6 research outputs found
Design of 2D Porous Coordination Polymers Based on Metallacrown Units
A 12âmetallacrownâ4 (MC) complex was designed and employed as the building block in the synthesis of coordination polymers, one of which is the first permanently porous MC architecture. The connection of the fourâfold symmetric MC subunits by CuII nodes led to the formation of 2D layers of metallacrowns. Channels are present in the crystalline architecture, which exhibits permanent porosity manifested in N2 and CO2 uptake capacity.Permanently porous metallacrowns: Metallacrowns have been exploited for the first time as tailored building blocks for the construction of new (porous) coordination polymers. Metallacrowns are metalârich complexes that have exhibited excellent properties in magnetism and luminescence. Benefiting from highâinterest metallacrown building blocks in the synthesis of MOFs can unfold a whole new class of functional materials (see figure).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137586/1/chem201600562-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137586/2/chem201600562.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137586/3/chem201600562_am.pd
Silver(I) and Thioether-bis(pyrazolyl)methane Ligands: The Correlation between Ligand Functionalization and Coordination Polymer Architecture
This
work examines the crystal structures of 15 AgÂ(I) complexes
with thioether functionalized bisÂ(pyrazolyl)Âmethane derivatives to
rationalize the influence of the ligand on the formation of (a) coordination
polymers (CPs), (b) oligonuclear (hexameric and dinuclear) complexes,
and (c) mononuclear complexes. It was previously reported how this
ligand class could generate microporous architectures with permanent
porosity. Some ligand modifications could induce a cavity size modulation
while preserving the same overall architecture. The bisÂ(pyrazolyl)Âmethane
scaffold can be easily functionalized with various structural fragments;
hence the structural outcomes were studied in this work using various
ligand modifications and AgÂ(I) salts. In particular, six new ligand
classes were prepared with the following features: (1) The steric
hindrance on the pyrazole rings L<sup>3,3â˛Me</sup>, L<sup>5,5â˛Me</sup>, L<sup>5,3â˛Me</sup>, L<sup>CF3</sup>, and L<sup>Br</sup> was
modified. (2) The steric hindrance was reduced on the peripheral thioether
group: L<sup>SMe</sup>. (3) Finally, the presence of fluorine and
bromine atoms in L<sup>CF3</sup> and L<sup>Br</sup> offered the possibility
to expand the type of interaction with respect to the ligands based
on hydrocarbon substituents (CH<sub>3</sub>, phenyl, naphthyl). The
effect of the anions was explored using different AgÂ(I) precursors
such as AgPF<sub>6</sub>, AgBF<sub>4</sub>, AgCF<sub>3</sub>SO<sub>3</sub>, or AgNO<sub>3</sub>. A comparison of the crystal structures
allowed for the tentative identification of the type of substituents
able to induce the formation of CPs having permanent porosity to include
a symmetric and moderate steric hindrance on the pyrazolyl moieties
(four CH<sub>3</sub>) and an aromatic and preorganized thioether moiety.
An asymmetric steric hindrance on the pyrazole groups led to the formation
of more varied structural types. Overall, the most frequently reported
structural motifs are the porous hexameric systems and the molecular
chains
Elucidation of 1H NMR Paramagnetic Features of Heterotrimetallic Lanthanide(III)/Manganese(III) 12-MC-4 Complexes
The paramagnetic one-dimensional 1H NMR spectra of twelve LnIIINaI(OAc)4[12-MCMnIII(N)shi-4] complexes, where LnIII is PrIII-YbIII (except PmIII) and YIII, are reported. Their solid-state isostructural nature is confirmed in methanol-d4 solution, as a similar pattern in the 1H NMR spectra is observed along the series. Notably, a relatively well-resolved spectrum is reported for the GdIII complex. The chemical shift data are analyzed using the "all lanthanides" method, and the Fermi contact and pseudo-contact contributions are calculated for the lanthanide-induced shift (LIS). For the TbIII-YbIII complexes, the pseudo-contact contributions are typically 1 order of magnitude higher than the Fermi contact contributions; however, for the GdIII complex, the Fermi contact is the main contribution to the paramagnetic chemical shift. For the methyl protons of the axial acetate (-OAc) ligands, the LIS is opposite in sign, with respect to that of the aromatic salicylhydroximate (shi3-) protons, because of structural rearrangements that occur upon dissociation of the NaI cation in solution. The calculated crystal field parameters (BLn) for the TbIII (360 cm-1), DyIII (250 cm-1), HoIII (380 cm-1), ErIII (410 cm-1), TmIII (620 cm-1), and YbIII (380 cm-1) complexes are not constant, likely as a consequence of the inaccuracy of the Bleaney's constants and, to a smaller extent, the small structural changes that occur in solution. Overall, the metallacrown scaffold retains structural integrity and similarity in solution for the entire series; however, small structural features, which do not affect the overall similarity, do likely occur
Oxidative Stress Induced by Copper and Iron Complexes with 8âHydroxyquinoline Derivatives Causes Paraptotic Death of HeLa Cancer Cells
Here,
we report the antiproliferative/cytotoxic properties of 8-hydroxyquinoline
(8-HQ) derivatives on HeLa cells in the presence of transition metal
ions (Cu<sup>2+</sup>, Fe<sup>3+</sup>, Co<sup>2+</sup>, Ni<sup>2+</sup>). Two series of ligands were tested, the arylvinylquinolinic <b>L1âL8</b> and the arylethylenequinolinic <b>L9</b>â<b>L16</b>, which can all interact with metal ions
by virtue of the N,O donor set of 8-HQ; however, only <b>L9</b>â<b>L16</b> are flexible enough to bind the metal in
a multidentate fashion, thus exploiting the additional donor functions. <b>L1</b>â<b>L16</b> were tested for their cytotoxicity
on HeLa cancer cells, both in the absence and in the presence of copper.
Among them, the symmetric <b>L14</b> exhibits the highest differential
activity between the ligand alone (IC<sub>50</sub> = 23.7 ÎźM)
and its copper complex (IC<sub>50</sub> = 1.8 ÎźM). This latter,
besides causing a significant reduction of cell viability, is associated
with a considerable accumulation of the metal inside the cells. Metal
accumulation is also observed when the cells are incubated with <b>L14</b> complexed with other late transition metal ions (Fe<sup>3+</sup>, Co<sup>2+</sup>, Ni<sup>2+</sup>), although the biological
response of HeLa cells is different. In fact, while Ni/<b>L14</b> and Co/<b>L14</b> exert a cytostatic effect, both Cu/<b>L14</b> and Fe/<b>L14</b> trigger a caspase-independent
paraptotic process, which results from the induction of a severe oxidative
stress and the unfolded protein response