scholarly journals Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

2020 ◽  
Vol 16 ◽  
pp. 22-31
Author(s):  
Andreas H Heindl ◽  
Hermann A Wegner
Keyword(s):  
Nmr Spectroscopy ◽  
Smart Materials ◽  
Storage Capacity ◽  
Aryl Halides ◽  
Information Storage ◽  
The Other ◽  
Coupling Reactions ◽  
Efficient Synthesis ◽  
H Nmr ◽  
New Class

Multistate switches allow to drastically increase the information storage capacity and complexity of smart materials. In this context, unsymmetrical 1,3,5-tris(arylazo)benzenes – ‘starazos’ – which merge three photoswitches on one benzene ring, were successfully prepared. Two different synthetic strategies, one based on Baeyer–Mills reactions and the other based on Pd-catalyzed coupling reactions of arylhydrazides and aryl halides, followed by oxidation, were investigated. The Pd-catalyzed route efficiently led to the target compounds, unsymmetrical tris(arylazo)benzenes. These triple switches were preliminarily characterized in terms of their isomerization behavior using UV–vis and 1H NMR spectroscopy. The efficient synthesis of this new class of unsymmetrical tris(arylazo)benzenes opened new avenues to novel multistate switching materials.

Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XXXI [1]. Synthese und Dynamik von Acetyl-carbonyl-η5-cyclopentadienyl-η4-dien-wolfram-Komplexen / Hindered Ligand Movements in Transition Metal Complexes, XXXI [1]. Syntheses and Dynamics of Acetyl-carbonyl-η5-cyclopentadienyl-η4-diene-tungsten Complexes

1986 ◽  
Vol 41 (5) ◽  
pp. 599-605 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Kurt Nist ◽  
Joachim Kögler
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Conjugated Dienes ◽  
The Other ◽  
Molecular Plane ◽  
H Nmr ◽  
Tungsten Complexes ◽  
Diene Ligands

Tricarbonyl-η5-cyclopentadienyl-methyl-tungsten (1) reacts upon UV irradiation with conjugated dienes, like 1,3-butadiene (2), E-1,3-pentadiene (3), 2-methyl-1,3-butadiene (4), 2,3-dimethyl-1,3- butadiene (5), 1,3-cyclopentadiene (6) and 1,3-cyclohexadiene (7), to give the corresponding, quasisquare- pyramidal [(η5-C5H5)W(CO)(COCH3)(η4-diene)] complexes (8-13). With the unsymmetrically substituted dienes 3 and 4, only one of the possible diastereotopic complexes are obtained. At 200 to 230 K, 8-12 show two isomers, which are distinguished by the orientations (o or u) of the diene with respect to the other ligands. The interconversion of the o- and u-isomers was studied by dynamic 1H NMR spectroscopy and is explained by an intramolecular ±180° rotation of the diene ligands in the molecular plane. The barriers o f activation ⊿G* 300 are between 57.8 and 61.0 ± 1 kJ/mol.

Synthesis and properties of oxytocin analogues modified in the tripeptide side chain

1984 ◽  
Vol 49 (3) ◽  
pp. 642-652 ◽  
Author(s):  
Zdenko Procházka ◽  
Michal Lebl ◽  
Tomislav Barth ◽  
Jan Hlaváček ◽  
Antonín Trka ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Biological Activities ◽  
The Other ◽  
Side Chain ◽  
H Nmr ◽  
Fragment Condensation

Two oxytocin analogues were synthesized by fragment condensation (6 + 3) in the presence of dicyclohexylcarbodiimide and 1-hydroxybenzotriazole. In one of the analogues, proline in the position 7 and leucine in the position 8 were substituted by 2-[1-(2-oxo-3-aminopyrrolidinyl)]-4-methylpentanoic acid, in the other proline was replaced by 1-aminocyclopropane-1-carboxylic acid. Biological activities of the first analogue were strongly reduced and dissociation of the uterotonic and galoctogogic activities was observed with both the analogues. The structure of 2-(3-tert-butyloxycarbonylaminopyrrolidin-2-on-1-yl)-4-methylpentanoylglycine and its amide was confirmed by mass and 1 H NMR spectroscopy.

scholarly journals Discrimination of enantiomers of dipeptide derivatives with two chiral centers by tetraaza macrocyclic chiral solvating agents using 1H NMR spectroscopy

2016 ◽  
Vol 3 (12) ◽  
pp. 1716-1724 ◽  
Author(s):  
Lixia Fang ◽  
Caixia Lv ◽  
Guo Wang ◽  
Lei Feng ◽  
Pericles Stavropoulos ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
H Nmr ◽  
New Class ◽  
Chiral Centers

Enantiomers of dipeptide derivatives with two chiral centers were effectively discriminated by a new class of tetraaza macrocyclic chiral solvating agents via1H NMR spectroscopy.

Multinuclear magnetic resonance studies of the aqueous products of the complexes cis- and trans-Pt(Ypy)2(NO3)2 where Ypy = pyridine derivative

2002 ◽  
Vol 80 (4) ◽  
pp. 379-387 ◽  
Author(s):  
Fernande D Rochon ◽  
Christian Tessier
Keyword(s):  
Nmr Spectroscopy ◽  
The Other ◽  
Basic Medium ◽  
Pyridine Derivative ◽  
Neutral Medium ◽  
Coupling Constant ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Cis And Trans ◽  
Ortho Substituent

The hydrolyis or the aquation reactions of compounds of the types cis- and trans-Pt(Ypy)2(NO3)2 (Ypy = pyridine derivative) were studied in D2O and characterized by multinuclear (195Pt, 13C, and 1H) NMR spectroscopy. In acidic pD, the product of the cis complexes is cis-[Pt(Ypy)2(D2O)2]2+, whereas in basic medium cis-Pt(Ypy)2(OD)2 is formed. The 195Pt NMR resonances of the products containing ligands with an ortho substituent were observed at lower fields than the other complexes. The average coupling constant (3J(195Pt–1H) and 3J(195Pt–13C)) is 44 Hz for the diaqua species and 42 Hz for the dihydroxo compounds. At neutral pD, several hydrolyzed species were observed, except for the 2-picoline and 2,4-lutidine complexes, which contained only one compound, cis-[Pt(Ypy)2(D2O)(OD)]+. The other hydrolyzed products for the ligands with no ortho substituent were identified as the dihydroxo-bridged dimer, the monohydroxo-bridged dimer, the trimer, and possibly the tetramer. The trans analogues have shown two signals in acidic pD corresponding to the diaqua monomer and the monohydroxo-bridged aqua dimer. Two species (the dihydroxo compound and the monohydroxo-bridged hydroxo dimer) were also observed in basic pD. In neutral medium, a third signal assigned to a longer chain hydroxo-bridged oligomer or polymer was detected.Key words: platinum, pyridine derivative, nitrato, hydrolysis, NMR, aquation.

Zirconocene-mediated selective synthesis of 1,4-bis(alkynyl)benzenes

2020 ◽  
Vol 44 (9-10) ◽  
pp. 571-575
Author(s):  
Bo Zhang ◽  
Hongmei Qu ◽  
Zhongxuan Li ◽  
Yuanyuan Zhai ◽  
Xiaolu Zhou ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dimethyl Ester ◽  
Acid Ethyl Ester ◽  
Coupling Reactions ◽  
Benzene Derivatives ◽  
Phenylene Ethynylene ◽  
H Nmr ◽  
Vis Spectroscopy ◽  
High Yields ◽  
C Nmr

A series of novel 1,4-bis(alkynyl)benzene derivatives were synthesized from trimethylsilyl-substituted alkynes by the mediation of zirconocene with excellent regioselectivity in high yields. The 3,6-bis(trimethylsilyl)-4,5-dialkylphthalic acid dimethyl esters were prepared by cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclopentadienes to dimethyl acetylenedicarboxylate. After iodination with iodine monochloride, 3,6-diiodo-4,5-dialkylphthalic acid dimethyl esters reacted with terminal alkynes to prepare the corresponding 1,4-bis(alkynyl)benzene derivatives by Sonogashira coupling reactions. After removal of trimethylsilyl, 4,5-dibutyl-3,6-bis(ethynyl)phthalic acid dimethyl ester (compound 3) reacted with 4-iodobenzoic acid ethyl ester and 2-iodothiophene, respectively, to obtain the corresponding products 4a and 4c. Compound 3 can be extended to higher oligomers, which reacted with 1-bromo-4-iodobenzene and phenylacetylene in a stepwise manner under Sonogashira conditions to give the phenylene-ethynylene oligomer 5 in an isolated yield of 85%. The structures of the products were confirmed by 1H NMR spectroscopy, 13C NMR spectroscopy, and MS. The optical properties of the 1,4-bis(alkynyl)benzene derivatives were studied by UV-Vis spectroscopy and fluorescence spectra. The results indicated that some can be developed into potential photovoltaic materials.

scholarly journals Electron Release and Proton Acceptance Reactions of (dpp-BIAN)Mg(THF)3

2008 ◽  
Vol 63 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Igor L. Fedushkin ◽  
Valentina A. Chudakova ◽  
Markus Hummert ◽  
Herbert Schumann
Keyword(s):  
Nmr Spectroscopy ◽  
Carboxylic Acid ◽  
Ir Spectroscopy ◽  
The Other ◽  
X Ray ◽  
H Nmr ◽  
Trigonal Bipyramidal ◽  
Electron Release ◽  
Coordination Spheres ◽  
Centrosymmetric Dimers

(dpp-BIAN)Mg(THF)3 (1) (dpp-BIAN = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) and (PhCOO)2 react with splitting of the peroxide bridge and formation of the dimeric magnesium benzoate [(dpp-BIAN)MgOCOPh(THF)]2 (2). The reaction of 1 with PhCOOH yields the dimeric magnesium benzoate [(dpp-BIAN)(H)MgOCOPh(THF)]2 (3), whereas 1 and furanyl-2-carboxylic acid react with liberation of hydrogen and formation of (dpp-BIAN)Mg[OCO(2-C4H3O)]2 Mg(dpp-BIAN)(THF) (4). Compounds 2, 3, and 4 have been characterized by elemental analysis, IR spectroscopy, and X-ray structure analysis, compound 3 also by 1H NMR spectroscopy. The eightmembered metallacycles of the centrosymmetric dimers 2 and 3 are almost completely planar. The two magnesium atoms in 4 show different coordination spheres; one is surrounded by its ligands in a trigonal bipyramidal manner, the other one in a tetrahedral fashion. The Mg···Mg separations in 2, 3 and 4 are 4.236, 4.296, and 4.030 Å, respectively

Mixed behavior of p-phenylenediaminium guest binding with the inverted cucurbit[6]uril host

2015 ◽  
Vol 13 (30) ◽  
pp. 8330-8334 ◽  
Author(s):  
De-Qing Zhang ◽  
Rui-Lian Lin ◽  
Wen-Qi Sun ◽  
Zhu Tao ◽  
Qian-Jian Zhu ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Sandwich Structure ◽  
The Other ◽  
Binding Interaction ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Guest Binding ◽  
Different Types ◽  
Inclusion Structure

The binding interaction between inverted cucurbit[6]uril (iQ[6]) and p-phenylenediaminium has been investigated by X-ray crystallography, 1H NMR spectroscopy and ITC. Our data indicate that the host and the guest can form two different types of complexes: one is an inclusion structure and the other is a sandwich structure.

scholarly journals Figure-of-Eight Helicene Carbon Nanohoop with Möbius Topology

2021 ◽  
Author(s):  
Juraj Malinčík ◽  
Sudhakar Gaikwad ◽  
Marc-Aurèle Boillat ◽  
Daniel Häussinger ◽  
Tomas Solomek
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Yield ◽  
Dft Calculations ◽  
Variable Temperature ◽  
High Quantum Yield ◽  
Chiroptical Properties ◽  
Design And Synthesis ◽  
H Nmr ◽  
New Class ◽  
Present Design

We present design and synthesis of a new class of chiral figure-of-eight carbon nanohoops by integrating [6]helicene into [7]cycloparaphenylene. The stereogenic [6]helicene unit endows the helicene carbon nanohoop with chiroptical properties and configurational stability typical for higher helicenes, while the presence of radially conjugated oligo-<i>p</i>-phenylene moiety provides the optoelectronic properties similar to <i>meta</i>[8]cycloparaphenylene, such as emission of visible light with a high quantum yield. We discovered that the synthesized helicene carbon nanohoop possesses a Mobius topology in solution and confirmed this hypothesis by variable-temperature <sup>1</sup>H NMR spectroscopy and DFT calculations. Our results suggest that a single helicene stereogenic unit and high molecular strain are sufficient to induce Mobius topology in molecular nanocarbon systems. <br>

An Efficient Synthesis of 1-Thia-5-azaspiro[5.5]undec-2-ene and its Recyclization to 1,5-Diazaspiro[5.5]undec-2-ene and/or Spiro-Thieno[2,3-d]pyrimidin-4(1H)-one Derivatives

2011 ◽  
Vol 66 (5) ◽  
pp. 487-492
Author(s):  
Raafat M. Shaker ◽  
Asmaa Hamoda ◽  
Yusria R. Ibrahim ◽  
Kamal M. El-Shaieb ◽  
Fathy F. Abdel-Latif
Keyword(s):  
Nmr Spectroscopy ◽  
Direct Synthesis ◽  
Efficient Synthesis ◽  
H Nmr ◽  
Elemental Analyses ◽  
C Nmr

An efficient and direct synthesis of 1-thia-5-azaspiro[5.5]undec-2-ene is described, and the basecatalyzed recyclization of this compound was studied. The products have been characterized by elemental analyses, and IR, MS, 1H NMR, and 13C NMR spectroscopy

scholarly journals Figure-of-Eight Helicene Carbon Nanohoop with Möbius Topology

2021 ◽  
Author(s):  
Juraj Malinčík ◽  
Sudhakar Gaikwad ◽  
Marc-Aurèle Boillat ◽  
Daniel Häussinger ◽  
Tomas Solomek
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Yield ◽  
Dft Calculations ◽  
Variable Temperature ◽  
High Quantum Yield ◽  
Chiroptical Properties ◽  
Design And Synthesis ◽  
H Nmr ◽  
New Class ◽  
Present Design

We present design and synthesis of a new class of chiral figure-of-eight carbon nanohoops by integrating [6]helicene into [7]cycloparaphenylene. The stereogenic [6]helicene unit endows the helicene carbon nanohoop with chiroptical properties and configurational stability typical for higher helicenes, while the presence of radially conjugated oligo-<i>p</i>-phenylene moiety provides the optoelectronic properties similar to <i>meta</i>[8]cycloparaphenylene, such as emission of visible light with a high quantum yield. We discovered that the synthesized helicene carbon nanohoop possesses a Mobius topology in solution and confirmed this hypothesis by variable-temperature <sup>1</sup>H NMR spectroscopy and DFT calculations. Our results suggest that a single helicene stereogenic unit and high molecular strain are sufficient to induce Mobius topology in molecular nanocarbon systems. <br>

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