We present the results of our research on the use of microwaves as an unconventional heat source for the acceleration of iridium(III) chloro-bridged dimer preparation. The results enabled us to ...revise and improve known guidelines for the very quick and highly efficient synthesis of iridium(III) dimeric complexes in a very simple isolation manner. According to the developed methodology, the already known dimers containing ligands based on the 2-phenylpyridinato motif, as well as new ones stabilized with functionalized benzohquinolinato and 2-phenoxypyridinato-based ligands, were efficiently synthesized. The scope of the incorporated ligands included compounds equipped with electron-donating (−Me, −OMe, −OPh, −NMe2), electron-withdrawing (−F, −Br, −CF3, −C6F5), and hole-transporting (−NPh2, −C6H4NPh2) groups. The obtained complexes were characterized by NMR, X-ray diffraction, and electrospray ionization mass spectrometry methods, and their behavior was examined in the presence of coordinating solvents such as dimethyl sulfoxide and acetonitrile. Investigation of the interactions between the above-mentioned solvents and dimers enabled us to confirm the ability of the former to cleave μ-chloride bridges, which enriches the knowledge in the field of organometallic chemistry. This knowledge can be particularly useful for the scientists working in the field of iridium-based materials, helping to avoid misinterpretation of the spectroscopic data.
A number of imines, including 12 new compounds, previously not reported in the literature, derived from variously fluorinated benzaldehydes and different anilines or chiral benzylamines were ...synthesized by a solvent-free mechanochemical method, which was based on the manual grinding of equimolar amounts of the substrates at the room temperature. In a very short reaction time of only 15 min, the method produced the expected products with good-to-excellent yields. The yields were comparable or significantly higher than those reported in the literature for the imines synthesized by other methods. Importantly, the conditions used for the reactions with aniline derivatives also resulted in the high yields of imines obtained from chiral benzylamines, and can be extended to the synthesis with other similar amines. Structures of all imines were confirmed by NMR spectroscopy: 1H, 13C and 19F. For four compounds, X-ray structures were also obtained. The synthetic approach presented in this paper contributes to the prevention of environmental pollution and can be easily extended for larger-scale syntheses. The mechanochemical solvent-free method provides a convenient strategy particularly useful for the preparation of fluorinated imines being versatile intermediates or starting material in the synthesis of drugs and other fine chemicals.
High-quality crystals of a certain polymorphic form of thiobarbituric acid containing both keto and enol tautomers in the asymmetric unit were obtained. High-resolution X-ray diffraction data up to ...sinθ/λ = 1.0 Å
were collected and subsequently successfully used for the refining of the multipolar model of electron density distribution. The use of a crystal containing both ketone and enol forms allowed a direct comparison of the topological analysis results and a closer look at the differences between these two forms. The similarities and differences between the deformation densities, electrostatic potentials, Laplacian maps and bond characteristics of the tautomers were analysed. Additionally, the spectrum of the intermolecular interactions was identified and studied from classical, relatively strong N-H···O and O-H···O hydrogen bonds through weaker N-H···S hydrogen bonds to weak interactions (for instance, C-H···O, C-H···S and N···O). The results of these studies point toward the importance of including both the geometrical features and the details of the electron density distribution in the analysis of such weak interactions.
A series of functionalized dialkenylsilsesquioxanes were obtained by efficient and highly stereoselective silylative coupling and cross‐metathesis of divinylsubstituted double‐decker silsesquioxanes ...(DDSQ‐2SiVi) with substituted styrenes and other olefins. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. The optimized reaction conditions for styrene were adopted for successful silylative coupling polycondensation of DDSQ‐2SiVi with 1,4‐divinylbenzene yielding stereoregular cooligomer containing double‐decker (silsesquioxyl‐silylene)‐vinylene‐phenylene units.
Divinyl‐substituted double‐decker silsesquioxanes (DDSQ‐2SiVi) have been functionalized by a highly effective silylative coupling and/or metathesis with olefins. Both reactions proceed highly stereoselectively and lead to nearly quantitative formation of E isomers. Preliminary studies on the silylative coupling of DDSQ‐2SiVi with 1,4‐divinylbenzene resulted in a stereoregular cooligomer containing double‐decker (silsesquioxyl‐silylene)‐vinylene‐phenylene units.
This study aimed to synthesize new thioderivative chalcones and analyze their impact on the NF-κB, STAT3, EGFR and Nrf2 signaling pathways in colorectal cancer cells. Among the studied compounds, ...derivatives 4 and 5 decreased the activation of NF-κB and the expression of the target gene COX-2. In the case of STAT3, we observed the inhibition of activation of this signaling pathway after influencing derivative 4. Increased activation of the Nrf2 signaling pathway was demonstrated for derivatives 5 and 7 in DLD-1 and HCT116 cells. The results of this study indicated that new chalcone derivatives, especially compounds 4, 5, and-to some degree-7, possess potential applications in the prevention of colorectal cancer.
Two coordination polymers (CPs) material, Zn(μ-Cl)
2
(μ-bpy)
∞
(bpy = 4,4′-bipyridine) and Cu(bpy)(phen)(ClO
4
)
2
n
(phen = 1,10-phenanthroline), were prepared, and their structures were determined ...by single-crystal X-ray crystallography showing grid-like 2D network and 1D zigzag chain, respectively. Both CPs and their mixtures were investigated as potential catalysts for ammonium perchlorate (AP) thermal decomposition by means of thermogravimetery and differential scanning calorimetery analysis. The results revealed their significant catalytic activity by decreasing the peak temperature of AP decomposition from 434 to 300 °C and increasing evolved heat from 409 up to 1622 Jg
−1
. The decomposition temperature ranges of catalyzed samples have also contracted from 178 to 47 °C, almost one-third comparing to decomposition temperature range of AP. Kissinger method was used to calculate the kinetic parameters of thermal decomposition of pure and mixed AP samples. The calculated activation energy and pre-exponential factor revealed effective thermokinetic influence of CPs and their mixtures on thermal decomposition of AP, by increasing the decomposition rate constant for AP from 4.6 × 10
−3
s
−1
at its peak temperature (434 °C), up to 15 × 10
−3
s
−1
at a much lower decomposition temperature (310 °C).
Herein, a two-component cocrystal Ph
3
SnCl(4-PCAPh)
1
encompassing 4-PCAPh =
N
-isonicotinyl,
N′,N″
-bis(hexamethylenyl) phosphoric triamide and triphenyltin(IV) chloride in 1:1 stoichiometric ...ratio has been reported. Crystallographic information and theoretical calculations, mainly analysis based on the non-covalent interactions (NCI) visualization index, were pursued to generate a profound understanding of the structure-directing interactions in this cocrystal. Two crystallographically independent molecules are present for each component in the crystalline lattice,
1(A)
and
1(B)
. Different conformational structures of 4-PCAPh primarily form centrosymmetric N–H⋯O hydrogen-bonded dimers in the crystal. Geometrical parameters around tin(IV) centers reveal that cocrystal components are interlinked through Sn⋯N
py
semi-coordination. The formation of cocrystal and failure in achieving an adduct can be justified in terms of the steric bulk of phenyl groups along with π⋯π-stacking forces between components. The importance of non-covalent interactions in the stability of crystalline structure was elucidated by computing their binding energies using theoretical studies. QTAIM and NBO analyses data also justify the presence of two different Sn⋯N interactions, in agreement with crystal data and NCI-RDG analyses. The small HOMO–LUMO bandgap for Ph
3
SnCl(4-PCAPh) also signifies more reactivity for the cocrystal than 4-PCAPh.
Two isostructural (in room temperature) complexes of Bi(III) with halogens and sulfur ligands have been investigated in terms of the solid-to-solid phase transitions indicated by temperature. Both ...chloride and bromide (X) complexes of the general formula (µ
-X)-(BiX
L
)
exhibit some phase transitions between 100 and 333 K, which, apart from the numerous similarities, show significant differences, which have been noted and analyzed in detail in this paper by using different techniques, i.e., powder and single crystal diffraction or DSC. The obtained results have also been collated with those obtained for solid solutions of both complexes.
The new homodinuclear complexes of the general formula Ln
(NO
)
(where
is newly synthesized 2-((2-(benzoxazol-2-yl)-2-methylhydrazono)methyl)phenol and Ln = Sm
(
), Eu
(
), Tb
(
,
), Dy
(
), Ho
(
), ...Er
(
), Tm
(
), Yb
(
)), have been synthesized from the lanthanide(III) nitrates with the polydentate hydrazone Schiff base ligand. The flexibility of this unsymmetrical Schiff base ligand containing N
O binding moiety, attractive for lanthanide metal ions, allowed for a self-assembly of these complexes. The compounds were characterized by spectroscopic data (ESI-MS, IR, UV/Vis, luminescence) and by the X-ray structure determination of the single crystals, all of which appeared to be different solvents. The analytical data suggested 2:3 metal:ligand stoichiometry in these complexes, and this was further confirmed by the structural results. The metal cations are nine-coordinated, by nitrogen and oxygen donor atoms. The complexes are two-centered, with three oxygen atoms in bridging positions. There are two types of structures, differing by the sources of terminal (non-bridging) coordination centers (group A: two ligands, one nitro anion/one ligand, two nitro anions, group B: three ligands, three anions).
A synthesis of a series of mono-T
and difunctionalized double-decker silsesquioxanes bearing substituted triazole ring(s) has been reported within this work. The catalytic protocol for their ...formation is based on the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) process. Diverse alkynes were in the scope of our interest-i.e., aryl, hetaryl, alkyl, silyl, or germyl-and the latter was shown to be the first example of terminal germane alkyne which is reactive in the applied process' conditions. From the pallet of 15 compounds, three of them with pyridine-triazole and thiophenyl-triazole moiety attached to T
or DDSQ core were verified in terms of their coordinating properties towards selected transition metals, i.e., Pd(II), Pt(II), and Rh(I). The studies resulted in the formation of four SQs based coordination compounds that were obtained in high yields up to 93% and their thorough spectroscopic characterization is presented. To our knowledge, this is the first example of the DDSQ-based molecular complex possessing bidentate pyridine-triazole ligand binding two Pd(II) ions.
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