Chirality is ubiquitous within biological systems where many of the roles and functions are still undetermined. Given this, there is a clear need to design and develop sensitive chiral optical probes ...that can function within a biological setting. Here we report the design and synthesis of magnetically responsive Circularly Polarized Luminescence (CPL) complexes displaying exceptional photophysical properties (quantum yield up to 31 % and |glum| up to 0.240) by introducing chiral substituents onto the macrocyclic scaffolds. Magnetic CPL responses are observed in these chiral EuIII complexes, promoting an exciting development to the field of magneto‐optics. The |glum| of the 5D0 → 7F1 transition increases by 20 % from 0.222 (0 T) to 0.266 (1.4 T) displaying a linear relationship between the Δglum and the magnetic field strength. These EuIII complexes with magnetic CPL responses, provides potential development to be used in CPL imaging applications due to improved sensitivity and resolution.
A series of chiral, water‐soluble, DO3A‐based EuIII complexes was designed and synthesized. The chiral substituents introduced onto the macrocyclic scaffolds enhanced the photophysical properties with quantum yields up to 31 % and |glum| up to 0.240. The |glum| value increased by 20 % from 0.222 to 0.267 under external magnetic field showing a linear response.
Abstract
Predictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively ...influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages. One ligand exhibits a highly diastereoselective assembly into homochiral (either ΔΔΔΔ or ΛΛΛΛ) Eu tetrahedral cages whereas the two other ligands, with two different approaches of loosened point chirality, lead to a significant breakdown of the diastereoselectivity to generate a mixture of (ΔΔΔΔ and ΛΛΛΛ) isomers. The cages are highly emissive (luminescence quantum yields of 16(1) to 18(1)%) and exhibit impressive circularly polarized luminescence properties (|
g
lum
|: up to 0.16). With in-depth studies, we present an example that correlates the nonlinear enhancement of the chiroptical response to the nonlinearity dependence on point chirality.
Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the ...syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes. The Gd chiral DOTA complexes are shown to be orders of magnitude more inert to Gd release than GdDOTA
. These compounds also exhibit very-fast water exchange rates in an optimal range for high field imaging. Radiolabeling studies with (Cu-64/Lu-177) also demonstrate faster labelling properties. These chiral DOTA chelators are alternative general platforms for the development of stable, high relaxivity contrast agents, and for radiometal complexes used for imaging and/or therapy.
An efficient selenium‐catalyzed direct oxidation of benzylpyridines in aqueous DMSO has been successfully developed by using molecular oxygen as the oxidant. A variety of benzoylpyridines with broad ...functional group tolerance were obtained in modest to excellent yields and with exclusive chemoselectivity.
Chiroptical probes based on circular dichroism (CD) and circularly polarized luminescence (CPL) are crucial for understanding chirality in nature. Lanthanide chiroptical complexes are considered as ...promising candidates for the more sensitive CPL because of their unique optical properties, such as the magnetic dipole-allowed but electric-dipole-forbidden f-f transitions, large pseudo-Stokes shift, and long luminescence lifetime. However, due to the non-directional nature of lanthanide ions which allows variable coordination numbers, the design of their chiral complexes, especially at the supramolecular level, remains a challenge. Recent developments demonstrate the assemblies of chiroptical helices, cages, wheels, knots, and frameworks, which opens up future potential for applications such as in sensing and chiral guest recognition. This review provides the basics of coordination chemistry and photophysics of lanthanide ions, introduces chiroptical characterization, and summarizes the progress on the development of chiroptical lanthanide molecular and supramolecular systems. Perspectives on future development and applications are also discussed.
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Chirality governs the fundamental properties of life, from how our left and right hands complement each other to the drastically different efficacy of two drug enantiomers. Light can be used to characterize chirality by observing its circular polarization when passed through a chiral environment. In this work, the basics of chiroptical properties and the progression of developing lanthanide compounds for chiroptical spectroscopy are reviewed, a wide spectrum of chelate systems and strategies to construct molecular and supramolecular assemblies are summarized, and the relationship between the chiral environment and chiroptical properties is elucidated; moreover, applications based on specific chiral interactions are also reported. The authors are convinced that chiral lanthanide assemblies could help explore new, previously unappreciated avenues in applications that will improve the health and well-being of mankind, benefiting from increased specificity and selectivity.
Chirality is essential in life, and light is employed to understand it. The unique photophysical and magnetic properties of lanthanides allow a sizable signal of circularly polarized luminescence. Herein, we discuss the perspective of this field and summarize the coordination chemistry, chiroptical properties, and applications of lanthanide molecular and supramolecular assemblies.
Discrete lanthanide(III) tetranuclear cubane-like clusters seldom occur throughout the LnIII series and behave as single-molecule magnets (SMMs). Herein, a series of cubanes, ...Ln4(μ3-OH)4(μ-tfa)4(hfa)4(phen)4 (1–9, Ln = La–Dy (except Pm), tfa = trifluoroacetate, hfa = hexafluoroacetylacetonate, phen = 1,10-phenanthroline), and dinuclear clusters, Ln2(μ-OH)2(hfa)4(phen)2 (10–16, Ln = Tb–Lu), were synthesized and characterized. Two types of clusters were formed due to the change of preferred coordination geometry for lighter and heavier LnIII ions which favor nine-coordinated cubanes and eight-coordinated dimers, respectively. A magnetic study shows that 8-Tb4 and 9-Dy4 are ferromagnetically coupled and SMM in nature because of the larger Ln···Ln distance compared to other discrete cubanes. The anisotropic barriers, U eff, of 9-Dy4 are determined to be 67.0 K. In addition, the photophysical properties of 6-Eu4, 8-Tb4, and 10-Tb2 owing to tfa, hfa, and phen sensitization and O–H quenching are discussed.
We developed the functionalized upconversion nanoprobe with ultrasensitive and responsive properties for glucose detection, the responsive emission and satisfactory differentiated performances are ...observed in situ and in vitro.
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•Ultrasensitive and rapid detection strategy of glucose was constructed based on lanthanide-doped upconversion nanoprobe.•The functionalized nanoprobe can distinguish cancer cells from normal cells by in vitro emission intensity via optical bioimaging.•The designed nanoprobe would facilely achieve glucose detection in situ and in vitro with ultralow detection limit.
Various approaches for detecting glucose concentration in real time are emerging at a breakneck pace. Glucose metabolism is closely linked to severe pathological events, which would either cause or predispose many progressive diseases in human. Herein, hydrophilic upconversion nanoprobes NaGdF4: Yb3+, Er3+@Ag anchored with glucose oxidase (GOx) for glucose detection with lower detection limits have been efficaciously constructed. In the upconversion nanoprobes, NaGdF4: Yb3+, Er3+ cores, and Ag layers act as energy donors and effective quenchers, respectively, through energy transfer. Moreover, the layer of Ag may disintegrate by H2O2 in the presence of glucose when glucose oxidase anchoring on the exterior of NaGdF4: Yb3+, Er3+@Ag nanoprobes, which leads to the phenomenon of upconverting emission recovery. Additionally, NaGdF4: Yb3+, Er3+@Ag-GOx has an ultralow detection limit of 1.77 μmol L−1 on glucose detection, and it can achieve optical bioimaging to distinguish cancer cells from normal cells. As a result, the NaGdF4: Yb3+, Er3+@Ag nanoprobes could be expanded to detect diverse H2O2-involved analytes. Overall, this nanoprobe has promising potential to be a compelling tool for the biomedical applications.
Using Epstein‐Barr virus (EBV)‐induced cancer cells and HeLa cells as a comparative study model, a novel and safe dual‐EBV‐oncoproteins‐targeting pH‐responsive peptide engineering, coating, and ...guiding approach to achieve precision targeting and treatment strategy against EBV‐associated cancers is introduced. Individual functional peptide sequences that specifically bind to two overexpressed EBV‐specific oncoproteins, EBNA1 (a latent cellular protein) and LMP1 (a transmembrane protein), are engineered in three different ways and incorporated with a pH‐sensitive tumor microenvironment (TME)‐cleavable linker onto the upconversion nanoparticles (UCNP) NaGdF4:Yb3+, Er3+@NaGdF4 (UCNP‐Pn, n = 5, 6, and 7). A synergistic combination of the transmembrane LMP1 targeting ability and the pH responsiveness of UCNP‐Pn is found to give specific cancer differentiation with higher cellular uptake and accumulation in EBV‐infected cells, thus a lower dose is needed and the side effects and health risks from treatment would be greatly reduced. It also gives responsive UC signal enhancement upon targeted dual‐protein binding and shows efficacious EBV cancer inhibition in vitro and in vivo. This is the first example of simultaneous imaging and inhibition of two EBV latent proteins, and serves as a blueprint for next‐generation peptide‐guided precision delivery nanosystem for the safe monitoring and treatment against one specific cancer.
The upconversion nanoplatform with desired responsiveness toward tumor microenvironment is introduced. Thereafter, EBV‐cancer model is used to investigate by utilizing the safe nanoplatform via targeting LMP1 and EBNA1 with responsive emission, satisfactory prohibitive performances are observed in vitro and in vivo, thanks to the specific dual‐targeting peptides. This proposed multifunctional nanoplatform can achieve both monitoring and treatment for EBV cancer.
Detailed understanding of the interaction between a chiral molecule and a noble metal surface is essential to rationalize and advance interfacial self‐assembly of amino acids and metal‐mediated ...anchoring of proteins. Here we demonstrate that individual Au@Ag core–shell nanocuboids can serve as a plasmonic reporter of an extended helical network formed among chemisorbed cysteine molecules, through generating an interband absorption enhanced, Ag‐surface‐exclusive circular dichroism (CD) band in the UV region. The observed unusual, strong CD response in the hybrid Au@Ag–cysteine system can be used to probe in real time conformational evolution and structural rearrangement of biomolecules in general and also monitor the interfacial interaction between a metal surface and an adsorbed molecule, opening up the possibility of using Ag nanostructures as promising stereochemically attuned nanosensors.
Plasmonic reporter: Discrete Au@Ag core–shell nanocuboids capped with cysteine molecules exhibit two bisignate circular dichroism (CD) resonances in the UV region. One corresponds to the molecular electronic CD of cysteine, the other is an induced, unusual CD band originating from the formation of extended helical networks among neighboring cysteine molecules, which is dramatically amplified by the interband absorption of Ag.
A highly diastereoselective bidirectional C(sp3)−H bond functionalization of piperazine compounds, triggered by a Lewis acid catalyzed sequential hydride shift/cyclization process, is reported. ...Catalysts and ligands are key factors that control the diastereoselectivity of the reaction. The reaction affords the product with good yield and high diastereoselectivity. Detailed investigation of the reaction mechanism reveals that the energy barrier between the cis products and trans products results in the diastereoselectivity of the reaction. The trans products, which have higher energy and which are generated from the cis products, act as intermediate products.
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