Extensive Studies on π-Stacking of Poly(3-alkylthiophene-2,5-diyl)s and Poly(4-alkylthiazole-2,5-diyl)s by Optical Spectroscopy, NMR Analysis, Light Scattering Analysis, and X-ray Crystallography

1998 ◽  
Vol 120 (9) ◽  
pp. 2047-2058 ◽  
Author(s):  
Takakazu Yamamoto ◽  
Dharma Komarudin ◽  
Minoru Arai ◽  
Bang-Lin Lee ◽  
Hajime Suganuma ◽  
...  
Keyword(s):  
Light Scattering ◽  
Optical Spectroscopy ◽  
Nmr Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Π Stacking

Preparation and structural analysis of (±)-threo-ritalinic acid

2013 ◽  
Vol 69 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Sara Wyss ◽  
Irmgard A. Werner ◽  
W. Bernd Schweizer ◽  
Simon M. Ametamey ◽  
Selena Milicevic Sephton
Keyword(s):  
Methyl Ester ◽  
Free Acid ◽  
Nmr Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Ritalinic Acid ◽  
Methyl Phenidate ◽  
Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

Synthesis and characterization of a linked, π-π stacked organotin compound of 2-mercapto-6-nitrobenzothiazolyl diphenyltin chloride with 2-ethoxyl-6-nitrobenzothiazole

2003 ◽  
Vol 81 (7) ◽  
pp. 825-831 ◽  
Author(s):  
Chunlin Ma ◽  
Qin Jiang ◽  
Rufen Zhang
Keyword(s):  
Title Compound ◽  
Organotin Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stacking Interaction ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Π Stacking ◽  
Π Stacking Interaction ◽  
Molecular Components

The new organotin compound, Ph2Sn(Cl)[S(C7H3N2O2S)]·[(C7H3N2O2S)OEt], assembled by an intermolecular aromatic benzothiazole–benzothiazole π-π stacking interaction, has been synthesized by the reaction of diphenyltin dichloride with 2-mercapto-6-nitrobenzothiazole. The title compound was characterized by elemental, IR, 1H NMR, and X-ray crystallography analyses. Single-crystal X-ray diffraction data reveals that the title compound has two different molecular components. The component Ph2Sn(Cl)[S(C7H3N2O2S)] has a pentacoordinate tin, which further forms an infinite one-dimensional chain by intermolecular non-bonded Cl···S interactions, resulting in an intercalation lattice that holds (C7H3N2O2S)OEt molecules. The formation of the molecule (C7H3N2O2S)OEt as well as its intercalated mechanism has also been discussed.Key words: organotin, assemble, π-π stacking interaction, 2-mercapto-6-nitrobenzothiazole, non-bonded interaction, crystal structure.

scholarly journals CAAC Boranes. Synthesis and characterization of cyclic (alkyl) (amino) carbene borane complexes from BF3 and BH3

2010 ◽  
Vol 6 ◽  
pp. 709-712 ◽  
Author(s):  
Julien Monot ◽  
Louis Fensterbank ◽  
Max Malacria ◽  
Emmanuel Lacôte ◽  
Steven J Geib ◽  
...  
Keyword(s):  
Silica Gel ◽  
Synthesis And Characterization ◽  
Gel Chromatography ◽  
Nmr Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
In Situ Formation ◽  
Silica Gel Chromatography

In situ formation of two cyclic (alkyl) (amino) carbenes (CAACs) followed by addition of BF3•Et2O provided the first two examples of CAAC–BF3 complexes: 1-(2,6-diisopropylphenyl)-3,5,5-trimethyl-3-phenylpyrrolidin-2-ylidene trifluoroborane, and 2-(2,6-diisopropylphenyl)-3,3-dimethyl-2-azaspiro[4.5]decan-1-ylidene trifluoroborane. These CAAC–BF3 complexes are robust compounds that are stable to ambient laboratory conditions and silica gel chromatography. They were characterized by spectroscopy and X-ray crystallography. In contrast, a CAAC complex with borane (BH3) was readily formed in situ according to 1H and 11B NMR analysis, but did not survive the workup conditions. These results set the stage for further studies of the chemistry of CAAC boranes.

scholarly journals Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 194 ◽  
Author(s):  
Miriam Rossi ◽  
Kelly Wen ◽  
Francesco Caruso ◽  
Stuart Belli
Keyword(s):  
Density Functional ◽  
Superoxide Radical ◽  
Therapeutic Option ◽  
Color Variation ◽  
Stable Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Π Stacking ◽  
Vis Spectroscopy ◽  
Voltaic Cell

The naturally occurring anthraquinone emodin is found in many plants that have been part of traditional Chinese medicine (TCM) for thousands of years. Recent pharmacological studies suggest that emodin might be a valuable therapeutic option for the treatment of various diseases. We describe the antioxidant effects of emodin on the superoxide radical. Our techniques include X-ray crystallography, density functional theory (DFT), and a recently developed cyclovoltammetry improvement, the rotating ring-disk electrode (RRDE) method. X-ray results show offset π–π stacking of emodin units in the crystal, and this type of interaction is supported by the DFT, which indicates one superoxide interacting via π–π stacking with the quinone moiety, by transferring one electron to the ring, and inducing some quinone aromatization. The second superoxide seems to form a stable complex after interacting with the H(hydroxyl) in position 3 of emodin. We show that one molecule of emodin sequesters two molecules of superoxide: one forming a complex with H(hydroxyl) in position 3, and the other due to π–π oxidation of superoxide and emodin ring reduction. We conclude that emodin is a very strong antioxidant. Color variation in the voltaic cell was observed during the RRDE study. This was analyzed and explained using a mini-grid gold electrode for UV-Vis spectroscopy in the voltaic cell.

scholarly journals [3.3]Dithia-bridged cyclophanes featuring a thienothiophene ring: synthesis, structures and conformational analysis

2009 ◽  
Vol 5 ◽  
Author(s):  
Sabir H Mashraqui ◽  
Yogesh Sanghvikar ◽  
Shailesh Ghadhigaonkar ◽  
Sukeerthi Kumar ◽  
Auke Meetsma ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Energy Minimization ◽  
Elevated Temperatures ◽  
Variable Temperature ◽  
Energy Difference ◽  
Nmr Analysis ◽  
Stable Conformation ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr

The synthesis of [3.3]dithia-bridged cyclophanes 7, 9 and 11 incorporating a fused heterocycle, thieno[2,3-b]thiophene is described. The structures are established by 1H NMR analysis and, in the case of 11, also by single crystal X-ray crystallography. Conformational analysis by variable temperature NMR suggests that cyclophanes 7, 9 and 11 exhibit conformationally rigid bridges and rings at least up to 130 °C. Energy minimization of 11 revealed anti -11 to be the most stable conformation. Although, the computed energy difference between the most stable conformation anti -11 and the next higher energy conformation syn-anti -11 is only 2.98 kJ/mol, it is intriguing that 11 does not exhibit thia-bridge inversion even at elevated temperatures.

scholarly journals Structural characterization and Hirshfeld surface analysis of a CoII complex with imidazo[1,2-a]pyridine

2018 ◽  
Vol 74 (5) ◽  
pp. 600-606 ◽  
Author(s):  
Saikat Kumar Seth
Keyword(s):  
Surface Analysis ◽  
Crystal Packing ◽  
Building Blocks ◽  
Hirshfeld Surface ◽  
Title Complex ◽  
Hirshfeld Surface Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Π Stacking ◽  
Coii Complex

A new mononuclear tetrahedral CoII complex, dichloridobis(imidazo[1,2-a]pyridine-κN 1)cobalt(II), [CoCl2(C7H6N2)2], has been synthesized using a bioactive imidazopyridine ligand. X-ray crystallography reveals that the solid-state structure of the title complex exhibits both C—H...Cl and π–π stacking interactions in building supramolecular assemblies. Indeed, the molecules are linked by C—H...Cl interactions into a two-dimensional framework, with finite zero-dimensional dimeric units as building blocks, whereas π–π stacking plays a crucial role in building a supramolecular layered network. An exhaustive investigation of the diverse intermolecular interactions via Hirshfeld surface analysis enables contributions to the crystal packing of the title complex to be quantified. The fingerprint plots associated with the Hirshfeld surface clearly display each significant interaction involved in the structure, by quantifying them in an effective visual manner.

Syntheses, characterization, and X-ray crystal structures of diorganotin(IV) derivatives of 2-pyridinethiolato-N-oxide

2003 ◽  
Vol 81 (10) ◽  
pp. 1070-1075 ◽  
Author(s):  
Chunlin Ma ◽  
Junhong Zhang ◽  
Rufen Zhang
Keyword(s):  
Crystal Structure ◽  
Stacking Interactions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nmr Data ◽  
Π Stacking ◽  
Oxide Crystal ◽  
Distorted Trigonal Bipyramid ◽  
Π Stacking Interaction ◽  
Derivatives Of

The diorganotin(IV) dichloride reacts with sodium 2-pyridinethiolato-N-oxide in a 1:1 ratio to produce [Me2SnCl(2-SpyO)] (1), [Et2SnCl(2-SpyO)] (2), [Bu2SnCl(2-SpyO)] (3), [Ph2SnCl(2-SpyO)] (4), and [(PhCH2)2SnCl(2- SpyO)] (5). The new complexes have been characterized by elemental analysis and IR and NMR (1H, 119Sn, and 13C) spectroscopy. On the basis of 119Sn NMR data the effective coordination number in solution is five. The structures 1 and 4 have been confirmed by X-ray crystallography. Crystals of 1 are triclinic with space group P[Formula: see text] and those of 4 are monoclinic, P21/n. The tin environment is a distorted trigonal bipyramid with the Cl and oxygen atoms in apical positions. Both complexes exhibit strong π–π stacking interactions. Key words: diorganotin, π–π stacking interaction, 2-pyridinethiolato-N-oxide, crystal structure.

scholarly journals (Z)-N'-(1H-Benzo[d]imidazol-2-Yl)-Arylimidamide Adducts of 2-Aminobenzimidazole and Aromatic Nitriles: Structural and Spectroscopic Proof of Regiochemical and Stereochemical Outcomes

2019 ◽  
Author(s):  
Martin Stoermer ◽  
Simon Egan ◽  
Craig M. Forsyth ◽  
Gerard Moloney
Keyword(s):  
Nucleophilic Addition ◽  
Medicinal Chemistry ◽  
Amino Derivative ◽  
Amino Group ◽  
Nmr Analysis ◽  
X Ray ◽  
Aromatic Nitriles ◽  
X Ray Crystallography ◽  
Lead Generation ◽  
Selection Of

The selection of a core scaffold or template is of enormous importance in medicinal chemistry. Benzimidazoles are a recurring fragment in medicinal chemistry, and the 2-amino derivative is a versatile example in lead generation. Alkylated and acylated examples abound, however, alternative linkage chemistries leading do more diverse structures are needed. <br>Here we discuss the regiochemistry of nucleophilic addition of 2-aminobenzimidazole to nitriles, leading to imidamide (amidine) adducts. Additionally, we use extensive NMR analysis and ultimately X-ray crystallography to demonstrate both the regiochemistry and stereochemistry of the addition products, arising from derivatisation of the exocylic 2-amino group.

Novel quinazolinones and enniatins from Fusarium lateritium Nees

1993 ◽  
Vol 71 (9) ◽  
pp. 1362-1367 ◽  
Author(s):  
Youla S. Tsantrizos ◽  
Xiao-Jin Xu ◽  
Françoise Sauriol ◽  
Rosemary C. Hynes
Keyword(s):  
Antifungal Activity ◽  
Spectroscopic Analysis ◽  
Bioactive Metabolites ◽  
The Novel ◽  
Nmr Analysis ◽  
Biological Phenomenon ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fusarium Lateritium ◽  
Absolute Stereochemistry

Fusarium lateritium Nees is a natural antagonist of the plant pathogen Eutypa armeniacae. In an effort to show that this biological phenomenon is chemically mediated, the bioactive metabolites of F. lateritium were investigated. The cytotoxic alkaloids 2-(1-hydroxyethyl)-4(3H)quinazolinone (1) and 2-acetyl-4(3H)quinazolinone (2), and the three cyclohexadepsipeptides, enniatins B (3), B1 (4), and A1 (5), were isolated and characterized. Metabolites 3, 4, and 5 were found to exhibit strong antifungal activity against E. armeniacae. The structures of the novel metabolites 1 and 2 were elucidated by spectroscopic analysis and that of 2 was confirmed by X-ray crystallography. The absolute stereochemistry of 1 was investigated by 1H and I9F NMR analysis of its Mosher ester derivative.

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