Effects of Substituents on Photophysical and CO-Photoreleasing Properties of 2,6-Substituted meso-Carboxy BODIPY Derivatives

Abstract

Carbon monoxide (CO) is an endogenously produced signaling molecule involved in the control of a vast array of physiological processes. One of the strategies to administer therapeutic amounts of CO is the precise spatial and temporal control over its release from photoactivatable CO-releasing molecules (photoCORMs). Here we present the synthesis and photophysical and photochemical properties of a small library of meso-carboxy BODIPY derivatives bearing different substituents at positions 2 and 6. We show that the nature of substituents has a major impact on both their photophysics and the efficiency of CO photorelease. CO was found to be efficiently released from π-extended 2,6-arylethynyl BODIPY derivatives possessing absorption spectra shifted to a more biologically desirable wavelength range. Selected photoCORMs were subjected to in vitro experiments that did not reveal any serious toxic effects, suggesting their potential for further biological research.

Coupling BODIPY with nitrogen-doped graphene quantum dots to address the water solubility of photosensitizers

“…38 8-Carboxyl-4,4′-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza- s -indacene derivatives with iodine and bromine substituents at positions 2 and 6 (BODIPY-X where X = I or Br in Fig. 1) were synthesized according to a previously reported procedure 38 (see the ESI†). BODIPY-I and BODIPY-Br show a high 1 O 2 production quantum yield in methanol ( Φ Δ = 72 and 59%, respectively).…”

“…S20-S23, ESI †) were calculated using rose bengal as a standard photosensitizer. 42 The F D values are higher than those of non-functionalized BODIPYs (F D = 0.59 and 0.72 for BODIPY-Br and BODIPY-I, respectively), 38 indicating that the BODIPY modification with NGQDs enhances the 1 O 2 generation. Reports of the use of GQDs as PDT agents are controversial; recent results indicate that GQDs are not potential PSs, but the dots may be helpful for delivering the PSs into the cells (i.e., as a drug delivery system).…”

“…Still, substituents, such as halogen or chalcogen atoms, can enhance the ISC via a strong spin-orbit coupling (heavy atom effect, HAE), [35][36][37] thus promoting their better PDT performance. 38 8-Carboxyl-4,4 0 -difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-sindacene derivatives with iodine and bromine substituents at positions 2 and 6 (BODIPY-X where X = I or Br in Fig. 1) were synthesized according to a previously reported procedure 38 (see the ESI †).…”

Rethinking Uncaging: A New Antiaromatic Photocage Driven by a Gain of Resonance Energy

“…Deeper insight into these processes can be gained with computational methods, spectroscopically, with systematic synthetic work – or ideally with all of these approaches working together. The change of one parameter for example the solubility can have an impact on the excited state reactivity and therefore change the entire photochemistry [6–9] . Hence, the design of new photoactivatable compounds needs to be based on elementary, but relevant concepts, as for example nitro‐push–pull‐systems or Zimmerman's meta ‐effect (Figure 1a,b) [10–12] .…”

“…The change of one parameter for example the solubility can have an impact on the excited state reactivity and therefore change the entire photochemistry. [ 6 , 7 , 8 , 9 ] Hence, the design of new photoactivatable compounds needs to be based on elementary, but relevant concepts, as for example nitro‐push–pull‐systems or Zimmerman's meta ‐effect (Figure 1 a,b). [ 10 , 11 , 12 ] In the last decades, numerous new photocleavable protecting groups (PPGs, photocages) evolved from these existing concepts in photochemistry.…”