Chromo-fluorogenic Sensor Research Articles

Selective Chromo-Fluorogenic Chemoprobe for nM Al3+ Recognition: Experimental and Living-Cell Applications.

A rhodamine based chemoprobe BESN was engineered and employed as a selective ''OFF-ON'' chromo-fluorogenic sensor for Al3+ in H2O:MeOH (1:9, v:v). Notable changes in the absorption and emission spectra of BESN were clearly detectable upon the addition of Al3+. Sensitivity and binding mechanism studies demonstrated a good sensing performance of BESN with nanomolar detection limit (130nM), and it was found to be highly selective towards interfering metal ions. Besides, the binding constant between BESN and Al3+ was found to be 3.19 × 103M-1. Then, the validation study of BESN for Al3+ was performed based on significant analytical parameters and statistical tests. The binding of Al3+ with BESN (1:1) was probed via infrared, high-resolution mass and emission (Job's plot) spectroscopy measurements. The sensing performance of BESN could make it ideal chemosensor for real applications including vegetable, tuna fish and water samples, also for Smartphone and test-kit applications. The recovery values of the BESN to Al3+ were estimated within a range from 95.13% to 105.30% for water, 94.63% to 109.62% for tuna fish and 94.80% to 109.80% for vegetable samples. Additionally, the BESN has very low cytotoxicity and was triumphantly utilized for the recognition of Al3+ in living-cells.

A Pyrene Coupled Azaine-linkage Chromo-fluorogenic Probe for Specific Detection of Sarin Gas Stimulant, Diethylchlorophosphate.

Owing to the extreme toxicity and easy synthesis protocol of G-series nerve agents, developing an efficient sensor for selective detection is necessary. Although various traditional methods are utilized to identify these nerve agents, chromo-fluorogenic probes have gained attractive attention from the scientific communities. In the present contribution, we have introduced a new symmetrical aza-substituted chromo-fluorogenic sensor, BPH, for specific detection of sarin gas, one of the fatal G-series nerve agents surrogate, diethylchlorophosphate (DCP). BPH shows a noticeable naked eye colorimetric change from pale yellow to light pink in the presence of DCP, displaying highly intense bright greenish cyan color photoluminosity under a 365nm UV lamp,which is also manifested from the color chromaticity diagram. A BPH-staining paper stirps-based test kit experiment has been demonstrated for the on-site detection of nerve agent mimics. A more attractive and efficient application of BPH as a sarin gas vapor phase sensor mimics DCP in solid and solution phases. The BPH-based chromo-fluorogenic sensor shows excellent selectivity toward DCP with a detection and quantification limit in the µM range. This report invokes a new way for the researchers to detect DCP employing a simple chromo-fluorogenic sensor, which could be prepared by a time-saving,straightforward, handy protocol from the cost-effective starting materials.

An azine-based chromogenic, fluorogenic probe for specific cascade detection of Al3+ and PO43- ions

An azine-based chromo-fluorogenic sensor, 2,2′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylyidene)) bis(4-nitrophenol) (DBMN), has been introduced for cascade detection of Al3+ and PO43- ions with high selectivity and sensitivity with a detection limit in the nM to μM range. Upon introducing Al3+ ions into the DBMN solution, a remarkable colorimetric change from yellow to colorless has been noticed in the naked eye due to inhibiting the intramolecular charge transfer process. A 120 times photoluminescence intensity enhancement displaying bluish-green fluorescence under the exposure of a 365 nm UV lamp is observed because of chelation-enhanced fluorescence (CHEF) from the solution of Al3+ ions chelated DBMN complex, which is also well-supported by the color chromaticity diagram. Al3+ ions chelated DBMN complex is selective and sensitive to detecting PO43- ions by rebirthing DBMN. A paper strips-based test kit has been fabricated for on-site cascade detection of Al3+ and PO43- ions, respectively. By employing either Al3+ and PO43- ions as single chemically encoded input and photoluminescence intensity as optical output, we have framed YES and NOT single input and single output opto-chemical logic circuits. Also, based on the photoluminescence off–on-off mechanism, we have designed two inputs and one output-based INHIBIT logic gate with the help of sequential addition of Al3+ and PO43- ions as the two chemically encoded inputs and the luminosity at 500 nm as a single output. Also, a set-reset memorized molecular device has been framed based on photoluminescence as the optical output due to the sequential addition of Al3+ and PO43- ions in the DBMN solution.

A PET and ESIPT-communicated ratiometric, turn-on chromo-fluorogenic sensor for rapid and sensitive detection of sarin gas mimic, diethylchlorophosphate

Fast and precise identification of toxic G-series nerve agents in the solution and vapor phase is urgently needed to save human beings from unwanted wars and terrorist attacks, which is challenging to execute practically. In this article, we have designed and synthesized a sensitive and selective phthalimide-based chromo-fluorogenic sensor, DHAI, by a simple condensation process that shows ratiometric and turns on chromo-fluorogenic behavior towards Sarin gas mimic diethylchlorophosphate (DCP) in liquid and vapor phases, respectively. A colorimetric change, from yellow to colorless, is observed in the DHAI solution due to the introduction of DCP in daylight. A remarkable cyan color photoluminescence enhancement is noticed in the presence of DCP in the DHAI solution, which is observable to the naked under a portable 365nm UV lamp. The mechanistic aspects of the detection of DCP by employing DHAI have been revealed by time-resolved photoluminescence decay analysis and 1H NMR titration investigation. Our probe DHAI exhibits linear photoluminescence enhancement from 0 to 500μM with a detection limit of nanomolar range from non-aqueous to semi-aqueous media. For practical utility, a DHAI-stained test kit employing Whatman-41 filter paper has been fabricated and used as a portable and displayable photonic device for on-site detection of Sarin gas surrogate, DCP. Also, a dip-stick experiment has been demonstrated to identify the vapor of Sarin gas mimics DCP colorimetrically and fluorometrically. The concentrations of DCP in various water samples have been evaluated with the help of a standard fluorescence curve for real sample analysis.

A ratiometric, turn-on chromo-fluorogenic sensor for sequential detection of aluminium ions and picric acid

A simple ratiometric, turn-on chromo-fluorogenic sensor, (E)-2-((2-hydroxybenzylidiene) amino)-5-nitrophenol (HBAN), has been developed, synthesized, and characterized by several conventional analytical methods. HBAN is found to be selective for the sequential detection of Al3+ ions and picric acid (PA), respectively, based on the fluorescence ‘off-on-off’ method. A remarkable fluorescence enhancement of HBAN is detected at 540 nm upon binding with Al3+ ions with a visual yellow color fluorescence under a portable 365 nm UV light irradiation. Among the various tested nitroaromatic compounds, PA selectively quenches the fluorescence of the Al3+ ions chelated HBAN complex. The formation of the complex between HBAN and Al3+ ions is found to be in a 1:1 stoichiometric ratio, and the LOD is found to be nanomolar range. The mechanistic aspects of detecting Al3+ ions have been elucidated by different spectroscopic and density functional theoretical analyses. Additionally, a test kit based on paper strips coated with HBAN is demonstrated to selectively detect Al3+ ions.

A chromo-fluorogenic probe for detecting water traces in aprotic solvents based on C2-symmetry dianthrimide-hydroxide complexes: experimental and theoretical studies.

A C2-symmetry dianthrimide based probe (D) and its hydroxide complex (D-OH) are reported as a chromo-fluorogenic sensor for rapid and sensitive detection of trace amounts of water in polar aprotic solvents. Based on intramolecular charge transfer in the excited state, the pink-coloured probe binds with the hydroxide ions to induce a colorimetric response of the resulting complex (D-OH), green in colour. The hydroxide based complex is used as a H2O or moisture sensor, tested in DMF and DCM, due to its high instability in moisture-containing organic solvents and paper materials/fabrics. The probe exhibits higher sensitivity towards pure H2O in DMSO with the LOD measured at 0.0067% v/v, perhaps even lower, in DMF (LOD = 0.100% v/v) and DCM (LOD = 0.013% v/v). The dissociation of OH- from D in the presence of H2O is responsible for the colorimetric and fluorometric responses. The litmus test paper strips prepared by adsorbing or coating them with the D-OH complex in DMSO could not be entirely achieved in an open system, due to the highly unstable state of the complex in the presence of water traces or the atmospheric moisture accumulated in the paper materials. The complex D-OH is also highly suspected to compete for adsorbed water in silica gel crystals in desiccators, due to its high affinity towards water molecules. The experimental studies were complemented by theoretical calculations using the Spartan'14 software package, and the computed data are in good agreement with the spectral data.

Colorimetric assay of fluoride goes digital: On the spot testing of F− ions in water using smartphone's digital imaging and test strip assay by a novel chromofluorogenic receptor based on 1,8-naphthalimide

A novel hydrazone Schiff's base, (E)-6-(2-(2,4-dihydroxybenzylidene)hydrazinyl)-2-(2-hydroxyethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione, DHB based on 1,8-naphthalimide has been designed and synthesized that acts as a dual mode chromofluorogenic sensor with a noticeable color change from orange to blue and fluorometric “turn-off” response towards F− with high sensitivity and selectivity. A detailed study to establish the binding mechanism of the receptor DHB with F− ion has been carried out by visual colorimetric (naked eye), UV–visible and fluorescence spectroscopy which was then further validated by 1H NMR titration studies and theoretical calculations. Interestingly, color response towards chromogenic model formed between receptor DHB and F− ion were explored by reading RGB values of digital image using smartphone. Smartphones based quantification of F− minimizes expensive, sophisticated instruments handled by trainers and provide the simple, cheap, rapid, handy, and easy available analytical tool that any person can easily use in remote areas. Test strips validate that DHB acts as a cheaper and proficient solid-state probe for the quantification of F− ion. The association constant and limit of detection for F− were determined as 0.817 × 1013 M−3 and 1.34 nM respectively. Further, the proposed smartphone-based method quantified fluoride in real water samples and obtained promising results that make it a more futuristic, hassle free and straightforward approach to the common man without requiring a skilled person to monitor F− in environmental water samples.

Mechanistic Insight into Selective Sensing of Hazardous Hg2+ and Explosive Picric Acid by Using a Pyrene‐Azine‐Hydroxyquinoline Framework in Differential Media

AbstractA pyrene‐hydroxyquinoline tethered ingeniously designed and developed azine based Schiff base luminophoric system, 2‐((Z)‐((E)‐(pyren‐1‐ylmethylene)hydrazono)methyl)quinolin‐8‐ol (PHQ) has been explored as a selective ‘TURN ON’ chromofluorogenic sensor for hazardous Hg2+ ions in ethanol/H2O (9 : 1,v/v) medium with detection limit of 0.22 μM and binding constant of 1.09 x 103 M−1. The detail scrutiny of mechanism of interaction between PHQ and Hg2+ is rationalized through various techniques like 1H NMR titration, FT‐IR, mass spectral analysis, theoretical computations, Job's plot, dynamic light scattering (DLS), transmission electron microscopy (TEM), time resolved excited state decay dynamics and fluorescence reversibility studies, which concretely declare a synergistic effect of supramolecular aggregation induced enhanced emission and deactivation of photo‐induced electron transfer (PET) processes. On the other hand, a ‘TURN OFF’ luminescence feature of highly fluorescent PHQ hydrosol is utilized for the selective screening of powerful explosive picric acid (PA) in aqueous medium and mechanism is deciphered by means of steady state, time‐resolved emission as well as computational studies which altogether reflect a combined effect of PET and ground state complexation between probe and PA. The commendable detection limit of 55 nM and Stern‐Volmer quenching constant of 1.48 x 104 M−1 with high quenching efficiency of 84% increases the pertinency of the nano‐probe.

A novel turn-on red light emitting chromofluorogenic hydrazone based fluoride sensor: Spectroscopy and DFT studies

A new simple, small molecule hydrazone was synthesized from 1:1 condensation reaction of anthrone and 2-hydrazinobenzoic acid. It was characterized by absorption, emission spectrometry, FTIR, NMR, mass studies and investigated as a ratiometric, turn-on, luminescent chemosensor of fluoride ion (F−) in the red region (550−700 nm). The sensor is highly selective for fluoride ion in the DMSO medium in presence of other anions (Cl−, Br−, I−, PO43−, CN−, AcO−) with the limit of detection of ∼10−5 M. Upon addition of fluoride this chromofluorogenic sensor showed an instant color change from pale orange to red which was observed in naked eye and emitted red fluorescence under the UV light. A huge red shift of the ligand was observed in presence of F− which is of great interest. The energy optimized structure, electronic transitions involved in absorption and emission spectroscopy were supported by DFT and TDDFT studies. This color change was captured in RGB grabber application, installed in a smart phone which might be applicable for monitoring fluoride ion concentration in non-aqueous environment. In addition the sensor was used for the detection and estimation of F− in real samples using UV–vis spectroscopy. The results obtained were close to values obtained from the fluoride meter. Thus the above sensor might be used for the analysis of fluoride for real applications.

A rhodamine-deoxylactam based sensor for chromo-fluorogenic detection of nerve agent simulant

N-(rhodamine B)-deoxylactam-5-amino-1-pentanol (dRB-APOH) was designed and prepared as the chromo-fluorogenic sensor for detection of a nerve agent simulant via analyte triggered tandem phosphorylation and opening of the intramolecular deoxylactam. The successful detection of diethyl chlorophosphate suggests the utility of rhodamine-deoxylactams as the chromo-fluorogenic signal reporting platform for design of sensors targeting reactive chemical species via various chemistries.