In this work, we synthesized a series of lanthanide(III) β-diketonate complexes to investigate the induction of triboluminescence. Triboluminescence (TL) spectra, solid-state emission spectra, and luminescence lifetimes of the complexes were obtained to prove consistent emitting species for steady-state and triboluminescence measurements. Detailed analyses of the crystal lattice packing were conducted in an attempt to correlate crystal symmetry, gas discharge, and structural arrangements with “triboexcitation”, and it is found that either noncentrosymmetric or centrosymmetic compounds can be TL-active. Furthermore, an intensely TL compound, Eu(dbm)4TMP, was achieved, and its light emission can be seen under daylight upon mechanical stress.

AbstractA stable cyclen-based EuIII-complex precursor was synthesized in a one-step coupling reaction as a fast-screening tool and template to select suitable chromophores for sensitizing EuIII luminescence. A library of chromophores was synthesized and screened by either Sonogashira or Suzuki reaction to confirm the proof of concept and the ease of this methodology. The photophysical properties of these corresponding complexes as well as their potential properties for biological applications has been assessed.

AbstractAn 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.

High glum values of +0.30 (ΔJ = 1, 591 nm, in DMSO) and −0.23 (ΔJ = 1, 589 nm, in H2O) were recorded in our series of newly designed macrocyclic europium(III) complexes. A sterically locking approach involving a bidentate chromophore is adopted to control the formation of one stereoisomer, giving rise to extreme rigidity, high stability, and high emission intensity. The combination of a chiral substituent on a macrocyclic chelate for lanthanide ions opens up new perspectives for the further development of circulary polarized luminescent chiral tags in optical and bioapplications.

Sensitization of lanthanide luminescence in the visible and near infra-red (NIR) region was achieved via a non-triplet energy transfer pathway by long-wavelength excitation of an intraligand charge transfer (ILCT) band of a diethylamino-based ligand system. A comprehensive photophysical and solvatochromic study is conducted to evaluate the luminescence properties of our Eu(III), Sm(III) and Yb(III) complexes. The effects of solvent coordination and solvent quenching on lanthanide luminescence were studied in detail and efforts were also devoted into examining the ambiguous energy transfer mechanism of Yb(III) sensitization.

•A turn-on NIR-emissive 1O2 probe has been synthesized for potential biological applications.•It has a binding constant of 1.9×106 M−1 and the emission intensity has a 5-fold increase upon binding.•The probe was also found to quench singlet oxygen in vitro generated by known photosensitizer TMPyP.A responsive neodymium NIR emission (4F3/2→4I11/2, 9/2) was recorded upon binding with singlet oxygen (KB=1.79×106 M−1) via the anthracene moiety. The motif ytterbium analog served as a negative control with no significant NIR enhancement/quenching with the addition of the same amount of singlet oxygen. Our complex was also found to react with 1O2 generated by a known photosensitizer TMPyP inside HeLa cells without inducing cell death and display no significant cytotoxicity.

The self-assembly of lanthanide (europium or lanthanium) bimetallic triple helicates from two closely related chiral ligands resulted in a very different supramolecular phenomenon. One gave rise to significantly diastereoselective formation of a triple helicate, whereas the other led to diastereoselective breaking to generate a mixture of P and M diastereomers in ∼1:1.1 ratio. The first X-ray crystal structure of a chiral ligand based lanthanide triple-helicate indicates that successive CH–π interactions were found to maintain the supramolecular helical structure.

Samarium complexes with the highest quantum yields to date have been synthesized, and their luminescence properties were studied in 12 solvents. Sensitization via a nontriplet intraligand charge-transfer pathway was also successfully demonstrated in solution states with good quantum yields.

In this work, we demonstrate a modality of photodynamic therapy (PDT) through the design of our truly dual-functional—PDT and imaging—gadolinium complex (Gd-N), which can target cancer cells specifically. In the light of our design, the PDT drug can specifically localize on the anionic cell membrane of cancer cells in which its laser-excited photoemission signal can be monitored without triggering the phototoxic generation of reactive oxygen species—singlet oxygen—before due excitation. Comprehensive in vitro and in vivo studies had been conducted for the substantiation of the effectiveness of Gd-N as such a tumor-selective PDT photosensitizer. This treatment modality does initiate a new direction in the development of “precision medicine” in line with stem cell and gene therapies as tools in cancer therapy.

Six water-soluble europium complexes (Eu–L11–Pnnn and Eu–L22–Pnnn, n = 1, 2 and 3) with one antenna chromophore, two different linkers (L11 and L22) and three proposed cyclin A specific peptides (P11: -GAKRRLIF-NH2; P22: -GGAKRRLIF-NH2; P33: -Hex- GAKRRLIF-NH2) have been synthesized. With structural information available, comparisons of the cyclin grooves of cyclin A and the six europium complexes have been made, and insights have been gained into the determinants for peptide binding and the foundation of differential binding. Experiment-wise, the linear and two-photon induced photophysical properties of these conjugates were monitored in aqueous solution. Numerous in situ/in vitro biological assays have been carried out, such as responsive emission changes in situ/in vitro, Western blot and cellular uptake. As imaging agents, complexes with peptides P33: -Hex-GAKRRLIF-NH2 showed high selectivity to cyclin A in numerous cancer cells. When it comes to responsive optical signal changes, complex Eu–L22–P33 exhibited a threefold emission enhancement upon binding with cyclin A (100 nM cyclin A, ϕ = 8% to 21%, log KB = 5.83, detection limit = 5 nM), and this could be initiated by the shortened distance between the antenna and the lanthanide after they bind/get into cyclin A. It is promising that our compounds (especially compound Eu–L22–P33) could serve as the template for structure-guided efforts to develop potential imaging therapeutics on the basis of selective imaging of CDK2/cyclin A activity.

An amphiphilic water-soluble ytterbium complex which is photo-selective, functional and Golgi apparatus specific has been designed as a responsive dual probe capable of sensitizing emission within the biological window (660 and 750 nm), generating the singlet oxygen (ΦΔ = 0.45) and triggering local cell damage only upon exposure to visible and near-infrared laser excitation.

Six water-soluble europium complexes (Eu–L11–Pnnn and Eu–L22–Pnnn, n = 1, 2 and 3) with one antenna chromophore, two different linkers (L11 and L22) and three proposed cyclin A specific peptides (P11: -GAKRRLIF-NH2; P22: -GGAKRRLIF-NH2; P33: -Hex- GAKRRLIF-NH2) have been synthesized. With structural information available, comparisons of the cyclin grooves of cyclin A and the six europium complexes have been made, and insights have been gained into the determinants for peptide binding and the foundation of differential binding. Experiment-wise, the linear and two-photon induced photophysical properties of these conjugates were monitored in aqueous solution. Numerous in situ/in vitro biological assays have been carried out, such as responsive emission changes in situ/in vitro, Western blot and cellular uptake. As imaging agents, complexes with peptides P33: -Hex-GAKRRLIF-NH2 showed high selectivity to cyclin A in numerous cancer cells. When it comes to responsive optical signal changes, complex Eu–L22–P33 exhibited a threefold emission enhancement upon binding with cyclin A (100 nM cyclin A, ϕ = 8% to 21%, log KB = 5.83, detection limit = 5 nM), and this could be initiated by the shortened distance between the antenna and the lanthanide after they bind/get into cyclin A. It is promising that our compounds (especially compound Eu–L22–P33) could serve as the template for structure-guided efforts to develop potential imaging therapeutics on the basis of selective imaging of CDK2/cyclin A activity.

An amphiphilic water-soluble ytterbium complex which is photo-selective, functional and Golgi apparatus specific has been designed as a responsive dual probe capable of sensitizing emission within the biological window (660 and 750 nm), generating the singlet oxygen (ΦΔ = 0.45) and triggering local cell damage only upon exposure to visible and near-infrared laser excitation.

The self-assembly of lanthanide (europium or lanthanium) bimetallic triple helicates from two closely related chiral ligands resulted in a very different supramolecular phenomenon. One gave rise to significantly diastereoselective formation of a triple helicate, whereas the other led to diastereoselective breaking to generate a mixture of P and M diastereomers in ∼1:1.1 ratio. The first X-ray crystal structure of a chiral ligand based lanthanide triple-helicate indicates that successive CH–π interactions were found to maintain the supramolecular helical structure.