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Harmful metal ions have received intense attention. In particular, palladium, a rare inner transition metal, is the subject of intense research in light of its catalytic capabilities and the restrictions on the levels of residual harmful metal ions in end products，has attracted wide spread interest from chemists. A near-infrared Pd2+ probe Cy202 has been synthesized that exhibits pronounced fluorescence enhancement in the presence of Pd2+. The Pd2+ recognition properties were examined by using UV–Vis spectroscopy and fluorescence spectroscopy in DMSO/PBS buffer solution (pH 7.40, 8/2, v/v). The solution of the probe exhibits color change turned from yellow to brown upon the addition of Pd2+ while no significant response to other metal ions. The detection limit was calculated as low as 0.52 μM. The probe could be useful for imaging Pd2+ in palladium-containing catalyst and samples.

In this study, we developed a fluorescence-enhanced probe (1) based on a simple Schiff-based condensation reaction for Cu2+ selection. We investigated its distinct recognition mechanism through mass spectra, 1H NMR studies, and DFT calculations. The imaging and costaining experiments indicated that the probe could successfully image lysosomal Cu2+.

A fluorescent coordination polymer [Zn(H3TTA)(H2O)2]·2H2O (JLNU-3, JLNU = Jilin Normal University; H3TTA = [2,2′:6′,2″-terpyridine]-4,4′,4″-tricarboxylic acid) has been hydrothermally synthesized and carefully characterized. Particularly, stable suspension of JLNU-3 in aqueous solution showed significant quenching towards Hg2+. The quenching efficiency is up to 98% in the existence of 10−2 M Hg2+. JLNU-3 can be regenerative for 5 cycles by centrifugation of the solution after use and washing several times with H2O. In addition, JLNU-3 displays preeminent anti-interference ability and could be used for sensing in the systems with complicated components. Therefore, JLNU-3 can be used as a fluorescent probe for selective, sensitive and recyclable sensing of heavy-metal cation Hg2+ in aqueous solution.

A luminescent coordination polymer, [Cd(H2biim)2SO4]·3H2O (JLNU-1, JLNU = Jilin Normal University); H2Biim = 2,2′-biimidazole, has been prepared by hydrothermal method and characterized by corresponding analytical tools. JLNU-1 exhibits outstanding chemical stability in aqueous solution and solvent-dependent luminescent behaviour. In particular, stable suspension of JLNU-1 in nitrobenzene showed highest quenching. The emission spectra were nearly completely quenched at a concentration of 100 ppm nitrobenzene in aqueous solution. JLNU-1 can be regenerative for 6 cycles by centrifugation of the solution after use and washing several times with H2O. Therefore, JLNU-1 can be used as a fluorescent probe for sensitive and recyclable sensing of small-molecule pollutant nitrobenzene in aqueous solution.

A novel dicyanomethylene-4H-pyran-based sensor bearing 2-thiophenecarbonyl as a masking group was established for the detection of cyanide anions. Upon the addition of cyanide, sensor 1 manifested a near-infrared emission band at 717 nm, with an extremely large red-shift (~180 nm) in the absorption spectrum. It also showed an obvious color change from yellow to green. Sensor 1 was used to sensitively measure CN− with low detection limit of 1.44 μM. The stoichiometric ratio between probe and CN− were determined as 1:1, with the association constant of 7.87 × 102 M−1. The reaction mechanism was investigated by ESI-MS, 1H NMR, HPLC, and density functional theory methods. Results indicate that the nucleophilicity of the cyanide catalyzes the elimination of 2-thiophenecarbonyl, which strengthens the intramolecular charge transfer effect of the dicyanomethylene-4H-pyran fluorophore. Furthermore, sensor 1 was found to be efficient in detecting cyanide in the intracellular region of MCF-7 cells.

By varying the ratio of mixed reaction solvent, the reactions of PbAc2 with N,N′-bis(1,3,4-thiobiazolyl)-2,6-pyridyldicarboxamide (H2btapca) afford two different crystal structures: a novel discrete hexanuclear cage of formula [Pb6(btapca)6]·(H2O)2 (1) and a 1-D double-chain polymer [Pb2(btapca)2(H2O)2]n (2). Fluorescence investigations reveal that both complexes display enhanced emissions in contrast to the free ligand H2btapca.

Two rhodamine-based Hg2 + probes L1 and L2 were prepared and confirmed by NMR, MS and crystal data. The sensing behavior of these probes was studied by UV–visible and fluorescence spectroscopy. The probe L1 couldn't be widely applied in aqueous media or mixed media because of its poor solubility. However, the probe L2 displayed selective and sensitive fluorescence enhancement response to Hg2 + at physiological pH value for biological use. The selectivity of this system for Hg2 + over other metal ions was remarkably high, and its sensitivity was at ppb level. The probe L2 responded rapidly to Hg2 + in aqueous solutions with a 1:1 stoichiometry and was successfully applied to image Hg2 + in living cells.

Through varying the volume ratio of mixed solvent, we obtained two distinct polymers {[Pb6(2,6-pda)6] · H2O}n (1) (2,6-pda = 2,6-pyridyldicarboxylate) and [Pb(mpcp)(OAc)]n (2) (mpcp = methyl-6-(pyridin-2-ylcarbamoyl)picolinate) by reaction of Pb(OAc)2 · 3H2O and 2,6-dicarboxamido-(2-pyridyl)-pyridine (H2dcapp) decomposed through lead-induced hydrolysis. Photoluminescence investigations reveal that both polymers display enhanced emissions in contrast to the free ligand, respectively.

A new ruthenium(II) polypyridyl complex, [Ru(phen) 2 MHPIP] 2+ (phen = 1,10-phenanthroline, MHPIP=2-(3-methoxy-4-hydroxyphenyl)imidazo[4,5- f ]1,10-phenanthroline), has been synthesized and characterized. The binding of this complex with yeast tRNA has been investigated by UV, fluorescence and CD spectroscopy systematically. The experimental results suggest that the complex can bind to yeast tRNA enantioselectively, and that spectroscopic method is effective on studying the interaction of metal complexes with RNA.