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¹H NMR spectra of (a) compound MFO in DMSO-d6 and (b) probe MFC in DMSO-d6 and (c) probe MFC upon addition of 2 equiv. of Pd(PPh3)4 in DMSO-d6 and D2O
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We have synthesized a novel long-wavelength fluorescent probe MFC for detection of palladium (Pd⁰). This probe not only shows high selectivity for palladium, but also could quickly discriminate different palladium species (Pd⁰, Pd²⁺, Pd⁴⁺) in phosphate buffered solution. After the reaction with Pd(PPh3)4, the UV absorption of the probe MFC shifts f...
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A family of V-shaped fluorophores with different numbers and positions of vinyl are rationally designed, using which a largely wide and approximately successive range of solid-state emission wavelengths can be achieved before and after force stimuli. These compounds are intensely emissive and highly mechanofluorochromic (MFC), and many physical pro...
Citations
... The 2-dicyanomethylene-3-cyano-4,5,5trimethyl-2,5-dihydrofuran (TCF)-based fluorophore (TCF-OH) was synthesized according to a reported procedure (Scheme 1). 25 Synthesis of Probe EW3. EW3 was synthesized according to a previously reported procedure with some modifications. ...
... Interest for TCF as the electron acceptor is also supported by the easiness of synthesis of the dyes, but also by the easy access to TCF itself. Indeed, TCF can be prepared in one step, by reaction of malononitrile and 3-hydroxy-3-methylbutan-2-one i.e. from cheap starting materials and in high reaction yields (85-90%) [60][61][62][63]. As far as the synthesis of dyes is concerned, synthetic approaches that do not require the use of transition metal catalysts, drastic reaction conditions (inert atmosphere, anhydrous solvents, low temperature reactions) and the use of expensive reagents are also highly appealing. ...
A series of chromophores was designed and synthesized using 2-(3-cyano-4,5,5-trimethylfuran-2 (5H) -ylidene) malononitrile (TCF) as the electron acceptor and differing from each other by the use of thirteen different electron donors. The different dyes were characterized for their optical and electrochemical properties and theoretical calculations were also carried out to support the experimental results. By changing the electron donor in the thirteen dyes, chromophores absorbing between 430 nm and 700 nm could be synthesized. Solvatochromism of the different dyes was analyzed in 23 solvents of different polarity and a positive solvatochromism was determined for all chromophores using the semi-empirical solvent polarity scales based on the Kamlet-Taft parameters (π *) or the Catalan parameters (SdP and SPP).
In recent years, bioorthogonal uncaging reactions have been developed to proceed efficiently under physiological conditions. However, limited progress has been made in the development of protecting groups combining stability under physiological settings with the ability to be quickly removed via bioorthogonal catalysis. Herein, we present a new water-soluble coumarin-derived probe bearing an internal nucleophilic group capable of promoting Tsuji–Trost deallylation under palladium catalysis. This probe can be cleaved by a bioorthogonal palladium complex at a faster rate than the traditional probe, namely N-Alloc-7-amino-4-methylcoumarin. As the deallylation process proved to be efficient in mammalian cells, we envision that this probe may find applications in chemical biology, bioengineering, and medicine.
Gold (Au) and palladium (Pd) species have been widely used in synthetic chemistry, biology, and environmental sciences, raising hard-to-ignore health and environment risks due to their potential toxicity. Herein, a novel dual-functional fluorescent probe was rationally designed and developed for simultaneous quantification and visualization of Au³⁺ and Pd species in the environmental and biological systems. Significant fluorescence enhancement at 484 and 606 nm and color changes were observed upon addition of Au³⁺ and Pd⁰ with high sensitivity. The detection limit for Au³⁺ and Pd⁰ was as low as 68 nM and 7 nM, respectively. Combined with smartphone chromaticity and dual-channel fluorescence imaging analysis, this probe was successfully applied to the quantification and visualization of Au³⁺ and Pd species in real water samples. Thus, simultaneous naked-eye visualization and quantification of Au³⁺ and Pd⁰ in real water samples was achieved using this probe. The probe was also successfully applied to fluorescence imaging of Au³⁺ and Pd⁰ in HeLa cells and zebrafish, promoting the monitor and understanding about gold and palladium species in environmental and biological systems.
The chromophore 2‐2‐(3‐cyano‐5,5‐dimethyl‐4‐((2‐(thiazol‐2‐yl)hydrazono)methyl)‐furan‐2(5H)‐ylidene)malononitrile (TzHTCF) was prepared by diazo‐coupling of diazotized 2‐aminothiazole with 3‐cyano‐2‐(dicyanomethylene)‐4,5,5‐trimethylfuran (TCF). The TzHTCF absorption solvatochromism, in different polarity solvents, offered ΔEmax = +4.74 where the positive sign implied red shift occurrence and the TzHTCF lowest excited state was more polar than its ground one. While, the TzHTCF fluorescence spectrum afforded λem, in 416‐670 nm range, and was more dependent on the solvent polarity than the absorption λmax, despite both exhibited red shift by 24 and 254 nm, respectively. To discover the Stokes’ shift ( ∆ν¯) behaviour of TzHTCF derivative, Lippert‐Mataga and linear solvation‐energy relationship (LSER) formulations have been utilized where the LSER displayed better results than the Lippert–Mataga (R2 = 0. 9931). Furthermore, the LSER showed that the absorption and fluorescence solvatochromic behaviours were dependent on the solvent’s hydrogen‐bond donor (α) and acceptor (β), along with the solvent’s polarizability (π*). Moreover, DFT calculations showed that TzHTCF has a planar configuration and its simulated absorption and emission spectra in DMSO revealed that λmax was primarily originated from HOMO→LUMO and HOMO‐1→LUMO transitions, respectively.
The chromophore 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl) hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile (PPHTCF) was synthesized through coupling of diazotized 3-amino-4,6-dimethyl-5-nitropyrazolo[3,4-b]pyridine with 3-cyano-2-(dicyanomethylene)-4,5,5-trimethylfuran (TCF). The absorption solvatochromism behaviour of PPHTCF, in various solvents, presented ΔEmax = +5.40 where the positive sign suggested red shift occurrence, implying that the PPHTCF has more polar lowest excited state than its ground one. While, the PPHTCF fluorescence spectra afforded λem, in 575-633 nm range, and was more dependent on the solvent polarity than the absorption λmax, despite both exhibited red shift by 58 and 42 nm, respectively. To discover the PPHTCF solvatochromism behaviour in term of “Stokes’ shift”, both of Lippert-Mataga and linear solvation-energy relationship (LSER) formulations have been utilized and the outcomes endorsed that the later was better than the former (R² = 0.9728). Finally, TD-DFT simulated absorption and emission spectra in EtOH revealed that λmax has been resulted mainly from HOMO→LUMO; HOMO-5→LUMO and HOMO-2→LUMO transitions, respectively.
The development of a multifunctional single molecule phototherapeutic agent with excellent fluorescence imaging, photothermal therapy and photodynamic therapy at the same time is still a challenging task, which mainly arises from the low absorbance of the molecule, and the complexity of energy dissipation and molecular design. Herein, four donor-acceptor (D-A) compounds were synthesized by linking triphenylamine (TPA), thiophene/thieno[3,2-b]thiophene and different cyano acceptor structures. In this design, we propose a molecular design strategy to redshift absorption and increase the molar extinction coefficient (ε) by enhancing electron-withdrawing acceptors and enlarging the π-conjugation plane unit. Due to the twisted structure of TPA, these compounds exhibit aggregation-induced emission (AIE) characteristics. Notably, these AIEgens have long emission wavelengths, excellent photostability, biocompatibility, photothermal stability and singlet oxygen (1O2) generation performance. Among them, the photothermal conversion efficiency of a compound (named TCF-SS-TPA NPs) can reach 84.5%. Cellular internalization and therapy showed that TCF-SS-TPA NPs have good biocompatibility, excellent cell bioimaging and cancer phototherapy capabilities in vitro. This study will stimulate the molecular design of multifunctional phototherapeutics to realize effective synergistic cancer therapy.
Palladium (Pd)has drawn worldwide attentions because its connections to industry, chemistry, biological material and public health. Quantitative and selective detection tools for Pd and its ion forms are in urgent necessity. Here an umbelliferone derivative Umb-Pd2 was provided as a small, steady, safe and selective sensor for detecting Pd(II). It indicated advantages including sensitive (LOD 1.1 nM), wide pH tolerance (5.0–10.0), applicable linear range (0–1.8 equivalent)and low toxicity. The most attractive point was its explicit selectivity towards Pd(II)from Pd(0)in both independent and coexistence systems. This distinguishing ability was further utilized in imaging in living cells, raising this work as a rare and important example among all the published papers on palladium sensing. Thus, Umb-Pd2 supplied a potential approach for further improvement and applications in both daily chemistry and public health.
Harmful metal ions have received intense attention. In particular, palladium, a rare inner transition metal, is the subject of intense research in light of its catalytic capabilities and the restrictions on the levels of residual harmful metal ions in end products，has attracted wide spread interest from chemists. A near-infrared Pd²⁺ probe Cy202 has been synthesized that exhibits pronounced fluorescence enhancement in the presence of Pd²⁺. The Pd²⁺ recognition properties were examined by using UV–Vis spectroscopy and fluorescence spectroscopy in DMSO/PBS buffer solution (pH 7.40, 8/2, v/v). The solution of the probe exhibits color change turned from yellow to brown upon the addition of Pd²⁺ while no significant response to other metal ions. The detection limit was calculated as low as 0.52 μM. The probe could be useful for imaging Pd²⁺ in palladium-containing catalyst and samples.
