ABSTRACT
Two fluorescent probes, Y1-2 were synthesized from 2-acetonaphthone, 4-acetylbiphenyl, and phenyl hydrazine by Vilsmeier-Haack reaction and Knoevenagel condensation. Their recognition efficacies for N2H4 were tested by UV-visible absorption spectroscopy and fluorescence emission spectroscopy. The recognition mechanism were studies by density-functional theory calculations, and the effect of pH on N2H4 recognition was also studied. The results showed that the probe Y1-2 has high selectivity and a low detection limit for N2H4, and the recognition of N2H4 can be accomplished at physiological pH. The probes have had obvious aggregation-induced luminescence effect, large Stokes shift, high sensitivity, and can be successfully applied to live cell imaging.
ABSTRACT
In this paper, four novel hydrazine fluorescent probes X1-X4 with bis-chalcone structure were designed and synthesized. Through the measurement of its optical properties, it is found that it can quickly identify hydrazine, high sensitivity, low detection limit, and good anti-interference ability. The recognition of hydrazine by probes X1-X4 is not affected in the pH range of 4-10, X2 has the highest sensitivity, and the detection limit is as low as 0.336 × 10-7 M. Through Gaussian quantization calculation of probe molecules and their reaction products with hydrazine, it is speculated that the recognition mechanism is the closure of intramolecular charge transfer effect. In addition, the cytotoxicity and imaging of HeLa cells were tested, which showed that probes X1-X4 could be used to detect hydrazine in cells.
ABSTRACT
The reaction of a macrocyclic ligand 1,4,7-triazacyclononane-1,4,7-tripropionic acid (tacntpH3) with Ni(II)/Co(II) sources in the presence or absence of lanthanide cations yielded a series of doubly mononuclear ionic complexes (H3O+)[LnIII(H2O)8][NiII(tacntp)]4 (1-NiLn, Ln = La, Ce, Yb) and a mononuclear Co(III) complex [CoIII(tacntp)]·4H2O (2-Co) incorporating transition metal centers enveloped by both an azamacrocycle ring and pendant carboxylate groups. Either of the two preorganized mononuclear species [MII/III(tacntp)]-/0 was taken as a tripodal 3d metalloligand for the further assembly of modular architectures. Two pentanuclear metallocage-[Ln(NO3)6]3- complexes [NiII5(tacntp)2(H2O)12][LnIII(NO3)6]Cl·2H2O (3-NiLn, Ln = La, Ce), one nonanuclear metallocage [NiII9(tacntp)4(H2O)18](ClO4)6·10H2O (4-Ni), and two types of 2D layered heterometallic 3d-4f coordination networks ((H3O+)[NiII2YbIII(tacntp)2](ClO4)2·3H2O (5-NiYb) and [CoIII2TbIII(tacntp)2(H2O)3](ClO4)·Cl2·5H2O (6-CoLn, Ln = La, Eu, Tb, Dy)) differing largely in their weaving architecture were controllably prepared via the precise regulation of multiple reaction parameters. Furthermore, the time-dependent evolution of metalloligand-derived species was tracked via electrospray ionization-mass spectrometry, to elucidate the modular assembly pathway for the nonanuclear Ni(II) metallocage 4-Ni. Analysis of the structural details and the assembly procedures of the modular architectures revealed that the pH, metalloligand size, and the type of metal bound to the metalloligand considerably influence the structural evolution from mononuclear metalloligands to cage-like and polymeric coordination architectures. Magnetic property studies disclosed that pendant syn-anti carboxylate groups favor a weak ferromagnetic exchange between the adjacent Ni(II) ions within the metallocages of 3-NiLa and 4-Ni but facilitate an antiferromagnetic coupling between the alternating Ni(II) and Yb(III) centers in 5-NiYb.
ABSTRACT
In the present paper, the interaction of bovine hemoglobin (BHb) and realgar nanoparticles has been investigated by ultraviolet-visible (UV-Vis) and fluorescence spectroscopy. The Soret band of oxygen-BHb at 406 nm shifted to 413 nm, and its absorption intensity decreased gradually after adding realgar nanoparticles. The Soret band decreases gradually with the increasing the amount of realgar NPs, suggesting the detachment of some heme chromophores from their matrixes in BHb. The red-shift of characteristic peak leads to be conjecture that the arsenic of realgar combined with the oxygen of BHb. The oxygen-BHb was deoxidated by realgar nanoparticles, and the surface binding induces conformation change of BHb from the high-affinity R state to the low-affinity T state. The fluorescence intensity of BHb is quenched by realgar nanoparticles when its concentration gradually increased. The analysis of Stern-Volmer equation revealed that the mechanism was a static quenching procedure. The order of the magnitude of binding constant k was 10(9), obtained from the calculation of UV-Vis and fluorescence spectra.
