Infrared Dye Research Articles

Light-Emitting Coordination Polymers: Stimuli-Responsive Gels, PMMA-Based Composite Films, and UV-Shielding.

Lanthanide-based light-emitting coordination polymers (CPs) and CP gels (CPGs) have significance for applications in optical systems, image processing/multiplexing, and optical sensors. In this study, we report two new luminescent CPs (EuL-CP (1) and TbL-CP (2)) and CPGs (EuL-gel (5) and TbL-gel (6)) using lanthanide(III) ions (Ln(III) = Eu(III) and Tb(III)) and 4-(4-carboxyphenyl)-2,2:6,2-terpyridine ligand (L) capable of forming stable thermoreversible gels. Probable structures of EuL-CP (1) and TbL-CP (2) and the formations of EuL-gel (5) and TbL-gel (6) are proposed based on adequate computational studies. The CPGs are stimuli-responsive and could be utilized as invisible security inks for encryption. Further, poly(methyl methacrylate) (PMMA) polymer doped with respective CPs (0.75 wt %) is found to be suitable for forming composite films with UV-shielding properties.

Novel AIE and solvatochromism exhibiting TPE based organic fluorophore with excellent emission properties in solid and solution phase for latent fingerprint and metronidazole sensing in real samples

Organic molecules with extended aromaticity are important when designing probes with optical properties. Herein, we designed and synthesized a novel tetraphenylethylene (TPE) based organic molecule TC exhibiting excellent photophysical characteristics. A thorough and in-depth study of the optical properties of probe TC was performed including solvatochromism, aggregation and solid-state studies using ultraviolet–visible (UV Vis) and fluorescence spectroscopy. Also, its optical properties under a UV 365 nm laser were investigated. The compound exhibited aggregation induced emission (AIE) which was thoroughly investigated in a H2O/DMF system and later utilized in formulation of invisible ink and latent fingerprint sensing. Moreover, the excellent emission properties of probe TC were utilized for the highly selective detection of the antibiotic metronidazole (MET) in real samples including human serum and artificial urine. Furthermore, portable TLC and paper-based strips were designed for the on-site detection of MET. Additionally, the mechanism of selective sensing of MET was thoroughly investigated through spectroscopic studies including titration NMR, fluorescence, UV Vis studies and DFT studies. Photoinduced electron transfer (PET) was attributed as the plausible sensing mechanism for the detection of MET. Scanning electron microscopy (SEM) also supported the sensing of MET through change in morphology. DFT calculations involved the measurement of thermodynamic stability, reduced density gradient (RDG) analysis, molecular orbital, and charge transfer studies as well as analysis of quantum theory of atoms in molecules (QTAIM). All the studies supported the presence of non-covalent interactions between probe TC and MET.

AB001. Development of tumour-targeted therapy for the treatment of adult and paediatric high-grade gliomas.

Brain cancer patients, especially those suffering from high-grade gliomas (HGGs) face a bleak future with very dismal long-term disease-free survival outcomes due to the limited treatment options currently available. Therefore, there is an unmet need for new therapeutic intervention that extends patients' progress-free survival and improves their quality of life. A significant hurdle is the inability of current chemotherapy agents to cross the blood-brain barrier (BBB). BBB acts as a protective shield that filters the blood to ensure nothing harmful makes it to the brain. This protection is usually good, but it becomes a problem if you want to deliver therapeutic cancer drugs through it. This barrier blocks 98% of drugs from entering the brain. Even the ones that cross BBB are unevenly distributed in the normal brain and tumour tissue, resulting in mediocre treatment and severe side effects. We are developing drug delivery systems that can cross the BBB and facilitate the specific accumulation of drugs in the tumour tissue. This will significantly improve the efficacy of anticancer drugs in treating various brain cancers and reduce systemic toxicity. Our group has explored and developed BBB crossing and tumour targeting near infra-red dyes, which can be covalently attached to Food and Drug Administration (FDA)-approved chemotherapy agents (drug-dye conjugates), thereby delivering it to the tumour tissue. We synthesized such drug-dye conjugates to target various aberrant pathways in HGG and tested these conjugates against patient-derived HGG cell lines. One such conjugate was tested on a mouse model of glioblastoma, an aggressive form of HGG, and shown to cross the BBB and specifically accumulate in tumour tissue, bringing forth tumour burden reduction. The results obtained from this work serve as proof of principle that enables tumour-specific drug delivery to treat HGG. This work also paves the way for treating other brain cancers and central nervous system (CNS) disorders like Parkinson's and Alzheimer's disease, for which no adequate therapy exists.

Naphthalene-embedded spiropyran derivative-A type of conjugated expanded material with solid-state photochromic properties and tunable color switching range

Due to the limited free volume in the solid state, spiropyrans generally exhibit photochromic properties in solution or mixed thin films. However, few spiropyrans can display the photoisomerization process in the solid state. One conventional solution for solid-state photochromism is to embed the spiropyran on polymer chains or introduce bulky groups to create an efficient free volume in the solid state. In this article, we attempt to introduce large conjugated fragments on the spiropyran backbone to construct a donor-acceptor (D-A) building block that not only possesses an enlarged π-electron system with enhanced electronic delocalization capability but also exhibits an improved free volume for efficient solid-state photoisomerization. Through this strategy, we have successfully embedded the naphthalene ring on the spiropyran backbone to obtain a novel D-A type conjugated building block, SP-Naph, which exhibits excellent solid-state photochromic performance and reversibility. Furthermore, the D-A structure of SP-Naph significantly tuned its photochromic color-switching range to blue. Consequently, SP-Naph was successfully applied in optical printing and invisible inks. The excellent solid photochromic properties make it exhibit remarkable photochromic effects, indicating significant potential for optical printing and anti-counterfeiting applications.

Multi-Colored Aqueous Ink for Rewritable Paper.

As sustainable and eco-friendly replacements to conventional paper, rewritable paper is a very attractive alternative for communication, information circulation, and storage. Development is made for rewritable paper using chromogenic materials that change its color in presence of external stimuli. However, the new techniques have faced several major challenges including feasible operational method, eco-friendly approach. Herein, a simple, convenient, and eco-friendly strategy is described for the preparation of rewritable paper substrate, and multi colored ink for efficient use in writing, painting or printing purpose. In addition, writing with "invisible ink" on the rewritable paper can be realized for potential anti-counterfeiting application. The written, painted, or printed information on the paper substrate can be easily erased using an aqueous solution. Thus, the original paper can be retrieved and the paper substrate can be reused multiple times. Besides, the written or printed information can be retained for a prolonged time at ambient conditions. Overall, this approach shows the rewritable paper as a prototype of multicolor writing/painting application, offering a sustainable solution for reducing paper waste and promoting environmental stewardship.

Advanced imaging to recover illegible text in historic documents. The challenge of past chemical treatments for ink enhancement

From fires to floods, from invisible inks to redactions, information has been accidentally or intentionally obscured on countless documents, maps and photographs, in collections from archives, libraries, and museums across the world. Removed from catalogues and reading rooms and therefore inaccessible to researchers and the general public, what new knowledge would these obscured documents reveal if we were able to read them? This paper demonstrates that current imaging technologies can be used to unlock this lost content.We used High Resolution Multiband Imaging (MBI), Reflectance Imaging Spectroscopy (RIS) and micro X Ray Fluorescence (µXRF) imaging to reveal illegible letter-forms and whole words written in iron gall ink on parchment from medieval documents relevant to the 'Virtual Record Treasury of Ireland' project, a digital reconstruction of archives destroyed in 1922 at the Public Record Office of Ireland at the outset of the Irish Civil War.The readability of text in historic documents with faded iron gall ink and/or parchment obscured by damp stains and ingrained dirt was successfully enhanced with MBI techniques, such as UV-induced visible luminescence (UVL) and UV reflected (UVR) imaging, which were able to recover the contrast of the ink. However, visualising text in documents showing chemical damage caused by the application of reagents for ink enhancement in the 19th century (a practice known as “galling”) was more challenging because of the similar composition of the ink and the staining. RIS proved helpful to read documents with moderate to severe chemical damage, particularly after applying Principal Component Analysis (PCA). Text in documents that were severely damaged by galling was also recoverable with µXRF imaging of the distribution of iron from the ink. This also posed several challenges, such as minimising movement of the parchment during overnight scans and separating the data corresponding to iron on the front of the parchment which was combined with the signal from the back. Through subtraction of elemental maps during post-processing, we managed to tackle the latter issue. The combination of these different imaging techniques enabled palaeographers and medieval records specialists to identify individual characters and whole words, thereby recovering the meaning of texts that were previously indecipherable.Further research will adapt the methodology to the broad range of causes of information loss, including other reagents historically used for ink enhancement, as well as the variety of document media and temporalities, which require an extensive and multi-faceted approach of advanced imaging and post-processing techniques, in balance with the preservation needs of these fragile and invaluable historic materials.

Detection of Secret Writing by using Various Methods - A Review

In recent times the secret writing is obtained as key evidence from crime scenes. This plays vital role in solving the crime. Secret writing detection by various methods is easy methods for visualization the invisible messages. numerous techniques have been documented in the literature for revealing secret messages by using various methods. In the present review paper, physical and chemical methods are used for secret writing detection. Secret inks like biological fluids, vegetable juices, fruits juices etc. are use. secret writing using different biological, vegetable, and chemical fluids involves using substances like lemon juice, onion juice, or invisible ink. Heat treatment can reveal hidden messages written with certain substances, while iodine fuming is effective for detecting invisible inks, causing them to become visible.

Dynamic photo-enhanced polyacrylic acid-based room temperature phosphorescence materials with persistent long-wavelength and even near-infrared luminescence via Förster resonance energy transfer

Stimulus-responsive organic room temperature phosphorescence (RTP) materials have attracted widespread attention in chemical sensors, bioimaging and information security. In this work, a dynamic photo-enhanced RTP material is prepared by doping 1,8-naphthalic anhydride (NA) into the polyacrylic acid (PAA) matrix. After 10 min irradiation of 302 nm UV light, the RTP properties of the doping systems PAA-NA are significantly enhanced and the photo-enhanced performances show excellent reversibility. More interestingly, PAA-NA as energy donor and the commercial dye rhodamine B (RhB) as energy acceptor are used to construct the ternary doping systems PAA-NA-RhB, which exhibit color-tunable long afterglow from orange to red through the triplet-to-singlet Förster resonance energy transfer (TS-FRET) process. Significantly, RhB as the intermediate and near infrared (NIR) dye Nile blue (NiB) as energy acceptor are codoped into energy donor PAA-NA matrices to facilely prepare the quaternary doping systems PAA-NA-RhB-NiB, and persistent NIR luminescence is realized successfully via the stepwise FRET process after 10 min irradiation of 302 nm UV light. The great application potential of the prepared photo-enhanced PAA-based RTP materials in high-level information encryption has been confirmed due to their excellent RTP performance. This study broadens the range of photo-enhanced polymer-based RTP materials and extends the persistent luminescence of PAA-based RTP materials to the long-wavelength and NIR regions.

Prospective evaluation of patient-reported outcomes of invisible ink tattoos for the delivery of external beam radiation therapy: the PREFER trial.

Invisible ink tattoos (IITs) avoid cosmetic permanence of visible ink tattoos (VITs) while serving as more reliable landmarks for radiation setup than tattooless setups. This trial evaluated patient-reported preference and feasibility of IIT implementation. In an IRB-approved, single institution, prospective trial, patients receiving proton therapy underwent IIT-based treatment setup. A survey tool assessed patient preference on tattoos using a Likert scale. Matched patients treated using our institutional standard tattooless setup were identified; treatment times and image guidance requirements were evaluated between tattooless and IIT-based alignment approaches. Distribution differences were estimated using Wilcoxon rank-sum tests or Chi-square tests. Of 94 eligible patients enrolled, median age was 58 years, and 58.5% were female. Most common treatment sites were breast (18.1%), lung (17.0%) and pelvic (14.9%). Patients preferred to receive IITs versus VITs (79.8% pre-treatment and 75.5% post-treatment, respectively). Patients were willing to travel farther from home to avoid VITs versus IITs (p<0.01). Females were willing to travel (45.5% vs. 23.1%; p=0.04) and pay additional money to avoid VITs (34.5% vs. 5.1%; p<0.01). Per-fraction average +treatment time and time from on table/in room to first beam were shorter with IIT-based vs. tattooless setup (12.3min vs. 14.1min; p=0.04 and 24.1min vs. 26.2min; p=0.02, respectively). In the largest prospective trial on IIT-based radiotherapy setup to date, we found that patients prefer IITs to VITs. Additionally, IIT-based alignment is an effective and efficient strategy in comparison with tattooless setup. Standard incorporation of IITs for patient setup should be strongly considered.

The Poetics of (Un)Mournability: Emma Donoghue’s Hood (1995) as an Elegy in Invisible Ink

Abstract Emma Donoghue’s Hood is an Irish tale of closeted lesbian love in which the narrator cannot mourn the death of her partner publicly because of the compulsory social invisibility of their relationship. While in her monograph Frames of War: When is Life Grievable? Judith Butler correlates the (un)grievability of certain lives (their ability to be grieved over) with ethical frames of perception, this paper focuses on the invisibilisation of public mourning. Since the term “mourning” is often used to evoke public displays and rituals of grief, I propose to confront Butler’s concept of “(un)grievability” with what I call “(un)mournability,” in order to investigate the three metaphors of (in)visibility that shape the aesthetics of Donoghue’s contemporary narrative elegy. The images of the closet, the hood, and the invisible ink, which are instrumental to Donoghue’s narrative strategies of linguistic invisibility, map out the evolving representation of lesbian invisibility in the novel.

Visualisation of Secret Handwriting by Physical and Chemical Method

Secret handwriting is a written note or message that is hidden and written with the help of invisible ink. There is a long history of using invisible ink for secret writing for various purposes. The practise involves writing information using fluids that are hardly visible under normal light. Invisible ink used as writing instruments makes the written message invisible to the reader, thus a visualisation or development technique is required to make the message visible . In this paper we are going to visualise the secret handwriting with both physical and chemical methods that is heat, UV, phenolphthalein and silver nitrate respectively. There’s a lot of physical as well as chemical methods to develop or visualise secret writing, that has been written by using the biological fluids(saliva, milk, tears), chemical fluid(vinegar, saline, baking soda), fruit or vegetables(garlic, ginger, onion, tomatoes, grapes, lemon), secret writing can be developed with the help of UV light, iodine fuming method, candle flame, oven, pH indicators, silver nitrate, phenolphthalein, etc. After the development of handwriting, it’s possible for the Forensic investigator to analyse the writing and identify the person behind it as every individual has individual handwriting characteristics which enables the identification of the suspect. Secret handwriting is most commonly used by the prisoners, criminals, drug dealers, terrorists, international spies, and intelligence departments. Visualisation and development of secret writing is important as it plays significant role in identifying the suspect, and it helps to solve the crime through the analysis of the handwriting, verification of documents, historical document analysis.

Infirmities and invisible ink: enslaved Muslims and magic in Malta, c.1598–c.1608

This article examines accusations of magic made against enslaved Muslims in Malta over the period 1598–1608. In this period numerous enslaved Muslims were accused of magic before the Roman Inquisition, and the surviving records describe these accusations and magical practices in detail. This article explores the types of magic Muslims were accused of, and why they seem to have been attractive to Christians as magical practitioners. It employs a statistical analysis to outline patterns of accusation, and uses the detail from individual cases to discuss these patterns. The authors argue that accusations against enslaved Muslims had several distinctive features. Muslims were believed to be particularly good at curing illnesses caused by sorcery, which was linked to wider early modern stereotypes about Islam. They were also more likely to use books and writing in the Arabic language. Finally, their practice of love magic for Christian women crossed gender boundaries in a way that male Christian practitioners did not, although this particular aspect should be seen in the context of a wide variety of types of magic practised for both men and women. However, despite these differences, their services were not seen as completely distinct from those of Christian practitioners. Magic was thus an area where people of different faiths interacted, especially in certain circumstances. This picture corresponds to some degree to patterns identified in recent studies of enslaved and non-Christian healers who came before the Inquisition in Latin America and Africa, and the article thus offers suggestions for comparison with these studies.

Highly luminescent heteroatom codoped carbon dots for multitudinous applications

Carbonaceous nanomaterials have shown great potential in the analytical and environmental domains due to their natural intriguing properties. Rich in quantum yield and reliable performances are necessary for carbon dots to be effectively used in the real-world applications. Carbon dots (CDs) exhibits high blue-emission with a quantum yield (ϕ) of 11% were synthesized through a single-step superficial pyrolysis technique. In this work, the derived carbon dots were employed as reducing and stabilizing agents in a unique one-step approach for the synthesis of AgNPs. The fluorescence of CDs was found to be quenched in the presence of dopamine with greater sensitivity, the minimum limit of detection was determined as 0.35 μM and possible mechanism could be the inner filter effect along with photoinduced electron transfer. In addition to this, the outstanding optical properties of CDs enable them to use as invisible ink in loading secret information and provide enhanced counterfeit protection. The solid-state quenching is successfully prevented when the CDs were dispersed in a polymer matrix for solid-state films preparation. The CDs-polymer composite is packed on top of a 365 nm UV LED chip, which emits blue light, to fabricate blue LED. Hence, we suggest that the synthesized CDs may serve as a future trend setter by as a single molecular probe for multifarious applications such as optoelectronics and forensic fields. Previously, we utilized these CDs for fingerprint detection and now apply them for new emerging applications.

Interrater agreement and reliability of a palpation method for locating C1 transverse process in the cervical spine

ObjectivesTo examine the agreement and interrater reliability of a palpation method for locating the C1 transverse processes (C1TP) and the association between personal characteristics with the observed agreement. MethodsSingle-blinded, inter-rater reliability study. Ninety-nine participants (58 women, age 44 ± 10 years, body mass index 26.1 ± 4.3 kg/m2, neck disability index = 8.4 ± 7.3 points) were enrolled in this study. Two raters blinded to each other's assessment performed the palpation for locating the C1TP and marked it with invisible ultra-violet ink. A research assistant measured the distance between the skin marks labeled as C1TP. The association between sex, age, body mass index, neck pain intensity and disability on the interrater agreement was verified using a point-serial correlation coefficient. ResultsAbsolute and percent agreement for the right and left body sides were 90/99 (90.9 %, 95%CI 83.4 to 95.8) and 96/99 (97.0 %, 95%CI [91.4 to 99.4]), respectively. Interrater reliability was excellent for both right (Gwet's AC1 0.883, 95%CI [0.881 to 0.885]) and left body sides (Gwet's AC1 0.894, 95%CI [0.894 to 0.896]). After adjustment for multiple comparisons, no statistical evidence of correlation was observed for age, sex, body mass index, and NDI with the agreement for location of C1TP (r = −0.206 or lower, adjusted P-value = 0.328 or higher). ConclusionsThe palpatory method for the location of C1TP has excellent interrater agreement and reliability. Age, sex, body mass index, and disability show weak-to-negligible correlation with the agreement for location of C1TP. Implication for practice•A palpation method should be accurate and reliable for being introduced in clinical and laboratory settings•This is the first study to report interrater reliability results for locating C1 and the reliability is excellent•The result of our study increases our confidence in recommending the location of C1 in clinical practices when performing mobility tests for C0–C1–C2, the great nerve occipital palpation, as a start landmark for suboccipital muscle palpation and when applying direct manual procedures to restore mobility in C1–C2 segments as muscle energy technique, high-velocity low amplitude (HVLA) manipulation and mobilization with movement techniques•These results benefit the manual therapist's education process as palpatory skills and surface anatomy are core subjects in manual therapy education, including osteopathy, despite the lack of validation of most palpation methods

Liquid Crystalline Network Microstructures for Stimuli Responsive Labels with Multi-Level Encryption.

Two-photon direct laser writing enables the fabrication of shape-changing microstructures that can be exploited in stimuli responsive micro-robotics and photonics. The use of Liquid Crystalline Networks (LCN) allows to realize 3D micrometric objects that can contract along a specific direction in response to stimuli, such as temperature or light. In this paper, the fabrication of free-standing LCN microstructures is demonstrated as graphical units of a smart tag for simple physical and optical encryption. Using an array of identical pixels, information can be hidden to the observer and revealed only upon application of a specific stimulus. The reading mechanism is based on the shape-change of each pixel under stimuli and their color that combinetogether in a two-level encryption label. Once the stimulus is removed, the pixels recover their original shape and the message remains completely hidden. Therefore, an opto-mechanical equivalent of an "invisible ink" is realized. This new concept paves the way for introducing enhanced functionalities in smart micro-systems within a single lithography step, spanning from storage devices with physical encryption to complex motion actuators.

An Ineffable Haunting: Language, Embodiment, and Ghosts in Toni Morrison’s Beloved

AbstractRereading Toni Morrison’s novel Beloved, this article explores how Morrison’s work at the limits of language performs the haunting ties between the Reconstruction era and the present day by offering readers a way to experience a rememory of their own. By repeatedly emphasizing the inadequacy of language in expressing traumatic experience, Beloved encourages its readers to, like its characters, look beyond language and seek out a kind of ineffable, embodied knowledge to better understand the lingering traumas of slavery. Through Morrison’s concept of “invisible ink,” which points to the inevitability that lived experience cannot be captured in language by the author alone but must be filled in by an active reader, this article makes a larger argument: that Beloved acts as both an invitation and a guide to read the ghostly, invisible ink of history that exists outside the novel, haunting our world itself.

Targeted delivery of organic small-molecule photothermal materials with engineered extracellular vesicles for imaging-guided tumor photothermal therapy

Imaging-guided photothermal therapy (PTT) for cancers recently gathered increasing focus thanks to its precise diagnosis and potent therapeutic effectiveness. Croconaine (CR) dyes demonstrate potential in expanding utility for near infrared (NIR) dyes in bio-imaging/theranostics. However, reports on CR dyes for PTT are scarce most likely due to the short of the efficacious delivery strategies to achieve specific accumulation in diseased tissues to induce PTT. Extracellular vesicles (EVs) are multifunctional nanoparticle systems that function as safe platform for disease theragnostics, which provide potential benefits in extensive biomedical applications. Here, we developed a novel delivery system for photothermal molecules based on a CR dye that exerts photothermal activity through CDH17 nanobody-engineered EVs. The formed CR@E8-EVs showed strong NIR absorption, excellent photothermal performance, good biological compatibility and superb active tumor-targeting capability. The CR@E8-EVs can not only visualize and feature the tumors through CR intrinsic property as a photoacoustic imaging (PAI) agent, but also effectively retard the tumor growth under laser irradiation to perform PTT. It is expected that the engineered EVs will become a novel delivery vehicle of small organic photothermal agents (SOPTAs) in future clinical PTT applications.

Rational Design of Dual‐Mode Emitting Carbon Dots to Exploit the Synergistic Effect of Matrices for High‐Efficiency WLEDs and Anti‐Counterfeiting

AbstractLong‐lived room‐temperature phosphorescence (RTP) materials have been widely applied in various fields. However, achieving high‐performance carbon dots (CDs) RTP remains a great challenge. Here, a facile synthetic strategy is rationally designed for the synthesis of high‐performance dual‐mode emitting CDs by constructing rigid structures through the synergistic effect of the matrices. The obtained CD RTP powder possesses an ultrahigh photoluminescence quantum yield (PLQY) of 70.7%, a phosphorescence lifetime of about 0.45 s, and an afterglow that lasts for 15 s to the naked eyes. Most importantly, the prepared CD RTP powder can be utilized as a commercial phosphor powder for the fabrication of a high‐performance white lighting‐emitting diode (WLED) with a CIE coordinate of (0.39, 0.39), a high color rendering index of 93.6, and a color temperature of 3805 K for warm WLED. Especially the luminous efficiency of the fabricated WLED can reach up to 66.89 lm W−1, which is much higher than the values reported for most CDs‐based WLED devices. Additionally, CD RTP can be applied to advanced invisible inks for information encryption due to its excellent water solubility and can also be exploited for advanced information anti‐counterfeiting by utilizing phosphorescent properties.

Aggregation enhanced emissive orange carbon dots for information encryption and detection of Fe3+ and tetracycline

In this study, N-doped fluorescent carbon dots with aggregation enhanced emission (N-CDs) were synthesized by a simple and rapid microwave-assisted method using o-phenylenediamine (OPD) and urea as raw materials and water as solvent. The fluorescence quantum yield of N-CDs was 20.64 %. N-CDs can be applied as invisible inks for message encryption. Furthermore, the fluorescence intensity of N-CDs can be quenched by Fe3+ and enhanced by tetracycline (TC). Therefore, two fluorescent probes were simultaneously designed in this study. Namely, “turn-off” fluorescence probe for Fe3+ and “turn-on” fluorescence probe for TC. The linear detection range of Fe3+ is from 1 to 70 μM, and detection limit is 0.1011 μM; the linear detection range of TC is from 0.1 to 10 μM, and the detection limit can be as low as 0.0555 μM. In this paper, the mutual interference between Fe3+ and TC was investigated for the first time. The detection of Fe3+ and TC was made more accurate by optimizing pH conditions and adding masking agent.

An AIE active imidazole conjugated α-cyanostilbene based sensor for the selective and sensitive detection of picric acid in an aqueous medium

Due to increasing pollution threats, terrorism-sensitive rapid sensing of aromatic nitro explosives (picric acid) has gained predominant significance in environmental safety. Herein, imidazole-derived monofunctional fluorescent sensor 2-(4-aminophenyl)-3-(3-(4,5-diphenyl-1H-imidazol-2-yl)-2-hydroxyphenyl) acrylonitrile (ADHA) was successfully developed for the selective recognition of explosive picric acid. The D-π-A configuration of ADHA facilitates extraordinary photophysical properties with remarkable aggregation-induced emission (AIE). The detection process is induced by the photon-induced electron transfer (PET) and resonance energy transfer (RET) and results in the generation of ADHA+PA complex. The structural relationship and the photophysical properties of ADHA were extensively studied by DFT (Density Functional Theory) methods and spectroscopic analysis. It has been calculated that the detection limit of the formed complex is 6.26 nM. In addition, 1H NMR titrations DFT calculations, and HRMS analysis were performed to understand the detection mechanism better. Test strip-aided detection and invisible ink applications confirmed that ADHA is a versatile sensor for sensitively detecting picric acid without sophisticated instruments. In addition, ADHA was implemented to detect PA in real water samples with remarkable recovery.