1.Kinetic analysis of demetalation of synthetic zinc cyclic tetrapyrroles possessing an acetyl group at the 3-position: effects of tetrapyrrole structures and peripheral substitution.
Saga Y1, Miura R, Sadaoka K, Hirai Y. J Phys Chem B. 2011 Oct 13;115(40):11757-62. doi: 10.1021/jp206534x. Epub 2011 Sep 22.
Demetalation of three synthetic zinc cyclic tetrapyrroles that possess identical peripheral substituents, zinc methyl bacteriopyropheophorbide a (zinc bacteriochlorin 1), zinc methyl 3-devinyl-3-acetyl-pyropheophorbide a (zinc chlorin 2), and zinc methyl 3-devinyl-3-acetyl-protopyropheophorbide a (zinc porphyrin 3), was kinetically analyzed under acidic conditions to examine the effects of macrocyclic structures on demetalation without peripheral substitution effects. Zinc bacteriochlorin 1 exhibited much slower demetalation kinetics than zinc chlorin 2 and zinc porphyrin 3. These results indicate that the bacteriochlorin skeleton provides significant resistance to the removal of the central metal from the tetrapyrrole ligand. Comparison of demetalation kinetics of 3-acetyl zinc complexes 2 and 3 with that of 3-vinyl zinc complexes under the same reaction condition demonstrated that the relative ratio (5.0 × 10(-2)) of the demetalation rate constant of the 3-acetyl zinc chlorin 2 to that of the corresponding 3-vinyl zinc chlorin 4 resembled the case of the 3-acetyl zinc porphyrin 3 to the 3-vinyl zinc porphyrin 5 (the relative ratio was 6.
2.Synthesis of zinc chlorophyll materials for dye-sensitized solar cell applications.
Erten-Ela S1, Vakuliuk O2, Tarnowska A3, Ocakoglu K4, Gryko DT5. Spectrochim Acta A Mol Biomol Spectrosc. 2015 Jan 25;135:676-82. doi: 10.1016/j.saa.2014.07.026. Epub 2014 Aug 1.
To design sensitizers for dye sensitized solar cells (DSSCs), a series of zinc chlorins with different substituents were synthesized. Novel zinc methyl 3-devinyl-3-hydroxymethyl-20-phenylacetylenylpyropheophorbide-a (ZnChl-1), zinc methyl 20-bromo-3-devinyl-3-hydroxymethylpyropheophorbide-a (ZnChl-2), zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide-a (ZnChl-3), zinc propyl 3-devinyl-3-hydroxymethyl-pyropheophorbide-a (ZnChl-4) were synthesized and their photovoltaic performances were evaluated in dye-sensitized solar cells. Photoelectrodes with a 7 μm thick nanoporous layer and a 5 μm thick light-scattering layer were used to fabricate dye sensitized solar cells. The best efficiency was obtained with ZnChl-2 sensitizer. ZnChl-2 gave a Jsc of 3.5 mA/cm(2), Voc of 412 mV, FF of 0.56 and an overall conversion efficiency of 0.81 at full sun (1000 W m(-2)).
3.A mild conversion from 3-vinyl- to 3-formyl-chlorophyll derivatives.
Oba T1, Uda Y, Matsuda K, Fukusumi T, Ito S, Hiratani K, Tamiaki H. Bioorg Med Chem Lett. 2011 Apr 15;21(8):2489-91. doi: 10.1016/j.bmcl.2011.02.054. Epub 2011 Feb 17.
The C3-vinyl group of a chlorophyll derivative, methyl pyropheophorbide-a, was converted into the formyl group by a novel one-pot reaction with thiophenol at room temperature. The mild reaction can provide insight into development of 'green' catalysts displacing OsO(4) or O(3), and into elucidation of unknown biosynthetic processes of chlorophyll-d.
4.Alternative synthesis of 3-acetyl, 3-epoxy, and 3-formyl chlorins from a 3-vinyl chlorin, methyl pyropheophorbide-a, via iodination.
Oba T1, Masuya T2, Yasuda S2, Ito S2. Bioorg Med Chem Lett. 2015 Aug 1;25(15):3009-12. doi: 10.1016/j.bmcl.2015.05.024. Epub 2015 May 22.
We developed novel methods to convert the C3-vinyl group of a chlorophyll derivative, methyl pyropheophorbide-a, into an acetyl group, an epoxy group, and a formyl group via iodination with I2 and phenyliodine(III) bis(trifluoroacetate). Reaction of the iodinated intermediate with ethylene glycol and subsequent treatment with base led to formation of the C3-acetyl chlorin. Reaction of the iodinated intermediate with ethylenediamine afforded the C3-oxiranyl chlorin. The C3-formyl chlorin was readily derived from the epoxide without hazardous reagents such as OsO4. These reactions were facile and useful alternatives to the previous methods.