scholarly journals Boron-Enabled Geometric Isomerization of Small Alkene Fragments via Selective Energy Transfer Catalysis

2020 ◽  
Author(s):  
John James Molloy ◽  
Michael Schäfers ◽  
Max Wienhold ◽  
Tobias Morack ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Retinoic Acid ◽  
Visual Cycle ◽  
Triplet Energy ◽  
Molecular Precursors ◽  
Highly Efficient ◽  
Geometric Isomerization ◽  
Gating Mechanism ◽  
Triplet Energy Transfer

The mammalian visual cycle epitomizes the importance of complex polyenes in biology. However, isomerization-based strategies to enable the sterodivergent construction of these important biomolecules from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low molecular precursors. Herein, we report a general ambiphilic C3 scaffold that can be isomerized and bi-directionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of β-15 borylacrylates is contingent on the participation of the boron p-orbital in the substrate chromophore. Rotation of the C(sp2)-B bond by 90° in the product renders re-excitation inefficient and endows directionality. This subtle stereoelectronic gating mechanism enables the stereocontrolled syntheses of well-defined retinoic acid derivatives.<br>

scholarly journals Boron-Enabled Geometric Isomerization of Small Alkene Fragments via Selective Energy Transfer Catalysis

2020 ◽  
Author(s):  
John James Molloy ◽  
Michael Schäfers ◽  
Max Wienhold ◽  
Tobias Morack ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Retinoic Acid ◽  
Visual Cycle ◽  
Triplet Energy ◽  
Molecular Precursors ◽  
Highly Efficient ◽  
Geometric Isomerization ◽  
Gating Mechanism ◽  
Triplet Energy Transfer

The mammalian visual cycle epitomizes the importance of complex polyenes in biology. However, isomerization-based strategies to enable the sterodivergent construction of these important biomolecules from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low molecular precursors. Herein, we report a general ambiphilic C3 scaffold that can be isomerized and bi-directionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of β-15 borylacrylates is contingent on the participation of the boron p-orbital in the substrate chromophore. Rotation of the C(sp2)-B bond by 90° in the product renders re-excitation inefficient and endows directionality. This subtle stereoelectronic gating mechanism enables the stereocontrolled syntheses of well-defined retinoic acid derivatives.<br>

Boron-enabled geometric isomerization of alkenes via selective energy-transfer catalysis

Science ◽  
2020 ◽  
Vol 369 (6501) ◽  
pp. 302-306
Author(s):  
John J. Molloy ◽  
Michael Schäfer ◽  
Max Wienhold ◽  
Tobias Morack ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Energy Transfer ◽  
Retinoic Acid ◽  
Low Molecular Weight ◽  
Triplet Energy ◽  
Highly Efficient ◽  
Geometric Isomerization ◽  
Gating Mechanism ◽  
Triplet Energy Transfer

Isomerization-based strategies to enable the stereodivergent construction of complex polyenes from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low–molecular weight precursors. In this work, we report a general ambiphilic C3 scaffold that can be isomerized and bidirectionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of β-borylacrylates is contingent on the participation of the boron p orbital in the substrate chromophore. Rotation of the C(sp2)–B bond by 90° in the product renders re-excitation inefficient and endows directionality. This subtle stereoelectronic gating mechanism enables the stereocontrolled syntheses of well-defined retinoic acid derivatives.

Highly Efficient Light-Harvesting System Based on a Phosphorescent Acceptor Coupled with Dendrimer Donors via Singlet−Singlet and Triplet−Triplet Energy Transfer

2007 ◽  
Vol 19 (15) ◽  
pp. 3673-3680 ◽  
Author(s):  
Tae-Hyuk Kwon ◽  
Myoung Ki Kim ◽  
Jongchul Kwon ◽  
Dae-Yup Shin ◽  
Su Jin Park ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Triplet Energy ◽  
Highly Efficient ◽  
Triplet Energy Transfer

Enhancing Shielding of Triplet Energy Transfer to Poly(p-phenylene)s from Phosphor Dopant by Addition of Branched Alcohol for Highly Efficient Electrophosphorescence

2010 ◽  
Vol 2 (4) ◽  
pp. 1094-1099 ◽  
Author(s):  
Yu-Kai Huang ◽  
Tzu-Hao Jen ◽  
Yao-Tang Chang ◽  
Neng-Jye Yang ◽  
Hsin-Hung Lu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Highly Efficient ◽  
Triplet Energy Transfer

Enhancing the electroluminescence performances of novel platinum(ii) polymetallayne-based phosphorescent polymers through employing functionalized IrIII phosphorescent units and facilitating triplet energy transfer

RSC Advances ◽  
2015 ◽  
Vol 5 (16) ◽  
pp. 12100-12110 ◽  
Author(s):  
Zuan Huang ◽  
Boao Liu ◽  
Jiang Zhao ◽  
Yue He ◽  
Xiaogang Yan ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Triplet State ◽  
State Energy ◽  
Triplet Energy ◽  
Highly Efficient ◽  
Triplet State Energy ◽  
Triplet Energy Transfer

Novel phosphorescent polymers are developed with platinum(ii) polymetallayne-based backbones bearing functionalized IrIII phosphorescent units to promote highly efficient triplet state energy-transfer and achieve high EL performances.

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

Triplet energy transfer in conjugated polymers. II. A polaron theory description addressing the influence of disorder

2008 ◽  
Vol 78 (4) ◽  
Author(s):  
Ivan I. Fishchuk ◽  
Andrey Kadashchuk ◽  
Lekshmi Sudha Devi ◽  
Paul Heremans ◽  
Heinz Bässler ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Conjugated Polymers ◽  
Triplet Energy ◽  
Polaron Theory ◽  
Triplet Energy Transfer
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