Tetra(pyrazino[2,3-b]pyrazino)porphyrazines: Synthesis, absorption, photophysical and electrochemical properties of strongly electron-deficient macrocycles

2017 ◽  
Vol 21 (04-06) ◽  
pp. 302-310 ◽  
Author(s):  
Veronika Novakova ◽  
Bartosz Małachwiej ◽  
René Šebl ◽  
Miroslav Miletin ◽  
Petr Zimcik
Keyword(s):  
Electrochemical Properties ◽  
Absorption Spectra ◽  
Zinc Acetate ◽  
Heavy Atom ◽  
Blue Shift ◽  
Strong Electron ◽  
Reduction Potentials ◽  
Photophysical Parameters ◽  
Atom Effect ◽  
Template Reaction

Highly electron deficient 6,7-disubstituted (tert-butylsufanyl, 2,6-diisopropylphenoxy, diethylamino, 2-pyridyl, 2-thienyl, 2-furyl) pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles were prepared and attempted in cyclotetramerization to corresponding tetra(pyrazino[2,3-[Formula: see text]]pyrazino)porphyrazines (TPyzPyzPzs). Only the template reaction in pyridine with zinc acetate and only for the compounds substituted with tert-butylsulfanyl or 2,6-diisopropylphenoxy substituents resulted in efficient cyclotetramerization. Absorption spectra of these zinc TPyzPyzPzs indicated considerable blue shift of the main absorption Q-band ([Formula: see text] 693 nm and 669 nm in pyridine for tert-butylsulfanyl or 2,6-diisopropylphenoxy derivatives) when compared to other aza-analogs of naphthalocyanines. Photophysical parameters ([Formula: see text] [Formula: see text] 0.25, [Formula: see text] [Formula: see text] 0.65) seemed to be unaffected by change of the macrocycle core and only slightly by different peripheral substituents in agreement with heavy-atom effect. Electrochemical data revealed strong electron-deficient character of hetaryl disubstituted pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles. The first reduction potentials of tert-butylsulfanyl or 2,6-diisopropylphenoxy substituted zinc TPyzPyzPzs were even more cathodically shifted when compared to their corresponding pyrazino[2,3-[Formula: see text]]pyrazino-2,3-dicarbonitriles. TPyzPyzPzs represent an example of the strongest electron-deficient core among the phthalocyanines, naphthalocyanines and their aza-analogs.

Die Bedeutung von Donor-Acceptor-Wechselwirkungen im äußeren Schweratom-Effekt von AgNO3 auf das Lumineszenzverhalten von Aza-aromaten und Carbazolen / The Significance of Donor-Acceptor Interactions in the External Heavy Atom Effect of AgNO3 on the Luminescence Behaviour of Aza-aromatic Systems and Carbazoles

1978 ◽  
Vol 33 (8) ◽  
pp. 998-1000 ◽  
Author(s):  
M. Zander
Keyword(s):  
Aromatic Hydrocarbons ◽  
Transition Probabilities ◽  
Heavy Atom ◽  
Fluorescence Analysis ◽  
Electronic System ◽  
Electron Donors ◽  
Strong Electron ◽  
Donor Acceptor ◽  
Aromatic Systems ◽  
Atom Effect

The transition probabilities of spin-forbidden processes become much more enhanced in the case of aza-aromatic systems than for structurally related aromatic hydrocarbons when AgNO3 is used as an external heavy atom perturber. This is explained with the strong electron donor properties of aza-aromatic systems thus causing strong interaction between the π-electronic system and the perturber. Since carbazoles are weaker electron donors than aza-aromatic systems, the enhancement of the phosphorescence/fluorescence quantum yield ratio by AgNO3 is lower than for aza-aromatic systems. The different behaviour of aza-aromatic systems and aromatic hydrocarbons in the heavy atom experiment with AgNO3 can find applications in fluorescence analysis.

The effect of substitutents at alkylsulfanyl/arylsulfanyl non-peripherally substituted phthalocyanines: Spectral and photophysical properties, basicity and photostability

2015 ◽  
Vol 19 (10) ◽  
pp. 1095-1106 ◽  
Author(s):  
Antonin Cidlina ◽  
Zuzana Pausimova ◽  
Miroslav Miletin ◽  
Petr Zimcik ◽  
Veronika Novakova
Keyword(s):  
Photophysical Properties ◽  
Heavy Atom ◽  
Blue Shift ◽  
Red Shift ◽  
Oxygen Production ◽  
Metal Free ◽  
Peripheral Position ◽  
Magnesium Complexes ◽  
Derivatives Of ◽  
Atom Effect

A series of magnesium, zinc and metal-free derivatives of non-peripherally substituted phthalocyanines (Pcs) bearing alkylsulfanyl or arylsulfanyl groups of different bulkiness was synthesized. Their spectral and photophysical properties including also the basicity of azomethine nitrogens and photostability were compared within the series as well as with similar peripherally substituted Pcs. Non-peripheral position of substituents led to the 70[Formula: see text]nm red-shift of Q-band in comparison to the peripherally substituted Pcs. However, unexpected blue-shift of approximately 50[Formula: see text]nm was observed in the series of non-peripherally substituted Pcs for the most bulky tert-butylsulfanyl derivative caused probably by extreme distortion of the macrocycle. The substitution had no effect on photophysical properties and compounds reached [Formula: see text] values 0.74–0.76 and [Formula: see text] 0.053–0.080 for zinc complexes, and [Formula: see text] 0.47–0.51 and [Formula: see text] 0.10–0.17 for magnesium complexes following the rule of heavy atom effect. Generally, non-peripherally substituted Pcs possessed improved singlet oxygen production in comparison to peripherally substituted ones. The photostability of the target compounds decreased with the red-shift of their absorption maxima with the arylsulfanyl derivatives being less photostable. The basicity of azomethine nitrogens was clearly dependent on the position and the character of substituent. Thus, non-peripherally substituted Pcs showed extraordinary increased basicity over the peripherally substituted ones with the most pronounced effect at alkylsulfanyl derivatives.

Achieving high singlet-oxygen generation by applying the heavy-atom effect to thermally activated delayed fluorescent materials

2021 ◽  
Author(s):  
Ya-Fang Xiao ◽  
Jia-Xiong Chen ◽  
Wen-Cheng Chen ◽  
Xiuli Zheng ◽  
Chen Cao ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Heavy Atom ◽  
Synergetic Effect ◽  
Heavy Atom Effect ◽  
Oxygen Generation ◽  
Thermally Activated ◽  
Singlet Oxygen Generation ◽  
Fluorescent Materials ◽  
Atom Effect

Applying the heavy-atom effect to TADF photosensitizers achieves ultra-high 1O2 generation (ФΔ = 0.91) by the synergetic effect of small ΔEST and considerable SOC.

Enhancement of Reverse Intersystem Crossing in Charge‐Transfer Molecule through Internal Heavy Atom Effect

2021 ◽  
pp. 2104646
Author(s):  
Hyung Suk Kim ◽  
Ja Yeon Lee ◽  
Seongjun Shin ◽  
Wonkyo Jeong ◽  
Sang Hoon Lee ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Heavy Atom ◽  
Intersystem Crossing ◽  
Heavy Atom Effect ◽  
Atom Effect

scholarly journals Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions

2021 ◽  
Vol 22 (2) ◽  
pp. 633
Author(s):  
Konrad Skotnicki ◽  
Slawomir Ostrowski ◽  
Jan Cz. Dobrowolski ◽  
Julio R. De la Fuente ◽  
Alvaro Cañete ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Density Functional ◽  
Reduction Potential ◽  
Biological Significance ◽  
Radical Cations ◽  
Basis Sets ◽  
Double Bonds ◽  
Reduction Potentials

The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●−, CO3●−) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●− with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning’s aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.

scholarly journals Etude par résonance magnétique nucléaire de composés organiques contenant des chalcogènes. II. L'éther de diphényle et ses analogues soufré, sélénié et telluré

1979 ◽  
Vol 57 (22) ◽  
pp. 2967-2970 ◽  
Author(s):  
Gabriel Llabrès ◽  
Marcel Baiwir ◽  
Léon Christiaens ◽  
Jean-Louis Piette
Keyword(s):  
Crystal Structure ◽  
Theoretical Calculations ◽  
Heavy Atom ◽  
Mesomeric Effect ◽  
Heavy Atom Effect ◽  
Inductive Effects ◽  
Structure Determinations ◽  
Résonance Magnétique ◽  
Atom Effect ◽  
Good Agreement

The 1Hmr study of the title compounds has revealed a screw conformation, with defined interconversion processes, in good agreement with crystal structure determinations and theoretical calculations. The mesomeric effect of the heteroatom is smaller than in the anisole series, due to steric inhibitions.The 13Cmr enhances, to some extent, these conclusions. In the case of Te compounds, a heavy atom effect adds to the classical mesomeric and inductive effects to account for the experimental observations.

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