Octaethylhemiporphycene: Synthesis, Molecular Structure and Photophysics

Vogel, Emanuel; Bröring, Martin; Weghorn, Steven J.; Scholz, Peter; Deponte, Reiner; Lex, Johann; Schmickler, Hans; Schaffner, Kurt; Braslavsky, Silvia E.; Müller, Martin; Pörting, Sigrid; Sessler, Jonathan L.; Fowler, Christopher J.

doi:10.1002/anie.199716511

Cited by 89 publications

(75 citation statements)

References 32 publications

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“…[41] Figure 10. Correlation established for the main absorbance bands in UV/Vis spectra of polypyrrolic macrocycles versus the number of π-electrons involved in the main conjugation pathway; A: porphyrin; [40,42] B: corrphycene; [43,44] C: hemiporphycene; [45,46] D: sapphyrin; [3,42,47,48] E: pentaphyrin; [4] F: smaragdyrine; [49] G: rubyrine; [7] H: (3.3.3.3)porphyrin; [40] I: (5.5.5.5)porphyrin; [40] J: orangarin; [50] K: amethyrin; [50] L: heptaphyrin; [12] M: octaphyrin(1.0.0.0.1.0.0.0); [12] N: turcasarin; [9] 1; [10] 2; [11] 3 [11] The observed correlations ( Figure 10) with two different slopes rationalise the results of the spectroelectrochemical experiments. As reported above, the spectra from cyclooctaphyrins possessing 4n π-electrons undergo a red shift after two one-electron reductions, generating (4n ϩ 2) π-electron species.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical and Spectroelectrochemical Investigations of “Figure-Eight” Octapyrrolic Macrocycles, Free Bases, and Their Mononuclear, Homo- and Heterodinuclear Complexes with Divalent Transition Metals

Bley-Escrich

Gisselbrecht

Vogel

et al. 2002

Eur. J. Inorg. Chem.

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This work reports on electrochemical investigations of ''figure-eight''-shaped cyclooctapyrrolic macrocycles (octaphyrins) 1−3 and of some of their mono-and dinuclear transition metal complexes. The octaphyrins 1−3 differ mainly in the size of the main conjugation pathway, which involves either 4n π-electrons for 1 and 3, or (4n + 2) π-electrons for 2. All species studied undergo six redox steps, namely two reductions and four oxidations. The two reductions and the first three oxidations are reversible one-electron transfers. The fourth oxidation is either reversible, or irreversible due to a subsequent chemical reaction. Depending on the complex studied, the third and fourth oxidations occur either at similar potentials, so that a global two-electron step is observed, or at distinct potentials, leading to two well-separated signals.

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Section: Discussionmentioning

confidence: 99%

Electrochemical and Spectroelectrochemical Investigations of “Figure-Eight” Octapyrrolic Macrocycles, Free Bases, and Their Mononuclear, Homo- and Heterodinuclear Complexes with Divalent Transition Metals

Bley-Escrich

Gisselbrecht

Vogel

et al. 2002

Eur. J. Inorg. Chem.

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“…Porphycene 1 ([18]porphyrin-(2.0.2.0), see Figure 54) is the structural isomer of porphyrin 2 ([18]porphyrin-(1.1.1.1)) first synthesized [317] in a series including corrphycene ( [18]porphyrin-(2.1.0.1)) [318] and hemiporphycene ( [18]porphyrin-(2.1.1.0)) [319]. Porphycenes have attracted much attention since their synthesis [320].…”

Section: Porphycenesmentioning

confidence: 99%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]-and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

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“…[9] The most dramatic difference between the four porphyrin isomers 5 ± 8, lies in the obvious disparities in core shape as well as in more subtle variations in core size. [11] Data available from previously solved X-ray structures, [4,6,8,12] as shown in Table 1, provides for a simple, graphical representation of each core and its respective geometry and area. As detailed below, these manifest disparities in structure and symmetry give rise to differences in observable optical properties as well as in the chemistry of representative metal complexes derived from these dianionic ligands.…”

Section: Dedicated To Professor Heinz a Staab On The Occasion Of Hismentioning

confidence: 99%

“…As detailed below, these manifest disparities in structure and symmetry give rise to differences in observable optical properties as well as in the chemistry of representative metal complexes derived from these dianionic ligands. [1,4,8,13] Results and Discussion Spectroscopic properties of metal-free systems: It has been well documented that changes in the conjugation pathway and symmetry of a porphyrin can affect its UV/Vis absorption spectrum. [1,14,15] Stern and Wenderlein [16] and Gouterman [14] have discussed the importance of charge localization on electronic spectroscopic properties.…”

Section: Dedicated To Professor Heinz a Staab On The Occasion Of Hismentioning

confidence: 99%

Metal Complexes of Porphycene, Corrphycene, and Hemiporphycene: Stability and Coordination Chemistry

et al. 2002

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Porphyrin (P), porphycene (Pc), corrphycene (Cn), and hemiporphycene (Hpc) represent a series of well defined “4‐N in” constitutional porphyrin isomers. These isomers, in the form of their octaethyl derivatives, represent a congruent set of porphyrinoids whose properties can be compared. In this study we report how variations in electronic structure and nitrogen‐core size in the free‐base forms of these four systems are reflected in the properties of their corresponding metal complexes. Specifically, the effects that these differences have on the axial ligation properties of the ZnII, MgII, NiII, and CoII complexes of P, Pc, Cn, and Hpc in toluene using pyridine as the axial ligand are detailed. Also reported are the relative stabilities of these complexes under acidic conditions. It is shown that for the zinc, magnesium, and cobalt complexes, there are distinct differences in the ability to maintain four‐, five‐, or six‐coordinate geometries in the presence of similar concentrations of pyridine. By contrast, no apparent differences in axial ligand binding affinity are seen for the four nickel complexes. Little difference in stability was likewise seen when these same complexes were subject to acid‐mediated demetallation, with all four falling into stability class II, according to the accepted porphyrin stability ranking system. High stabilities were also seen in the case of the cobalt complexes, with the Pc and Cn complexes being of stability class III and the P and Hpc derivatives falling into stability class II. The ZnII and MgII complexes were all far less stable than the corresponding NiII and CoII complexes. In this case, semiquantitative analyses of the rate of acid‐induced decomposition revealed the following stability sequence P>Cn>Hpc>Pc for both the ZnII and MgII complexes. Single‐crystal X‐ray diffraction structures were solved for the ZnII, MgII, and NiII complexes of the octaethyl derivatives of Hpc, Cn, and Pc as well as a CoII octamethylcorrphycene and are reported as part of this study. These solid‐state structures confirm four‐coordinate species for the NiII complexes, four‐ and five‐coordinate species for the MgII and ZnII complexes, and a six‐coordinate species for the lone CoII complex.

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Octaethylhemiporphycene: Synthesis, Molecular Structure and Photophysics

Cited by 89 publications

References 32 publications

Electrochemical and Spectroelectrochemical Investigations of “Figure-Eight” Octapyrrolic Macrocycles, Free Bases, and Their Mononuclear, Homo- and Heterodinuclear Complexes with Divalent Transition Metals

Electrochemical and Spectroelectrochemical Investigations of “Figure-Eight” Octapyrrolic Macrocycles, Free Bases, and Their Mononuclear, Homo- and Heterodinuclear Complexes with Divalent Transition Metals

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Metal Complexes of Porphycene, Corrphycene, and Hemiporphycene: Stability and Coordination Chemistry

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