3 research outputs found
<i>meso</i>-Tetrakis(pentafluorophenyl)porphyrin-Derived Chromene-Annulated Chlorins
The synthesis of mono- and bis-chromene-annulated <i>meso</i>-(pentafluorophenyl)Âchlorins from <i>meso</i>-tetrakisÂ(pentafluorophenyl)Âporphyrins by an OsO<sub>4</sub>-mediated
dihydroxylation reaction, followed by an intramolecular nucleophilic
aromatic substitution reaction, is described. The reaction sequence
is applicable to the free base systems as well as their ZnÂ(II), NiÂ(II),
PdÂ(II), and PtÂ(II) complexes. The optical properties (UVâvis
and fluorescence spectra) of the (metallo)Âchlorin-like chromophores
that possess slightly red-shifted optical spectra compared to the
corresponding 2,3-dihydroxychlorins are reported. Molecular modeling
and <sup>1</sup>Hâ<sup>19</sup>F-HOESY NMR spectroscopy provide
indications for the conformation of the chromene-annulated chromophores.
Using <sup>1</sup>Hâ<sup>1</sup>H COSY and <sup>19</sup>Fâ<sup>19</sup>F QF-COSY NMR spectra, we interpret the <sup>1</sup>H and <sup>19</sup>F NMR spectra of the porphyrins and chlorins, thus providing
a refined reference point for the use of <sup>19</sup>F NMR spectroscopy
as a diagnostic tool in the analysis of <i>meso</i>-pentafluorophenyl-substituted
porphyrinoids
Porphyrin-Metalation-Mediated Tuning of Photoredox Catalytic Properties in MetalâOrganic Frameworks
Photoredox catalytic activation of
organic molecules via single-electron
transfer processes has proven to be a mild and efficient synthetic
methodology. However, the heavy reliance on expensive ruthenium and
iridium complexes limits their applications for scale-up synthesis.
To this end, photoactive metalâorganic frameworks (MOFs) exhibit
unique advantages as novel heterogeneous photocatalytic systems, yet
their utilization toward organic transformations has been limited.
Here we describe the preparation and synthetic applications of four
isostructural porphyrinic MOFs, namely, UNLPF-10a, -10b, -11, and
-12, which are composed of free base, In<sup>III</sup>-, Sn<sup>IV</sup>Cl<sub>2</sub>-, and Sn<sup>IV</sup>-porphyrin building blocks, respectively.
We demonstrate that the metalation with high valent metal cations
(In<sup>III</sup> and Sn<sup>IV</sup>) significantly modifies the
electronic structure of porphyrin macrocycle and provides a highly
oxidative photoexcited state that can undergo efficient reductive
quenching processes to facilitate organic reactions. In particular,
UNLPF-12 exhibits both outstanding photostability and efficient photocatalytic
activities toward a range of important organic transformations including
aerobic hydroxylation of arylboronic acids, amine coupling, and the
Mannich reaction
Porphyrin-Metalation-Mediated Tuning of Photoredox Catalytic Properties in MetalâOrganic Frameworks
Photoredox catalytic activation of
organic molecules via single-electron
transfer processes has proven to be a mild and efficient synthetic
methodology. However, the heavy reliance on expensive ruthenium and
iridium complexes limits their applications for scale-up synthesis.
To this end, photoactive metalâorganic frameworks (MOFs) exhibit
unique advantages as novel heterogeneous photocatalytic systems, yet
their utilization toward organic transformations has been limited.
Here we describe the preparation and synthetic applications of four
isostructural porphyrinic MOFs, namely, UNLPF-10a, -10b, -11, and
-12, which are composed of free base, In<sup>III</sup>-, Sn<sup>IV</sup>Cl<sub>2</sub>-, and Sn<sup>IV</sup>-porphyrin building blocks, respectively.
We demonstrate that the metalation with high valent metal cations
(In<sup>III</sup> and Sn<sup>IV</sup>) significantly modifies the
electronic structure of porphyrin macrocycle and provides a highly
oxidative photoexcited state that can undergo efficient reductive
quenching processes to facilitate organic reactions. In particular,
UNLPF-12 exhibits both outstanding photostability and efficient photocatalytic
activities toward a range of important organic transformations including
aerobic hydroxylation of arylboronic acids, amine coupling, and the
Mannich reaction