Fluorescent Ionic Liquid Research Articles

Fluorescent Ionic Liquid Aggregates: A Self-Assembled Approach for Pesticide Detection and Catalysis.

The unregulated use of pesticides, industrial discharge of heavy metals, waste, and agricultural runoff may contaminate surface water and groundwater, consequently threatening ecosystems and human health. Thus, the sensitive detection and degradation of pesticides are essential for safety. In this context, herein, we have developed benzimidazolium-based fluorescent surfactant assemblies TA-1/SDS and TA-2/SDBS, which exhibit aggregation-induced emission enhancement in an aqueous medium. The aggregates (TA-1/SDS and TA-2/SDBS) displayed a turn-on emission response upon interaction with carbendazim and azamethiphos with limits of detection 7.5 and 7.8 nM, respectively. The FE-SEM and AFM studies revealed that TA-1/SDS and TA-2/SDBS undergo self-assembly with the addition of AZA and CBZ, resulting in the formation of dendritic structures. In addition to the quantification of AZA and CBZ, TA-1/SDS and TA-2/SDBS have also been evaluated to degrade both pesticides and validated using 31P NMR spectroscopy and LC-MS spectrometry.

Development of an “on-off-on” fluoroprobe utilizing an anthrylimidazole-based fluorescent ionic liquid for sensitive Cr(VI) and ascorbic acid detection

Developing a rapid detection method of Cr(VI) and ascorbic acid (AA) is vital in the food and environmental fields. Herein, an anthrylimidazole-based fluorescent ionic liquid (AI-FIL) with the advantageous fluorescent properties was successfully prepared and used to construct a promising “on-off-on” fluoroprobe for rapid/sensitive Cr(VI) and AA detection. Cr(VI) could effectively quench the fluorescence of AI-FIL owing to the inner-filter effect and photoinduced electron-transfer process. However, the decreased fluorescence could be rapidly recovered by AA owing to the redox reaction between AA and Cr(VI). For Cr(VI) detection, a satisfactorily linear response (0.03–300 μM) was achieved with the corresponding detection limit of 9 nM. For AA detection, a good linearity from 1 to 1000 μM was obtained with the resultant detection limit of 0.3 μM. Moreover, the AI-FIL based fluoroprobe was successfully utilized for Cr(VI) and AA detection in food and water samples with satisfactory accuracy and precision.

A tailor-made fluorescent ionic liquid integrating tetrapropylammonium hydroxide with 1-naphathoic acid to construct a dual-emitting fluoroprobe for sensing hydroquinone in environmental waters

Herein, a dual-emitting fluoroprobe was pioneered for the sensitive and selective detection of hydroquinone (HQ) in environmental waters, which was based on integration of a tailor-made fluorescent ionic liquid ([TBAOH][NA]) with Eu3+ (([TBAOH][NA]/Eu3+). HQ could substantially enhance the 365-nm fluorescence intensity (FI365) of [TBAOH][NA]/Eu3+, whereas no prominent variation ocurred in FI615. After HQ binding with [TBAOH][NA], the electronic structure of S1 was completely pi-pi*, and the orbital overlap of the latter was much higher, thereby promoting photon transitions. After some key factors were optimized using a central-composite-design (CCD) approach, this fluroprobe provided a linear response from 0.5 to 100 μM and detection limit of 0.15 μM for HQ assay, which was comparable to analytical performance by conventional HPLC-DAD analysis. Overall, the prominent advantages of as-developed fluoroprobe lie in two aspects: (1) Employing the ratio of two well-resolved emission and significantly differential responses to HQ greatly enhance sensitivity and accuracy through a self-calibration system; and (2) [TBAOH][NA] has not only the superiority of “green solvent” like conventional ionic liquids, but also possesses strong luminescence signal owing to introducing 1-naphathoic acid as an anion into tetrapropylammonium hydroxide. Consequently, this dual-emitting fluoroprobe is endowed with great potential in on-site and outdoor HQ monitoring.

Red-Emitting AIEE-Active Rhodamine-Based Ionic Liquid for the Ultrasensitive and Selective Detection of Mercury Ions.

A highly fluorescent, red-emitting rhodamine-based imidazolium ionic liquid (RhB-IL) was synthesized, and its structure was extensively verified using various spectroscopic techniques. The novel molecule showed exceptional selectivity toward Hg2+ ions over other competitive metal ions. Additionally, inspired by the solution results, a paper-based device was fabricated by embedding RhB-IL on paper strips and tested for the on-site detection of Hg2+ ions using a portable UV light source. Significantly, the device displayed excellent PL sensing behavior toward Hg2+ with a detection limit of 0.21 nM. In addition, RhB-IL showed the phenomena of aggregation-induced enhanced emission. In fact, when compared to the pure THF solution of RhB-IL, a remarkable 7.7-fold increase in PL intensity was seen for the 90% water fraction. Evidently, this is the first report of a paper-based Hg2+ detection system that uses a red fluorescent ionic liquid.

AIEE active ionic liquid based on triphenyl amine functionalized Schiff base for the selective and sensitive detection of Sn2+ ion

A triphenylamine and imidazolium based fluorescent ionic liquid (IL) [TPA-SB][Br] was synthesized and its structure was elucidated using 1H, 13C NMR, FT-IR, UV–visible spectroscopy, and mass spectrometry. Furthermore, TGA and DSC studies were carried out to establish the thermal resilience of [TPA-SB][Br]. The novel molecule revealed distinct fluorescent recognition behavior for Sn2+ ions over eleven other transition metals in the solution phase. This encouraged us to devise a paper-based fluorescent sensor embed with [TPA-SB][Br]. The paper sensor also revealed outstanding sensing properties for Sn2+ ions. As a matter of fact, aggregation induced enhanced emission (AIEE) based fluorophores are extremely pivotal in devising fluorescent sensors. Interestingly, [TPA-SB][Br] exhibited remarkable 31.2 fold increase in fluorescence intensity for 5:95 ratio of THF:water, which reveals its exceptional AIEE characteristics. Notably, ours is the first report on a paper-based Sn2+ sensor based on fluorescent ionic liquid.

A new electroactive fluorescent ionic liquid enables high-performance reflective/emissive dual-modal display device

Integrated reflective and emissive dual-modal displays capable of versatile applicability in both bright and dark environments have promoted the development of electrochromic/electrofluorochromic bifunctional materials, whose color and fluorescence properties can be electrochemically modulated on demand. However, conventional electrochromic/electrofluorochromic devices suffer from slow response speed and low long-term durability. Herein, an electroactive fluorescent ionic liquid (EFIL-TTM) was facilely synthesized based on electroactive triphenylamine, fluorescent tetraphenyl ethylene, and ionic conductive imidazole groups, exhibiting desired electrochemically-induced color and fluorescence change synchronously. A quasi-solid-state electrochromic/electrofluorochromic device based on EFIL-TTM exhibited desirable simultaneous reflective and emissive display behavior of low driving voltage (0.7 V), fast response speed (color: 0.8/1.1 s; fluorescence: 1.7/2.3 s), and outstanding cycling durability (color retention of 97 % and fluorescence retention of 94 % after 10,000 cycles). It was intriguing that an EFIL-TTM//BQ device without electrolyte salt could still exhibit acceptable reflective/emissive dual-modal display behavior. Considering its facile synthetic strategy, scalable assembled approach, and superior performance, this EFIL-TTM-based electrochemical device may provide another avenue for the synergetic improvement of reflective/emissive dual-modal display performance.

First Gemini-type fluorescent ionic liquid crystals: Synthesis, fluorescence emission and self-assembly in liquid crystals and gels

Although many Gemini-type ionic liquids crystals (ILCs) had been studied, the Gemini-type fluorescence ionic liquid was not presented so far. In this work, the first Gemini-type fluorescence ILCs based on dicyanodivinylbenzene unit and imidazole cations with –CH3, –C4H9 and –C6H13 chains were prepared. They emitted strong fluorescence in aggregated states based on the aggregation-induced emission effect. They displayed the reversible smectic mesophase in wide scope of temperature. Furthermore, the stable gels in DMSO-toluene (1:1) system were observed for these new ILCs and the gels possessed the excellent thermal reversible response. The novel ionic liquid with C6H13 chains presented the orderly rectangular columnar stacking in gel. The CVs studies suggested that these Gemini-type fluorescence ILCs possessed the stable electrochemical properties. This research not only reported the first Gemini-type ILCs bearing high fluorescence, good liquid crystalline and gel properties, but also presented a unique self-assembled change from a coated mesophase in liquid crystal to a rectangular columnar stacking in gel.

HYPHa project: a low-cost alternative for integrated photonics

In this paper, a brief introduction to the Hybrid sensor platforms of integrated photonic systems based on ceramic and polymer materials (HYPHa) is presented. The project's goal is to establish a collaborative effort of institutes specialized in integrated optics. The newly formed group of professionals will be founded on research groups' experience, collaboration, and devotion. We intend to develop a method for combining competencies and a universal material platform for integrated photonics, based on newly validated hybrid materials as part of the project. Silica compounds with additions including TiO2, SnO2, used as structural matrices, polymer coatings with dopants (active or protective layers), organic dyes, and active two-dimensional materials such as transition metal dichalcogenides, graphene hybrids, and boron nitride will be the foundation for these materials. Full Text: PDF ReferencesK. Rola, A. Zajac, M. Czajkowski, A. Szpecht, M. Zdonczyk, M. Smiglak, J. Cybinska, K. Komorowska, "Ionic liquids for active photonics components fabrication", Opt. Mater. 89, 106-111 (2019). CrossRef D. Kowal, K. Rola, J. Cybinska, M. Skorenski, A. Zajac, A. Szpecht, M. Smiglak, S. Drobczynski, K. Ciesiolkiewicz, K. Komorowska, "Fluorescent ionic liquid micro reservoirs fabricated by dual-step E-beam patterning", Mater. Res. Bull. 142, 111434 (2021). CrossRef T. Martynkien, J. Olszewski, M. Szpulak, G. Golojuch, W. Urbanczyk, T. Nasilowski, F. Berghmans, and H. Thienpont, "Experimental investigations of bending loss oscillations in large mode area photonic crystal fibers", Opt. Express 15, 13547-13556 (2007). CrossRef E. Środa, J. Olszewski, and W. Urbańczyk, "Reducing bend-induced loss and crosstalk in a two-mode ridge waveguide by steplike thickness structuring", Appl. Opt. 61, 1164-1170 (2022). CrossRef P. Karasinski, C. Tyszkiewicz, A. Domanowska, A. Michalewicz, J. Mazur, "Low loss, long time stable sol–gel derived silica–titania waveguide films", Mater. Lett. 143, 5-7 (2015). CrossRef P. Karasinski, C. Tyszkiewicz, A. Maciaga, I.V. Kityk, E. Gondek, "Two-component waveguide SiO2:TiO2 films fabricated by sol–gel technology for optoelectronic applications", J. of Mater. Sci.: Mater. Electron. 26, 2733-2736 (2015). CrossRef M.A. Butt, A. Kazmierczak, C. Tyszkiewicz, P. Karasinski, R. Piramidowicz, "Mode Sensitivity Exploration of Silica–Titania Waveguide for Refractive Index Sensing Applications", Sensors 21, 7452 (2021). CrossRef A. Kazmierczak, M. Slowikowski, K. Pavlov, M. Filipiak, M. Vervaeke, C. Tyszkiewicz, H. Ottevaere, R. Piramidowicz, P. Karasinski, "Efficient, low-cost optical coupling mechanism for TiO2-SiO2 sol-gel derived slab waveguide surface grating coupler sensors", Opt. Appl. 50, 539 (2020). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "A highly sensitive design of subwavelength grating double-slot waveguide microring resonator", Laser Phys. Lett. 17, 076201 (2020). CrossRef N.L. Kazanskiy, M.A. Butt, S.N. Khonina, "Silicon photonic devices realized on refractive index engineered subwavelength grating waveguides-A review", Opt. Laser Technol. 138, 106863 (2021). CrossRef M.A. Butt, S.N. Khonina, N.L. Kazanskiy, "Recent advances in photonic crystal optical devices: A review", Opt. Laser Technol. 142, 107265 (2021). CrossRef L. Xu, Y. Wang, E. El-Fiky, D. Mao, A. Kumar, Z. Xing, Md. G. Saber, M. Jacques, D.V. Plant, "Compact Broadband Polarization Beam Splitter Based on Multimode Interference Coupler With Internal Photonic Crystal for the SOI Platform", J. Light. Technol. 37, 1231 (2019). CrossRef R. Marchetti, C. Lacava, A. Khokhar, X. Chen, I. Cristiani, D.J. Richardson, G. T. Reed, P. Petropoulos, P. Minzioni, "High-efficiency grating-couplers: demonstration of a new design strategy", Sci. Rep. 7, 16670 (2017). CrossRef

Fluorescent Ionic Liquid Membranes Based on Coumarin for the Real-Time and Visual Detection of Gaseous SO2

Fluorescent Ionic Liquid Membranes Based on Coumarin for the Real-Time and Visual Detection of Gaseous SO₂

A label-free fluorescent aptasensor based on the AIE effect and CoOOH for ultrasensitive determination of carcinoembryonic antigen.

Highly sensitive and specific detection of cancer markers (such as carcinoembryonic antigen) is very important for early diagnosis and treatment of cancer. Herein, we developed a label-free fluorescent aptamer biosensor based on the aggregation-induced emission (AIE) effect and hydroxycobalt oxide (CoOOH) platform, and used it to detect carcinoembryonic antigen (CEA) with high sensitivity and specificity. Fluorescent ionic liquid Compound B can combine with a CEA aptamer (CEA-Apt) through electrostatic attraction and hydrophobic interaction to form an ionic liquid/aptamer (CEA-Apt/B) complex and produce the AIE effect, thereby enhancing the fluorescence intensity of B. CEA-Apt/B was adsorbed on the surface of CoOOH when CoOOH was added to the buffer solution, and the fluorescence of B was quenched. After adding CEA to the solution, CEA-Apt/B bound to CEA and separated from the surface of CoOOH because CEA-Apt had stronger affinity for CEA, resulting in fluorescence recovery of B. In the level range of 0.67-10000 pg mL-1, the fluorescence recovery intensity of the sensor had an excellent linear relationship with the level of CEA, and its LOD was 0.2 pg mL-1 (S/N = 3). In addition, the sensor had good selectivity and can be directly used to detect CEA in human serum with high accuracy.

Tunable Cytotoxicity and Selectivity of Phosphonium Ionic Liquid with Aniline Blue Dye.

Ionic liquids are an interesting class of materials that have recently been utilized as chemotherapeutic agents in cancer therapy. Aniline blue, a commonly used biological staining agent, was used as a counter ion to trihexyltetradecylphosphonium, a known cytotoxic cation. A facile, single step ion exchange reaction was performed to synthesize a fluorescent ionic liquid, trihexyltetradecylphosphonium aniline blue. Aqueous nanoparticles of this hydrophobic ionic liquid were prepared using reprecipitationmethod. The newly synthesized ionic liquid and subsequent nanoparticles were characterized using various spectroscopic techniques. Transmission electron microscopy and zeta potential measurements were performed to characterize the nanoparticles' morphology and surface charge. The photophysical properties of the nanoparticles and the parent aniline blue compound were studied using absorption and fluorescence spectroscopy. Cell viability studies were conducted to investigate the cytotoxicity of the newly developed trihexyltetradecylphosphonium aniline blue nanoparticles in human breast epithelial cancer cell line (MCF-7) and its corresponding normal epithelial cell line (MCF-10A) in vitro. The results revealed that the synthesized ionic nanomedicines were more cytotoxic (lower IC50) than the parent chemotherapeutic compound in MCF-7 cells. Nanoparticles of the synthesized ionic liquid were also shown to be more stable in both aqueous and cellular media and more selective than parent compounds towards cancer cells.

Fluorescent ionic liquid micro reservoirs fabricated by dual-step E-beam patterning

In this work the fabrication of fluorescent microstructures through the e-beam induced solidification of two types of room temperature ionic liquids (RTILs) with fluorescent organic dyes is reported. It is shown that, by introducing dual-step e-beam patterning method with controlled accelerating voltage, solid micro-sized reservoirs are fabricated with liquid phase RTIL sealed inside. The presence of liquid inside the containers is confirmed by measuring their fluorescence spectra and comparison with results obtained for solid RTIL. The impact of the electron dose (ED) used in the exposure process on robustness and fluorescence characteristics of the fabricated structures is investigated. The temperature response of the micro reservoirs is also examined. The advantage of liquid – filled micro reservoirs is that they remain highly fluorescent, while solid RTIL structures exhibit significant fall in fluorescence ability associated with e-beam exposure damage.

Sensitive Detection of Sulfide Ion Based on Fluorescent Ionic Liquid-Graphene Quantum Dots Nanocomposite.

Sulfide ions (S2−) that are widely distributed in biological and industrial fields are extremely toxic and pose great harms to both ecological environment and human health. However, fluorescent sensors toward S2− ions commonly use S2−-recovered fluorescence of fluorophore that is first quenched mainly by metal ions. Fluorescent probe which enables direct, selective, and sensitive detection of S2− ion is highly desirable. Herein, we demonstrate one-step preparation of fluorescent ionic liquid–graphene quantum dots (IL-GQDs) nanocomposite, which can act as a fluorescent probe for direct and sensitive detection of S2− ion. The IL-GQDs nanocomposite is easily synthesized via facile molecular fusion of carbon precursor and in situ surface modification of GQDs by IL under hydrothermal condition. The as-prepared IL-GQDs nanocomposite has uniform and ultrasmall size, high crystallinity, and bright green fluorescence (absolute photoluminescence quantum yield of 18.2%). S2− ions can strongly and selectively quench the fluorescence of IL-GQDs because of the anion exchange ability of IL. With IL-GQDs nanocomposite being fluorescent probe, direct and sensitive detection of S2− is realized with a linear detection range of 100nM–10μM and 10μM–0.2mM (limit of detection or LOD of 23nM). Detection of S2− ions in environmental river water is also achieved.

Highly sensitive determination of 4-nitrophenol with coumarin-based fluorescent molecularly imprinted poly (ionic liquid)

A coumarin-based fluorescent molecularly imprinted poly (ionic liquid) (FL-MIPIL) was prepared using a new coumarin-based alkenyl fluorescent ionic liquid (coumarin-FL-IL) as the functional monomer, IL [V2C4(mim)2][(PF6)2] and ethyleneglycol dimethacrylate as the cross-linkers, and 4-NP as the template molecule. The absolute quantum yields of coumarin-FL-IL and FL-MIPIL were 7.26 % and 30.66 %, respectively. As a result of the electron transfer between coumarin-FL-IL which contains amino groups and 4-NP bearing hydroxyl groups, FL-MIPIL fluorescence was effectively quenched by 4-NP. The prepared FL-MIPIL sensor can rapidly respond to 4-NP within 60 s. The FL-MIPIL sensor had good linear response to 4-NP from 0.001–7.5 μM and low detection limit of 0.5 nM (S/N = 3). The FL-MIPIL sensor exhibited high sensitivity and good selectivity for 4-NP. The outstanding performance of FL-MIPIL could be ascribed to high fluorescence intensity of FL-MIPIL without matrixes and more interactions between FL-MIPIL and 4-NP. The FL-MIPIL sensor has successfully applied to the determination of 4-NP in lake, rain and waste water samples, river sediment, soil and urine samples.

Real-time monitoring of intracellular pH in live cells with fluorescent ionic liquid

Real-time monitoring of intracellular pH is of great significance due to its essential role in physiological and pathological processes. In present work, the ionic liquid (IL) N-methyl-6-hydroxyquinolinium bis(trifluoromethylsulfonyl) imide ([6MQc][NTf2]) is proposed as a fluorescence probe for the quantitative imaging of intracellular pH in response to external stimuli. The fluorescence of the IL [6MQc][NTf2] exhibits a sensitive response to pH variations, as the deprotonation of [6MQc][NTf2] generates the highly fluorescent zwitterionic product [6MQz]. pH fluctuations in the range of 6.0–7.5 can be accurately sensed by monitoring the fluorescence change at 555 nm. Moreover, this IL probe exhibits favorable biocompatibility, excellent anti-photobleaching properties, and high tolerance to ionic strength. Using the IL probe, real-time sensing of hypoxia- and drug-induced intracellular pH changes in MCF-7 cells is achieved.

Design of functionalized fluorescent ionic liquid and its application for achieving significant improvements in Al3+ detecting

Specific fluorophore was introduced into ionic liquid based on its tunability, thus a kind of novel fluorescent ionic liquid probe [P66614][HQS] was designed, synthesized and characterized. Compared with non-fluorescent HQS, ionic liquid [P66614][HQS] emitted a certain amount of fluorescence, which could be attributed to the well-delocalized frontier orbitals and its charge transfer character, as demonstrated by quantum chemical calculation. Considering the interaction of [P66614][HQS] with metal ions, the application for detecting specific substance as a chemical sensor, such as Al3+ was investigated. Compared with the traditional probe HQS, significant improvements in Al3+ detecting was achieved by [P66614][HQS] with stronger binding ability, better sensitivity and selectivity. The better performance of [P66614][HQS] was contributed to the changed charge distribution, leading to the stronger binding interaction. We believe that this new fluorescent ionic liquid exhibited unique properties in detecting Al3+ in aqueous solution, which would broaden the application of ionic liquids.

Enzyme-responsive Fluorescent Ionic Liquid.

Herein, we describe the development of a novel material, "enzyme-responsive fluorescent ionic liquid", which enabled a highly sensitive detection of alkaline phosphatase (ALP). We prepared a plasticized poly(vinyl chloride) (PVC) membrane using this new material as a plasticizer and quantified ALP in aqueous solutions. Preliminary results suggested that the PVC membrane responded to ALP at an interface between the membrane and the sample solution with anion extraction to maintain electroneutrality in the membrane phase. The developed PVC membrane showed an approximately six-times higher sensitivity than the conventional membrane, thereby demonstrating highly sensitive ALP detection. These results suggested the potential applicability of the proposed membrane for highly sensitive protein detection by using ALP-labeled antibodies.

Ionic liquids as solvents for Čerenkov counting and the effect of a wavelength shifter

We study the wavelength shift of the Čerenkov light – generated in the ionic liquid (BMIMCl) – caused by the addition of the highly fluorescent ionic liquid (BMIMHPTS). 18F and 32P efficiencies increases up to 124% and 14%, respectively, compared with the values obtained with pure BMIMCl. With this improvement, ionic liquid mixtures become a good alternative – when using the TDCR-Cherenkov technique – to standardize radionuclides having electron emissions energies close to the threshold energy in water (∼ 260keV). As an advantage compared with other solvents, the Ionic liquid mixture can be reused, in the case of short-lived radionuclides, by simply removing all water content in a vacuum oven.

Designing an anion-functionalized fluorescent ionic liquid as an efficient and reversible turn-off sensor for detecting SO2.

A novel anion-functionalized fluorescent ionic liquid was designed and prepared, which was capable of capturing sulphur dioxide with high capacity and could also be used as a good colorimetric and fluorescent SO2 sensor. Compared to conventional fluorescent sensors, this fluorescent ionic liquid did not undergo aggregation-caused quenching or aggregation-induced emission, and the fluorescence was quenched when exposed to SO2, and the fluorescence would quench when exposed to SO2. The experimental absorption, spectroscopic investigation, and quantum chemical calculations indicated that the quenching of the fluorescence originated from SO2 physical absorption, not chemical absorption. Furthermore, this fluorescent ionic liquid exhibited high selectivity, good quantification, and excellent reversibility for SO2 detection, and showed potential for an excellent liquid sensor.

Selective detection of picric acid by a fluorescent ionic liquid chemosensor

A fluorescent ionic liquid with a dansylamide chromophore was designed and synthesized, which exhibited strong green fluorescence both in the solution and in the condensed phase. As a fluorescent sensor, this ionic probe showed highly sensitive and selective detection of nitroaromatic explosives, especially for picric acid (PA). Theoretical calculations and NMR studies have demonstrated that a ground-state charge transfer through a protonation process and favorable electrostatic π–π interactions between ionic probe and PA may be responsible to the fluorescence quenching mechanism. Moreover, the resonance energy transfer (RET) studies explained the higher sensitivity and selectivity of this ionic probe towards PA than other nitro-containing explosives. A fluorescent test paper was also prepared for the on-site and accurate detection of PA, which provided a new clue of thoughts for instant and highly selective detection of nitroaromatic explosives.