Tuning Photosensitized Singlet Oxygen Generation Efficiency of Novel Aza-BODIPY Dyes

Abstract

Novel aza-BODIPY derivatives substituted with heavy atoms such as bromine and iodine were synthesized, and their triplet and singlet oxygen generation efficiencies have been investigated. These derivatives showed absorption in the NIR region with high molar extinction coefficients. The dye substituted with four iodine atoms showed yields of Φ(T) = 0.78 and Φ((1)O(2)) = 0.70, which are the highest values so far obtained for the aza-BODIPY derivatives.

Synthesis and properties of 3-ethynylthiophene containing BODIPY derivatives

“…Compound 2 which has two iodine atoms at the 2,6 position was used as the reference since iodine containing compounds are known to sensitize singlet oxygen generation. Rapid DPBF oxidation in compound 2 is consistent with the well-known fact that iodine increases singlet oxygen generation due to the heavy atom effect [39,40]. Compound 4 which has one 3-ethynylthiophene unit and one iodine showed only slight decrease in oxidation rate in comparison to compound 2 ( Figure 3).…”

Visible‐Light Photoactive, Highly Efficient Triplet Sensitizers Based on Iodinated Aza‐BODIPYs: Synthesis, Photophysics and Redox Properties

“…Figure 8p resents, for comparison, the structures, triplet state properties and singlet oxygen formation quantum yields of all halogenated aza-BODIPYs reportedu ntil 2017. [35,41,64,65] We demonstrated that the iodinated aza-BODIPYs 5-8,i n contrastt ot he non-iodinated counterparts 1-4,p roduce highly populated triplet state upon excitation, as evidenced by the observation of transient absorption spectra and lack of room-temperature emission from the singlet excited state (S 1 !S 0 ). In addition, iodinated aza-BODIPYs 5-8 efficiently harvest visible light, as evidenced by their relatively high molar absorption coefficients (e), viz.…”

“…Owing to their advantageous and tunable photophysical properties and ability to generate singlet oxygen ( 1 O 2 )c oupled with absorption of light from the socalled "therapeuticw indow"( 600 nm-1100 nm), aza-BODIPY dyes have been proposed as potential triplet photosensitizers for both anti-microbiala nd anti-cancer photodynamic therapy. [20,[30][31][32][33][34][35][36][37][38][39][40][41] Aza-BODIPYs continue to attracta ttention as chemosensors for the detection of ammonia, [42] cysteine, homocysteine and glutathione in living cells, [43] Hg 2 + , [44][45][46] F À , [47,48] in vivo detection of H 2 S, [49] carbon dioxide, [50] glucosei nw hole blood, [51] detection of saxitoxin [52] and pH-sensitive sensors. [52] Furthermore, aza-BODIPYs have been proposed as photoactive components in photovoltaic devices [54][55][56] and nonlinear optical materials.…”

Visible‐Light‐Harvesting Triphenylamine Ethynyl C60‐BODIPY Dyads as Heavy‐Atom‐Free Organic Triplet Photosensitizers for Triplet‐Triplet Annihilation Upconversion

“…[19][20][21] Although heavyatom-free organic triplet photosensitizers do exist, such as porphyrins or perylenedimides [22] and the recently reported C 60 dyads for TTA upconversion, [17d, e] it is clear that the molecular diversity needs to be increased substantially. Unfortunately, the rules of molecular structure design acquired in the study of fluorophores are not really applicable to the triplet-state manifold.…”