scholarly journals Strategic Synthesis of ‘Picket Fence’ Porphyrins Based on Nonplanar Macrocycles

2021 ◽  
Author(s):  
Karolis Norvaisa ◽  
Kathryn Yeow ◽  
Brendan Twamley ◽  
Marie Roucan ◽  
Mathias Senge
Keyword(s):  
Single Crystal ◽  
Molecular Design ◽  
Crystallographic Analysis ◽  
Target Compound ◽  
X Ray ◽  
Playing Field ◽  
New Concepts ◽  
Picket Fence ◽  
Supramolecular Ensembles ◽  
Shielding Effects

Traditional ‘picket fence’ porphyrin systems have been a topic of interest for their capacity to direct steric shielding effects selectively to one side of the macrocycle. Sterically overcrowded porphyrin systems that adopt macrocycle deformations have recently drawn attention for their applications in organocatalysis and sensing. Here we explore the combined benefits of nonplanar porphyrins and the old molecular design to bring new concepts to the playing field. The challenging ortho-positions of meso-phenyl residues dodecasubstituted porphyrin systems led us to transition to less hindered para- and meta-sites and develop selective demethylation based on the steric interplay. Isolation of the symmetrical target compound [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(3,5-dipivaloyloxyphenyl)porphyrin] was investigated under two synthetic pathways. The obtained insight was used to isolate unsymmetrical [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-nitro-5-pivaloyloxyphenyl)porphyrin]. Upon separation of the atropisomers, a detailed single-crystal X-ray crystallographic analysis highlighted intrinsic intermolecular interactions. The nonplanarity of these systems in combination with ‘picket fence’ motifs provides an important feature in the design of supramolecular ensembles.<br>

scholarly journals Strategic Synthesis of ‘Picket Fence’ Porphyrins Based on Nonplanar Macrocycles

2021 ◽  
Author(s):  
Karolis Norvaisa ◽  
Kathryn Yeow ◽  
Brendan Twamley ◽  
Marie Roucan ◽  
Mathias Senge
Keyword(s):  
Single Crystal ◽  
Molecular Design ◽  
Crystallographic Analysis ◽  
Target Compound ◽  
X Ray ◽  
Playing Field ◽  
New Concepts ◽  
Picket Fence ◽  
Supramolecular Ensembles ◽  
Shielding Effects

Traditional ‘picket fence’ porphyrin systems have been a topic of interest for their capacity to direct steric shielding effects selectively to one side of the macrocycle. Sterically overcrowded porphyrin systems that adopt macrocycle deformations have recently drawn attention for their applications in organocatalysis and sensing. Here we explore the combined benefits of nonplanar porphyrins and the old molecular design to bring new concepts to the playing field. The challenging ortho-positions of meso-phenyl residues dodecasubstituted porphyrin systems led us to transition to less hindered para- and meta-sites and develop selective demethylation based on the steric interplay. Isolation of the symmetrical target compound [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(3,5-dipivaloyloxyphenyl)porphyrin] was investigated under two synthetic pathways. The obtained insight was used to isolate unsymmetrical [2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetrakis(2-nitro-5-pivaloyloxyphenyl)porphyrin]. Upon separation of the atropisomers, a detailed single-crystal X-ray crystallographic analysis highlighted intrinsic intermolecular interactions. The nonplanarity of these systems in combination with ‘picket fence’ motifs provides an important feature in the design of supramolecular ensembles.<br>

Revised Absolute Configurations of Latifolic Acid and the Pyrrolizidine Alkaloid Latifoline

1988 ◽  
Vol 41 (11) ◽  
pp. 1781 ◽  
Author(s):  
JN Roitman ◽  
RY Wong
Keyword(s):  
Carboxylic Acid ◽  
Single Crystal ◽  
Pyrrolizidine Alkaloid ◽  
Crystallographic Analysis ◽  
Side Chain ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of (+)- latifolk acid has been determined by single-crystal X-ray crystallographic analysis to be (2S,3R,4R)-3- hydroxy-2,4-dimethyl-5-oxotetrahydrofuran-3-carboxylic acid. The configuration of the three chiral centres is opposite to that presently recorded in the literature. Accordingly, the configuration of the pyrrolizidine alkaloid, latifoline, which includes a latifolic acid side chain, must be revised.

Stereoselective synthesis and X-ray crystallographic analysis of mixed 6,6-dihalo penicillanates

1985 ◽  
Vol 63 (11) ◽  
pp. 3177-3181 ◽  
Author(s):  
Diego U. Belinzoni ◽  
Oreste A. Mascaretti ◽  
Pedro M. Alzari ◽  
Graciela Punte ◽  
Carlos Faerman ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Stereoselective Synthesis ◽  
Crystallographic Analysis ◽  
Displacement Reaction ◽  
X Ray ◽  
Single Crystal Analysis

The pivaloyloxy methyl 6,6-dihalo penicillanates 1a, 1b, and 1c have been stereoselectively prepared from the reaction of pivaloyloxy methyl 6-diazo penicillanate 2 with either N-halosuccinimide/halide or the interhalogens Xl (X = Cl, Br). The crystal structures of 3S,5R,6R pivaloyloxy methyl 6-bromo, 6-chloro penicillanate1a; 3S,5R,6R pivaloyloxy methyl 6-iodo, 6-bromo penicillanate 1b, and 3S, 5R, 6R pivaloyloxymethyl 6-iodo, 6-chloro penicillanate 1c have been determined by X-ray single crystal analysis. The stereochemistry of the displacement reaction is discussed.

Two- and three-dimensional β,β’-N-heterocycle fused porphyrins: concise construction, singlet oxygen production and electro-catalytic hydrogen evolution reaction

2021 ◽  
Author(s):  
Jianxin Song ◽  
Yan Fan ◽  
Zhiming Zeng ◽  
Hui Shu ◽  
Mingbo Zhou ◽  
...  
Keyword(s):  
Single Crystal ◽  
Hydrogen Evolution Reaction ◽  
Three Dimensional ◽  
Coupling Reaction ◽  
Crystallographic Analysis ◽  
Oxygen Production ◽  
X Ray ◽  
Palladium Catalyzed ◽  
Catalytic Hydrogen ◽  
Catalytic Hydrogen Evolution

A powerful and concise synthesis of two- and three-dimensional β,β’-N-heterocycle fused porphyrins by palladium-catalyzed C-N coupling reaction of bromoporphyrins with arylamines has been demonstrated. Single crystal X-ray crystallographic analysis revealed...

scholarly journals Efficient S-Acylation of Thiourea

SynOpen ◽  
2018 ◽  
Vol 02 (04) ◽  
pp. 0263-0267
Author(s):  
David Jones ◽  
Uday Khandavilli ◽  
Eileen O’Leary ◽  
Simon Lawrence ◽  
Timothy O’Sullivan
Keyword(s):  
Single Crystal ◽  
Sulfur Atom ◽  
Crystallographic Analysis ◽  
Acid Chlorides ◽  
X Ray

Efficient S-acylation of thiourea using a variety of acid chlorides is reported. Structurally diverse aryl and alkyl substrates are compatible with this methodology. Confirmation that acylation occurs exclusively­ on the sulfur atom of thiourea is provided by single-crystal X-ray crystallographic analysis.

Pigments of Fungi. LVII. Structure and X-Ray Crystallographic Analysis of Dermocanarin 10, a New Naphthalene - Dihydroanthracenone Dimer from an Australian Dermocybe Toadstool

1999 ◽  
Vol 52 (9) ◽  
pp. 881 ◽  
Author(s):  
Melvyn Gill ◽  
Petra M. Millar ◽  
Evelin Raudies ◽  
Somphone Phonh-Axa ◽  
Jonathan M. White ◽  
...  
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Spectroscopic Data ◽  
Crystallographic Analysis ◽  
Fungal Metabolite ◽  
X Ray ◽  
Absolute Stereochemistry

The structure and absolute stereochemistry of the fungal metabolite dermocanarin 10 (2), which differs from all previous members of the dermocanarin group by virtue of the connectivity between the anthraquinone and dimethoxynaphthol rings, is deduced from spectroscopic data and confirmed by a single-crystal X-ray structure analysis.

scholarly journals Synthesis of a Tetraepoxy Nanobelt and Its Reductive Aromatization Attempts

2020 ◽  
Vol 02 (04) ◽  
pp. 330-335
Author(s):  
Yi Han ◽  
Shaoqiang Dong ◽  
Yuan Cheng Liau ◽  
Chunyan Chi
Keyword(s):  
Carbon Nanotube ◽  
Single Crystal ◽  
Building Block ◽  
Recent Progress ◽  
Computational Results ◽  
Target Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Release ◽  
Backbone Structure

Hydrocarbon nanobelts have recently attracted tremendous interest. Herein, we report our recent progress towards the synthesis of a newly designed hydrocarbon nanobelt tetrabenzo[10]cyclacene, which can be regarded as a sidewall fragment of the (10,0) carbon nanotube. The structures of both key intermediates — “U”-shape diepoxy building block and tetraepoxy nanobelt — were confirmed by single-crystal X-ray diffraction. Our preliminary reductive aromatization reactions revealed that a tetrahydrogenated species instead of tetrabenzo[10]cyclacene was formed during this process. Computational results further revealed that hydrogenation can lead to significant strain release of the backbone structure of tetrabenzo[10]cyclacene, which may attribute to the absence of the target compound during the reductive aromatization.

Synthesis and characterization of (η5-C5Me5)W(NO)I2, a monomeric, formally 16-electron complex

1988 ◽  
Vol 66 (8) ◽  
pp. 2100-2103 ◽  
Author(s):  
Neil H. Dryden ◽  
Peter Legzdins ◽  
Frederick W. B. Einstein ◽  
Richard H. Jones
Keyword(s):  
Molecular Structure ◽  
Molecular Weight ◽  
Solid State ◽  
Single Crystal ◽  
Significant Degree ◽  
Crystallographic Analysis ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Degree Of Association

The compound (η5-C5Me5)W(NO)I2 has been prepared by treating (η5-C5Me5)W(NO)(CO)2 with I2. A single crystal X-ray crystallographic analysis establishes that the formally 16-electron complex possesses a monomeric, three-legged piano stool molecular structure in the solid state. Solution molecular weight measurements also indicate no significant degree of association of the compound.

Detailed example of the identification and crystallographic analysis of a pseudo-merohedrally twinned crystal

2012 ◽  
Vol 68 (2) ◽  
pp. 150-157 ◽  
Author(s):  
Ilia Guzei ◽  
Regine Herbst-Irmer ◽  
Apollinaire Munyaneza ◽  
James Darkwa
Keyword(s):  
Single Crystal ◽  
Crystallographic Analysis ◽  
Structural Determination ◽  
Organometallic Complex ◽  
X Ray ◽  
Positional Disorder ◽  
Crystal Structural

A detailed description of the procedures utilized in the non-routine X-ray single-crystal structural determination and refinement of a pseudo-merohedrally twinned crystal of an Fe/Ni organometallic complex is presented. It illustrates to the practitioners of crystallography how to properly handle such cases and describes the logic and concrete steps necessary to account for the twinning, pseudo-symmetry and atomic positional disorder.

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