“…In a previous publication guided by theoretical predictions [21] we presented the improved dimethylamino‐NDBF ( DMA‐NDBF ) group, [22] which showed a surprising excitation‐specific behavior: A one‐photon (1P) irradiation into the red‐shifted main absorbance band around 420 nm did not afford any photolysis any more (φ 420 <0.05 %) in contrast to NDBF (φ 420 =13.6 %), while two‐photon (2P) irradiation at 840 nm was very effective (17 times better than NDBF ). Our present study contributes to the understanding of the reason for this unusual behavior which might not be a rare case but rather a rarely recognized one [23] . Preferably, we wanted to maintain all the positive properties like the red‐shift and high ϵ , to obtain a desirable example of a green‐light activatable PPG which can be cleaved by 1PE.…”
Section: Resultsmentioning
confidence: 94%
“…Our present study contributes to the understanding of the reasonf or this unusual behavior whichm ight not be ar are case but rather ar arely recognized one. [23] Preferably, we wanted to maintain all the positive properties like the redshift and high e,t oo btain ad esirable example of ag reen-light activatable PPG which can be cleaved by 1PE. Azetidinyl N(CH 2 ) 3 should act as ad onor substituent at ring position7 (Az-NDBF), replacing NMe 2 in DMA-NDBF [22] (Figure1).…”
We developed three bathochromic, green‐light activatable, photolabile protecting groups based on a nitrodibenzofuran (NDBF) core with D‐π‐A push–pull structures. Variation of donor substituents (D) at the favored ring position enabled us to observe their impact on the photolysis quantum yields. Comparing our new azetidinyl‐NDBF (Az‐NDBF) photolabile protecting group with our earlier published DMA‐NDBF, we obtained insight into its excitation‐specific photochemistry. While the “two‐photon‐only” cage DMA‐NDBF was inert against one‐photon excitation (1PE) in the visible spectral range, we were able to efficiently release glutamic acid from azetidinyl‐NDBF with irradiation at 420 and 530 nm. Thus, a minimal change (a cyclization adding only one carbon atom) resulted in a drastically changed photochemical behavior, which enables photolysis in the green part of the spectrum.
“…In a previous publication guided by theoretical predictions [21] we presented the improved dimethylamino‐NDBF ( DMA‐NDBF ) group, [22] which showed a surprising excitation‐specific behavior: A one‐photon (1P) irradiation into the red‐shifted main absorbance band around 420 nm did not afford any photolysis any more (φ 420 <0.05 %) in contrast to NDBF (φ 420 =13.6 %), while two‐photon (2P) irradiation at 840 nm was very effective (17 times better than NDBF ). Our present study contributes to the understanding of the reason for this unusual behavior which might not be a rare case but rather a rarely recognized one [23] . Preferably, we wanted to maintain all the positive properties like the red‐shift and high ϵ , to obtain a desirable example of a green‐light activatable PPG which can be cleaved by 1PE.…”
Section: Resultsmentioning
confidence: 94%
“…Our present study contributes to the understanding of the reasonf or this unusual behavior whichm ight not be ar are case but rather ar arely recognized one. [23] Preferably, we wanted to maintain all the positive properties like the redshift and high e,t oo btain ad esirable example of ag reen-light activatable PPG which can be cleaved by 1PE. Azetidinyl N(CH 2 ) 3 should act as ad onor substituent at ring position7 (Az-NDBF), replacing NMe 2 in DMA-NDBF [22] (Figure1).…”
We developed three bathochromic, green‐light activatable, photolabile protecting groups based on a nitrodibenzofuran (NDBF) core with D‐π‐A push–pull structures. Variation of donor substituents (D) at the favored ring position enabled us to observe their impact on the photolysis quantum yields. Comparing our new azetidinyl‐NDBF (Az‐NDBF) photolabile protecting group with our earlier published DMA‐NDBF, we obtained insight into its excitation‐specific photochemistry. While the “two‐photon‐only” cage DMA‐NDBF was inert against one‐photon excitation (1PE) in the visible spectral range, we were able to efficiently release glutamic acid from azetidinyl‐NDBF with irradiation at 420 and 530 nm. Thus, a minimal change (a cyclization adding only one carbon atom) resulted in a drastically changed photochemical behavior, which enables photolysis in the green part of the spectrum.
“…6c shows a molecular dyad described in [54], where the lower part of the molecule serves as two-photon absorbing antenna, which excites usual o -nitrobenzyl caging groups (upper part) via charge transfer, inducing the release of acetic acid. Recently, compounds based on bisstyrylthiophene (BIST) was developed for photorelease of calcium and GABA [62], [63].Fig. 6Two-photon absorbing caged compounds a) Biphenyl-based PPGs [48]; b) PPG based on 1,2-dihydronaphthalene structure [49]; c) a two-photon absorbing antenna with o -nitrobenzyl- and d) nitroindoline-caged acetic acid [54]; e) Structure of unsubstituted coumarin PPG; f) Structure of unsubstituted quinoline PPG.…”
Photoremovable protective groups (PPGs) and related “caged” compounds have been recognized as a powerful tool in an arsenal of life science methods. The present review is focused on recent advances in design of “caged” compounds which function in red or near-infrared region. The naive comparison of photon energy with that of organic bond leads to the illusion that long-wavelength activation is possible only for weak chemical bonds like N-N. However, there are different means to overcome this threshold and shift the uncaging functionality into red or near-infrared regions for general organic bonds. We overview these strategies, including the novel photochemical and photophysical mechanisms used in newly developed PPGs, singlet-oxygen-mediated photolysis, and two-photon absorption. Recent advances in science places the infrared-sensitive PPGs to the same usability level as traditional ones, facilitating in vivo application of caged compounds.
“…Expansion of the chromophore structure can lead to loss of aqueous solubility, necessary for biological applications, but can be addressed by conjugation of chromophores to water solubilizing polymers. [ 24 ] The electronics of the system need to be considered. The energy of the absorbed light must be sufficient to induce bond dissociation or isomerization, to allow for generation of a thermodynamically unstable state.…”
Section: Overcoming the Light Barrier: Penetration Limit Of Light In mentioning
Bioorthogonal chemistry is revolutionizing the fields of biological chemistry and nanomedicine, providing tools to actively probe and perturb native biochemical processes. Photochemistry provides the opportunity to actively and non‐invasively control bioorthogonal reactions, providing sophisticated optochemical tools. Despite the opportunities in bioorthogonal photochemistry, there remain many significant challenges to the clinical translation of current research. This review aims to provide an overview of these challenges and highlight recent examples from the literature that are providing revolutionary solutions to overcoming these barriers. It will highlight new photochemical systems that can be triggered by near infrared light in aqueous solutions and have been demonstrated to function in complex biological systems, including in living animals. It will cover diverse classes of photochemical reactions including photopolymerization, uncaging, conjugation, and photoswitching. The discussion will detail how new approaches are being integrated into polymers or highlight unexploited opportunities. This review intends to showcase how the unique synergy of bioorthogonal photochemistry and polymer science provides vast opportunities in the fields of biomaterials, nanomedicine, and theranostics. This will hopefully provide inspiration to material scientists to integrate bioorthogonal photochemistry into new adaptable materials and ensure translation to solve clinical challenges.
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