Bright, Color-Tunable Fluorescent Dyes Based on π-Expanded Diketopyrrolopyrroles

Abstract

A synthetic approach to the structurally diverse family of π-expanded diketopyrrolopyrroles is described. A three-step strategy appears to be very general and starts with the preparation of diketopyrrolopyrroles followed by N-alkylation with bromoacetaldehyde diethyl acetal and electrophilic aromatic substitution. The final reaction regioselectively furnishes S-shaped, violet and blue functional dyes of previously unknown structure. New dyes possess sharp absorption and emission peaks, with very high molar absorption coefficients and reasonable fluorescence quantum yields. As a proof of principle, cell uptake of selected dye was demonstrated.

Two‐Photon‐Induced Fluorescence in New π‐Expanded Diketopyrrolopyrroles

“…The photophysical data are summarized in Table 3. The maxima in absorption ( λ abs ) and emission ( λ em ) for ADPP‐1 a–c and ADPP‐2 are similar to those reported for previously described DPPs possessing benzene and benzofuran unit18a (Table 3), which indicates negligible perturbation by the N substituents. The absorption and emission of non‐fused DPPs possessing fluorene units ADPP‐3 – 6 are significantly redshifted relative to those of ADPP‐1 a–c .…”

Efficient red electroluminescence from diketopyrrolopyrrole copolymerised with a polyfluorene

“…These are chemically and thermally stable materials with optical properties tunable by para and meta position substituents. 32 They have found important industrial applications as dyes, such as pigment red 254 -known colloquially as "Ferrari red" for its extensive use in automotive paints -but their derivatives have also been investigated as photoluminescent materials 33,34 (including for cellular imaging 35 ), dyes in solar cells, 36 sensors, 37 high-mobility ambipolar semiconductors, 36,38 and light-emitting diodes. [39][40][41][42][43][44][45][46] Their use as solid-state emitters has, however, been limited by quenching of the emission by a strong propensity towards aggregation of molecules caused by π -π interactions and hydrogen bonding.…”

Diketopyrrolopyrrole‐Porphyrin Conjugates with High Two‐Photon Absorption and Singlet Oxygen Generation for Two‐Photon Photodynamic Therapy

“…In PDT, upon light excitation, a photosensitizer undergoes an efficient intersystem crossing that populates the triplet excited state which reacts with molecular oxygen, thus producing singlet oxygen and/or other cytotoxic reactive oxygen species. [10] More recently, these dyes have received attention for biological applications as TP dyes for fluorescence microscopy, after incorporation of water-solubilizing groups, [11] or p expansion of the DPP core. Light excitation is usually performed in the UV-visible region and its low penetration in tissues for wavelengths below l = 700 nm limits the treatment to superficial damage.…”

“…An emerging and promising development concerns two-photon PDT. [10] More recently, these dyes have received attention for biological applications as TP dyes for fluorescence microscopy, after incorporation of water-solubilizing groups, [11] or p expansion of the DPP core. Such improvements are dependent on the development of new photosensitizers characterized by a high TP absorption cross-section (s 2 ) in the near infrared since the ones currently used in clinics have low TP efficiency.…”

“…[3] Many organic or inorganic TP absorbing chromophores presenting high s 2 values have been reported for applications in materials science [4] and biology. [10] More recently, these dyes have received attention for biological applications as TP dyes for fluorescence microscopy, after incorporation of water-solubilizing groups, [11] or p expansion of the DPP core. Since porphyrin and its derivatives absorb light in the visible range, generate singlet oxygen efficiently, and are already used in clinics in classical one-photon PDT, [6] TP absorbing molecules in the near infrared were developed by extending the p system of the porphyrin core.…”