The Synthesis and Structural Characterization of Peralkylated Triguanide Superbases

2014 ◽  
Vol 67 (7) ◽  
pp. 1129 ◽  
Author(s):  
Vjekoslav Štrukil ◽  
Edislav Lekšić ◽  
Ernest Meštrović ◽  
Mirjana Eckert-Maksić
Keyword(s):  
Diffraction Analysis ◽  
Gas Phase ◽  
Structural Characterization ◽  
Positive Charge ◽  
Coupling Reaction ◽  
Chloride Salt ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

Organic superbases derived from a peralkylated triguanide framework have been synthesized in a coupling reaction between monosubstituted guanidines and a Vilsmeier salt. Single crystal X-ray diffraction analysis of the chloride salt allowed the structural characterization of the benzyl derivative for the first time and revealed an effective delocalization of the positive charge despite significant distortion of the triguanide cation planarity. With the calculated gas phase basicity ranging from 262 to 265 kcal mol–1 and pKa values in acetonitrile between 28 and 30, these compounds have been evaluated as potential organocatalysts in the transesterification reaction of vegetable oil.

scholarly journals Synthesis and Structural Characterization of the Tetranuclear Iron(Iii) Cluster with Salicylic Acid

2020 ◽  
Vol 15 (2) ◽  
pp. 62-68
Author(s):  
Viorina Gorinchoy
Keyword(s):  
Salicylic Acid ◽  
Diffraction Analysis ◽  
Structural Characterization ◽  
Spectroscopic Method ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ir Spectroscopic ◽  
Oxygen Atoms

A new tetra-homonuclear iron(III) cluster, [Fe4O2(Sal)4(H2O)6]·4DMA·0.75H2O, where Sal= salicylic acid and DMA= N,N-dimethylacetamide consolidated via two µ3-oxo- and four salicylate-bridges was synthesized and characterized by IR spectroscopic method as well as by single crystal X-ray diffraction analysis. The structure of the obtained tetranuclear compound consists of four FeIII atoms in a “butterfly” arrangement. The coordination sphere of each of the two central FeIII atoms is generated by two μ3-oxo-bridging atoms and four oxygen atoms provided by the tridentate-bridging Sal2- ligands, while the coordination polyhedron of another two iron atoms involve six oxygen atoms from three water molecules, two salicylic and one μ3-oxigen atom. The Fe-O distances within Fe-O-Fe bridge are of 2.102(3) Å (for wing-body) and 2.038(3) Å (for body-body).

Synthesis and characterization of meso-to-meso directly linked porphyrin-diazaporphyrin triads

2018 ◽  
Vol 22 (09n10) ◽  
pp. 814-820
Author(s):  
Yingying Jia ◽  
Ling Xu ◽  
Bangshao Yin ◽  
Mingbo Zhou ◽  
Jianxin Song
Keyword(s):  
Nickel Complex ◽  
High Resolution Mass Spectrometry ◽  
Dihedral Angles ◽  
X Ray Diffraction ◽  
Extinction Coefficients ◽  
X Ray ◽  
H Nmr ◽  
First Time ◽  
Molar Extinction Coefficients

Beginning with 5,10,15-triarylporphyrin-nickel complex, five meso-to-meso directly linked porphyrin-diazaporphyrin triads were successfully prepared for the first time through a series of reactions including formylation via Vilsmeier–Haack reaction, condensation with pyrrole, bromination with [Formula: see text]-Bromosuccinimide (NBS), oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), metal-templated cyclization of dibromodipyrrin-metal complexes with NaN[Formula: see text] and demetalization. All these triads were comprehensively characterized by [Formula: see text]H NMR, high-resolution mass spectrometry and UV-vis absorption. In addition, the structure of compound 6Ni was unambiguously determined by X-ray diffraction analysis, which showed that the two dihedral angles are both 86.65 (4)[Formula: see text] between each mean plane of porphyrin and that of central diazaporphyrin The UV-vis absorption spectra disclosed that the longest wavelengths of Soret bands and Q bands for these triads were observed at 429 and 642 nm, respectively. In contrast to diazaporphyrin-porphyrin dyads, diazaporphyrin dimers and diazaporphyrin monomers reported previously the molar extinction coefficients, particularly for triad 8Ni are much higher.

scholarly journals Structural characterization of self-assembled quantum dot structures by X-ray diffraction techniques

1997 ◽  
Vol 306 (2) ◽  
pp. 198-204 ◽  
Author(s):  
A.A. Darhuber ◽  
J. Stangl ◽  
V. Holy ◽  
G. Bauer ◽  
A. Krost ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Structural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Assembled
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