A new metal-free benzorhodol-based photoluminophore selective for carbon monoxide detection applicable in both in vitro and in vivo bioimaging

Abstract

A new benzorhodol based non-fluorescent organic frame (DEB-CO) detects carbon monoxide (CO) selectively through a spirolactam ring-opening mechanism. Here, the selective off-on fluorogenic behavior of this probe toward CO has...

On the Question of Uncatalyzed CO Insertion into a Hydrazone Double Bond: A Comparative Study Using Different CO Sources and Substrates

“…We synthesized RCO using two independent literature procedures and confirmed its identity using NMR and MS (Figures S4− S10). 23,24 The most straightforward way for us to observe CO's reaction with RCO is through monitoring structural changes by an appropriate method such as NMR. To probe this, pure CO gas was directly bubbled into the MeOH-d 4 solution of RCO at 1 mM for 5 min (at 20 °C, the solubility of CO in methanol is around 7 mM 32 ) and then incubated at 37 °C for 30 min under seal.…”

“…We synthesized RCO using two independent literature procedures and confirmed its identity using NMR and MS (Figures S4–S10). , …”

“…We conducted similar studies with another CO probe (DEB-CO), which was developed based on the same mechanism . Briefly, we synthesized DEB-CO and established its identity by NMR and MS (Figures S12–S15).…”

“…Importantly, such results are different from what was reported in the original publication. 24 Again, we have no explanation of the different experimental observations. Overall, our results do not support an uncatalyzed COinsertion reaction to lead to fluorescence response of RCO and DEB-CO to CO in a meaningful fashion.…”

“…Since the initial report of such a CO-insertion reaction in 2019, this paper has been cited about 90 times. Further, the same chemistry has since been used in other designs of fluorescent CO probes including those published in 2022 and 2023 , with extensive implications including CO imaging and detection in animal models, and the “accurate diagnosis of non-alcoholic fatty liver disease” in animal models . With such a broad impact in chemistry and biology of this type of chemistry and the continuous publication of new results using such chemistry, we are interested in understanding the feasibility and scope of the proposed CO-insertion reaction.…”