Browsing by Author "Pranjalee Yadav"

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A colorimetric and ‘OFF-ON’ fluorometric chemosensor based on a rhodamine-pyrazole derivative for the detection of Al3+, Fe3+and Cr3+metal ions, and its intracellular application
(Royal Society of Chemistry, 2023) Sarita Gond; Pranjalee Yadav; Aayoosh Singh; Somenath Garai; Anusmita Shekher; Subash Chandra Gupta; Vinod P. Singh
The colorimetric and fluorescence responses of a new rhodamine-functionalized probe (E)-2-(((5-chloro-3-methyl-1-phenyl-1H-pyrazol-4-yl)methylene)amino)-3′,6′-bis(diethylamino)spiro[isoindoline-1,9′-xanthen]-3-one (RMP) are investigated. RMP has been thoroughly characterized using various spectroscopic tools and single crystal X-ray diffraction. Among different competing cations, it shows highly sensitive colorimetric and “OFF-ON” fluorescence responses towards Al3+, Fe3+and Cr3+metal ions. The spectral shifts are clearly noticeable in the visible region of the absorption spectrum and can be observed with the naked eye. Fluorescence quantum yield, stoichiometric ratio, binding constant and detection limit of RMP towards Al3+, Fe3+and Cr3+metal ions have been calculated. Furthermore, RMP-M3+ complexes are reversible and sensitive to EDTA, which effectively mimics a molecular logic gate. Al3+, Fe3+and Cr3+metal ions have been further applied in intracellular application in model human cells. © 2023 The Royal Society of Chemistry
A coumarin derived turn ‘off–on-off’ probe for selective sequential monitoring of Al3+ and Cu2+ ions with bio-imaging application
(Elsevier B.V., 2024) Sarita Gond; Avanish Kumar Singh; Pranjalee Yadav; Pradeep Kumar; S. Srikrishna; Vinod P. Singh
Herein, a coumarin-based chemosensor (E)-N'-(1-(2-oxo-2H-chromen-3-yl)ethylidene) thiophene-2-carbohydrazide (ACT) has been synthesized and thoroughly characterized by using various spectroscopic techniques. The molecular structure of the probe has been confirmed by single crystal X-ray diffraction technique. Hirshfeld surface analysis has also been carried out to investigate weaker interactions in the probe molecule. ACT shows a highly selective enhanced fluorometric response towards Al3+ in ethanol among different competing cations. Upon interaction with Al3+, a new complex ACT-Al3+ is formed which displays a strong yellow fluorescence due to chelation enhanced fluorescence process (CHEF). Furthermore, in situ ACT-Al3+ complex is exploited for sequential recognition of Cu2+ with fluorescence turn-off via paramagnetic quenching mechanism among different competing cations. This study presents an exceptionally low detection limits of ACT for Al3+ and Cu2+ ions (2.33 × 10−11 and 1.96 × 10−11 M, respectively). Furthermore, the binding constants of ACT for Al3+ and Cu2+ were found to be 7.97 × 104 and 9.79 × 104 M−1, respectively. The binding mechanism has been verified by 1H NMR titration and DFT calculations. Sensing behaviour of ACT towards Al3+ and Cu2+ have also been exploited in the development of paper strip kit and intracellular application in 3rd instar larvae of Drosophila. © 2024 Elsevier B.V.
A coumarin-derived multi-faceted optical material with molecular logic gate for bioimaging
(Royal Society of Chemistry, 2025) Amit Kumar Singh; Pranjalee Yadav; Aayoosh Singh; Avanish Kumar Singh; Shashi Kant Sharma; Vijay Kumar Sonkar; Vinod Prasad Singh
The development of stimuli-responsive, multi-faceted chromic materials has gained the interest of the material science community recently, owing to their vast range of applications in several areas simultaneously, such as viscosity, temperature, and pressure detectors. In this context, a coumarin-derived organic luminophore, HCFH, has been designed and extensively investigated for its characteristics, such as aggregation-induced emission (AIE), viscochromism, piezochromism, thermochromism, and distinguishable fluorometric detection of Zn2+ and Cu2+ ions in water. The emission intensity of HCFH amplifies 111-fold with the addition of water in tetrahydrofuran (THF), validating its aggregation-induced emission (AIE) nature. Multi-colored piezochromism is observed in the ‘crystalline’, ‘pristine’, and ‘ground’ forms of HCFH as non-emissive, weakly cyan-emissive, and bright green-emissive, respectively. Further, powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses indicate a crystalline-to-amorphous phase transition during grinding. HCFH exhibits remarkable photophysical properties, including viscosity, polarity, and temperature-dependent emissions. The probe selectively detects Zn2+ and Cu2+ ions with limits of detection (LOD) of 1.14 and 1.54 nM, respectively, employing chelation-enhanced fluorescence (CHEF) and inhibition of photo-induced electron transfer (PET) for Zn2+ and paramagnetic fluorescence quenching for Cu2+. The Job's plots indicate 1 : 2 and 1 : 1 (M : L) binding stoichiometries for Zn2+ and Cu2+, respectively, which are confirmed by their single-crystal structures. Molecular logic gates and paper strip kits are also developed utilizing their sensing capabilities. HCFH has been found highly effective in bio-imaging of Zn2+ and Cu2+ in HeLa cells. Microscopic examination of the cells indicates that the probe is localized in both the cytosol and mitochondria of the cells. © 2025 The Royal Society of Chemistry.
A multifunctional basic pH indicator probe for distinguishable detection of Co2+, Cu2+ and Zn2+ with its utility in mitotracking and monitoring cytoplasmic viscosity in apoptotic cells
(Royal Society of Chemistry, 2022) Pranjalee Yadav; Sarita Gond; Anusmita Shekher; Subash Chandra Gupta; Udai P. Singh; Vinod P. Singh
Metal ions such as Co2+, Cu2+ and Zn2+ have extensive applications in biological and industrial realms, but the toxicity caused by these ions poses a serious threat to mankind. However, there is no report in the literature on the development of a chemosensor for distinguishable detection of these toxic ions. Addressing this challenge, a multifunctional probe as a basic pH indicator with both colorimetric and fluorescence turn-on responses has been reported. The probe selectively discriminates Co2+, Cu2+ and Zn2+ ions with brown, dark yellow and greenish yellow colors, respectively, in DMF : water (9 : 1 v/v, HEPES 10 mM). Additionally, a fluorescence turn-on response specific to Zn2+ has also been observed. The sensing mechanism has been explored using UV-Vis, fluorescence spectroscopy and 1H NMR titration and confirmed with computational results. The inhibition of C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N isomerization and excited state intramolecular proton transfer (ESIPT) along with chelation enhanced fluorescence emission (CHEF) result in fluorescence enhancement with Zn2+. Job's plot and HRMS spectra confirm a 1 : 1 (L : M) stoichiometry between the probe and metal ions. The probe is able to exhibit excellent viscochromism in DMF : glycerol medium. Live cell imaging on SiHa cells has been successfully performed for intra-cellular detection of Zn2+ at basic pH. Furthermore, the probe displays its utility in mitotracking and monitoring cytoplasmic viscosity changes in SiHa cells. It is efficiently used to recognize the apoptosis process by displaying an enhancement in fluorescence intensity from cancerous SiHa cells to apoptotic cells. © 2022 The Royal Society of Chemistry.
A multifunctional coumarin-based probe for distinguishable detection of Cu2+ and Zn2+: its piezochromic, viscochromic and AIE behavior with real sample analysis and bio-imaging applications
(Royal Society of Chemistry, 2023) Aayoosh Singh; Pranjalee Yadav; Saumya Singh; Pradeep Kumar; S. Srikrishna; Vinod P. Singh
A multifunctional coumarin based organic luminophore, CTH, has been synthesized and its fluorescence properties are investigated. The probe displays the properties of aggregation-induced emission (AIE), viscochromism, piezochromism and distinguishable flourometric sensing of Cu2+ and Zn2+ ions. The molecular structure of the probe has been determined by FT-IR, UV-Vis, NMR, and HRMS spectral studies. Powder XRD, dynamic light scattering (DLS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and density functional theory (DFT) calculations have been carried out to explore the photo-physical properties of the synthesized probe. CTH is non-emissive in ethanol, but upon adding water its emission intensity increases by 8-fold and fluorescence quantum yield increases from Φ = 1.19 × 10−3 (fw = 70%) to Φ= 8.50 × 10−3 (fw = 99%), indicating typical AIE behaviour. The probe demonstrates excellent viscochromism with increasing glycerol fraction in EtOH. Upon grinding, the probe exhibits piezochromic properties and shows an emissive color change from blue to bright green along with a bathochromic shift of 83 nm. In addition to the aforementioned properties, the probe selectively discriminates Cu2+ and Zn2+ from a pool of different metal ions in DMF : H2O (3 : 7, v/v, pH 7.4) HEPES buffer. CTH detects Cu2+ and Zn2+ ions via paramagnetic fluorescence quenching and CHEF induced fluorescence enhancement, respectively. Job's plots suggest 1 : 1 binding stoichiometry for both CTH-Cu2+ and CTH-Zn2+ complexes. Significant low detection limits (LODs) of 6.75 nM for Cu2+ and 2.97 nM for Zn2+ have been observed and molecular logic gates have also been constructed. The probe has been effectively utilized in the bio-imaging of Cu2+ and Zn2+ in the gut tissue of Drosophila and in the quantification of Cu2+ and Zn2+ in real water samples. © 2023 The Royal Society of Chemistry.
A novel 3-acetyl coumarin based AIE luminophore for colorimetric recognition of Cu2+ and F− ions
(Elsevier B.V., 2023) Sarita Gond; Pranjalee Yadav; Avanish Kumar Singh; Vinod P. Singh
A 3-acetyl coumarin appended probe 3-((Z)-1-((E)-((2-hydroxynaphthalen-1-yl) methylene) hydrazono)ethyl)-2H-chromen-2-one (CNH) has been successfully synthesized and characterized by different spectroscopic tools via IR, 1H & 13C NMR and HRMS. The probe displays solvent dependent colorimetric detection of Cu2+ and F− ions in THF and DMF media, respectively. CNH interacts with Cu2+ in 1:1 stoichiometry with limit of detection 1.4 × 10−6 M. The color change of probe with addition of Cu2+ ions is due to ligand to metal charge transfer (LMCT) as suggested by UV–Vis spectra and DFT studies. Furthermore, CNH interacts with F− in 1:1 stoichiometry with detection limit 1.32 × 10−6 M by proton transfer mechanism from O-H to F−, which enhances the electron density on CNH molecule as suggested by UV–Vis, NMR titration and DFT studies. In addition to intriguing colorimetric sensing applications, CNH displays remarkable aggregation induced emission (AIE) property in DMF/water binary mixture. The probe is almost non-fluorescent in solution but becomes strongly emissive in aggregate/solid state. The formation of aggregates at higher water content is confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS) studies in mixed water media. DLS measurements suggest the increase in average particle size from 100 nm to 299 nm upon increasing water fractions from (fw = 10%) to (fw = 90%). AFM studies also provide additional information about the aggregates at higher water fraction. In the range of 100–500 nm, the topography of surface shows that the aggregates are spherical in shape (fw = 90%). © 2022 Elsevier B.V.
A pyrene-thiophene based probe for aggregation induced emission enhancement (AIEE) and naked-eye detection of fluoride ions
(Elsevier B.V., 2019) Pranjalee Yadav; Sarita Gond; Ashish Kumar Singh; Vinod P. Singh
A pyrene based probe (E)-N’-(pyren-1-ylmethylene)thiophene-2-carbohydrazide (PTH), was synthesized and characterized by IR, NMR and HRMS spectroscopic tools. The probe exhibited aggregation induced emission enhancement (AIEE) in binary solvent mixture (ACN/water) on increasing water fraction and displayed bright yellow emission in solid state. Fluorescence spectroscopy, time resolved fluorescence and DLS analysis have been exploited to gain insight into the mechanism. These results indicated an enhancement in quantum yield and average lifetime with an increase in water content. In addition to intriguing AIEE property, PTH demonstrated excellent selectivity and sensitivity for F− over various other anions. A plausible mechanism for interaction of the probe with F− has been proposed on the basis of 1H NMR titration, absorption spectra and DFT study. The recognition process was found to be driven by the high electronegativity of F− leading hydrogen bonded adduct followed by deprotonation of PTH. Instant naked eye response along with commendable detection limit (2.02 × 10−7 M) and binding constant (6.18 × 104 M−1) increased the pertinency of the probe. © 2019 Elsevier B.V.
A reversible and efficient probe for dual mode recognition of Al3+ and Cu2+ with logic gate behaviour: Crystal structure, theoretical and in-vivo bio-imaging investigations
(Elsevier B.V., 2022) Pranjalee Yadav; Rohit Kumar; S. Srikrishna; Anoop Kumar Pandey; Lokman H. Choudhury; Chandan Upadhyay; Vinod P. Singh
This work presents the synthesis, characterization, crystal structure and spectroscopic investigations of isophthalohydrazide based probe. Among various tested metal ions, the probe selectively detects Al3+ and Cu2+ in aqueous ethanol via fluorometric and colorimetric methods, respectively. It displays a fluorescence “turn-on” response with Al3+ and visual colour change from colourless to yellow with Cu2+. Sensing mechanism is explored with UV–Vis, fluorescence spectroscopy and 1H NMR titration, and confirmed with computational results. Suppression of C[dbnd]N isomerization and photo-induced electron transfer (PET) along with chelation enhanced fluorescence emission (CHEF) result in “turn-on” fluorescence with Al3+ while ligand to metal charge transfer (LMCT) accounts for visual colour change with Cu2+. Job's plot and HRMS confirm 1:2 (L:M) stoichiometry. The probe also exhibits efficient reversibility and reproducibility with EDTA which are successfully mimicked with combinatorial logic gate and truth table. Additionally, solid state applications and bio-imaging investigation on gut tissue of Drosophila 3rd instar larvae are performed. © 2021 Elsevier B.V.
A reversible and selective chromogenic thiazole tagged chemosensor for Hg2+in aqueous medium: Crystal structure, theoretical investigations and real sample analysis
(Elsevier B.V., 2023) Gautam Kumar; Ananya Srivastava; Sarita Gond; Pranjalee Yadav; Aayoosh Singh; Vinod P. Singh
A novel thiazole tagged Schiff base chemosensor, (E)-N'-((2-aminothiazol-5-yl)methylene)-2-hydroxybenzohydrazide (ATH) has been synthesized in excellent yield by a simple one pot method and characterized by single crystal X-ray diffraction and spectroscopic techniques. The sensing ability of ATH was determined for detection of Hg2+ ions in the presence of different metal ions in aqueous medium. It behaves as an extremely selective and sensitive chromogenic sensor for naked-eye detection of Hg2+ ions with a colour change from colourless to yellow due to ligand to metal charge transfer. Remarkably, the binding constant (Ka) and limit of detection (LOD) for ATH[sbnd]Hg2+ complex were found as 1.75 × 104 M −1 and 8.85 × 10−7 M, respectively. The Job's plot indicated that the stoichiometric ratio of ATH to Hg2+ is 1:1. The binding mechanism was established based on FT-IR, 1H NMR titration, mass spectrometry and density functional theory studies. The chemosensor exhibited an excellent colorimetric property in 7.0–12.0 pH range. The chemosensor was found to be reversible and reusable in the presence of CN− ions with logic gate behaviour. Further, the chemosensor was utilized to sense Hg2+ ions in tap and Ganga river water samples. © 2023 Elsevier B.V.
A Stimuli Responsive Multifunctional Smart Luminophore with Aggregation-Induced Enhanced Emission
(John Wiley and Sons Inc, 2025) Aayoosh Singh; Amit Kumar Singh; Pranjalee Yadav; Avanish Kumar Singh; Pradeep Kumar; Saripella Srikrishna; Vinod Prasad Singh
The development of multifunctional luminophores with tunable and stimuli-responsive optical properties is critical for the advancement of sensing, bioimaging, and optoelectronic technologies. Herein, a novel coumarin-based smart luminogen, (E)-N'-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)thiophene-2-carbohydrazide (ETH) is developed that exhibits pronounced multistimuli responsive behavior including aggregation-induced enhanced emission (AIEE), solvatochromism, viscochromism, reversible mechanochromism, and acidochromism. ETH shows solid-state fluorescence modulation on applying mechanical stress and exposing in acid/base vapor, with reversible redshifted emission. The ETH coated paper enables its practical applications in pressure-sensitive devices and portable acid vapor detection kits. In a mixed CH3CN–H2O system, ETH functions as a solvent-controlled dual-mode fluorescent probe, showing a turn-on response to Zn2+ and a turn-off response to Cu2+ with high sensitivity. Job's plot revealed 2:1 ligand-to-metal stoichiometry for Zn2+ and 1:1 for Cu2+. The fluorescent aggregates of ETH enable selective detection of Cu2+ through a disaggregation-induced fluorescence quenching mechanism. A portable cotton-swab-based test kit is developed for practical and on-site detection of Cu2+. ETH demonstrates excellent biocompatibility, as predicted by in vivo fluorescence imaging in Drosophila larval gut tissues. The combination of reversible optical switching, high fluorescence quantum yield and structural adaptability establish ETH as a novel multifunctional material for sensing, live-cell imaging, and smart optoelectronic devices. © 2025 Wiley-VCH GmbH.
Anthracene appended AIEgen as a reversible fluorescence sensor for hazardous cyanide ion in environmental samples and fabrication of portable test kit for on spot detection
(Elsevier B.V., 2025) Pranjalee Yadav; Aayoosh Singh; Gautam Kumar; Saumya Singh; Vinod Prasad Singh
CN− is a frequently encountered pollutant in water and soil. Due to its extreme lethal effect on mammals, serious consideration and efforts are needed for monitoring this hazardous anion. To address this challenge, herein, an anthracene-appended AIEgen (ACFH) has been synthesized and developed for selective fluorometric detection of CN− ion. The detection limit of the probe has been found to be 3.42 × 10−7 M (8.89 ppb), which is much lower than WHO standard (2.7 × 10−6 M). The interaction with CN− causes deprotonation of the probe and subsequent loss of planarity, which has been thoroughly confirmed from 1H NMR titrations and DFT calculations. The reversibility and reusability of ACFH and corresponding logic gates enhance its sensing performance and efficacy. Notably, it has been utilized to meritoriously quantify CN− in various water samples and the fabrication of a portable test kit for monitoring CN− in real time. In addition, the aggregation induced emission (AIE) property has been precisely explored with the aid of fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), fluorescence quantum yield and lifetime analysis. © 2024 Elsevier B.V.
Carbazole-quinoline based ultrasensitive fluorometric sensor for detection of Hg2+ in aqueous medium: Crystal structure, DFT and real sample application
(Elsevier B.V., 2025) Avanish Kumar Singh; Aayoosh Singh; Pranjalee Yadav; Amit Kumar Singh; Vinod Prasad Singh
A novel carbazole-quinoline tagged fluorophore, (E)-9-ethyl-3-((2-(quinolin-2-yl)hydrazineylidene)methyl)-9H-carbazole (QHC), has been synthesized with an excellent yield using the simple one-pot synthesis and its molecular structure is determined by single crystal X-ray diffraction, FT-IR, NMR and mass spectroscopic techniques. QHC has been developed as an ultrasensitive fluorometric sensor for detection of Hg2+ in the presence of competing metal ions in aqueous medium. It exhibited remarkable sensitivity and selectivity towards Hg2+ with limit of detection (LOD) of 2.59 × 10−8 M and a remarkable Stern-Volmer constant (Ksv) of 1.17 × 105 M−1. The Job's plot displayed 1:1 stoichiometry between QHC and Hg2+, with a binding constant (Ka) of 1.01 × 105 M−1. The binding mechanism has been demonstrated by FT-IR, mass spectrometry, 1H NMR titration and density functional theory (DFT) analysis. Upon interaction with Hg2+, the photo-induced electron transfer (PET) from quinoline-carbazole framework to Hg2+ is activated, thereby, completely quenching the fluorescence. The practical applicability of QHC was demonstrated through the development of test kits. Additionally, QHC was successfully employed to detect Hg2+ ions in real water samples, including lake water and Ganga river water, showing its significance in environmental monitoring. © 2025 Elsevier B.V.
Design and development of a highly efficient hydrazone based sensing material for selective detection of F− ions
(Elsevier B.V., 2023) Sarita Gond; Pranjalee Yadav; Vinod P. Singh
A 2,4-dinitrophenyl hydrazine appended sensing material has been synthesized and characterized by NMR, IR and HRMS spectral studies. The selective colorimetric sensing property of the chemosensor for F− has been thoroughly investigated with UV–Vis, NMR and DFT analysis. The limit of detection (LOD) and association constant has been found to be 1.37 μM and 3.09 × 107 M−1, respectively. High electronegativity of F− is responsible for hydrogen bonding induced deprotonation of chemosensor and subsequent color change from yellow to pink. Paper strip kit of the chemosensor has been applied successfully for sensing of F−. © 2023 Elsevier B.V.
Development of a reversible chromogenic sensor for Cu2+ in aqueous ethanol
(Elsevier B.V., 2021) Pranjalee Yadav; Sarita Gond; Aayoosh Singh; Vinod P. Singh
A naphthaldehyde appended sensor has been synthesized and characterized by spectroscopic techniques. The sensor has been efficiently utilized in selective chromogenic detection of Cu2+ in aqueous ethanol amongst various metal ions. Cu2+ interacts with the sensor in 1:2 (M:L) stoichiometry with binding constant of 1.1 × 103 M−1/2 and detection limit of 9.342 × 10−7 M. Ligand to metal charge transfer (LMCT) accounts for the selective color change from colorless to yellow with Cu2+ as suggested by UV–Vis and DFT studies. This sensor offers certain advantages over the existing chemosensors in terms of reversibility, reusability and solid state applications. © 2021 Elsevier B.V.
Development of an ‘OFF-ON-OFF’ colorimetric and fluorometric pH sensor for the study of physiological pH and its bioimaging application
(Elsevier B.V., 2022) Sarita Gond; Pranjalee Yadav; Brijesh Singh Chauhan; S. Srikrishna; Vinod P. Singh
2-hydroxyl-1-naphthaldehyde based probe 1,1′((1E,1′E)((4hydroxy1,3phenylene) bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) (NAP) has been synthesized and thoroughly characterized by IR, 13C & 1H NMR, fluorescence, UV-Vis, and mass spectral studies. The detection of pH is a necessary feature of the intracellular atmosphere and probably affects all cellular systems. NAP acts as a highly sensitive pH sensor in ethanol/HEPES (7:3, v/v) medium. Upon increasing the pH of NAP solution from acidic-neutral-basic medium, a distinct color change occurs from colorless-yellow-brown followed by a subsequent bathochromic shift in UV-Vis spectra and fluorescence response from ‘OFF-ON-OFF’. Photo-induced electron transfer (PET) mechanism has been proposed for the fluorescence change on the basis of theoretical studies on protonated, neutral and deprotonated NAP. Bioimaging investigations display a pH dependent fluorescence behavior of NAP in gut tissue of drosophila 3rd instar larvae. Additionally, NAP paper strips have been successfully developed for solid state pH sensing based on colorimetric and fluorescence responses. © 2021 Elsevier B.V.
Photoluminescence behaviour of a stimuli responsive Schiff base: Aggregation induced emission and piezochromism
(Elsevier Ltd, 2019) Pranjalee Yadav; Ashish Kumar Singh; Chandan Upadhyay; Vinod P. Singh
A naphthaldehyde based Schiff base, HMP has been synthesized by simple one-pot synthesis and characterized by IR, NMR and mass spectral techniques. HMP was non-emissive in acetonitrile, but its emission intensity was enhanced drastically (68 folds) upon addition of water, demonstrating typical aggregation induced emission (AIE) behaviour. Fluorescence quantum yield was increased drastically on aggregation from 0.3% (fw = 0%) to 8.1% (fw = 99%). Lifetime decay measurements were also performed in support of AIE property. Single crystal X-ray diffraction and DFT studies reveal that conformational transformation from benzenoid to quinonoid form induces restricted intramoleclar rotation (RIR) which contributes to AIE property. HMP was found to exhibit strong luminescence and piezochromism in solid state. Interestingly, dark yellow luminescence of crystalline HMP was changed to light green in response to grinding and a blue shift from 544 nm to 531 nm was observed. HMP exhibits good parent crystalline maintenance capability during grinding. Synthetic ease and reversible transformation of HMP are the key features to establish its application in pressjet printing and pressure sensing. © 2018 Elsevier Ltd
Ultrasound defect sensitive mechanochromic material with blue-shifted emission for the detection of Cu2+ in Alzheimer's disease cells
(Royal Society of Chemistry, 2025) Aayoosh Singh; Pranjalee Yadav; Amit Kumar Singh; Rupen Tamang; Biplob Koch; Vinod Prasad Singh
The mechanistic investigation and design of ultra-sensitive smart materials with multi-stimuli responsive properties are attracting much interest due to their utilization in several areas concurrently, such as mechanochromic and acidochromic materials, defect sensors, and chemosensors for analytes. Herein, the tailoring of an external stimuli-responsive novel coumarin-based luminogen (CFH) exhibiting green emission (λem = 515 nm) in the liquid state and red emission (λem = 698 nm) in the solid state opens up new avenues for the design of near-infrared emitting coumarin-based materials. CFH is an aggregation-induced enhanced emission (AIEE)-active material exhibiting solvatochromism and viscochromism. The weakly emissive crystals of CFH showed a relatively rare blue-shifted (48 nm) enhanced emission (3-fold) upon grinding. Fluorescence microscopy demonstrated that defect areas on the crystal surface become extremely emissive, indicating a “turn-on” defect-sensitive mechanochromism, susceptible to impact, friction, sculpting and ultrasonic vibrations. Solid CFH displayed acidochromic properties with extraordinary reversibility when exposed to trifluoroacetic acid (TFA)/triethylamine (TEA) vapour, displaying an on-off-on emission. Furthermore, CFH demonstrated “on-off” fluorescence responses to Cu2+ in water, exhibiting a detection limit (LOD) of 1.1 nM and Stern-Volmer constant (Ksv) of 2.84 × 106 M−1. The Job's plot and SC-XRD demonstrated a 1 : 1 binding stoichiometry for the CFH-Cu2+ complex. Leveraging this fluorescence response, portable test kit devices were developed for the detection of Cu2+. Bioimaging was carried out to examine the quenching of the probe with accumulated Cu2+ in SH-SY5Y model cells for neurodegenerative disorders compared to HEK-293 cells, suggesting that CFH can also be used for the intracellular sensing of Cu2+ in Alzheimer's disease (AD) cells. © 2025 The Royal Society of Chemistry.