13 research outputs found
Recognition of Polyfluorinated Compounds Through Self-Aggregation in a Cavity
Polyfluorinated
aliphatic compounds were encapsulated by a self-assembled M<sub>6</sub>L<sub>4</sub> coordination host in aqueous media. NMR titration and
X-ray crystallographic analyses clearly revealed that the aggregation
of the fluorinated moieties of the guests in the host cavity plays
a significant role in the binding. Polyfluorinated aromatics did not
show such aggregation in the cavity because of their “<i>nonfluorous</i>” nature
In the Pursuit of Efficient Anion-Binding Organic Ligands Based on Halogen Bonding
The syntheses and the crystal structures of new multitopic
anion-binding
organic ligands based on a benzenoid scaffold and bearing two or three
2-iodo-imidazolium arms are reported. The quite short C–I···Br¯
contacts observed in the solid state (0.77 times the normalized contacts)
demonstrate the excellent halogen bonding donor ability of iodine
atoms in 2-iodoimidazolium cations. The geometric features of obtained
bromide anion adducts afford valuable structural insights for the
design of effective and selective multitopic anion receptors based
on halogen bonding
KPF<sub>6</sub> 14.2 mM perfusion induced large amplitude depolarization events that propagated through the cortical mantel, from the hippocampus to the entorhinal (EC) and piriform cortex (PC).
<p>These events were interpreted as spreading depolarization phenomena (Somjen 2001). </p
A: Seizure occurrence after perfusion of the <i>in</i><i>vitro</i> isolated guinea pig brain with different K<sup>+</sup> salt solutions.
<p>The white columns represent the total number of experiments. The light grey, dark grey and black columns mark the effects of the perfusion of K<sup>+</sup> salts at 8, 14.2m 20 mM, respectively. <b>B</b>: Time at onset (black columns) and duration (white columns) of seizure activity after perfusion with 14.2 KPF<sub>6</sub>, 14.2 mM KClO<sub>4</sub> and 20 mM KBF<sub>4</sub>. <b>C</b>: Brain parenchyma concentration of two salts (KPF<sub>6</sub> and KBF<sub>4</sub>) estimated by <sup>19</sup>F MR spectroscopy on CA1-EC specimens, collected after arterial perfusion with 14.2 mM KPF<sub>6</sub> (n= 4; black column) and 20 mM KBF<sub>4</sub> (n= 3; grey column). </p
Effects of perfusion of K<sup>+</sup> salts in the <i>in</i><i>vitro</i> isolated guinea pig brain.
<p>A scheme of the position of the recording and stimulating (S1, on the lateral olfactory tract) electrodes is shown in the upper part of the figure. The upper set of traces illustrates the effect of 14.2 mM KPF<sub>6</sub> perfusion (right) compared to control (left); seizure activity was induced by this salt. In the lower part of the figure the effect of perfusion with 14.2 mM KClO<sub>4</sub> is shown. PC: piriform cortex; EC: entorhinal cortex; HIP: CA1 region of the hippocampus.</p
Effects of 4.2 mM KPF<sub>6</sub> (A), 14.2 mM KClO<sub>4</sub> (B) and 20 mM KCl (C) on the field potentials evoked in the piriform cortex by lateral olfactory tract (LOT) stimulation.
<p>Left, middle and right traces: before, during and after washout of the K<sup>+</sup> salts, respectively.</p
A. Schematic protocol of the experiments. Electrophysiological recordings are performed for the entire experimental period
<p>Each perfusion of salts lasted 15 min. and was followed by 30 min. wash-out. Brain tissue samples were than collected and processed for the <sup>19</sup>F MR spectroscopy. <b>B:</b> Structures of KX salts (X= PF<sub>6</sub><sup>-</sup>, BF<sub>4</sub><sup>-</sup>, ClO<sub>4</sub><sup>-</sup>, Br<sup>-</sup>, AcO<sup>-</sup> and Cl<sup>-</sup>) and electrostatic potential surfaces (B3LYP/6-311+G**) of individuals ions and ion pairs. Blue regions indicate positive potentials and red regions negative ones. Maximum values of the electrostatic potential, at K atom, and minimum values, at O, F, Br and Cl atoms are indicated besides each structure. Molecular volumes are also reported (Å<sup>3</sup>).</p
Solution and Solid State Synthesis of the Discrete Polyiodide I<sub>7</sub><sup><sup></sup>3–</sup> under Modular Cation Templation
Discrete I<sub>7</sub><sup>3</sup>¯ polyiodide is
obtained in pure form through solution and solid-state processes thanks
to templation by a triammonium cation which elicits the selective
formation of the size matching supramolecular anion
Dynamic Characterization of Crystalline Supramolecular Rotors Assembled through Halogen Bonding
A modular molecular kit for the preparation
of crystalline molecular
rotors was devised from a set of stators and rotators to gain simple
access to a large number of structures with different dynamic performance
and physical properties. In this work, we have accomplished this with
crystalline molecular rotors self-assembled by halogen bonding of
diazabicyclo[2.2.2]octane, acting as a rotator,
and a set of five fluorine-substituted iodobenzenes that take
the role of the stator. Using variable-temperature <sup>1</sup>H <i>T</i><sub>1</sub> spin–lattice relaxation measurements,
we have shown that all structures display ultrafast Brownian rotation
with activation energies of 2.4–4.9 kcal/mol and pre-exponential
factors of the order of (1–9) × 10<sup>12</sup> s<sup>–1</sup>. Line shape analysis of quadrupolar echo <sup>2</sup>H NMR measurements in selected examples indicated rotational trajectories
consistent with the 3-fold or 6-fold symmetric potential of the rotator
Halogen Bonding and Pharmaceutical Cocrystals: The Case of a Widely Used Preservative
3-Iodo-2-propynyl-<i>N</i>-butylcarbamate (IPBC) is an
iodinated antimicrobial product used globally as a preservative, fungicide,
and algaecide. IPBC is difficult to obtain in pure form as well as
to handle in industrial products because it tends to be sticky and
clumpy. Here, we describe the preparation of four pharmaceutical cocrystals
involving IPBC. The obtained cocrystals have been characterized by
X-ray diffraction, solution and solid-state NMR, IR, and DSC analyses.
In all the described cases the halogen bond (XB) is the key interaction
responsible for the self-assembly of the pharmaceutical cocrystals
thanks to the involvement of the 1-iodoalkyne moiety of IPBC, which
functions as a very reliable XB-donor, with both neutral and anionic
XB-acceptors. Most of the obtained cocrystals have improved properties
with respect to the source API, in terms, e.g., of thermal stability.
The cocrystal involving the GRAS excipient CaCl<sub>2</sub> has superior
powder flow characteristics compared to the pure IPBC, representing
a promising solution to the handling issues related to the manufacturing
of products containing IPBC