Thiophene and diaminobenzo- (1,2,5-thiadiazol)- based DAD-type near-infrared fluorescent probe for nitric oxide: A theoretical research

A near-infrared fluorescent probe (LS-NO) for the real-time detection of nitric oxide (NO) in inflammatory bowel disease (IBD) was developed recently. The probe used oligoglycol morpholine-functionalized thiophene as strong electron donors and diaminobenzene (1,2,5-thiadiazole) as a weak electron acceptor and NO trapping group. It could detect exogenous and endogenous NO in the lysosomes of living cells with high sensitivity and specificity. To further understand the fluorescent mechanism and character of the probes LS-NO and LS-TZ (after the reaction of the probe LS-NO with NO), the electron transfer in the excitation and emitting process within the model molecules DAD-NO and DAD-TZ was analyzed in detail under the density functional theory. The calculation results indicated the transformation from diaminobenzene (1,2,5-thiadiazole) as a weak electron acceptor to triazolo-benzo-(1,2,5-thiadiazole) as a strong electron acceptor made LS-NO an effective off-on near-infrared NO fluorescent probe.

Automated summary

A near-infrared fluorescent probe LS-NO has been developed for the real-time detection of nitric oxide in inflammatory bowel disease. The probe utilizes oligoglycol morpholine-functionalized thiophene as electron donors and diaminobenzene as a weak electron acceptor and NO trapping group. It can detect exogenous and endogenous NO in living cell lysosomes with high sensitivity and specificity. The analysis of electron transfer in model molecules DAD-NO and DAD-TZ under density functional theory reveals the transformation from diaminobenzene as a weak electron acceptor to triazolo-benzo-(1,2,5-thiadiazole) as a strong electron acceptor, making LS-NO an effective off-on near-infrared NO fluorescent probe.