Near-infrared benzodiazoles as small molecule environmentally-sensitive fluorophores

Abstract

The development of fluorophores emitting in the near-infrared spectral window has gained increased attention given their suitable features for biological imaging. In this work, we have optimised a general and straightforward synthetic approach to prepare a small library of near-infrared-emitting C-bridged nitrobenzodiazoles using commercial precursors. C-bridged benzodiazoles have low molecular weight and neutral character as important features that are not common in most near-infrared dyes. We have investigated their fluorescence response in the presence of a wide array of 60 different biomolecules and identified compound 3i as a potential chemosensor to discriminate between Fe2+ and Fe3+ ions in aqueous media.

Small Fluorogenic Amino Acids for Peptide‐Guided Background‐Free Imaging

“…Furthermore, this strategy proved to be compatible with batches ≈100 mg and suitable for the preparation of building blocks for SPPS. For the synthesis of compound 11 , a different route was needed, mostly due to the acid lability of C‐bridged nitrobenzodiazoles [17] . In this case, 2‐fluoro‐5‐nitro‐ o ‐phenylene‐diamine was obtained by removal of the Se atom from compound 1 and utilized in a Cu‐catalyzed condensation with acetone to render the C‐bridged benzodiazole 4 .…”

Miniaturized Chemical Tags for Optical Imaging

“…[15] This chemical platform enabled multicolor labeling and live cell tracking of metabolites (e.g., glucose, lactate, ceramides) that retained affinity for their cognate transporters, including some of the smallest NIR fluorophores reported to date (Figure 2). [16] Another emerging class of small sized fluorophores are single benzene ring carbocycles. Fully carbocyclic fluorescent molecules such as aminonaphthalenes and azulene had long been known, [17] but only recently reported as fluorogenic bioorthogonal probes for intracellular imaging of organelles, [18] labeling of β-lactam antibiotics [19] and twophoton fluorescent probes for imaging reactive oxygen species in cells and tissues.…”

“…This chemical platform enabled multicolor labeling and live cell tracking of metabolites (e.g., glucose, lactate, ceramides) that retained affinity for their cognate transporters, including some of the smallest NIR fluorophores reported to date (Figure 2). [16] …”

A Photoinduced Electron Transfer-Based Hypochlorite-Specific Fluorescent Probe for Selective Imaging of Proinflammatory M1 in a Rheumatoid Arthritis Model

“…However, differentiating macrophages (M1 and M2) is mainly based on different biomarkers like the cytokine expressed in the two different phenotypes of macrophages. − This involves immunohistochemistry, which is tedious and expensive. As an alternative, small molecular fluorescent probes − are promising diagnostic tools due to their simplicity, cost-effectiveness, and high sensitivity with good resolution. Moreover, a molecular fluorescent probe detecting hypochlorite (OCl – ) that can differentiate different macrophages is not known, as per our knowledge.…”