A lanthanide‐complex‐based ratiometric luminescence probe specific for peroxynitrite (ONOO?), 4′‐(2,4‐dimethoxyphenyl)‐2,2′:6′,2′′‐terpyridine‐6,6′′‐diyl]bis(methylenenitrilo)tetrakis(acetate)‐Eu3+/Tb3+ ([Eu3+/Tb3+(DTTA)]), has been designed and synthesized. Both [Eu3+(DTTA)] and [Tb3+(DTTA)] are highly water soluble with large stability constants at ≈1020, and strongly luminescent with luminescence quantum yields of 10.0 and 9.9 %, respectively, and long luminescence lifetimes of 1.38 and 0.26 ms, respectively. It was found that the luminescence of [Tb3+(DTTA)] could be quenched by ONOO? rapidly and specifically in aqueous buffers, while that of [Eu3+(DTTA)] did not respond to the addition of ONOO?. Thus, by simply mixing [Eu3+(DTTA)] and [Tb3+(DTTA)] in an aqueous buffer, a ratiometric luminescence probe specific for time‐gated luminescence detection of ONOO? was obtained. The performance of [Tb3+(DTTA)] and [Eu3+/Tb3+(DTTA)] as the probes for luminescence imaging detection of ONOO? in living cells was investigated. The results demonstrated the efficacy and advantages of the new ratiometric luminescence probe for highly sensitive luminescence bioimaging application. 相似文献
Four new three‐dimensional isostructural lanthanide–cadmium metal–organic frameworks (Ln–Cd MOFs), [LnCd2(imdc)2(Ac)(H2O)2]?H2O (Ln=Pr ( 1 ), Eu ( 2 ), Gd ( 3 ), and Tb ( 4 ); H3imdc=4,5‐imidazoledicarboxylic acid; Ac=acetate), have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, inductively coupled plasma (ICP) analysis, and X‐ray diffraction. Single‐crystal X‐ray diffraction shows that two LnIII ions are surrounded by four CdII ions to form a heteronuclear building block. The blocks are further linked to form 3D Ln–Cd MOFs by the bridging imdc3? ligand. Furthermore, the left‐ and right‐handed helices array alternatively in the lattice. Eu–Cd and Tb–Cd MOFs can emit characteristic red light with the EuIII ion and green light with the TbIII ion, respectively, while both Gd–Cd and Pr–Cd MOFs generate blue emission when they are excited. Different concentrations of Eu3+ and Tb3+ ions were co‐doped into Gd–Cd/Pr–Cd MOFs, and tunable luminescence from yellow to white was achieved. White‐light emission was obtained successfully by adjusting the excitation wavelength or the co‐doping ratio of the co‐doped Gd–Cd and Pr–Cd MOFs. These results show that the relative emission intensity of white light for Gd–Cd:Eu3+,Tb3+ MOFs is stronger than that of Pr–Cd:Eu3+,Tb3+ MOFs, which implies that the Gd complex is a better matrix than the Pr complex to obtain white‐light emission materials. 相似文献
Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)2(NO3)3] as well as Ce3+‐ and Tb3+‐substituted [La(bipy)2(NO3)3] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)2(NO3)3] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce3+ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce3+ ions, indicating their desolvation and incorporation into the [Ce(bipy)2(NO3)3] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)2(NO3)3] crystallized within days instead of minutes, unless influenced by high Ce3+ and Tb3+ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence. 相似文献
Terbium complexes with polymer ligands of poly(2- and 4-vinylpyridine N-oxide)s (P2VPNO, P4VPNO) in aqueous solution were prepared and characterized. Multi-exponential decays of the 5D4 → 7F5 terbium transition at 545 nm of [P2VPNO-Tb3+] and [P4VPNO-Tb3+] complexes were measured. The non-linearity of semi-logarithmic plots of time-resolved luminescence was more pronounced in [P4VPNO-Tb3+] than in [P2VPNO-Tb3+], being reduced by addition of salts such as sodium formate or acetate. We assume that multi-exponential decays of Tb3+ in the complexes are caused by a back metal-to-ligand energy transfer via triplet state of N-oxide polymer ligand. By carrying out separate experiments in water and deuterium oxide, the number of coordinated water molecules in the [P4VPNO-Tb3+] complex was estimated as 4-5, assuming that the Tb3+ aqua complex contains nine water molecules. 相似文献
A rare example of an organometallic terbium single‐ion magnet is reported. A Tb3+–[1]ferrocenophane complex displays a larger barrier to magnetization reversal than its isostructural Dy3+ analogue, which is reminiscent of trends observed for lanthanide–bis‐phthalocyanine complexes. Detailed ab initio calculations support the experimental observations and suggest a significantly larger ground‐state stabilization for the non‐Kramers ion Tb3+ in the Tb complex than for the Kramers‐ion Dy3+ in the Dy complex. 相似文献
Bridged polysilsesquioxanes (BPs) show great potential in the development of lanthanide‐based luminescent materials, owing to their capacity to loading lanthanide complexes with high concentration and their flexible processability. A novel BP precursor, consisting of a C 3‐symmetrical benzene central core moiety, capable of sensitizing the luminescence of Eu3+ and Tb3+ is reported. Tunable, full‐color luminescent gels were facilely prepared by mixing the as‐synthesized precursor and Ln3+ ions in appropriate solvents. By either changing the Eu3+/Tb3+ molar ratio or altering the excitation wavelength, the emission colors of the final gels can be finely tuned. Additionally, the yellow‐colored emissive gel with a molar ratio of Eu3+ to Tb3+ of 0.5 can be used as an effective ratiometric luminescent sensor for distinguishing amines with lower pK a (<5) from those with higher pK a (>9). 相似文献
The complex formation of d‐metal ions at the interface of TbIII‐doped silica nanoparticles modified by amino groups is introduced as a route to sensing d‐metal ions and some organic molecules. Diverse modes of surface modification (covalent and noncovalent) are used to fix amino groups onto the silica surface. The interfacial binding of d‐metal ions and complexes is the reason for the TbIII‐centered luminescence quenching. The regularities and mechanisms of quenching are estimated for the series of d‐metal ions and their complexes with chelating ligands. The obtained results reveal the interfacial binding of CuII ions as the basis of their quantitative determination in the concentration range 0.1–2.5 μM by means of steady‐state and time‐resolved fluorescence measurements. The variation of chelating ligands results in a significant effect on the quenching regularities due to diverse binding modes (inner or outer sphere) between amino groups at the interface of nanoparticles and FeIII ions. The applicability of the steady‐state and time‐resolved fluorescence measurements to sense both FeIII ions and catechols in aqueous solution by means of TbIII‐doped silica nanoparticles is also introduced. 相似文献
Phenanthroline‐based hexadentate ligands L1 and L2 bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as LaIII, EuIII, TbIII, LuIII, and YIII metal ions, were synthesized, and the crystal structures of [ML1Cl3] (M=LaIII, EuIII, TbIII, LuIII, or YIII) complexes were determined. Solvent or water molecules act as coligands for the rare‐earth metals in addition to halide anions. The big LnIII ion exhibits a coordination number (CN) of 10, whereas the corresponding EuIII, TbIII, LuIII, and YIII centers with smaller ionic radii show CN=9. Complexes of L2, namely [ML2Cl3] (M=EuIII, TbIII, LuIII, or YIII) ions could also be prepared. Only the complex of EuIII showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine‐5′‐triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐monophosphate (AMP) was found. 31P NMR spectroscopic studies revealed the formation of a [EuL2(ATP)] coordination species. 相似文献
We describe herein the synthesis and photophysical characterization of new lanthanide complexes that consist of a (9,9‐dimethylfluoren‐2‐yl)‐2‐oxoethyl or a (9,9′‐spirobifluoren‐2‐yl)‐2‐oxoethyl unit as the antenna, covalently linked to a 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid (DO3A) unit as the Ln3+ (Gd3+, Eu3+, Sm3+, Tb3+, Dy3+) coordination site. We were able to translate the spectroscopic properties of the innovative bipartite ligands into the formation of highly luminescent europium complexes that exhibit efficient emission (?se>0.1) upon sensitization in the near‐visible region, that is, with an excitation wavelength above 350 nm. The luminescence of the Eu3+complexes is clearly detectable at concentrations as low as 10 pM . Furthermore, the structural organization of these bipartite ligands makes the complexes highly soluble in aqueous solutions and chemically stable over time. 相似文献
A novel water‐soluble poly(para‐phenylene) derivative with pendant thymine and sulfonate units (PBTS) has been prepared and its metal ion sensing properties have been investigated. PBTS exhibited a reversible and selective fluorescence quenching behavior toward Hg2+ ions as compared to Ag+, Ni2+, Mg2+, Ca2+, Hg2+, Co2+, Cd2+, Cu2+, Pb2+, Ba2+, Fe3+, and Zn2+ ions in aqueous solution. The fluorescence quenching resulted from the interpolymeric π‐stacking aggregation which was induced by the specific thymine–Hg–thymine interaction.
Two generations of lipophilic pyrenyl functionalized poly(benzyl ether) dendrimers (P1 and P2) have been synthesized. The thermal properties of the two functionalized dendrimers have been investigated, and the pyrenyl group of the dendritic molecules encapsulated in the arene–ruthenium metalla‐cage, [Ru6(p‐cymene)6(tpt)2(donq)3]6+ ([ 1 ]6+) (tpt=2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine; donq=5,8‐dioxydo‐1,4‐naphthoquinonato). The host–guest properties of [P1⊂ 1 ]6+ and [P2⊂ 1 ]6+ were studied in solution by NMR and UV/Vis spectroscopic methods, thus allowing the determination of the affinity constants. Moreover, the cytotoxicity of these water‐soluble host–guest systems was evaluated on human ovarian cancer cells. 相似文献
Two macrobicyclic ligands derived from an 18‐membered tetralactam ring and 2,2′‐bipyridine or 2,6‐bis(pyrazol‐1‐yl)pyridine moieties, 1 and 2 , respectively, form stable complexes with GdIII, EuIII, and TbIII ions in aqueous solution. The ligand‐based luminescence is retained in the GdIII cryptates, whereas this radiative deactivation is quenched in the EuIII and TbIII cryptates by ligand‐to‐metal energy transfer, resulting in the usual metal‐centered emission spectra. Singlet‐ and triplet‐state energies, emission‐decay lifetimes, and luminescence yields were measured. [Tb⊂ 1 ]3+ cryptate shows a long luminescence lifetime (τ=1.12 ms) and a very high metal luminescence quantum yield (Φ=0.25) in comparison with those reported in the literature for Tb3+ complexes sensitized by a bipyridine chromophore. By comparison to [Ln⊂ 1 ]3+, [Ln⊂ 2 ]3+ presents markedly lower luminescence properties, due to worse interaction between the 2,6‐bis(pyrazol‐1‐yl)pyridine unit and the metal ion. Moreover, the luminescent metal and the triplet ligand energy levels of [Eu⊂ 2 ]3+ do not match. The effects of H2O molecules coordinated to the metal centre and of thermally activated decay processes on nonradiative deactivation to the ground‐state are also reported. 相似文献
The reaction of lanthanide(III) nitrates with 4‐(pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole (L) was studied. The compounds [Ln(NO3)3(H2O)3] ? 2 L, in which Ln=Eu ( 1 ), Gd ( 2 ), Tb ( 3 ), or Dy ( 4 ), obtained in a mixture of MeCN/EtOH have the same structure, as shown by XRD. In the crystals of these compounds, the mononuclear complex units [Ln(NO3)3(H2O)3] are linked to L molecules through intermolecular hydrogen‐bonding interactions to form a 2D polymeric supramolecular architecture. An investigation into the optical characteristics of the Eu3+‐, Tb3+‐, and Dy3+‐containing compounds ( 1 , 3 , and 4 ) showed that these complexes displayed metal‐centered luminescence. According to magnetic measurements, compound 4 exhibits single‐ion magnet behavior, with ΔEeff/kB=86 K in a field of 1500 Oe. 相似文献
The association constant K of mono-acetato complex of Tb3+ has been determined at normal p and T conditions by measurement of its luminescence lifetime in aqueous solution containing increasing concentrations of acetate. Two experimental arrangements used for the measurement are described. 相似文献