pathways in generating white light, exemplifications of large Stokes shift molecules as white light candidates from organic and inorganic-based materials are illustrated. Various possible ways to design such molecules have been revealed by integrating the photophysical mechanisms that are essential to produce red-shifted emission upon photoexcitation, such as excited state intramolecular proton transfer (ESIPT), intramolecular charge transfer (ICT), excited state geometrical relaxation or structural deformation, aggregation-induced emission (AIE) alongside the different formations of aggregates, interplay between monomer and excimer emission, host-guest interaction, and lastly metal to ligand charge transfer (MLCT) via harvesting triplet state. Furthermore, previously reported fluorescent materials are described and categorized based on luminescence behaviors on account of the Stokes shifts value. This review will serve as a rationalized introduction and reference for researchers who are interested in exploring large or mega Stokes shift molecules, and will motivate new strategies along with instigation of persistent efforts in this prominent subject area with great avenues.

Modulation of Aggregation-Induced Emission by Excitation Energy Transfer: Design and Application

Excitation energy transfer (EET) as a fundamental photophysical process is well-explored for developing functional materials with tunable photophysical properties. Compared to traditional fluorophores, aggregation-induced emission luminogens (AIEgens) exhibit unique advantages for building EET systems, especially serving as energy donors, due to their outstanding photophysical properties such as bright fluorescence in aggregation state, broad absorption and emission spectra, large Stokes shift, and high photobleaching resistance. In addition, the photophysical properties of AIEgens can be modulated by energy transfer for improved luminescence performance. Therefore, a variety of EET systems based on AIEgens have been constructed and their applications in different areas have been explored. In this review, we summarize recent progress in the design strategy of AIE-based energy transfer systems for light-harvesting, fluorescent probes and theranostic systems, with an emphasis on design strategies to achieve desirable properties. The limitations, challenges and future opportunities of AIE-EET systems are briefly outlined. Design strategies and applications (light-harvesting, fluorescent probe and theranostics) of AIEgen-based excitation energy systems are discussed in this review.

Energy transduction through FRET in self-assembled soft nanostructures based on surfactants/polymers: current scenario and prospects

The self-assembled systems of surfactants/polymers, which are capable of supporting energy funneling between fluorophores, have recently gained significant attraction. Surfactant and polymeric micelles form nanoscale structures spanning a radius of 2-10 nm are generally suitable for the transduction of energy among fluorophores. These systems have shown great potential in Förster resonance energy transfer (FRET) due to their unique characteristics of being aqueous based, tendency to remain self-assembled, spontaneous formation, tunable nature, and responsiveness to different external stimuli. This review presents current developments in the field of energy transfer, particularly the multi-step FRET processes in the self-assembled nanostructures of surfactants/polymers. The part one of this review presents a background and brief overview of soft systems and discusses certain aspects of the self-assemblies of surfactants/polymers and their co-solubilization property to bring fluorophores to close proximity to transduce energy. The second part of this review deals with single-step and multi-step FRET in the self-assemblies of surfactants/polymers and links FRET systems with advanced smart technologies including multicolor formation, data encryption, and artificial antenna systems. This review also discusses the diverse examples in the literature to present the emerging applications of FRET. Finally, the prospects regarding further improvement of FRET in self-assembled soft systems are outlined.

Controlling fluorescence resonance energy transfer of donor–acceptor dyes by Diels–Alder dynamic covalent bonds

Two new dyes, consisting of an aromatic amine donor and dansyl acceptor connected by Diels–Alder bonds, display a switchable energy transfer. Dynamic covalent properties enable the mutual conversion of the two dyes by maleimide exchanges.

Metal-Free White Light-Emitting Fluorescent Material Based on Simple Pillar[5]arene-tripodal Amide System and Theoretical Insights on Its Assembly and Fluorescent Properties

The booming of host-guest assembly-based supramolecular chemistry provides abundant ways to construct functional systems and materials. Attracted by the important application prospect of white light emission and aggregation-induced emission (AIE) materials, herein, we report an efficient way for fabricating metal-free white light-emitting AIE materials through the supramolecular assembly of simple organic compounds: methoxyl pillar[5]arene (MP5) and tri-(pyridine-4-ylamido)benzene (TAP). By host-guest assembly, MP5 and TAP formed a supramolecular polymer (MP5-T); meanwhile, the MP5-T xerogel powder emitted white light at CIE coordinates (0.29 and 0.29). The supramolecular assembly and white light-emitting mechanisms were carefully investigated by experiments as well as quantum chemical calculations including density functional theory (DFT), reduced density gradient, electrostatic surface potential, independent gradient model, and frontier molecular orbital (highest-occupied molecular orbital-lowest-unoccupied molecular orbital) analyses. Interestingly, according to the experiments and calculations, the supramolecular assembly is critical in the white light-emitting phenomenon. Moreover, in this work, the quantum chemical calculations could not only support experimental phenomena but also provide deep understanding and visualized presentation of the assembly and emission mechanism. In addition, the obtained MP5-T solid powder could serve as a novel and easy means to make material for white light-emitting devices.

pH-Induced Transition Between Single-Chain Macrocyclic Amphiphile and [c2]Daisy Chain-Based Bola-Type Amphiphile and the Related Self-Assembly Behavior in Water

Macrocyclic amphiphiles, a type of amphiphiles synthesized based on macrocyclic compounds, have attracted much attention over the past decades due to their unique superiority in the construction of various functional nanomaterials. The regulation of the state of macrocyclic amphiphiles by introducing stimuli-responsive motif to macrocyclic amphiphiles is an efficient way to extend their applications in diverse fields. Herein, pillararene-based macrocyclic amphiphile H1 was prepared. H1 can act as single-chain amphiphile to self-assemble into micelles in water when the pH was ≥5.0. H1 can be protonated to turn into H2 when pH changed to <5.0. Interestingly, H2 formed [c2]daisy chain-based bola-type supramolecular amphiphile. This bola-type supramolecular amphiphile self-assembled into nanosheets in water. Therefore, pH-induced transition between single-chain macrocyclic amphiphile and bola-type amphiphile and the corresponding self-assembly system based on pillararene in water were constructed.

Guanidinocalix[5]arene for sensitive fluorescence detection and magnetic removal of perfluorinated pollutants

Perfluorinated alkyl substances, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), are toxic materials that are known to globally contaminate water, air, and soil resources. Strategies for the simultaneous detection and removal of these compounds are desired to address this emerging health and environmental issue. Herein, we develop a type of guanidinocalix[5]arene that can selectively and strongly bind to PFOS and PFOA, which we use to demonstrate the sensitive and quantitative detection of these compounds in contaminated water through a fluorescent indicator displacement assay. Moreover, by co-assembling iron oxide nanoparticle with the amphiphilic guanidinocalix[5]arene, we are able to use simple magnetic absorption and filtration to efficiently remove PFOS and PFOA from contaminated water. This supramolecular approach that uses both molecular recognition and self-assembly of macrocyclic amphiphiles is promising for the detection and remediation of water pollution.

Broad Spectrum Tunable Photoluminescent Material Based on Cascade Fluorescence Resonance Energy Transfer between Three Fluorophores Encapsulated within the Self-Assembled Surfactant Systems

A broad spectrum tunable photoluminescent material with dual encryption based on a two-step fluorescence resonance energy transfer (FRET) between pyrene (Py), coumarin 480 (Cou480), and rhodamine 6G (R6G) in micelles of SDS and bmimDS is presented. The phenomenon is achievable due to the encapsulation of the fluorophores within these micelles. The transfer of energy as FRET between the pair Py and Cou480 showed ON at 336 nm and OFF at 402 nm in contrast to the FRET observed between the pair Cou480 and R6G that showed ON at 402 nm and OFF at 336 nm. However, the transfer of energy as FRET occurs from Py to R6G in the presence of Cou480 when excited at 336 nm, thereby making it a chain of three fluorophores with Cou480 acting as a relay fluorophore receiving energy from Py and transferring it to R6G. The different FRET scenarios between the three fluorophores in micelles provide a window for the generation of a matrix of colors, which occupies a significant 2D area in the chromaticity diagram, having potential applications in security printing. The different fluorophoric ratios generate different colors based on their individual photonic emissions and the FRET processes taking place between them. Writing tests were carried out using varied ratios of the fluorophores in the micellar systems producing different colored outputs under the UV light with insignificant visibility under the white light. We envision that this as-discovered three fluorophoric FRET system could form the basis for the future development of multi-FRET light-harvesting devices and anti-counterfeiting security inks based on much simpler non-covalent interaction aided encapsulation of the fluorophores within the self-assembled soft systems.

A Supramolecular Artificial Light-Harvesting System with Two-Step Sequential Energy Transfer for Photochemical Catalysis

An artificial light-harvesting system with sequential energy-transfer process was fabricated based on a supramolecular strategy. Self-assembled from the host-guest complex formed by water-soluble pillar[5]arene (WP5), a bola-type tetraphenylethylene-functionalized dialkyl ammonium derivative (TPEDA), and two fluorescent dyes, Eosin Y (ESY) and Nile Red (NiR), the supramolecular vesicles achieve efficient energy transfer from the AIE guest TPEDA to ESY. ESY can function as a relay to further transfer the energy to the second acceptor NiR and realize a two-step sequential energy-transfer process with good efficiency. By tuning the donor/acceptor ratio, bright white light emission can be successfully achieved with a CIE coordinate of (0.33, 0.33). To better mimic natural photosynthesis and make full use of the harvested energy, the WP5⊃TPEDA-ESY-NiR system can be utilized as a nanoreactor: photocatalyzed dehalogenation of α-bromoacetophenone was realized with 96 % yield in aqueous medium.

Mutualistic benefit in the self-sorted co-aggregates of peri-naphthoindigo and a 4-amino-1,8-naphthalimide derivative

Photoluminescence enhancement for all the members of a self-sorted co-aggregate was observed for the first time by successfully amalgamating AIEE and social self-sorting. Intermolecular H-bonding and π-π stacking were utilised to prepare several co-aggregates of peri-naphthoindigo (PNI) and a 4-amino-1,8-naphthalimide derivative dye, NH₂-NMI. In the heteromeric aggregates, photoluminescence intensities were increased by 28% for the imide and more than 400% for PNI. Due to spectral overlap between the emission of the imide and the absorption of PNI, energy transfer took place from the former to the latter. The heteromeric aggregates are dual emissive and the relative intensities of the emissions can easily be tuned by varying the stoichiometry of the dyes.

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

We herein describe the comprehensive investigation of the complexation behavior of a guanidinium-modified calix[5]arene pentaisohexyl ether (GC5A) with a variety of typical luminescent dyes. Fluorescein, eosin Y, rose bengal, tetraphenylporphine sulfonate and sulfonated aluminum phthalocyanine were employed as classical aggregation-induced quenching dyes. 2-(p-Toluidinyl)naphthalene-6-sulfonic acid and 1-anilinonaphthalene-8-sulfonic acid were selected as representatives of intramolecular charge-transfer dyes. Phosphated tetraphenylethylene was involved as the classical aggregation-induced emission dye. Sulfonated acedan representing one example of two-photon fluorescent probes, was also investigated. A ruthenium(II) complex with carboxylated bipyridyl ligands was included as a representative candidate of luminescent transition-metal complexes. We determined the association constants of the GC5A-dye complexes by fluorescence titration and discuss the complexation-induced photophysical changes. In addition, a comparison of the complexation behavior of GC5A with that of other macrocycles and potential applications according to the diverse photophysical responses are provided.

Rotaxane-Based Mechanophores Enable Polymers with Mechanically Switchable White Photoluminescence

Three mechanoresponsive polyurethane elastomers whose blue, green, and orange photoluminescence can be reversibly turned on by mechanical force were prepared and combined to create a blend that exhibits deformation-induced white photoluminescence. The three polyurethanes contain rotaxane-based supramolecular mechanoluminophores based on π-extended pyrene, anthracene, or 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) luminophores, respectively, and 1,4,5,8-naphthalenetetracarboxylic diimide as an electronically matched quencher. Each polymer shows instantly reversible, strain-dependent switching of its photoluminescence intensity when stretched and relaxed, as deformation leads to a spatial separation of the luminophore and quencher. The present study shows that the photoluminescence color can easily be tailored by variation of the luminophore and also by combining several mechanophores in one material and demonstrates that adaptability is a key advantage of supramolecular approaches to create mechanoresponsive polymers.

Gene delivery based on macrocyclic amphiphiles

Gene therapy, with an important role in biomedicine, often requires vectors for gene condensation in order to avoid degradation, improve membrane permeation, and achieve targeted delivery. Macrocyclic molecules are a family of artificial receptors that can selectively bind a variety of guest species. Amphiphilic macrocycles, particularly those bearing cationic charges and their various assemblies represent a new class of promising non-viral vectors with intrinsic advantages in gene condensation and delivery. The most prominent examples include amphiphilic cyclodextrins, calixarenes and pillararenes. Herein, we systemically reviewed reported assemblies of amphiphilic macrocycles for gene delivery and therapy. The advantages and disadvantages of each type of macrocyclic amphiphiles for gene delivery, as well as the perspectives on the future development of this area are discussed.

A nanodrug to combat cisplatin-resistance by protecting cisplatin with p-sulfonatocalix[4]arene and regulating glutathione S-transferases with loaded 5-fluorouracil

A nanodrug that can effectively combat cisplatin-resistant A549/CDDP cells was developed by protecting cisplatin from glutathione (GSH) detoxification trough a host–guest interaction between cisplatin and p-sulfonatocalix[4]arene.

White-light emission from a structurally simple hydrazone

Two hydrazones featuring a unique excitation wavelength-dependent dual fluorescence emission have been developed.

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

Based on the indicator displacement assay (IDA) approach, we herein report the fluorescence "switch-on" sensing and quantitative detection of bisphosphonates (BPs), a class of drugs extensively used in the treatment of patients with various skeletal diseases. Guanidinium-modified calix[5]arene (GC5A) affords strong binding on the micromolar to nanomolar level towards BPs dominantly via multiple salt bridge interactions, which was evaluated by fluorescence competitive titrations. Fluorescent IDA enables the highly sensitive and label-free detection of BPs in buffer solution, and more importantly, in artificial urine. Calibration lines were therefore set up in untreated artificial urine, allowing for quantifying the concentrations of BPs in the biologically relevant low range.

Ultrasensitive and specific fluorescence detection of a cancer biomarker via nanomolar binding to a guanidinium-modified calixarene

We designed a water-soluble guanidinium-modified calix[5]arene to target lysophosphatidic acid (LPA), an ideal biomarker for early diagnosis of ovarian and other gynecologic cancers, achieving binding on the nanomolar level. An indicator displacement assay, coupled with differential sensing, enabled ultrasensitive and specific detection of LPA. Moreover, we show that using a calibration line, the LPA concentration in untreated serum can be quantified in the biologically relevant low μM range with a detection limit of 1.7 μM. The reported approach is feasible for diagnosing ovarian and other gynecologic cancers, particularly at their early stages.

Bistable [2]rotaxane encoding an orthogonally tunable fluorescent molecular system including white-light emission

By combining a rotaxane-type molecular switch and traditional fluorescent switch, an orthogonally tunable fluorescent molecular system was constructed, which can generate multicolor fluorescence including white light.

Facile synthesis of triphenylamine and phenothiazine-based Schiff bases for aggregation-induced enhanced emission, white light generation, and highly selective and sensitive copper(ii) sensing

Facile synthesis of triphenylamine and phenothiazine based Schiff bases for multiple applicability, viz., in AIEE, WLE and Cu²⁺ sensing.