Hypericin analog

Figure 1.12. Comparison of the transient infrared spectra on the microsecond time scale of hypericin, O-hexamethoxy hypericin, and a hypericin analog that lacks carbonyl groups (the hexaacetoxy analog). The salient feature of the data is that the latter two compounds, which cannot execute excited state H-atom transfer owing to the absence of either labile protons or appropriate carbonyl groups, lack the feature at 1450 cm-1. Ab initio calculations at the Hartree-Fock 3-21G level for the normal and two monotautomeric forms of the hypericin triplets indicate normal modes with substantial character in the region 1400-1460 cm-1 [77]. While these preliminary results do not demonstrate a time-resolved H-atom transfer, they do clearly point to a region of the spectrum that must be investigated in further studies. Hypericin and hexamethoxy hypericin, solid line, 0-1 p,s and dashed line, 14-18 ps reduced analog, solid line, 0-0.5 ps, and dashed line, 7-9 ps.

HYPERICIN AND ITS PERYLENE QUINONE ANALOGS PROBING STRUCTURE, DYNAMICS, AND INTERACTIONS WITH THE ENVIRONMENT... 

The major finding of this study is that a vibrational mode corresponding to H-atom translocation can been identified in hypericin by the joint contributions of synthetic, computational, and spectroscopic methods. Identification of this mode is only a first step in providing a direct demonstration of excited-state intramolecular H-atom transfer in hypericin and its analogs. There is considerable work to be accomplished. As indicated elsewhere [77], ab initio calculations predict that the normal modes in this region of the spectrum are close for the normal and the monotautomeric forms. The direct observation of the formation of the tautomer will require both adequate temporal and spectral resolution. 

We presented an overview of what we consider to be the current outstanding problems in understanding the photophysics of hypericin and its analogs. Many questions remain unanswered, and a wealth of theoretical and experimental techniques will be required to address them. It is surprising that given the richness of the physical, chemical, biological, and physiological behaviors of hypericin and... 

Hypericin and Its Perylene Quinone Analogs Probing Structure,... 

The intramolecular reaction can be extended to the cross-annulation reaction of aryl halides with unsaturated compounds [31,33]. For example, 2-halo-biphenyls react with alkynes to give phenanthrene derivatives [96,97]. By using the method, the analogs of hypericin known as antiviral agent (Eq. 45) [98] and indolocarbazoles (Eq. 46) [99] have been prepared. In these reactions, vinyl-palladium intermediates are involved. 

The photophysics of the polycyclic quinone hypericin and its analogs has been studied quite exhaustively by Petrich and co-workers [57]. The interest in this compound stems from its proven antiviral activity, induced by light. Ultrafast time-resolved transient absorption studies indicate that ESIPT is the primary non-radiative process in hypericin. 

Bisindolylmaleimides, fluorescent polymyxin B analogs, hypericin and hypocrellins, blue-fluorescent N-methylanthraniloyl (WANT) analog of cGMP, fluorescent forskolin... 

The reaction of 2-iodobiphenyl (162) with alkynes offers a good synthetic method of 9,10-disubstituted phenanthrenes 164. The intermediate 163 undergoes attack on an aromatic ring as one possibility [54]. The reaction of functionalized diarylacetylene 165 with 162 was applied to the syntheses of an analog of antiviral agent hypericin 167 via 166 [55]. Also the indolocarbazole 169 was prepared from 3-iodobiindole 168 by attack on the indole ring [56]. 

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