Highly Luminescent 4-Pyridyl-Extended Dithieno[3,2-b:2′,3′-d]phospholes

2020 ◽  
Author(s):  
Thomas Baumgartner ◽  
Paul Demay-Drouhard
Keyword(s):  
Electrochemical Properties ◽  
Quantum Yields

The unexpectedly challenging synthesis of 4-pyridyl-extended dithienophospholes is reported. The optical and electrochemical properties of the phosphoryl-bridged species were studied experimentally and computationally, and their properties compared to their non-<i>P</i>-bridged congeners. The 4-pyridyl-extended dithieno-phospholes display quantitative luminescence quantum yields in solution.<br><br>

Highly Luminescent 4-Pyridyl-Extended Dithieno[3,2-b:2′,3′-d]phospholes

2020 ◽  
Author(s):  
Thomas Baumgartner ◽  
Paul Demay-Drouhard
Keyword(s):  
Electrochemical Properties ◽  
Quantum Yields

The unexpectedly challenging synthesis of 4-pyridyl-extended dithienophospholes is reported. The optical and electrochemical properties of the phosphoryl-bridged species were studied experimentally and computationally, and their properties compared to their non-<i>P</i>-bridged congeners. The 4-pyridyl-extended dithieno-phospholes display quantitative luminescence quantum yields in solution.<br><br>

Synthesis and optical and electrochemical properties of water-soluble cationic fluorophores based on bispyridinium and dibenzothiophene-S,S-dioxide

2017 ◽  
Vol 41 (4) ◽  
pp. 1696-1703 ◽  
Author(s):  
Guiting Chen ◽  
Ruifeng He ◽  
Wei Yang ◽  
Bin Zhang
Keyword(s):  
Electrochemical Properties ◽  
Blue Emission ◽  
Water Soluble ◽  
Quantum Yields ◽  
Deep Blue

Two water-soluble cationic fluorophores (FSOPyCl and FSOmiCl) based on bispyridinium and dibenzothiophene-S,S-dioxide show deep blue emission, and exhibit high photoluminescence quantum yields of 69% and 50% in water, respectively.

scholarly journals New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

2017 ◽  
Vol 13 ◽  
pp. 1583-1595 ◽  
Author(s):  
Daria G Selivanova ◽  
Alexei A Gorbunov ◽  
Olga A Mayorova ◽  
Alexander N Vasyanin ◽  
Igor V Lunegov ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electrochemical Properties ◽  
Electrochemical Oxidation ◽  
Free Electron ◽  
Quantum Yields ◽  
Synthetic Approach ◽  
Fluorescence Quantum Yields ◽  
Starting Compound ◽  
Positive Solvatochromism

In this paper we present a synthetic approach to six new D–π–A–D conjugated chromophores containing the N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment. Such readily functionalizable heterocycle as carbazole was used as a main starting compound for their preparation. The investigation of the optical properties has shown that the positive solvatochromism is inherent to the chromophores containing an electron-withdrawing prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. The fluorescence quantum yields were experimentally determined for some of the synthesized chromophores; e.g., 1-(5-arylthiophen-2-yl)ethanones quantum yields were found to lie in an interval of 60–80%. Electrochemical oxidation of the synthesized chromophores has resulted in the formation of colored thin oligomeric films that became possible due to the presence of carbazole or pyrrole fragments with free electron-rich positions.

Synthesis and photophysical and electrochemical properties of novel unsymmetrical phthalocyanines with a Sudan IV moiety

2018 ◽  
Vol 22 (01n03) ◽  
pp. 112-120 ◽  
Author(s):  
İbrahim Özçeşmeci ◽  
Pınar Büyük ◽  
Ilgın Nar ◽  
Ahmet Gül
Keyword(s):  
Electrochemical Properties ◽  
Spectroscopic Data ◽  
Quantum Yields ◽  
Metal Free ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
Reduction Potentials ◽  
Elemental Analyses ◽  
Sudan Iv ◽  
Ft Ir

The synthesis of novel, A[Formula: see text]B type unsymmetrical metal-free and metallophthalocyanines bearing one aza dye group Sudan IV and three nitro terminal moieties was achieved by cyclotetramerization of novel 4-((1-((E)-(2-methyl-4-((E)-[Formula: see text]-tolyldiazenyl)phenyl)diazenyl)naphthalen-2-yl)oxy)phthalonitrile and 4-nitrophthalonitrile. The new unsymmetrical metal-free and metallophthalocyanines have been characterized using elemental analyses, [Formula: see text]H NMR, FT-IR, UV-vis and mass spectroscopic data. The aggregation properties of the compounds were investigated in a concentration range of 1.0 × 10[Formula: see text] M–6.25 × 10[Formula: see text] M. General trends were also studied for fluorescence quantum yields and lifetimes of these phthalocyanine compounds in tetrahydrofuran. The fluorescence of the synthesized unsymmetrical metal-free and metallophthalocyanines is effectively quenched by 1,4-benzoquinone (BQ) in THF. In-depth investigation of the electrochemical properties showed that nitro groups extended the reduction potentials.

High-Temperature Synthesis of CdSe-Based Core/Shell, Core/Shell/Shell, and Core/Graded-Shell Nanoplatelets for Stable and Efficient Narrowband Emitters

2019 ◽  
Author(s):  
Aurelio A. Rossinelli ◽  
Henar Rojo ◽  
Aniket S. Mule ◽  
Marianne Aellen ◽  
Ario Cocina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Equilibrium Shape ◽  
Size Variation ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Quantum Yields ◽  
Core Shell ◽  
Compositional Gradient ◽  
High Quality

<div>Colloidal semiconductor nanoplatelets exhibit exceptionally narrow photoluminescence spectra. This occurs because samples can be synthesized in which all nanoplatelets share the same atomic-scale thickness. As this dimension sets the emission wavelength, inhomogeneous linewidth broadening due to size variation, which is always present in samples of quasi-spherical nanocrystals (quantum dots), is essentially eliminated. Nanoplatelets thus offer improved, spectrally pure emitters for various applications. Unfortunately, due to their non-equilibrium shape, nanoplatelets also suffer from low photo-, chemical, and thermal stability, which limits their use. Moreover, their poor stability hampers the development of efficient synthesis protocols for adding high-quality protective inorganic shells, which are well known to improve the performance of quantum dots. <br></div><div>Herein, we report a general synthesis approach to highly emissive and stable core/shell nanoplatelets with various shell compositions, including CdSe/ZnS, CdSe/CdS/ZnS, CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S, and CdSe/ZnSe. Motivated by previous work on quantum dots, we find that slow, high-temperature growth of shells containing a compositional gradient reduces strain-induced crystal defects and minimizes the emission linewidth while maintaining good surface passivation and nanocrystal uniformity. Indeed, our best core/shell nanoplatelets (CdSe/Cd<sub>x</sub>Zn<sub>1–x</sub>S) show photoluminescence quantum yields of 90% with linewidths as low as 56 meV (19.5 nm at 655 nm). To confirm the high quality of our different core/shell nanoplatelets for a specific application, we demonstrate their use as gain media in low-threshold ring lasers. More generally, the ability of our synthesis protocol to engineer high-quality shells can help further improve nanoplatelets for optoelectronic devices.</div>

Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops

2019 ◽  
Author(s):  
Terri Lovell ◽  
Curtis Colwell ◽  
Lev N. Zakharov ◽  
Ramesh Jasti
Keyword(s):  
Symmetry Breaking ◽  
Theoretical Work ◽  
P Systems ◽  
Quantum Yields ◽  
Size Dependent ◽  
New Class ◽  
Carbon Carbon Bond ◽  
Conjugated Macrocycles ◽  
Structural Manipulation ◽  
Highly Strained

<p>[<i>n</i>]Cycloparaphenylenes, or “carbon nanohoops,” are unique conjugated macrocycles with radially oriented p-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as <i>meta</i>[<i>n</i>]cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent [<i>n</i>]cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficents and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented p-systems.</p>

Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops

2019 ◽  
Author(s):  
Terri Lovell ◽  
Curtis Colwell ◽  
Lev N. Zakharov ◽  
Ramesh Jasti
Keyword(s):  
Symmetry Breaking ◽  
Theoretical Work ◽  
P Systems ◽  
Quantum Yields ◽  
Size Dependent ◽  
New Class ◽  
Carbon Carbon Bond ◽  
Conjugated Macrocycles ◽  
Structural Manipulation ◽  
Highly Strained

<p>[<i>n</i>]Cycloparaphenylenes, or “carbon nanohoops,” are unique conjugated macrocycles with radially oriented p-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as <i>meta</i>[<i>n</i>]cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent [<i>n</i>]cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficents and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented p-systems.</p>

IN VITRO ELECTROCHEMICAL PROPERTIES OF BIODEGRADABLE YSZ-COATED MgCa ALLOY

2016 ◽  
Vol 15 (5) ◽  
pp. 955-963 ◽  
Author(s):  
Corneliu Munteanu ◽  
Bogdan Istrate ◽  
Daniel Mareci ◽  
Sergiu Stanciu ◽  
Carmen-Iulia Crimu ◽  
...  
Keyword(s):  
Electrochemical Properties
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