Hybrid Dyes Research Articles

Near-Infrared Absorbing BODIPY-Xanthene Hybrids for Multiplexed Photoacoustic Imaging.

We report a series of ethenylene-bridged D-π-A BODIPY-xanthene hybrid dyes with precisely regulated absorption bands ranging from the far-red to the near-infrared region (NIR, 700-1000 nm) through rational molecular design. These dyes have excellent photoacoustic properties, and their biocompatibility can be significantly improved by facilely introducing water-soluble groups. In vivo two-channel multiplexed photoacoustic imaging demonstrated their high-resolution imaging capabilities, making them promising candidates for future NIR bioimaging applications.

Ultrafast dyeing wastewater purification by high-performance and reusable lignin-derived activated porous carbon filter

Achieving ultrafast purification during filtration while maintaining high adsorption capacity and low-cost filter production is a critical challenge that must be addressed immediately to promote large-scale water filter applications, particularly in remote areas without wastewater purification plants. Herein, low-cost, renewable lignin was used as a carbon source precursor to produce a high-performance, reusable activated porous carbon filter for ultrafast dye wastewater purification. Lignin-derived active porous carbon (LAPC) can achieve a high specific surface area (2276 m2/g) by using a lower amount of KOH (a mass ratio of 0.4 KOH to precursor) during the activation process, which not only meets the requirements of water transport and dye adsorption, but also reduces manufacturing costs. Owing to the pore-filling effect and electrostatic interaction, the LAPC particles displayed a high removal capacity of 1800 mg/g in the static adsorption, higher than most of the reported porous carbon. Furthermore, LAPC filters assembled from a flow of LAPC particles achieve significant dye removal (99.82 % in 30 s) during the dynamic adsorption process. Both anionic and cationic dyes can be removed and clean water can be produced simultaneously by simple dynamic filtration. Moreover, the LAPC filter could be reused for wastewater purification with a high removal efficiency (more than 95 % after 7 cycles of regeneration and use). This continuous operation, strong absorption versatility, and high efficiency of LAPC filter device for complex hybrid dyes system make it have a bright prospect in industrial dyeing wastewater treatment fields.

The effect of rigidity on the emission of quadrupolar strongly polarized dyes

Planarization of the pyrrolopyrrole chromophore switches the mechanism of non-radiative deactivation from intersystem crossing to internal conversion.

Pyrazolo[1,5‐a]pyrimidine‐Dioxaborinine Hybrid Dyes: Synthesis and Substituent Effect in the Photophysical Properties

AbstractA novel family of pyrazolo[1,5‐a]pyrimidine‐dioxaborinine (PP‐DB) hybrid dyes was synthesized by the direct construction of the dioxaborinine (DB) fragment on the pyrazolo[1,5‐a]pyrimidine (PP) ring, which implies the formation of four new bonds in a one‐pot manner. The dyes’ optical properties were investigated and compared with the starting pyrazolo[1,5‐a]pyrimidines; a study evidencing large fluorescence quantum yields in products (φfup to 69 %) due to an intramolecular charge transfer (ICT) process from the PP core to a ring of DB (PP→DB) that is absent in precursors (φf=0.03–0.30). Time‐dependent density functional theory (TD‐DFT) calculations confirmed the fluorescence process involved in the novel dyes, where their ICT limits the non‐radiative process due to the restricted rotation in the D−A system. The present work provides insight into how phenyl and DB ring incorporation impact the optical properties of this new group of hybrids dyes based on PP‐DB.

The how and why of naphthalimide/heterocycle-fused hybrid dyes: an overview of the latest developments in the quest for dyes with innovative optical properties.

In this review, a variety of hybrid structures fusing aromatic heterocycles of different natures to a naphthalimide backbone are discussed. This strategy constitutes an efficient approach to generate original structures displaying singular photophysical properties and thus offering new perspectives in the fields of fluorogenic detection, optoelectronics, and photodynamic therapy. In this review, different synthetic approaches and structures reported in the literature are discussed. A critical look at the design and the applications of these new fused hybrids allows us to evaluate the benefits and drawbacks of a fused hybrid strategy applied to naphthalimides.

The magic of biaryl linkers: the electronic coupling through them defines the propensity for excited-state symmetry breaking in quadrupolar acceptor-donor-acceptor fluorophores.

Charge transfer (CT) is key for molecular photonics, governing the optical properties of chromophores comprising electron-rich and electron-deficient components. In photoexcited dyes with an acceptor-donor-acceptor or donor-acceptor-donor architecture, CT breaks their quadrupolar symmetry and yields dipolar structures manifesting pronounced solvatochromism. Herein, we explore the effects of electronic coupling through biaryl linkers on the excited-state symmetry breaking of such hybrid dyes composed of an electron-rich core, i.e., 1,4-dihydropyrrolo[3,2-b]pyrrole (DHPP), and pyrene substituents that can act as electron acceptors. Experimental and theoretical studies reveal that strengthening the donor-acceptor electronic coupling decreases the CT rates and the propensity for symmetry breaking. We ascribe this unexpected result to effects of electronic coupling on the CT thermodynamics, which in its turn affects the CT kinetics. In cases of intermediate electronic coupling, the pyrene-DHPP conjugates produce fluorescence spectra, spreading over the whole visible range, that in addition to the broad CT emission, show bands from the radiative deactivation of the locally excited states of the donor and the acceptors. Because the radiative deactivation of the low-lying CT states is distinctly slow, fluorescence from upper locally excited states emerge leading to the observed anti-Kasha behaviour. As a result, these dyes exhibit white fluorescence. In addition to demonstrating the multifaceted nature of the effects of electronic coupling on CT dynamics, these chromophores can act as broad-band light sources with practical importance for imaging and photonics.

Cover Feature: Tunable Naphthalimide/Cinnoline‐Fused (CinNapht) Hybrid Dyes for Fluorescence Imaging in Living Cells (ChemPhotoChem 11/2022)

The Cover Feature illustrates how the large Stokes shift that characterises tuned naphthalimide/cinnoline-fused hybrid fluorophores “CinNapht” can be exploited to illuminate cell organelles in red light during confocal microscope experiments using a blue laser. More information can be found in the Research Article by Arnaud Chevalier and co-workers.

Tunable Naphthalimide/Cinnoline‐Fused (CinNapht) Hybrid Dyes for Fluorescence Imaging in Living Cells

AbstractThis paper presents the synthesis, photophysical characterization and use for cell imaging of 14 fluorophores derived from a hybrid Naphthalimide/Cinnoline fused backbone called “CinNapht”. Photophysical properties of these fluorophores including absorbance, excitation and emission spectra have been recorded in CHCl3, DMSO and PBS+5 %BSA. They exhibit red emission associated to a large Stokes shift and fluorescence quantum yields up to 52 %. Theoretical calculations have been undertaken in order to provide elements of rationalization for a major part of the results. Some of these analogues have been tuned to enable imaging of cell organelles such as mitochondria, lysosome or lipid droplets. This study comes to confirm that CinNapht dyes can be considered as relevant alternatives to existing tools for cell imaging.

Graphene-Oxide-Based Fluoro- and Chromo-Genic Materials and Their Applications.

Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments.

Bandgap tunability from synergistic mixture of Pandanus amaryllifolius and Curcuma longa as photo-absorber candidates

The application of natural plant-derived dyes to replace ruthenium-based material as photo-absorber in solar cells application, have been extensively studied. Several advantages such as low cost, abundant in supply, sustainability and environmentally-safe make natural materials as current favourite photo-absorber. Natural plant-derived dyes are known containing natural compounds (e.g. carotenoids, chlorophylls, anthocyanins) that have the characteristics of electronic delocalization in extended ?-orbital system involving in electronic transfer mechanism. To date, massive investigations were done to exploit this system to be used as a potential photo-absorber in solar cells. Due to this matter, the hybrid dyes from the mixture of Pandanus amaryllifolius (pandan, P) and Curcuma longa (turmeric, T) were successfully prepared and several physical characterizations were carried out to analyse the photo-absorber (sensitizer) properties. From the results obtained, the ratios of P:T was varied into 1:2, 1:4, 4:1, and 8:1. This ratio has changed the wavelength of absorbers that were slightly shifted and the indirect bandgap (Eg) also were significantly changed. With this new approach, the bandgap of the hybrid dyes as core point in modulating electrical conductivity of photo-absorber can be simply tuned. By implying two different extract dyes to form hybrid dyes, the bandgap was found decreased with higher ratio of T used. Overall results suggesting that by adjusting the ratio of hybrid dyes, the photo-absorber properties and the Eg values were differed and with slightly modification, better electrical conductivity can be expected for solar cells application.

Benzo[1,2‐c;4,5‐cʹ]bis[1,2,5]thiadiazole‐porphyrin‐based near‐infrared dyes

AbstractBenzo[1,2‐c;4,5‐cʹ]bis[1,2,5]thiadiazole (BBT) has intrinsic diradical character and herein it is used to construct organic near‐infrared (NIR) dyes together with the aromatic porphyrin unit. Three BBT‐porphyrin hybrid dyes 1–3 with different linkage modes are synthesized by Pd‐catalyzed Sonogashira cross‐coupling between meso‐ethynylene porphyrin units and monobromo‐/dibromo‐ BBT, or through unexpected homocoupling between the BBT units. They all possess small open‐shell diradical character and display intense NIR absorption in the range of 800–1000 nm. They also exhibit amphoteric redox behavior. BBT‐based diradicaloids are thus good candidates for organic NIR dyes.

Plasma membrane staining with fluorescent hybrid benzothiadiazole and coumarin derivatives: Tuning the cellular selection by molecular design

In this work, two new hybrid benzothiadiazole-coumarin derivatives have been designed and applied as selective live cell fluorescence imaging probes. The developed dyes had their photoproperties evaluated and proved to be stable emitters. DFT calculations have been used to shed some light on the photophysical properties observed for both fluorophores and explained the obtained data. The lipophilic structures selectively stained the plasma membrane of both live and fixed cells of several tumoral and healthy lineages. Comparison of the novel hybrid fluorogenic dyes with the commercially available CellMask proved the preference for plasma membrane staining of the dyes. Finally, zebrafish embryos have been used as complexes models and these embryos were selectively stained, thus indicating the advantages of the hybrid dyes also for multicellular staining in comparison with the commercial dye.

N-Alkylation of 2-methoxy-10H-phenothiazine revisited. A facile entry to diversely N-substituted phenothiazine-coumarin hybrid dyes

N-Alkylation of 2-methoxy-10H-phenothiazine, a valuable building block for the synthesis of bioactive compounds and reaction-based fluorescent probes, has been revisited aimed at introducing a substituent easily convertible into cationic or zwitterionic side chains. We focused our attention on the 3-dimethylaminopropyl group since its derivatization through reactions with various alkyl halides or sultones is a well-established and effective way to enhance polarity of diverse hydrophobic molecular scaffolds. This two-step functionalization approach was applied to the synthesis of novel phenothiazine-coumarin hybrid dyes whose spectral features, especially their NIR-I emission, have been determined in aqueous media with the ultimate goal of identifying novel fluorescent markers for bioanalytical applications, including fluorogenic detection of reactive oxygen species (ROS) through selective S-oxidation reaction of phenothiazine scaffold.

Performance Investigation of Dye Sensitized Solar Cell using Hybrid Dyes

Performance Investigation of Dye Sensitized Solar Cell using Hybrid Dyes

Hybrid coumarin-difluoroboron dyes for mitochondrial staining

To develop new dyes with mitochondria staining capacity, a series of zwitterionic dyes of hybrid coumarin-difluoroboron have been synthesized. The hybrid dyes are conjugated by 7-diethylaminocoumarin, difluoroboron (BF2) β-diketone and electron-donating group. The dyes show deep-red emission (600–680 nm) and high fluorescence quantum yield in organic solvents. The nature of ICT and zwitterion has been fully researched by TD-DFT and ESP calculations. Co-staining with the Mito–Tracker Green shows staining capability to mitochondria in living cells by confocal cell imaging experiments. This work can provide a new strategy for the design of neutral cellular probes for mitochondria staining.

Synthesis and spectral properties of carbazole-coumarin hybrid dyes

In this study, three carbazole-coumarin hybrid dyes were successfully synthesized, and their UV-vis absorption spectra, fluorescence spectra, and structural properties were investigated. The results indicated that diethyl 12-hexyl-2,9-dioxo-9,12-dihydro-2H-dipyrano[2,3-b:3',2'-h]-carbazole-3,8-dicarboxylate showed a slight red shift of the maximum absorption wavelength, and its fluorescence intensity was above 4000 arb units, about 22 times higher than that of ethyl 10-hexyl-8-hydroxy-2-oxo-2,10-dihydropyrano[2,3-b]carbazole-3-carboxylate and ethyl 10-hexyl-8-(hexyloxy)-2-oxo-2,10-dihydropyrano[2,3-b]carbazole-3-carboxylate in CHCl3. The fluorescence intensity of the three compounds first increases and then decreases with the rise of concentration, and the maximum emission wavelength shows a slight red shift. The stability pH range of diethyl 12-hexyl-2,9-dioxo-9,12-dihydro-2H-dipyrano[2,3-b:3',2'-h]carbazole-3,8-dicarboxylate in THF was 2–10.

D-π-A-π-D coumarin hybrids derived from arylamine donors: DFT and Z-scan studies

Four new D-π-A-π-D hybrid dyes containing coumarin as a major donor (4a-b and 5a-b) together with carbazole and triphenylamine as auxiliary donor having dicyanovinylene as a common acceptor are synthesized and studied in terms of photophysical, charge transfer, and non-linear optical properties. Optical properties of hybrid dyes considerably shifted towards red to NIR region upon increasing the solvent polarity. Highest emission solvatochromism is observed for dye 5b (∼137 nm) from nonpolar to polar solvent. Charge transfer is well established using solvatochromism, natural bond orbital analysis, and HOMO-LUMO energy gap. Two photon absorption is calculated using the theoretical model and dye 4b shows high σ2PA in the range 186–464 GM. Non-linear optical properties were investigated using solvatochromic two-level model, computationally using two global hybrid functionls (B3LYP and BHHLYP) and four range separated hybrid functionals (CAM-B3LYP, ωB97, ωB97× and ωB97XD) and Z-scan technique. The computed values of the second order hyperpolarizability (γ0) and first order hyperpolarizability (β0) are high in the range of 993–5473 × 10−36 esu and 240-806 × 10−30 esu respectively for these dyes compared to urea. Z-scan results reveal saturable kind of behavior for 4a and 4b, whereas 5a and 5b show reverse saturable kind of behavior in acetone and ethanol and hence give optical limiting values. Thus, from the experimental and theoretical data, these dyes can be considered as promising candidates for NLO application in material science.

Influence of acceptors in NLOphoric aacenaphthene and morpholine-thiourea hybrid dyes: Photophysical, viscosity, DFT and Z-Scan study

Three novel fluorescent NLOphoric push-pull fluorophores (2a-c) constituted by different cyano containing acceptors linked to morpholine-thiourea (donor) and acenaphthene (rotor) hybrid were synthesized and characterized. They exhibit positive absorption and emission solvatochromism. The solvent polarity function based Lippert-Mataga plot provides the validation of charge transfer (CT) characteristics whereas, Rettig plot furnishes an alternative relaxation channel due to twisting around the σ-bonds between donor and acceptor on photoexcitation leading to the twisted intramolecular charge transfer (TICT) state in dyes 2a-c. Viscosity induced emission studies show 4.18, 17.61, and 5.30 fold increase in the emission intensity for dyes 2a, 2b, and 2c respectively which recommends these dyes as fluorescent molecular rotors (FMR). Density Functional Theory (DFT) calculations [(B3LYP/6-311++G(d,p)] give complete information of structural as well as electronic properties of dyes 2a-c. The difference in dipole moment (ca. 4.86–8.23 D) results in a strong non-linear optical (NLO) properties which increases in the order 2a<2b < 2c. Z-scan studies reveal that the dyes possesses reverse-saturable i.e. positive type of absorption non-linearity resulting in a positive values of β (2c > 2b > 2a). The lower optical limiting threshold values for dyes 2a-c, made them suitable for the use in the application of NLO materials.

Tetraphenylethylenepyrrolo[3,2- b]pyrrole Hybrids as Solid-State Emitters: The Role of Substitution Pattern.

Two hybrid dyes possessing tetraphenylethylene moieties weakly conjugated with a pyrrolo[3,2- b]pyrrole core have been synthesized. Both dyes display a weak emission in solution, however, in the solid state a ∼100-fold increase in the fluorescence quantum yield is observed. The position of the molecular rotors about the core greatly influences the photophysical characteristics. The variances in emission properties were assigned to entirely different changes in dihedral angles upon excitation, which in turn have substantial effects on radiative rate constants, allowed transitions, and HOMO/LUMO distribution.

Viscosity induced emission of red-emitting NLOphoric coumarin morpholine-thiazole hybrid styryl dyes as FMRs: Consolidated experimental and theoretical approach

Four new coumarin hybrid styryl dyes are synthesized by condensing 4-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)-2-morpholinothiazole-5-carbaldehyde with dicyanovinylene containing active methylene intermediates and their linear and non-linear optical properties are studied. The dye having dicyanovinylene-isophorone acceptor displayed a large Stokes shift of 3702–4795 cm−1 in non-polar to polar solvent respectively. The dyes exhibit a good charge transfer characteristics and positive emission solvatochromism (∼50 nm–72 nm) in non-polar to a polar solvent which is well supported by multi-linear regression analysis. Viscosity induced enhancement study in ethanol/polyethylene glycol-400 system shows 2.71–6.78 fold increase in emission intensity. The intra and twisted-intramolecular charge transfer (ICT-TICT) characteristics were established using emission solvatochromism, polarity plots, generalised Mullikan-Hush (GMH) analysis and optimized geometry. A dye having the highest charge transfer dipole moment relatively possess the maximum two-photon absorption cross-section area (KK-1 = 165–207 GM) which was established using theoretical two-level model. The NLO properties have been investigated employing solvatochromic and computational methods and were found to be directly proportional to the polarity of the solvent. Z-scan results reveal that the dyes KK-1 and KK-2 possesses reverse saturable kind of behaviour whereas KK-3 and KK-4 show saturable kind of behaviour. From the experimental and theoretical data, these coumarin thiazole hybrid dyes can be considered as promising candidates for FMR and NLOphores.