scholarly journals Visible Light-Mediated [2+2] Cycloaddition for the Synthesis of Azetidines via Energy Transfer

2018 ◽  
Author(s):  
Marc R. Becker ◽  
Alistair D. Richardson ◽  
Corinna S. Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Functional Group ◽  
Transfer Mechanism ◽  
Synthetic Methods ◽  
Energy Transfer Mechanism ◽  
Triplet Energy ◽  
Mechanistic Investigations ◽  
Triplet Energy Transfer ◽  
Operational Simplicity

<p>Due to the lack of synthetic methods for their synthesis, azetidines are an underrepresented class of nitrogen-containing heterocycles. Herein, we describe the development of a mild, general protocol for the synthesis of azetidines relying on a visible light-mediated [2+2] cycloaddition between oximes and olefins catalyzed by an iridium photocatalyst. This approach is characterized by its operational simplicity, low catalyst loadings and functional group tolerance. Mechanistic investigations suggest that a triplet energy transfer mechanism is operative.<br></p>

scholarly journals Triplet Energy Transfer Mechanism of Ternary Organic Hybrid Thin Films of PFO/MEH-PPV/CsPbBr3 Perovskite Quantum Dots

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2094
Author(s):  
Bandar Ali Al-Asbahi ◽  
Saif M. H. Qaid ◽  
Hamid M. Ghaithan ◽  
Abdullah S. Aldwayyan
Keyword(s):  
Thin Films ◽  
Energy Transfer ◽  
Transfer Mechanism ◽  
Ternary Blend ◽  
Energy Transfer Mechanism ◽  
Triplet Energy ◽  
Blending Method ◽  
Donor And Acceptor ◽  
Hybrid Thin Films ◽  
Triplet Energy Transfer

The triplet energy transfer mechanism of novel poly(9,9-di-n-octylflourenyl-2,7-diyl) (PFO)/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV)/CsPbBr3 perovskite quantum dot (PQD) hybrid thin films was comprehensively investigated. The concentrations of PFO and MEH-PPV in all the specimens were fixed, while the PQD content was varied with various weight ratios and premixed by a solution blending method before it was spin-coated onto glass substrates. The triplet non-radiative Förster resonance energy transfers (FRETs) in the PFO/MEH-PPV/PQDs ternary blend, the dual FRET from PFO to both PQDs and MEH-PPV, and the secondary FRET from PQDs to MEH-PPV were observed. The values of the Förster radius (Ro) of FRET from PFO to MEH-PPV in the presence of various PQD contents (Case I) increased from 92.3 to 104.7 Å, and they decreased gradually from 68.0 to 39.5 Å for FRET from PFO to PQDs in the presence of MEH-PPV (Case II). These Ro values in both cases confirmed the dominance of FRET in ternary hybrid thin films. Upon increasing the PQD content, the distance between the donor and acceptor molecules (RDA) and the conjugation length (Aπ) in both cases gradually decreased. The small values of Ro, RDA, and Aπ with a decrease in the energy transfer lifetime (τET) due to an increase in the PQD contents in both Cases I and II confirmed the efficient FRET in the hybrid. To prevent intermolecular transfer in PFO, the concentrations of MEH-PPV (Case I) and PQDs (Case II) should be decreased to a range of 0.57–0.39 mM and increased in the range of 1.42–7.25 mM.

Triplet energy transfer mechanism in isotopic mixed molecular crystals

1976 ◽  
Vol 80 (20) ◽  
pp. 2196-2196 ◽  
Author(s):  
S. D. Colson ◽  
F. B. Tudron ◽  
R. E. Turner ◽  
V. Vaida
Keyword(s):  
Energy Transfer ◽  
Molecular Crystals ◽  
Transfer Mechanism ◽  
Energy Transfer Mechanism ◽  
Triplet Energy ◽  
Triplet Energy Transfer

scholarly journals Synthesis of Azetidines via Visible Light-Mediated Intermolecular [2+2] Photocycloaddition

2020 ◽  
Author(s):  
Marc R. Becker ◽  
Emily R. Wearing ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Reactive Intermediates ◽  
Powerful Method ◽  
Triplet Energy ◽  
Mild Conditions ◽  
Broad Scope ◽  
Highly Strained ◽  
Triplet Energy Transfer ◽  
Operational Simplicity

<p>Intermolecular [2+2] photocycloadditions represent a powerful method for the synthesis of highly strained, four-membered rings. While this approach is commonly employed for the synthesis of oxetanes and cyclobutanes, the synthesis of azetidines via intermolecular aza Paternò-Büchi reactions remains highly underdeveloped. Herein we report a visible light-mediated intermolecular aza Paternò-Büchi reaction that utilizes glyoxylate oximes as reactive intermediates activated via triplet energy transfer. This approach is characterized by its operational simplicity, mild conditions and broad scope, and allows for the synthesis of highly functionalized azetidines from readily available precursors.<b></b></p>

scholarly journals Synthesis of Azetidines via Visible Light-Mediated Intermolecular [2+2] Photocycloaddition

2020 ◽  
Author(s):  
Marc R. Becker ◽  
Emily R. Wearing ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Reactive Intermediates ◽  
Powerful Method ◽  
Triplet Energy ◽  
Mild Conditions ◽  
Broad Scope ◽  
Highly Strained ◽  
Triplet Energy Transfer ◽  
Operational Simplicity

<p>Intermolecular [2+2] photocycloadditions represent a powerful method for the synthesis of highly strained, four-membered rings. While this approach is commonly employed for the synthesis of oxetanes and cyclobutanes, the synthesis of azetidines via intermolecular aza Paternò-Büchi reactions remains highly underdeveloped. Herein we report a visible light-mediated intermolecular aza Paternò-Büchi reaction that utilizes glyoxylate oximes as reactive intermediates activated via triplet energy transfer. This approach is characterized by its operational simplicity, mild conditions and broad scope, and allows for the synthesis of highly functionalized azetidines from readily available precursors.<b></b></p>

scholarly journals Visible Light-Enabled Paternò-Büchi Reaction via Triplet Energy Transfer for the Synthesis of Oxetanes

2020 ◽  
Author(s):  
Katie Rykaczewski ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Uv Light ◽  
Cycloaddition Reaction ◽  
High Energy ◽  
Triplet Energy ◽  
Reaction Conditions ◽  
Triplet Energy Transfer

<div> <p>One of the most efficient ways to synthesize oxetanes is the light-enabled [2+2] cycloaddition reaction of carbonyls and alkenes, referred to as the Paternò-Büchi reaction. The reaction conditions for this transformation typically require the use of high energy UV light to excite the carbonyl, limiting the applications, safety, and scalability. We herein report the development of a visible light-mediated Paternò-Büchi reaction protocol that relies on triplet energy transfer from an iridium-based photocatalyst to the carbonyl substrates. This mode of activation is demonstrated for a variety of aryl glyoxylates and negates the need for both, visible light-absorbing carbonyl starting materials or UV light to enable access to a variety of functionalized oxetanes in up to 99% yield.</p> </div> <br>

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