Design, Synthesis, And Spectroscopic Properties Of PDT-photosensitizers Based On BODIPY/Aza-BODIPY

Photodynamic therapy （abbreviated as PDT） is an emerging clinical modality for treatment ofneoplastic and non-malignant lesions. Applications of PDT require a photosensitizing drug, light, andoxygen. A series of photochemical reactions generate singlet oxygen from the3O2causing tissue damage inthe regions where these three key components come together. In cancer treatment, PDT can destroy thevasculature surrounding tumour cells, and activates immunological responses against them. One of theearliest clinical PDT agents is porfimer sodium （Photofrins）, a purified hematoporphyrin derivative. It isdifficult to be applied because of its short wavelength, bad stability, low solubility and selectivity. A newclass of PDT agents has emerged over the past decade: these are based on the4,4-difluoro-4-bora-3a,4a-diaza-s-indacene （BODIPY） core. BODIPYs have many ideal photosensitizer characteristics includinghigh extinction coefficients, environment insensitivity, resistance to photobleaching, and higher light-darktoxicity ratios41than phenothiazinium PDT agents. In recent years, PDT sensitizers based on BODIPY andAza-BODIPY caused wide public concern[1-3].In Part II, a series of PDT photosensitizers based on BODIPY was designed and synthesized, itsstructure as compound2shown in the fig. above. Research showed that wavelength of2-8were longer thanthose of2-7, their λabshad an obvious red-shift. Substituents like heavy atom could quench theirfluorescence to0.1with high efficiency. Via Knoevenagel reactions, their solubility was developed throughimporting hydrophilic group to some extent; their λabsreached to670nm with the red shift（130nm）. However,2-9were insensitive to acid possible due to the amino group far away from BODIPY cores.Therefore, other properties were characterized by1H NMR、13C NMR、UV.In Part III, PDT photosensitizers based on Aza-BODIPY was designed and synthesizedsuccessfully, its structure as compound3shown in the fig. above. Studied showed that λ_abs and λ_em were687-687nm and714-715nm, reached to near-infrared. However, fluorescence quantum yield of3-8（0.04）was mucher lower than that of3-7（0.30）. It is indicated that I atom probably promoted ISC process farmore effectively than Br atom. Therefore, other properties were characterized by¹H NMR、¹³C NMR、UV.The three others will be undertaken then..