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1.
Three new aza-BODIPY dyes incorporating fused fluorene or carbazole moieties have been prepared. The dyes show significant enhancement of photophysical properties compared to the parent 1,3,5,7-tetraphenyl aza-BODIPY (TPAB): a bathochromic shift of the absorption maximum (up to 2700 cm−1) and emission maximum (up to 2270 cm−1); an almost threefold increase in molar absorption coefficients (to ca. 230 000 M−1 cm−1) and a significant increase in the fluorescence quantum yield to 49–66 %. Owing to the combination of these properties, the new aza-BODIPY dyes belong to the brightest NIR dyes reported. The dyes also show excellent photostability. Due to their outstanding properties, the new dyes represent a promising platform for further exploration in biomedical research. A pH indicator containing only one fused carbazole unit was also prepared and shows absorption and emission spectra that are bathochromically shifted by about 110 and 100 nm, respectively, compared to the indicator dye based on the TPAB chromophore.  相似文献   

2.
《Supramolecular Science》1998,5(5-6):531-536
A series of dithiolene nickel complex compounds with a general formula (RCSCSR′)2Ni that have an intense absorption band in near-IR region were successfully synthesized and the maximum IR absorption wavelengths of these dyes vary from 875 to 1495 nm in different solvents. Their characteristics of Q-switching and mode-locking for different lasers were investigated. Q-switched 1064 and 1079 nm laser with a polymer film or organic solution work satisfactorily and the pulse widths are 4–10 ns. The dyes in a variety of solutions show excellent properties in mode-locking the 1079 nm laser, particularly in mode-locking the 1340 nm laser. The pulse widths are 90–120 ps. The experimental results show that the choice of different ring substitutes and solvents will greatly influence the corresponding dye laser properties. It is also implied that BDN16 and BDN17 as the mode-locking dyes for the 1500 nm laser are satisfactory.  相似文献   

3.
Novel NIR fluorescent, conformational restricted aza-dipyrromethene boron difluoride (aza-BODIPY) dyes were prepared by an efficient process. Such conformational restricted aza-BODIPY dyes possess intense absorption, strong fluorescence, high chemical and photostability. Additionally, the sharp fluorescence of non-amine containing aza-BODIPY dyes is insensitive to solvent polarity.  相似文献   

4.
We report herein the synthesis of aza-BODIPY substituted with strongly electron-donating p-(diphenylamino)phenyl substituents (p-Ph2N−) at 3,5-positions. The presence of p-Ph2N− groups lowers the energy of the singlet excited state (Es) to 1.48 eV and induces NIR absorption with λabs at 789 nm in THF. The compound studied is weakly emissive with the emission band (λf) at 837 nm and with the singlet lifetime (τS) equal to 100 ps. Nanosecond laser photolysis experiments of the aza-BODIPY in question revealed T1→Tn absorption spanning from ca. 350–550 nm with the triplet lifetime (τT) equal to 21 μs. By introducing a heavy atom (Br) into the structure of the aza-BODIPY, we managed to turn it into a NIR operating photosensitizer. The photosensitized oxygenation of the model compound–diphenylisobenzofuran (DPBF)-proceedes via Type I and/or Type III mechanism without formation of singlet oxygen (1O2). As estimated by CV/DPV measurements, the p-Ph2N− substituted aza-BODIPYs studied exhibits oxidation processes at relatively low oxidation potentials (Eox1), pointing to the very good electron-donating properties of these molecules. Extremely high photostability and thermal robustness up to approximately 300 °C are observed for the p-Ph2N− substituted aza-BODIPYs.  相似文献   

5.
Rare earth (Er3+ and Nd3+) ions doped cadmium lithium boro tellurite (CLiBT) glasses were prepared by melt quenching method. The vis–NIR absorption spectra of these glasses have been analyzed systematically. Judd–Ofelt intensity parameters Ωλ (λ = 2, 4, 6) have been evaluated and used to compute the radiative properties of emission transitions of Er3+ and Nd3+: CLiBT glasses. From the NIR emission spectra of Er3+: CLiBT glasses a broad emission band centered at 1538 nm (4I13/2 → 4I15/2) is observed and from Nd3+: CLiBT glasses, three NIR emission bands at 898 nm (4F3/2 → 4I9/2), 1070 nm (4F3/2 → 4I11/2) and 1338 nm (4F3/2 → 4I13/2) are observed with an excitation wavelength λexci = 514.5 nm (Ar+ Laser). The FWHM and stimulated emission cross-section values are calculated for Er3+ and Nd3+: CLiBT glasses. FWHM × σeP values are also calculated for Er3+: CLiBT glasses.  相似文献   

6.
N,N-Difluoroboryl complexes of 3,3′-diarylazadiisoindolylmethenes were synthesized by the reaction of BF3·OEt2 and 3,3′-diarylazadiisoindolylmethenes, which were easily prepared from a reaction between phthalonitrile and aryl Grignard reagents. These novel dyes exhibit strong absorption in the visible region and intense fluorescence in the vis/NIR region. Their synthesis, characterization, and optical properties are reported in this Letter.  相似文献   

7.
A series of novel aza-BODIPY dyes substituted with p-(dimethylamino)phenyl groups were synthesized and their spectral and electrochemical properties were compared. In particular, the impact of p-(Me2N)Ph- groups on these characteristics was of consideration. For two aza-BODIPYs studied, a near-IR absorption band was observed at circa λabs=796 nm. Due to the pronounced intramolecular charge transfer (ICT) exerted by the presence of strongly electron-donating p-(Me2N)Ph- substituents, the compounds studied were weakly emissive with the singlet lifetimes (τS) in the picosecond range. Nanosecond laser photolysis experiments of the brominated aza-BODIPYs revealed T1→Tn absorption spanning from ca. 350 nm to ca. 550 nm with the triplet lifetimes (τT) ranged between 6.0 μs and 8.5 μs. The optical properties of the aza-BODIPYs studied were pH-sensitive. Upon protonation of the dimethylamino groups with trifluoroacetic acid in toluene, a stepwise disappearance of the NIR absorption band at λabs=790 nm was observed with the concomitant appearance of a blue-shifted absorption band at λabs=652 nm, which was accompanied by a prominent emission band at λfl=680 nm. The transformation from a non-emissive to an emissive compound is associated with the inhibition of the ICT. As estimated by CV/DPV measurements, all aza-BODIPYs studied exhibited two irreversible oxidation and two quasi-reversible reduction processes. All compounds studied exhibit extremely high photostability and thermal stability.  相似文献   

8.
The fast relaxation processes in the excited electronic states of functionalized aza-boron-dipyrromethene (aza-BODIPY) derivatives ( 1 – 4 ) were investigated in liquid media at room temperature, including the linear photophysical, photochemical, and nonlinear optical (NLO) properties. Optical gain was revealed for nonfluorescent derivatives 3 and 4 in the near infrared (NIR) spectral range under femtosecond excitation. The values of two-photon absorption (2PA) and excited-state absorption (ESA) cross-sections were obtained for 1–4 in dichloromethane using femtosecond Z-scans, and the role of bromine substituents in the molecular structures of 2 and 4 is discussed. The nature of the excited states involved in electronic transitions of these dyes was investigated using quantum-chemical TD-DFT calculations, and the obtained spectral parameters are in reasonable agreement with the experimental data. Significant 2PA (maxima cross-sections ∼2000 GM), and large ESA cross-sections ∼10−20 m2 of these new aza-BODIPY derivatives 1–4 along with their measured high photostability reveal their potential for photonic applications in general and optical limiting in particular.  相似文献   

9.
A bright near-infrared (NIR) fluorescent molecule was developed based on the donor–acceptor–donor (D–A–D) approach using an aza-BODIPY analog called pyrrolopyrrole aza-BODIPY (PPAB) as an electron-accepting chromophore. Directly introducing electron-donating triphenylamine (TPA) to develop a D–A–D structure caused redshifts of absorption and emission of PPAB into the NIR region with an enhanced fluorescence brightness of up to 5.2×104 m −1 cm−1, whereas inserting a phenylene linker between the TPA donor and the PPAB acceptor induced solvatochromic behavior in emission. Transient absorption spectra and theoretical calculations revealed the presence of a highly emissive hybridized locally excited and charge-transfer state in the former case and the contribution of the dark charge-separated state to the excited state in the latter case. The bright D–A–D PPAB as a novel emitter resulted in a NIR electroluminescence with a high external quantum efficiency of 3.7 % and a low amplified spontaneous emission threshold of ca. 80 μJ cm−2, indicating the high potential for NIR optoelectronic applications.  相似文献   

10.
Fusion of two N‐annulated perylene (NP) units with a fused porphyrin dimer along the S0–S1 electronic transition moment axis has resulted in new near‐infrared (NIR) dyes 1 a / 1 b with very intense absorption (ε>1.3×105 M ?1 cm?1) beyond 1250 nm. Both compounds displayed moderate NIR fluorescence with fluorescence quantum yields of 4.4×10?6 and 6.0×10?6 for 1 a and 1 b , respectively. The NP‐substituted porphyrin dimers 2 a / 2 b have also been obtained by controlled oxidative coupling and cyclodehydrogenation, and they showed superimposed absorptions of the fused porphyrin dimer and the NP chromophore. The excited‐state dynamics of all of these compounds have been studied by femtosecond transient absorption measurements, which revealed porphyrin dimer‐like behaviour. These new chromophores also exhibited good nonlinear optical susceptibility with large two‐photon absorption cross‐sections in the NIR region due to extended π‐conjugation. Time‐dependent density functional theory calculations have been performed to aid our understanding of their electronic structures and absorption spectra.  相似文献   

11.
Near‐infrared (NIR) fluorescent dyes with favorable photophysical properties are highly useful for bioimaging, but such dyes are still rare. The development of a unique class of NIR dyes via modifying the rhodol scaffold with fused tetrahydroquinoxaline rings is described. These new dyes showed large Stokes shifts (>110 nm). Among them, WR3, WR4, WR5, and WR6 displayed high fluorescence quantum yields and excellent photostability in aqueous solutions. Moreover, their fluorescence properties were tunable by easy modifications on the phenolic hydroxy group. Based on WR6, two NIR fluorescent turn‐on probes, WSP‐NIR and SeSP‐NIR, were devised for the detection of H2S. The probe SeSP‐NIR was applied in visualizing intracellular H2S. These dyes are expected to be useful fluorophore scaffolds in the development of new NIR probes for bioimaging.  相似文献   

12.
Near infrared (NIR) photons are ideally suited for photomedicine because they are relatively harmless and penetrate deeply in biological tissues. However, their use is impaired by lack of straightforward methods to synthesize large quantities of stable infrared-absorbing molecules with long-lived excited states. Here we present a one-step synthesis of amphiphilic meso-phenyl halogenated bacteriochlorins, via hydrazide reduction, possessing strong absorption about 750 nm. The reaction proceeds efficiently, in large quantities, with a solid-solid solvent-free methodology, that is characterized by its simplicity, efficiency and minimum environmental impact. The new bacteriochlorins have unprecedented chemical and photophysical properties, namely strong electronic absorption above 720 nm, adequate photostability, low fluorescence quantum yield and n-octanol/water partition coefficients (log POW) ranging from −1.7 to >4, meaning that the library of compounds synthesized in this work is versatile enough to be applied in photodynamic therapy for a range of biological targets.  相似文献   

13.
The synthesis of organometallic complexes of modified 26π‐conjugated hexaphyrins with absorption and emission capabilities in the third near‐infrared region (NIR‐III) is described. Symmetry alteration of the frontier molecular orbitals (MOs) of bis‐PdII and bis‐PtII complexes of hexaphyrin via N‐confusion modification led to substantial metal dπ–pπ interactions. This MO mixing, in turn, resulted in a significantly narrower HOMO–LUMO energy gap. A remarkable long‐wavelength shift of the lowest S0→S1 absorption beyond 1700 nm was achieved with the bis‐PtII complex, t ‐Pt2‐3 . The emergence of photoacoustic (PA) signals maximized at 1700 nm makes t ‐Pt2‐3 potentially useful as a NIR‐III PA contrast agent. The rigid bis‐PdII complexes, t ‐Pd2‐3 and c ‐Pd2‐3 , are rare examples of NIR emitters beyond 1500 nm. The current study provides new insight into the design of stable, expanded porphyrinic dyes possessing NIR‐III‐emissive and photoacoustic‐response capabilities.  相似文献   

14.
The syntheses and characterizations of four zwitterionic betaines are presented. These dyes possess an uncommon heterocyclic 1,3-thiazol-4-olate donor moiety. The natures of the HOMO/LUMO transitions and of the intramolecular charge-transfer state were assigned with the help of quantum chemical calculations. Multiple intermolecular solute/solvent interactions were discussed using linear solvation energy relationship (LSER) with Kamlet–Taft and Catalán parameters. The dyes show a pronounced negative solvatochromism ranging from λmax 392 nm in TFE to 820 nm in THF (Δλ=428 nm or 1.65 eV). The X-ray structures of one of the tetrafluoroborate salts and of one of the betaines are discussed.  相似文献   

15.
The bis{4‐{2‐[2‐(dialkylamino)thiazol‐5‐yl]ethenyl}‐2,6‐dihydroxyphenyl}squaraines 12a , b were synthesized from ethyl carbonochloridate ( 1 ) in six steps (Scheme). The donor–acceptor–donor systems 12a , b are dark blue dyes with absorption maxima in the NIR region, unless the measurements are performed in the presence of EtOH. In the latter case, the long‐wavelength band disappears, and the absorption in the UV region is strongly enhanced. The λmax values in CHCl3 and CHCl3/EtOH differ by more than 450 nm. The completely reversible effect can be rationalized by the reversible degradation of intramolecular H‐bonds and a consequent torsion between the acceptor and the donor moieties.  相似文献   

16.
The UV–vis absorption properties of azo dyes are known to exhibit a variation with the polarity and acidity of the dye environment. The spectral properties of a series of anionic azo dyes were characterized to further probe the interaction of these dyes with two types of surfactant aggregates: (1) the spherical micelles formed in aqueous solution by alkyltrimethylammonium bromide (CnTAB) surfactants with n = 10–16 and (2) the unilamellar vesicles spontaneously formed in water from binary mixtures of the oppositely-charged double-tailed surfactants cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium dioctylsulfosuccinate (Aerosol OT or AOT). The observed dye spectra reflect the solvatochromic behavior of the dyes and suggest the location and orientation of the dye within the surfactant aggregates. Deconvolution of the overall spectra into sums of Gaussian curves more readily displays any contributions of tautomeric forms of the azo dyes resulting from intramolecular hydrogen bonding. The rich variation in UV/vis absorption properties of these anionic azo dyes supports their use as sensitive tools to explore the nanostructures of surfactant aggregates.  相似文献   

17.
Near-infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light-mediated therapies. Since long-wavelength photoluminescence typically involves extensive π-conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3-cyanoformazans affords efficient production of relatively simple NIR-active BF2 formazanate dyes (λabs=691–760 nm, λPL=834–904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF2 formazanate moieties. Density-functional calculations indicate that the NIR electronic transitions in BF2 formazanates are of π→π*-type, but do not always involve strong charge transfer.  相似文献   

18.
Six novel Ir(C^N)2(L^X)-type heteroleptic iridium complexes with deep-red and near-infrared region (NIR)-emitting coverage were constructed through the cross matching of various cyclometalating (C^N) and ancillary (LX) ligands. Here, three novel C^N ligands were designed by introducing the electron-withdrawing group CF3 on the ortho (o-), meta (m-), and para (p-) positions of the phenyl ring in the 1-phenylisoquinoline (piq) group, which were combined with two electron-rich LX ligands (dipba and dipg), respectively, leading to subsequent iridium complexes with gradually changing emission colors from deep red (≈660 nm) to NIR (≈700 nm). Moreover, a series of phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by employing these phosphors as dopant emitters with two doping concentrations, 5% and 10%, respectively. They exhibited efficient electroluminescence (EL) with significantly high EQE values: >15.0% for deep red light0 (λmax = 664 nm) and >4.0% for NIR cases (λmax = 704 nm) at a high luminance level of 100 cd m−2. This work not only provides a promising approach for finely tuning the emission color of red phosphors via the easily accessible molecular design strategy, but also enables the establishment of an effective method for enriching phosphorescent-emitting molecules for practical applications, especially in the deep-red and near-infrared region (NIR).  相似文献   

19.
《Chemical physics》2001,263(2-3):471-490
The triplet saturable absorption behaviour of the xanthene dyes eosin Y, erythrosin B, and rose bengal and of the fullerene molecule C70 is studied. The molecules are excited to the S1-state by intense picosecond pulses (wavelength λP=527 nm). They relax dominantly to the triplet system by intersystem crossing. The triplet–triplet saturable absorption is investigated with time-delayed intense picosecond pulses (wavelength λL=1054 nm) in the transparency region of the molecules in the singlet ground state. Higher excited-state triplet absorption cross-sections and higher excited-state triplet relaxation times are determined by numerical simulation of the experimental results. Time-resolved fluorescence measurements reveal higher excited-state triplet to singlet back-intersystem-crossing and multi-step triplet photoionization. Additionally the two-photon absorption cross-sections at λL=1054 nm are determined by measurement of the fundamental pulse two-photon induced fluorescence relative to the second-harmonic pulse single-photon induced fluorescence.  相似文献   

20.
Fluorescence imaging is a promising tool for the visualization of biomolecules in living systems and there is great demand for new fluorescent dyes that absorb and emit in the near‐infrared (NIR) region. Herein, we constructed three new fluorescent dyes ( NBC dyes) based on keto‐benzo[h]coumarin ( k‐BC ) and benzopyrilium salts. These dyes showed large Stokes shifts (>100 nm) and NIR emission (>800 nm). The relationship between the structures and optical properties of these dyes was further investigated by using density functional theory calculations at the B3LYP/6‐3G level of theory. Fluorescence images indicated that the fabricated dyes exhibited good photostability and low cytotoxicity and, thus, have potential applications as imaging agents in living cells and animals.  相似文献   

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