Formation Of J-aggregates Research Articles

Cyanide and chloroform detection through J-aggregates based aggregation induced emission probe with real sample applications

Isopthalamide based probe DPI has been synthesized by an easy two-step substitution reaction. Unique fluorescence properties of probe DPI were exploited for sensing of CNˉ and chloroform. Various spectroscopic techniques such as NMR, LC-MS, SEM, DLS, UV-Vis. and fluorescence spectroscopy in combination with DFT studies were used to confirm efficient detection of CN‾ through a non-covalent interaction of cyanide with probe. Furthermore, probe showed fluorescence emission at 360 nm which shifted significantly to 415 nm upon addition of water exhibiting unique AIE characteristics and formation of desired J-aggregates. Mechanistically, CN‾ and chloroform were selectively detected through fluorescence quenching with 9 nM and 0.2 % v/v limit of detection (LOD), respectively. Photoinduced electron transfer (PET) was proven to be involved as a sensing mechanism. Moreover, DPI exhibited interesting solvatochromism properties. DPI was proven to be a highly sensitive probe which showed solid-state and vapor phase on-field detection of CN‾. Similar sensing behavior of DPI probe towards CN‾ was seen in food and water samples.

Automated Image-Based Fluorescence Screening of Mitochondrial Membrane Potential in Daphnia magna: An Advanced Ecotoxicological Testing Tool.

This study demonstrated the strengths of in vivo molecular staining coupled with automated imaging analysis in Daphnia magna. A multiwell plate protocol was developed to assess mitochondrial membrane potential using the JC-1 dye. The suitability of five common anesthetics was initially tested, and 5% ethanol performed best in terms of anesthetic effects and healthy recovery. The staining conditions were optimized to 30 min staining with 2 μM JC-1 for best J-aggregate formation. The protocol was validated with the model compound carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and used to measure the effect of four environmental contaminants, 2,4-dinitrophenol, triclosan, n-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and ibuprofen, on mitochondrial health. Test organisms were imaged using an automated confocal microscope, and fluorescence intensities were automatically quantified. The effect concentrations for CCCP were lower by a factor of 30 compared with the traditional OECD 202 acute toxicity test. Mitochondrial effects were also detected at lower concentrations for all tested environmental contaminants compared to the OCED 202 test. For 2,4-dinitrophenol, mitochondria effects were detectable after 2 h exposure to environmentally relevant concentrations and predicted organism death was observed after 24 h. The high sensitivity and time efficiency of this novel automated imaging method make it a valuable tool for advancing ecotoxicological testing.

Phthalocyanine J-aggregate nanoparticles with enormous-redshifted and intense absorption: Potential structure-J-aggregation relationships and application in tumor-associated macrophages-targeted phototheranostics

Phthalocyanines (Pcs) are considered promising in cancer phototherapy. However, their maximum absorption wavelengths are only around 700 nm, which cannot allow deep tissue penetration and leads to poor therapeutic efficacy. To expand their clinical application, significantly shifting their absorption to longer wavelengths is urgently required. Dye J-aggregates exhibit a redshifted absorption relative to its monomer. However, Pc J-aggregates with enormous-redshifted and intense absorption is rarely reported, and little is known about the relationships between Pc structure and J-aggregation. Herein, such Pc J-aggregates are ingeniously conceived. With a yeast β-D-glucan-ursodeoxycholic acid conjugate as a potential tumor-associated macrophages (TAMs)-targeting carrier and 1-(4-carboxyethylphenoxy) zinc (II) phthalocyanine (Pc1) as a model, Pc1 J-aggregate nanoparticle (NanoPc1) is obtained via ultrasonication-aided emulsification-solvent evaporation technique. NanoPc1 displays strong absorption at 830 nm, with a 156 nm redshift. Further investigation on another twenty-four Pcs demonstrates that unsubstituted zinc (II) or magnesium (II) Pc and hydrophobic mono-substituted zinc (II) or magnesium (II) Pcs with mono-substituted phenoxy or phenylthio or naphthoxy as a substituent can readily form desired Pc J-aggregates with significant redshifts (140–165 nm). The other Pcs fail to form expected J-aggregates probably due to absence of central metals, steric hindrance on central metals (atoms), forming axial coordination on central metals, disorder tendency during self-assembly or hydrophilicity. The theoretical calculation indicates that Pc1 in its J-aggregates exhibits a spiral-like arrangement, and the reduction in the energy gap between HOMO and LUMO and variation of intermolecular π-π interaction caused by J-aggregate formation are responsible for the huge redshift. Additionally, using NanoPc1 as an exemplar, such Pc J-aggregate nanoparticles are substantiated to afford TAMs-targeted and efficient tri-modal imaging and photothermal therapy in a H22 mouse model.

AIE active blue light emitting pyridine functionalized quinoxaline and pyridopyrazine derivatives exhibiting reversible acidofluorochromism and thermal sensitivity

This work presents a systematic study of five novel closely related pyridine-substituted quinoxaline and pyridopyrazine derivatives 3a-e. Modifying the quinoxaline framework by introducing electron donating and accepting units led to fine-tuning of optical, thermal, and electrochemical properties. The single crystal X-ray diffraction studies revealed a Y-shaped structure with a herringbone packing arrangement. These compounds showed aggregation-induced emission (AIE) with the formation of J-aggregates. These compounds emitted blue fluorescence with one of the compounds showing CIEy as low as 0.08 in CHCl3 and 0.09 in the solid state. The band gaps were evaluated using UV-visible spectroscopy and density functional theory (DFT). The optical band gaps in the solid state were in the 2.81–3.05 eV range. They exhibited reversible switching of emission properties upon treatment with trifluoroacetic acid (TFA) followed by triethylamine (TEA) in both solution and solid states, which was utilized to fabricate filter paper strips to detect volatile acids. The emission of compounds also displayed linear temperature dependence.

Structurally Modulated Formation of Cyanine J-Aggregates with Sharp and Tunable Spectra for Multiplexed Optoacoustic and Fluorescence Bioimaging.

J-aggregation brings intriguing optical and electronic properties to molecular dyes and significantly expands their applicability across diverse domains, yet the challenge for rationally designing J-aggregating dyes persists. Herein, we developed a large number of J-aggregating dyes from scratch by progressively refining structure of a common heptamethine cyanine. J-aggregates with sharp spectral bands (full-width at half-maximum≤38 nm) are attained by introducing a branched structure featuring a benzyl and a trifluoroacetyl group at meso-position of dyes. Fine-tuning the benzyl group enables spectral regulation of J-aggregates. Analysis of single crystal data of nine dyes reveals a correlation between J-aggregation propensity and molecular arrangement within crystals. Some J-aggregates are successfully implemented in multiplexed optoacoustic and fluorescence imaging in animals. Notably, three-color multispectral optoacoustic tomography imaging with high spatiotemporal resolution is achieved, owing to the sharp and distinct absorption bands of the J-aggregates.

A twistable aggregation induced emission enhancement active multisite fluorescent sensor for targeted sensing of zinc ions, 4-nitrophenol and chloroform in diverse conditions

Excessive utilization of Zn2+ and 4-nitrophenol (4-NP) in multiple fields has been becoming a serious threat to the environment and human health from a long time. Considering this, a multipurpose, extremely sensitive and selective fluorescent sensor BMP has been developed for the sensing of Zn2+, 4-NP and chloroform. Chalcone based sensor BMP was easily synthesized through simple aldol condensation reaction that possessed remarkable aggregation induced emission enhancement (AIEE) features along with the formation of J-aggregates. The particle size of aggregates was measured by DLS analysis. Sensor BMP showed strong emission at wavelength 430 nm. Moreover, sensor BMP showed different emissive behavior in various solvents. Sensor BMP selectively detected the Zn2+ through Chelation Enhanced Fluorescence (CHEF) intensity. BMP sensor has selectively sensed the 4-NP through photo-induced electron transfer (PET) quenching mechanism. Along with Zn2+ and 4-NP the sensor BMP has interestingly detected the percentage of chloroform in DCM. The calculated values of limit of detection for Zn2+, 4-NP and chloroform is 43 nM, 18 nM and 0.1 % v/v, respectively. UV–Visible, 1H NMR, LC-MS titration, and SEM experiments were also executed to verify the interaction of BMP sensor with respective analytes. Furthermore, the experimental findings were further justified through the theoretical studies including energy calculation of orbitals and nature of interactions. BMP sensor was employed in both solution and solid state for successful sensing of Zn2+, 4-NP and chloroform in real samples.

Supramolecular Chiral Aggregation of Porphyrin Induced by Photo-Generated Triphenylamines Radical Cations.

Here, it is shown that photoirradiation triggered chiral J-aggregates formation of an achiral anionic porphyrin, TPPS (tetrakis(4-sulfonatophenyl) porphyrin), in the presence of chiral triphenylamine (TPA) derivatives. A series of chiral triarylamines linked with aromatic rings is designed through urea or amide bonds. UV-irradiation of self-assembled urea-linked triphenylamine derivatives causes the formation of persistent radical cations in the chlorinated solvents, which subsequently induces the aggregation of TPPS. Transferring chirality of TPA derivatives to achiral TPPS J-aggregates leads to the chiral assemblies with remarkable chiroptical signals. The experimental results demonstrate that, TPA derivatives linked by the urea bond can effectively promote the aggregation of TPPS rather than those with the amide bond although the photo-generated radical cations are both produced. It is suggested that the urea-linked TPA derivatives are more favorable to stable radical cations and thus cause the formation of TPPS chiral J-aggregation. This work may open up an avenue for designing photo-modulated chiral supramolecular assemblies.

Designing A-D-A Type Fused-Ring Electron Acceptors with a Bulky 3D Substituent at the Central Donor Core to Minimize Non-Radiative Losses and Enhance Organic Solar Cell Efficiency.

Designing and synthesizing narrow band gap acceptors that exhibit high photoluminescence quantum yield (PLQY) and strong crystallinity is a highly effective, yet challenging, approach to reducing non-radiative energy losses (▵Enr) and boosting the performance of organic solar cells (OSCs). We have successfully designed and synthesized an A-D-A type fused-ring electron acceptor, named DM-F, which features a planar molecular backbone adorned with bulky three-dimensional camphane side groups at its central core. These bulky substituents effectively hinder the formation of H-aggregates of the acceptors, promoting the formation of more J-aggregates and notably elevating the PLQY of the acceptor in the film. As anticipated, DM-F showcases pronounced near-infrared absorption coupled with impressive crystallinity. Organic solar cells (OSCs) leveraging DM-F exhibit a high EQEEL value and remarkably low ▵Enr of 0.14 eV-currently the most minimal reported value for OSCs. Moreover, the power conversion efficiency (PCE) of binary and ternary OSCs utilizing DM-F has reached 16.16 % and 20.09 %, respectively, marking a new apex in reported efficiency within the OSCs field. In conclusion, our study reveals that designing narrow band gap acceptors with high PLQY is an effective way to reduce ▵Enr and improve the PCE of OSCs.

A novel near-infrared polymethine dye biosensor for rapid and selective detection of lithocholic acid

Lithocholic acid (LCA), a secondary bile acid, has emerged as a potential early diagnostic biomarker for various liver diseases. In this study, we introduce a novel near-infrared (NIR) polymethine dye-based biosensor, capable of sensitive and selective detection of LCA in phosphate buffer and artificial urine (AU) solutions. The detection mechanism relies on the formation of J-aggregates resulting from the interplay of 3,3-Diethylthiatricarbocyanine iodide (DiSC2(7)) dye molecules and LCA, which induces a distinctive red shift in both absorption and fluorescence spectra. The biosensor demonstrates a detection limit for LCA of 70 μM in PBS solution (pH 7.4), while in AU solution, it responds to an LCA concentration as low as ∼60 μM. Notably, the proposed biosensor exhibits outstanding selectivity for LCA, effectively distinguishing it from common interferents such as uric acid, ascorbic acid, and glucose. This rapid, straightforward, and cost-effective spectrometer-based method underscores its potential for early diagnosis of liver diseases by monitoring LCA concentrations.

Absorption and Fluorescence Emission Investigations on Supramolecular Assemblies of Tetrakis-(4-sulfonatophenyl)porphyrin and Graphene Quantum Dots.

The one-pot synthesis of N-doped graphene quantum dots (GQDs), capped with a positively charged polyamine (trien), has been realized through a microwave-assisted pyrolysis on solid L-glutamic acid and trien in equimolar amounts. The resulting positively charged nanoparticles are strongly emissive in aqueous solutions and are stable for months. The interaction with the anionic tetrakis(4-sulphonatophenyl)porphyrin (TPPS4) has been investigated at neutral and mild acidic pH using a combination of UV/vis absorption spectroscopy together with static and time-resolved fluorescence emission. At pH = 7, the experimental evidence points to the formation of a supramolecular adduct mainly stabilized by electrostatic interactions. The fluorescence emission of the porphyrin is substantially quenched while GQDs remain still emissive. On decreasing the pH, protonation of TPPS4 leads to formation of porphyrin J-aggregates through the intermediacy of the charged quantum dots.

Investigating structural dynamics and sensing capabilities: Spectroscopic and DFT analysis of novel AIEE active deferasirox based organic sensor

A deferasirox based sensor DPA was rationally designed through single step amidation reaction. Sensor DPA exhibited aggregation induced emission enhancement (AIEE) property that was attributed to restriction in intramolecular rotation (RIR). Moreover, the sensor DPA displayed remarkable bathochromic shift (red-shift) of 110 nm in wavelength, ascribed to formation of J-aggregates. Furthermore, sensor DPA was employed for the selective and sensitive fluorescence based sensing of hazardous and carcinogenic nitrobenzene (NB). The sensor DPA successfully detected NB in solution through the quenching of emission intensity. The quenching of sensor fluorescence intensity was ascribed to photoinduced electron transfer (PET) mechanism. The sensing mechanism was investigated by 1H NMR titration experiment, Job's plot and density functional theory (DFT) calculations. Additionally, the existence of non-covalent interactions between sensor DPA and NB were examined by Bader's Quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. Finally, sensor DPA was employed for the detection of volatile nitrobenzene in vapor phase.

Exploring Efficient Dual-Phase Emissive Fluorophores with High Mobility by Integrating a Rigid Donor and Flexible Acceptor.

Developing luminogens with a high emission efficiency in both single-molecule and aggregate states, as well as high mobility, shows promise for advancing the iteration and update of organic optoelectronic materials. However, achieving a delicate balance between the plane configuration of luminophores and the strong exciton interactions of aggregates is a formidable task from the molecular design perspective. This dilemma was overcome by integrating a rigid donor and flexible acceptor to establish donor-acceptor (D-A) type emitters. The π-conjugate-extended donor ensures the substantial planarity of these molecules, allowing strong emission in solution with photoluminescence quantum yield values of 86% and 75%. Furthermore, the restricted molecular motion of the aggregation-induced emission moiety and the formation of J-aggregates reduce the quenching effect, leading to a high emissive efficiency of 85% and 91% in the aggregate state. The mildly distorted D-A geometry builds moderate electrostatic interaction, resulting in high mobility with μM,h of 7.12 × 10-5 and 3.27 × 10-4 cm2/V s. Additionally, an improved synthesized procedure for terminal E-configured acrylonitrile with metal-free and concise reaction conditions is presented. The successful application of the synthesized compounds in organic light-emitting diode devices demonstrates the practicability of the molecular design strategy with connecting a rigid donor and flexible acceptor.

Highly sensitive fluorescence turn-OFF and reversible chemical sensor for Hg2+ ion based on pyrene appended 2-thiohydantoin

A novel fluorometric chemical sensor (PY-2TH) based on 2-thiohydantoin (2TH) in conjugation with pyrene (PY) was designed by facile one-pot Knoevenagel condensation reaction and explored for the sensitive and selective detection of Hg2+ ion in solution and solid state methods. Different analytical techniques like NMR and LC-MS concomitantly confirmed the structure of PY-2TH. Absorption and emission studies demonstrate positive solvatochromic effects indicating intramolecular charge transfer in polar solvents. PY-2TH exhibits unprecedented selectivity for detecting Hg2+ ions in tetrahydrofuran (THF) through turn-OFF fluorescence with 90% decrease in the emission intensity with a limit of detection (LOD) of ∼4.4 ppb. The mechanistic investigation through NMR and optical studies confirm the formation of a 2:1 complex between PY-2TH and Hg2+. Thin films of PY-2TH exhibits the J-aggregate formation in the solid state leading to a shift in the emission towards the near-infrared region. Further, we have demonstrated the applicability of PY-2TH for detection of Hg2+ ions and fluorescence imaging in live Zebrafish larvae and the toxicological effects are explored. Cytotoxic evaluation on Zebrafish larval cells revealed that PY-2TH is found to be non-toxic. Detailed analysis demonstrate the potential of PY-2TH for ultra-sensitive Hg2+ ion detection and removal in aqueous environments, highlighting its applicability for identification of metal contamination in live organisms and environmental toxicity.

Harnessing J-aggregation for dual-color cellular imaging with chromenoquinoline-benzimidazole dyes.

Fluorescence imaging has revolutionized the visualization of cellular structures and biomolecules due to its non-invasive nature and high sensitivity. Chromenoquinoline (CQ)-based dyes offer promising optical properties, yet their widespread application is hindered by aggregation-caused quenching (ACQ). In contrast, J-aggregates, characterized by distinctive photophysical properties, present a solution to ACQ. Here, we introduce a novel platform employing chromenoquinoline-benzimidazole (CQ-BI) dyes, capable of forming J-aggregates, for dual-color cellular imaging. The incorporation of a methyl group into the benzimidazole moiety enhances J-aggregate formation, leading to robust emission in both dilute solutions and aggregated states. Our study demonstrates that methyl moiety-modified CQ-BI derivatives enable simultaneous imaging of mitochondria and lipid droplets in living cells. This work underscores the potential of CQ-BI dyes for dual-channel fluorescence imaging, leveraging the unique properties of J-aggregation.

Naturally J-aggregated F-BODIPYs: Self-assembly organization driven by substitution pattern

The development of self-assembled dyes able to display J-aggregation-induced emission has gained a renewed interest as an appealing and distinctive approach for the design of smart photoactive materials. F-BODIPY dyes have been exploited to this aim since J-type supramolecular organization has been effectively photoinduced under specific surrounding conditions (hydrophilic or constrained media) although, up to date, it has never been observed in pure organic media. Herein, we report the first systematic study of the self-assembly properties of F-BODIPYs in pure organic solvents and analyze in depth the control exerted by the substitution pattern of its carbon skeleton into the formation of emissive J-aggregates. Spontaneous J-aggregation in F-BODIPYs is evidenced by their lasing properties and supported by the analysis of their solid-state photophysics and X-ray crystalline packing as well as by molecular dynamics in solvent cages. These studies point out the key role of the stereoelectronic properties of the substituents orthogonally grafted at the dipyrrin core (meso and C-2 and C-6 positions) as the main driving force to control the molecular stacking arrangement of F-BODIPYs in common organic solvents. The understanding of the interplay between the molecular structure and the properties of the resulting aggregates sheds light on the workability of BODIPY-based self-assembly as a tool for advanced luminescent materials.

Investigation of Mechanochromic Luminescence of Pyrene-based Aggregation-Induced Emission Luminogens: Correlation between Molecular Packing and Luminescence Behavior.

To better understand the correlation between molecular structure and optical properties such as aggregation-induced emission (AIE) and mechanochromic luminescence (MCL) emission, two new pyrene-based derivatives with substitutions at the 4- and 5-positions (1HH) and at the 4-, 5-, 9-, and 10-positions (2HH) were designed and synthesized. Cyano groups were introduced at the periphery of the synthesized compounds (1HCN, 1OCN, 1BCN, 2HCN, 2OCN, and 2BCN) to investigate the influence of these groups on the emission properties of the pyrene derivatives both in solution and in the solid state. The fluorescence emission performance of these compounds in water/acetone mixtures was simultaneously studied, revealing outstanding aggregation-induced emission properties. The typical shift in emission maxima to higher values was attributed to J-aggregate formation in the aggregate state. Careful investigation of the crystal structures demonstrated abundant and intense intermolecular interactions, such as C-H…π and C-H…N hydrogen bonds, contributing to the remarkable mechanochromic luminescence performance of these compounds. The MCL properties of all the compounds were investigated using powder X-ray diffraction, and the remarkable mechanochromic properties were attributed to J-aggregate phenomena in the solid state. These results provide valuable insights into the structure-property relationship of organic MCL materials, guiding the design of efficient organic MCL materials.

J-Aggregate-Triggering BODIPYs: an Ultrasensitive Chromogenic and Fluorogenic Sensing Platform for Perfluorooctanesulfonate.

Contamination of water supplies by polyfluoroalkyl substances, notably perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), has serious health and environmental consequences. Therefore, the development of straightforward and effective means of monitoring and removing PFASs is urgently required. In this study, we report a rapid and sensitive method for the detection of PFOS and PFOA in water that rely on the J-aggregate formation of meso-ester-BODIPY dyes. The dye C10-mim, which contains a hydrophilic methylimidazolium group and a hydrophobic alkylated BODIPY, self-assembles in water into weakly green-emissive micellar assemblies. Upon binding to PFOS or PFOA, a spontaneous disassembly and reorganization forms orange-emissive J-aggregates. The rapid formation (≤5 s) of J-aggregates and the accompanying spectral shifts provide a superior sensing performance, with excellent sensitivity (limit of detection=0.18 ppb for PFOS) and distinct chromogenic and fluorogenic "turn-on" responses.

Luminescence of Boron Difluoride Ditoluoylmethanate. Formation of J-Aggregates

Luminescence of Boron Difluoride Ditoluoylmethanate. Formation of J-Aggregates

Trapping and release of NIR-active dye in porous silicon as a theranostic strategy for ROS photothermal monitoring and chronic wound management.

Reactive oxygen species (ROS)-sensitive theranostics hold great promise for personalized treatment of various diseases. However, most current theranostics rely on luminescence techniques with complex probe design, high background signals and bulky instruments. Herein, we propose a novel thermal signal-based theranostic for ROS monitoring by detecting the photothermal signal change of near-infrared (NIR)-active dye (IR820) that released from the porous silicon (PSi)-based carrier and demonstrate its application for synergistic theranostics of chronic wounds. Owing to the reduced energy level caused by J-aggregate formation and the improved non-radiative decay pathway, trapping of IR820 in calcium ion sealed PSi (I-CaPSi) exhibits significantly enhanced photothermal capability compared to free IR820. With the degradation of PSi induced by ROS, the trapped and aggregated IR820 is released to be dispersed and free state. Therefore, the decrease of photothermal signal in response to ROS stimuli can be recorded in real time. Using a portable smartphone equipped with a thermal camera, ROS levels at wounds can be monitored non-invasively and conveniently to indicate exacerbation or healing conditions. Moreover, the NIR-triggered smart delivery platform also triggers photothermal and photodynamic therapy to inhibit bacterial growth and exhibits bioactivity to promote cell migration and angiogenesis via the Si ions released from PSi. With the synergistic advantages of ROS-responsive property, pro-healing ability, anti-infection effect and excellent biosafety, the NIR-activated theranostic platform achieves convenient diagnosis and effective treatment in diabetic wound infection models in vivo. Overall, this work demonstrates a promising paradigm of I-CaPSi smart delivery platform with great clinical translation potential for home-based chronic wound theranostics.

Spectral features of the dispersion of carbocyanine dye J-aggregates in a liquid crystal matrix

Formation of J-aggregates of the anionic cyanine dye TDBC in a nematic liquid crystal (LC) matrix is reported, with analysis of optical-fluorescent and electro-optical properties of the obtained novel material. The TDBC J-aggregates show a rather long lifetime and high photostability in the nematic matrix. The electro-optical characteristics of the LC matrix are substantially modified, with the Fredericks transition threshold slightly increased, which is, on the other hand, accompanied by the improvement of the optical contrast. Only a minor effect of the forming J-aggregates on the molecular order of the LC structure could be noted.