3 research outputs found
Iron-57 NMR and Structural Study of [Fe(η<sup>5</sup>‑Cp)(SnPh<sub>3</sub>)(CO)(PR<sub>3</sub>)] (PR<sub>3</sub> = Phosphine, Phosphite). Separation of Steric and Electronic σ and π Effects
The complexes [Fe(Cp)(SnPh<sub>3</sub>)(CO)(PR<sub>3</sub>)] (PR<sub>3</sub> = PMe<sub>3</sub> (<b>1</b>), P<sup>n</sup>Bu<sub>3</sub> (<b>2</b>), PCy<sub>3</sub> (<b>3</b>), PMe<sub>2</sub>Ph (<b>4</b>), PMePh<sub>2</sub> (<b>5</b>), P(CH<sub>2</sub>Ph)<sub>3</sub> (<b>6</b>), PPh<sub>3</sub> (<b>7</b>), P(4-MeC<sub>6</sub>H<sub>4</sub>)<sub>3</sub> (<b>8</b>),
P(4-MeOC<sub>6</sub>H<sub>4</sub>)<sub>3</sub> (<b>9</b>), P(4-FC<sub>6</sub>H<sub>4</sub>)<sub>3</sub> (<b>10</b>), P(4-CF<sub>3</sub>C<sub>6</sub>H<sub>4</sub>)<sub>3</sub> (<b>11</b>), P(NMe<sub>2</sub>)<sub>3</sub> (<b>12</b>), P(OMe)<sub>3</sub> (<b>13</b>), P(OPh)<sub>3</sub> (<b>14</b>)), which have been
characterized by X-ray crystallography (except for <b>1</b> and <b>4</b>), infrared spectroscopy (carbonyl stretching frequency,
ν<sub>CO</sub>), and NMR spectroscopy (<sup>13</sup>C, <sup>31</sup>P, <sup>57</sup>Fe, <sup>119</sup>Sn) offer some insight
into the response of the iron nucleus to changes in the electronic
and steric properties of the PR<sub>3</sub> ligand. A fairly good
correlation is found between the <sup>57</sup>Fe chemical shift and
the Tolman cone angle θ for PR<sub>3</sub> and a rather poorer
correlation between δ(<sup>57</sup>Fe) and ν<sub>CO</sub>. However, for the subseries of complexes <b>7</b>–<b>11</b> having PR<sub>3</sub> = P(4-XC<sub>6</sub>H<sub>4</sub>)<sub>3</sub> (X = H, Me, MeO, F, CF<sub>3</sub>), the correlation
between δ(<sup>57</sup>Fe) and ν<sub>CO</sub> is very
good. Since the steric properties of these ligands, from the point
of view of the metal, are identical (θ = 145°), this provides
a means of separating the steric and electronic contributions of PR<sub>3</sub> to δ(<sup>57</sup>Fe). The electronic contribution
of PR<sub>3</sub> to δ(<sup>57</sup>Fe) can be further separated
into σ and π components by making use of the finding that
the π component of the Fe–P bond has a negligible influence
on δ(<sup>57</sup>Fe), unlike its influence on ν<sub>CO</sub>. The ligands PMe<sub>3,</sub> P<sup>n</sup>Bu<sub>3</sub>, PCy<sub>3</sub>, PMe<sub>2</sub>Ph, PMePh<sub>2</sub>, and P(NMe<sub>2</sub>)<sub>3</sub> are found to be “pure” σ donors,
P(OMe)<sub>3</sub> and P(OPh)<sub>3</sub> are found to be π
acceptors of differing strength, and P(4-XC<sub>6</sub>H<sub>4</sub>)<sub>3</sub> is found to show weak but clearly distinguishable π
acceptor properties
Synthesis, Conformational Analysis and Evaluation of the 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines as Potential α-Glucosidase and/or α-Amylase Inhibitors
The ambident electrophilic character of the 5-bromo-2-hydroxychalcones and the binucleophilic nature of 2-aminothiophenol were exploited to construct the 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines. The structures and conformation of these 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines were established with the use of spectroscopic techniques complemented with a single crystal X-ray diffraction method. Both 1H-NMR and IR spectroscopic techniques confirmed participation of the hydroxyl group in the intramolecular hydrogen-bonding interaction with a nitrogen atom. SC-XRD confirmed the presence of a six-membered intramolecularly hydrogen-bonded pseudo-aromatic ring, which was corroborated by the DFT method on 2b as a representative example in the gas phase. Compounds 2a (Ar = -C6H5), 2c (Ar = -C6H4(4-Cl)) and 2f (Ar = -C6H4(4-CH(CH3)2) exhibited increased inhibitory activity against α-glucosidase compared to acarbose (IC50 = 7.56 ± 0.42 µM), with IC50 values of 6.70 ± 0.15 µM, 2.69 ± 0.27 µM and 6.54 ± 0.11 µM, respectively. Compound 2f, which exhibited increased activity against α-glucosidase, also exhibited a significant inhibitory effect against α-amylase (IC50 = 9.71 ± 0.50 µM). The results of some computational approaches on aspects such as noncovalent interactions, calculated binding energies for α-glucosidase and α-amylase, ADME (absorption, distribution, metabolism and excretion) and bioavailability properties, gastrointestinal absorption and blood–brain barrier permeability are also presented