Syntheses, structures, modification, and optical properties of meso-tetraaryl-2,3-dimethoxychlorin, and two isomeric meso-tetraaryl-2,3,12,13-tetrahydroxybacteriochlorins

Abstract

The refined syntheses, modification, and first X-ray structural characterization of meso-tetraarylporphyrin-derived beta-tetraolbacteriochlorins are described. These investigations assign the relative stereochemistry of their two isomers (both cis-vic-diol pairs on the same or opposite sides of the porphyrin plane), an assignment that could not be provided by NMR, UV-vis or fluorescence spectroscopy, or mass spectrometry. Moreover, the first crystal structures of a 2-hydroxychlorin and a 2,3-dihydroxychlorin, as its dimethylether, are reported. Dihydroxylation and diimide reduction of the dimethoxychlorin result in the formation of stable mixed-functionality bacteriochlorins. The photophysical properties (UV-vis absorption and fluorescence emission) of all chromophores are contrasted against each other, delineating the electronic effects of diol substitution and conformational modulation. Lastly, the acid-induced dehydration/demethoxylation of the tetraol-, dioldimethoxy-, and tetramethoxybacteriochlorins to provide chlorins is delineated.

meso-Arylporpholactones and their Reduction Products

“…We have demonstrated before the distinct blue-shifts caused by OH-substitution of chlorin pyrrolidines. 19 Most surprisingly, the removal of the hydroxy group also results in a significant enhancement of the extinction coefficient of the Q x band relative to its Soret band. Thus, replacement of the CH 2 CH 2 group in chlorins by a CH 2 O group has an auxochromic effect, adding to the collection of groups that are known to substantially modify the chlorin chromophore.…”

“…14,16-19,20 This reaction was adopted by other groups, providing a range of dihydroxychlorins. 10,11,21-23 We further demonstrated the versatility of the chlorin diols as starting material for the preparation of porphyrinoids containing non-pyrrolic building blocks using our versatile ‘breaking and mending’ strategy.…”

The evaluation of NIR-absorbing porphyrin derivatives as contrast agents in photoacoustic imaging

“…18 The bacteriochlorins 4 though 6 were also prepared from TPP as previously described. 23 All solvents were of spectroscopic grade and used as received. Cremophore EL ® was acquired from Acros.…”

Axial Imidazole Binding Strengths in Porphyrinoid Cobalt(III) Complexes as Studied by Tandem Mass Spectrometry

“…However, the parent meso-tetraphenylchlorin (meso-tetraphenyldihydroporphyrin) is reportedly less Brønsted-basic than the corresponding porphyrin [39], and the pyrrolidine-M bonds in metallochlorin complexes are generally longer than the corresponding pyrrole-M bonds in porphyrins, suggesting that they are worse σ-donors. The UV-Vis spectra of 4 and [4]Co are, as a result of the hydroxy substitution at the benzylic positions [40], not bathochromically shifted compared with those of porphyrins 1 and [1]Co, respectively, indicating that all three chromophores have very similar HOMO-LUMO gaps. The inclusion of chlorins into this study will reveal to which extent their electronic structure will influence the binding of imidazole to their Co(III) complexes.…”

“…Free base diolchlorins 4 and 8 were prepared by OsO 4 -mediated dihydroxylation of the corresponding porphyrins [37,40]. Free bases of porpholactones 2 [43], dioxoporphyrin 7 [42], indaphyrin 5 [45], and morpholinochlorin 3 [43] were made by oxidation/derivatization of free base meso-tetraphenyl-2,3-diolchlorin 4.…”