Acid-Triggered Switchable Near-Infrared/Shortwave Infrared Absorption and Emission of Indolizine-BODIPY Dyes

Abstract

Fluorescent organic dyes that absorb and emit in the near-infrared (NIR, 700–1000 nm) and shortwave infrared (SWIR, 1000–1700 nm) regions have the potential to produce noninvasive high-contrast biological images and videos. BODIPY dyes are well known for their high quantum yields in the visible energy region. To tune these chromophores to the NIR region, fused nitrogen-based heterocyclic indolizine donors were added to a BODIPY scaffold. The indolizine BODIPY dyes were synthesized via microwave-assisted Knoevenagel condensation with indolizine aldehydes. The non-protonated dyes showed NIR absorption and emission at longer wavelengths than an aniline benchmark. Protonation of the dyes produced a dramatic 0.35 eV bathochromic shift (230 nm shift from 797 nm to 1027 nm) to give a SWIR absorption and emission (λmaxemis = 1061 nm). Deprotonation demonstrates that material emission is reversibly switchable between the NIR and SWIR.

NRF2 Activation by Nitrogen Heterocycles: A Review

“…Fused nitrogen heterocycles contain at least one nitrogen heterocyclic ring fused with either a heterocyclic or carbocyclic ring. They have been extensively studied [ 105 , 106 , 107 , 108 ]. They are found in a wide range of bioactive natural products and synthetic compounds.…”

“…It also exhibits blood brain barrier permeability (P e : 65.16 × 10 −6 ) which could be beneficial in CNS-related diseases [ 107 ]. Pyrimidine derivative 18 binds directly to KEAP1 with high affinity and dissociation constant (Kd) of 5.84 × 10 −10 M and causes an alteration in the plasma resonance [ 108 ]. Pharmacokinetic studies indicate that 18 has good bioavailability and permeates the brain after intravenous and oral administration [ 108 ].…”

“…Pyrimidine derivative 18 binds directly to KEAP1 with high affinity and dissociation constant (Kd) of 5.84 × 10 −10 M and causes an alteration in the plasma resonance [ 108 ]. Pharmacokinetic studies indicate that 18 has good bioavailability and permeates the brain after intravenous and oral administration [ 108 ]. 1,2,4-Triazine derivatives ( 21 , 22 and 23 ) permeate the blood brain barrier [ 104 ].…”