Modular synthesis of bis(monoacylglycero)phosphate for convenient access to analogues bearing hydrocarbon and perdeuterated acyl chains of varying length

A method involving silver-catalyzed aerobic oxidation/6-endo heterocyclization of ortho-alkynylbenzaldehydes to yield 3-substituted isocumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and...

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Palladium-catalyzed carbonylative transformation of aryl iodides and sulfonyl chlorides: convenient access to thioesters

Organic Chemistry Frontiers ◽

10.1039/d0qo00158a ◽

2020 ◽

Vol 7 (6) ◽

pp. 885-889 ◽

Cited By ~ 2

Author(s):

Xinxin Qi ◽

Zhi-Peng Bao ◽

Xiao-Feng Wu

Keyword(s):

Sulfonyl Chlorides ◽

Aryl Iodides ◽

Palladium Catalyzed ◽

Convenient Access

A palladium-catalyzed carbonylative transformation of aryl iodides and sulfonyl chlorides to thioesters has been studied.

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Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

10.26434/chemrxiv.13041830.v1 ◽

2020 ◽

Author(s):

Abhishek Singh ◽

Reman K. Singh ◽

G Naresh Patwari

Keyword(s):

Hydrogen Bonding ◽

Rational Design ◽

Biological Molecules ◽

Conformational Space ◽

X Ray Crystallography ◽

Simple Strategy ◽

Induced Folding ◽

Π Stacking ◽

Varying Length ◽

Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

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Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

10.26434/chemrxiv.13041830 ◽

2020 ◽

Author(s):

Abhishek Singh ◽

Reman K. Singh ◽

G Naresh Patwari

Keyword(s):

Hydrogen Bonding ◽

Rational Design ◽

Biological Molecules ◽

Conformational Space ◽

X Ray Crystallography ◽

Simple Strategy ◽

Induced Folding ◽

Π Stacking ◽

Varying Length ◽

Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

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Tris(pyrazolyl)borate Copper Hydroxide Complexes Featuring Tunable Intramolecular H-bonding

10.26434/chemrxiv.7878065.v1 ◽

2019 ◽

Author(s):

Evan Gardner ◽

Caitlyn Cobb ◽

Jeffery A. Bertke ◽

Timothy H. Warren

Keyword(s):

Single Crystal ◽

Copper Hydroxide ◽

X Ray ◽

Modular Synthesis ◽

Pendant Arm ◽

Copper Center ◽

Vibrational Studies

A modular synthesis provides access to a series of new tris(pyrazolyl)borate ligands XpyMeTpK that possess a single functionalized pendant pyridyl (py) or pyrimidyl (pyd) arm designed to engage in tunable intramolecular H-bonding to metal–bound functionalities. To illustrate such H-bonding interactions, a series of [XpyMeTpCu]2(𝜇–OH)2(6a–6e) complexes were synthesized from the corresponding XpyMeTpCu–OAc (5a–5e) complexes. Single crystal X-ray structures of three new dinuclear [XpyMeTpCu]2(𝜇–OH)2complexes reveal H-bonding between the pendant heterocycle and bridging hydroxide ligands while the donor arm engages the copper center in an unusual monomeric DMAPMeTpCu–OH complex. Vibrational studies (IR) of each bridging hydroxide complex reveal reduced 𝜈OH frequencies that tracks with the H-bond accepting ability of the pendant arm.

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Tris(pyrazolyl)borate Copper Hydroxide Complexes Featuring Tunable Intramolecular H-bonding

10.26434/chemrxiv.7878065 ◽

2019 ◽

Author(s):

Evan Gardner ◽

Caitlyn Cobb ◽

Jeffery A. Bertke ◽

Timothy H. Warren

Keyword(s):

Single Crystal ◽

Copper Hydroxide ◽

X Ray ◽

Modular Synthesis ◽

Pendant Arm ◽

Copper Center ◽

Vibrational Studies

A modular synthesis provides access to a series of new tris(pyrazolyl)borate ligands XpyMeTpK that possess a single functionalized pendant pyridyl (py) or pyrimidyl (pyd) arm designed to engage in tunable intramolecular H-bonding to metal–bound functionalities. To illustrate such H-bonding interactions, a series of [XpyMeTpCu]2(𝜇–OH)2(6a–6e) complexes were synthesized from the corresponding XpyMeTpCu–OAc (5a–5e) complexes. Single crystal X-ray structures of three new dinuclear [XpyMeTpCu]2(𝜇–OH)2complexes reveal H-bonding between the pendant heterocycle and bridging hydroxide ligands while the donor arm engages the copper center in an unusual monomeric DMAPMeTpCu–OH complex. Vibrational studies (IR) of each bridging hydroxide complex reveal reduced 𝜈OH frequencies that tracks with the H-bond accepting ability of the pendant arm.

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Аnticholinesterase and antioxidant activity of new binary conjugates of (с)-carbolines

Доклады Академии наук ◽

10.31857/s0869-56524841104-108 ◽

2019 ◽

Vol 484 (1) ◽

pp. 104-108

Author(s):

G. F. Makhaeva ◽

E. F. Shevtsova ◽

N. P. Boltneva ◽

N. V. Kovaleva ◽

E. V. Rudakova ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Antioxidant Activity ◽

Anticholinesterase Activity ◽

Amyloid Aggregation ◽

Varying Length ◽

Β Amyloid ◽

New Compounds

This study presents the synthesis of binary tetrohydro-γ-carbolines with ditriazol spacers of varying length, which exhibit anticholinesterase and antioxidant activity, as compared to the original Dimebon prototype. Anticholinesterase activity suggests the potential ability of the new compounds to block β-amyloid aggregation induced by anticholinesterase, making them promising candidates for further research preparations for the treatment of Alzheimer's disease. Particular attention should be paid to the conjugate with an intertriazol hexamethylene spacer, which can be regarded as the leading compound in this series.

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Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20032080 ◽

2003 ◽

Vol 68 (11) ◽

pp. 2080-2092 ◽

Cited By ~ 1

Author(s):

Martin Keppert ◽

Josef Krýsa ◽

Anthony A. Wragg

Keyword(s):

Mass Transfer ◽

Transfer Rate ◽

Mass Transfer Rate ◽

Mass Transfer Process ◽

Sulfate Solution ◽

Convective Mass Transfer ◽

Varying Length ◽

Inclined Surface ◽

Vertical Case ◽

Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

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