Azadipyrromethenes: from traditional dye chemistry to leading edge applications

Abstract

Azadipyrromethenes were first described over 70 years ago as blue pigments, but now are rapidly emerging as a compound class with highly desirable near infrared photophysical properties. Since the turn of the century several routes to azadipyrromethenes have been developed and numerous post-synthesis derivatizations have allowed for their exploitation in both biological and material sciences. The relative ease of access to specifically designed derivatives is now allowing their use in multiple technological formats from real-time fluorescence imaging, to solar energy materials, to optoelectronic devices and many more. In this review we have highlighted the synthetic component of this story as it is the ability to generate the designer azadipyrromethene that opens the door to exciting applications.

Visible‐Light Photoactive, Highly Efficient Triplet Sensitizers Based on Iodinated Aza‐BODIPYs: Synthesis, Photophysics and Redox Properties

“…Figure 2). The diagnostic resonance of the pyrrole ring protons observed for 1-4 (singlet between d = 7.05 ppm and 7.68 ppm) was no longer observed in the 1 HNMR spectrum of 5-8.F urthermore, the identityo ft he iodinated aza-BODIPYs presented in this work was supported by high resolution ESI mass spectrometry, 11 BNMR, 19 FNMR and FT-ATR-IR, respectively.…”

“…[16,17] An interesting group of organic chromophores that can be utilized ast riplet photosensitizers are aza-BODIPYs (aza-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene). [18,19] Structurally,a za-BODIPY dyes are derivatives of BODIPY (4,4-difluoro-4-bora3a,4a-diaza-s-indacene) dyes obtained by replacing the mesocarbona tom that connects both pyrrole rings with an azabridge. [20][21][22][23][24][25][26][27][28][29] The consequence of the introduction of an azabridge into the structure of the BODIPY chromophores ystem is the bathochromic shift of both absorption and emission bands of around 80 nm.…”

Development of a novel carboplatin like cytoplasmic trackable near infrared fluorophore conjugate via strain-promoted azide alkyne cycloaddition

“…[8][9][10] Significantly NIR probes have been successfully employed to image tumours in vitro and in vivo and as sensors for reactive oxygen species (ROS), reactive nitrogen species (RNS), thiols, ions, pH and enzyme activities. [8] The BF2-azadipyrromethene (NIR-AZA) fluorophore class, which have absorptions of c. 690 nm with emission at c. 725 nm in formulated aqueous solution, [11,12] offer excellent photophysical and stability properties and have attracted the attention of many research teams [10,13] including those interested in tracking metal-based drugs. [14] Specifically a number of Pt(II) anticancer type compounds have been reported where boron-fluorescent dipyrromethene (BODIPY) moieties have been tethered to Pt centres via prior direct covalent modification of the ammine carrier ligands.…”

“…[5] Trackable metal-based drugs which incorporate an organic fluorophore for example offer the prospect of real-time imaging of important biological processes in vitro and providing vital information concerning the biodistribution, cellular transport, subcellular localization, and mechanisms of action and resistance to metallotherapeutics. [8][9][10] The near-infrared (NIR) spectral region (700-900 nm) provides ideal imaging spectral wavelengths, reduced light toxicity and does not interfere with competing endogenous chromophore absorbance. [8][9][10] Significantly NIR probes have been successfully employed to image tumours in vitro and in vivo and as sensors for reactive oxygen species (ROS), reactive nitrogen species (RNS), thiols, ions, pH and enzyme activities.…”

“…[8][9][10] The near-infrared (NIR) spectral region (700-900 nm) provides ideal imaging spectral wavelengths, reduced light toxicity and does not interfere with competing endogenous chromophore absorbance. [8][9][10] Significantly NIR probes have been successfully employed to image tumours in vitro and in vivo and as sensors for reactive oxygen species (ROS), reactive nitrogen species (RNS), thiols, ions, pH and enzyme activities. [8] The BF2-azadipyrromethene (NIR-AZA) fluorophore class, which have absorptions of c. 690 nm with emission at c. 725 nm in formulated aqueous solution, [11,12] offer excellent photophysical and stability properties and have attracted the attention of many research teams [10,13] including those interested in tracking metal-based drugs.…”