3 research outputs found
Cd<sup>2+</sup>-Specific Fluorescence Response of Methoxy-Substituted <i>N</i>,<i>N</i>‑Bis(2-quinolylmethyl)-2-methoxyaniline Derivatives
The N3O1 tetradentate ligand, TriMeOBQMOA (N,N-bis(5,6,7-trimethoxy-2-quinolylmethyl)-2-methoxyaniline),
was developed as a Cd2+-specific fluorescent sensor. The
structure of TriMeOBQMOA is half of TriMeOBAPTQ (N,N,N′,N′-tetrakis(5,6,7-trimethoxy-2-quinolylmethyl)-1,2-bis(2-aminophenoxy)ethane),
which is a tetrakisquinoline derivative of the well-known calcium
chelator BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic
acid). The fluorescent Cd2+ selectivity of TriMeOBAPTQ
(IZn/ICd =
5.3% in the presence of 3 equiv of metal ions in MeOH–HEPES
buffer (9:1)) comes from the formation of fluorescent dinuclear cadmium
(M2L) and nonfluorescent OH-bridged dizinc ((μ-OH)M2L) complexes. TriMeOBQMOA also exhibits excellent Cd2+ specificity in fluorescence enhancement (IZn/ICd = 2.3% in the presence of
5 equiv of metal ions in DMF–HEPES buffer (1:1, HEPES 50 mM,
KCl 0.1 M, pH = 7.5)) via substantial formation of a highly fluorescent
bis(μ-chloro)dinuclear cadmium complex ([Cd2(μ-Cl)2L2]2+), which is in equilibrium with
the mononuclear Cd2+ complex ([CdLCl]+), and
extremely poor stability of the TriMeOBQMOA-Zn2+ complex.
The all-nitrogen derivatives of BQMOA and BAPTQ, namely, N,N-BQDMPHEN (N,N-bis(2-quinolylmethyl)-N′,N′-dimethyl-1,2-phenylenediamine) and BPDTQ (N,N,N′,N′-tetrakis(2-quinolylmethyl)-2,2′-(N,N′-dimethylethylenediamino)dianiline), respectively,
and their methoxy-substituted derivatives were also prepared, and
the fluorescent metal ion sensing properties are discussed
Sandglass-Typed Single Chameleon Luminophore for Water Mapping Measurements: Intramolecular Energy Migrations in the Hydrophilic Tb(III)/Sm(III) Cluster
Novel hydrophilic and color-changeable single chameleon
luminophores
composed of Tb(III)/Sm(III) nona-nuclear clusters [TbxSm9–x(Sal-PEG-n)16(μ-OH)10]+(NO3)− (x = 1, 2, 3, and 9;
Sal-PEG-n: salicylate polyethylene glycolmethylester, n = 2 and 4) are reported for water mapping measurements.
Their characteristic sandglass structures and aggregates were analyzed
using X-ray single crystal analysis and dynamic light scattering (DLS)
measurements. The green- and yellow-luminescence of [Tb3Sm6(Sal-PEG-4)16(μ-OH)]+(NO3)− in water were observed at 20 and 50 °C,
respectively. The ratio-metric luminescence analysis using green Tb(III)
and orange Sm(III) emission bands is a promising candidate for exact
temperature distribution measurements in fluid dynamics. The effective
temperature-sensing property based on the competitive intramolecular
energy transfer processes between Tb(III)-to-ligand and Tb(III)-to-Sm(III)
in a non-a-nuclear cluster is explained using temperature-dependent
kinetic analyses in the excited state
Nanotubes of Biomimetic Supramolecules Constructed by Synthetic Metal Chlorophyll Derivatives
Various
supramolecular nanotubes have recently been built up by lipids, peptides,
and other organic molecules. Major light-harvesting (LH) antenna systems
in a filamentous anoxygenic phototroph, <i>Chloroflexus</i> (<i>Cfl.</i>) <i>aurantiacus</i>, are called
chlorosomes and contain photofunctional single-wall supramolecular
nanotubes with approximately 5 nm in their diameter. Chlorosomal supramolecular
nanotubes of <i>Cfl. aurantiacus</i> are constructed by
a large amount of bacteriochlorophyllÂ(BChl)-<i>c</i> molecules.
Such a pigment self-assembles in a chlorosome without any assistance
from the peptides, which is in sharp contrast to the other natural
photosynthetic LH antennas. To mimic chlorosomal supramolecular nanotubes,
synthetic models were prepared by the modification of naturally occurring
chlorophyllÂ(Chl)-<i>a</i> molecule. Metal complexes (magnesium,
zinc, and cadmium) of the Chl derivative were synthesized as models
of natural chlorosomal BChls. These metal Chl derivatives self-assembled
in hydrophobic environments, and their supramolecules were analyzed
by spectroscopic and microscopic techniques. Cryo-transmission electron
microscopic images showed that the zinc and cadmium Chl derivatives
could form single-wall supramolecular nanotubes and their outer and
inner diameters were approximately 5 and 3 nm, respectively. Atomic
force microscopic images suggested that the magnesium Chl derivative
formed similar nanotubes to those of the corresponding zinc and cadmium
complexes. Three chlorosomal single-wall supramolecular nanotubes
of the metal Chl derivatives were prepared in the solid state and
would be useful as photofunctional materials