Properties of the [M(dppm)2M′]2+Building Blocks (M, M′ = Pd or Pt): Site Selectivity, Emission Features, and Frontier Orbital Analysis

2009 ◽  
Vol 48 (9) ◽  
pp. 4118-4133 ◽  
Author(s):  
Sébastien Clément ◽  
Shawkat M. Aly ◽  
Diana Bellows ◽  
Daniel Fortin ◽  
Carsten Strohmann ◽  
...  
Keyword(s):  
Building Blocks ◽  
Frontier Orbital ◽  
Site Selectivity ◽  
Orbital Analysis

scholarly journals Site-Selective [2+2+n] Cycloadditions for Rapid, Scalable Access to Alkynylated Polycyclic Aromatic Hydrocarbons

2019 ◽  
Author(s):  
Gavin R. Kiel ◽  
Harrison Bergman ◽  
T. Don Tilley
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Structural Complexity ◽  
Building Blocks ◽  
Synthetic Methods ◽  
Proof Of Concept ◽  
Site Selectivity ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Nanometer Regime

Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2+2+n] (n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2+2+2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups. The potential for generalization of the site-selectivity to other [2+2+n] reactions is demonstrated by identification of a Cp<sub>2</sub>Zr-mediated [2+2+1] / metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to Mo catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. More generally, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.

scholarly journals Biocatalytic oxidative cross-coupling reactions for biaryl bond formation

2021 ◽  
Author(s):  
Lara Zetzsche ◽  
Jessica Yazarians ◽  
Suman Chakrabarty ◽  
Meagan Hinze ◽  
April Lukowski ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Bond Formation ◽  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Cytochrome P450 Enzymes ◽  
Cross Coupling Reactions ◽  
Site Selectivity ◽  
Valuable Compounds ◽  
Selective Process

Despite their varied purposes, many indispensable molecules in medicine, materials, and asymmetric catalysis share a biaryl core. The necessity of joining arene building blocks to access these valuable compounds has inspired multiple approaches for biaryl bond formation and challenged chemists to develop increasingly concise and robust methods for this task. Oxidative coupling of two C–H bonds offers an efficient strategy for the formation of a biaryl C–C bond, however, fundamental challenges remain in controlling the reactivity and selectivity for uniting a given pair of substrates. Biocatalytic oxidative cross-coupling reactions have the potential to overcome limitations inherent to small molecule- mediated methods by providing a paradigm with catalyst-controlled selectivity. In this article, we disclose a strategy for biocatalytic cross-coupling through oxidative C–C bond formation using cytochrome P450 enzymes. We demonstrate the ability to catalyze cross-coupling reactions on a panel of phenolic substrates using natural P450 catalysts. Moreover, we engineer a P450 to possess the desired reactivity, site- selectivity, and atroposelectivity by transforming a low-yielding, unselective reaction into a highly efficient and selective process. This streamlined method for constructing sterically hindered biaryl bonds provides a programmable platform for assembling molecules with catalyst-controlled reactivity and selectivity.

Biodegradation Mechanism of Anionic Polyacrylamide in Coal Preparation Using Molecular Simulation

2021 ◽  
Author(s):  
Fanglue Wang ◽  
Dongchen Zhang ◽  
Xuefeng Wu ◽  
Shengsong Deng
Keyword(s):  
Hydrophobic Interactions ◽  
Interaction Mechanism ◽  
Docking Study ◽  
Binding Modes ◽  
Frontier Orbital ◽  
Orbital Theory ◽  
Orbital Analysis ◽  
Insight Into ◽  
Anionic Polyacrylamide ◽  
Rhodococcus Sp

Abstract Biodegradation of anionic polyacrylamide (HPAM) and polyacrylate (PAA) by key enzymes, such as amidase and bacterial laccase, have been reported. However, the interaction mechanism between HPAM or PAA and enzymes is still poorly unclear. Here, docking study was undertook to demonstrate the binding modes and interaction details for degradation of HPAM or PAA. Then, bioactivities between PAA and HPAM were compared with frontier orbital theory. The docking results showed that HPAM completely buried in pocket of Rhodococcus sp. N-771 amidase (Rh Amidase), while most of PAA molecule exposed outside pocket of Bacillus subtilis laccase ( B. subtilis laccase ), further suggesting PAA was much more difficult to degrade than HPAM. Hydrophobic interactions and hydrogen bonds were necessary for stabilizing HPAM-Rh Amidase or PAA- B. subtilis laccase complex. The frontier orbital analysis indicated that bioactivity of PAA was higher than that of PAA. These findings provide an insight into enzyme-catalyzed degradation of HPAM. It is helpful in designing highly efficient enzymes against HPAM or PAA to protect environment.

Substituent effects on the optical properties of naphthalenediimides: A frontier orbital analysis across the periodic table

2015 ◽  
Vol 37 (2) ◽  
pp. 304-313 ◽  
Author(s):  
Joshua R. Mulder ◽  
Célia Fonseca Guerra ◽  
J. Chris Slootweg ◽  
Koop Lammertsma ◽  
F. Matthias Bickelhaupt
Keyword(s):  
Optical Properties ◽  
Periodic Table ◽  
Substituent Effects ◽  
Frontier Orbital ◽  
Orbital Analysis

An MNDO study of sulfenium ions

1983 ◽  
Vol 61 (3) ◽  
pp. 589-593 ◽  
Author(s):  
Jack Leon Ginsburg ◽  
Richard Francis Langler
Keyword(s):  
Gas Phase ◽  
Substituent Effects ◽  
Frontier Orbital ◽  
Relative Stabilities ◽  
Ion Formation ◽  
Orbital Analysis

An MNDO study has been carried out on a variety of substituted sulfenium ions and sulfides. Relative stabilities in the gas phase have been calculated for several pairs of regioisomeric sulfenium ions. It is shown that sulfenium ions are stabilized by π-donors and that the substituent electronegativity is not an important factor. The potential implications of this result for the mechanism by which chlorosulfonium cations are converted into sulfenium ions in solution is discussed. Substituent effects on the energetics of sulfenium ion formation from sulfides have been obtained. It is shown that these effects also are related to the substituent's π-donating ability. A frontier-orbital analysis of selected sulfenium ions has been done and is discussed.

scholarly journals Site-Selective [2+2+n] Cycloadditions for Rapid, Scalable Access to Alkynylated Polycyclic Aromatic Hydrocarbons

2019 ◽  
Author(s):  
Gavin R. Kiel ◽  
Harrison Bergman ◽  
T. Don Tilley
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Structural Complexity ◽  
Building Blocks ◽  
Synthetic Methods ◽  
Proof Of Concept ◽  
Site Selectivity ◽  
Polycyclic Aromatic ◽  
Site Selective ◽  
Nanometer Regime

Polycyclic aromatic hydrocarbons (PAHs) are attractive synthetic building blocks for more complex conjugated nanocarbons, but their use for this purpose requires appreciable quantities of a PAH with reactive functional groups. Despite tremendous recent advances, most synthetic methods cannot satisfy these demands. Here we present a general and scalable [2+2+n] (n = 1 or 2) cycloaddition strategy to access PAHs that are decorated with synthetically versatile alkynyl groups and its application to seven structurally diverse PAH ring systems (thirteen new alkynylated PAHs in total). The critical discovery is the site-selectivity of an Ir-catalyzed [2+2+2] cycloaddition, which preferentially cyclizes tethered diyne units with preservation of other (peripheral) alkynyl groups. The potential for generalization of the site-selectivity to other [2+2+n] reactions is demonstrated by identification of a Cp<sub>2</sub>Zr-mediated [2+2+1] / metallacycle transfer sequence for synthesis of an alkynylated, selenophene-annulated PAH. The new PAHs are excellent synthons for macrocyclic conjugated nanocarbons. As a proof of concept, four were subjected to Mo catalysis to afford large, PAH-containing arylene ethylene macrocycles, which possess a range of cavity sizes reaching well into the nanometer regime. More generally, this work is a demonstration of how site-selective reactions can be harnessed to rapidly build up structural complexity in a practical, scalable fashion.

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