Fluorescence Quenching and the Chamber of Nitroaromatics: A Dinaphthoylated Oxacalix[4]arene's (DNOC) Adventure Captured through Computational and Experimental Study

This research presents the application of Dinaphthoylated Oxacalix[4]arene (DNOC) as a novel fluorescent receptor for the purpose of selectively detecting nitroaromatic compounds (NACs). The characterization of DNOC was conducted through the utilization of spectroscopic methods, including 1H-NMR, 13C-NMR, and ESI-MS. The receptor demonstrated significant selectivity in acetonitrile towards several nitroaromatic analytes, such as MNA, 2,4-DNT, 2,3-DNT, 1,3-DNB, 2,6-DNT, and 4-NT. This selectivity was validated by the measurement of emission spectra. The present study focuses on the examination of binding constants, employing Stern-Volmer analysis, as well as the determination of the lowest detection limit (3σ/Slope) and fluorescence quenching. These investigations aim to provide insights into the inclusion behavior of DNOC with each of the six analytes under fluorescence spectra investigation. Furthermore, the selectivity trend of the ligand DNOC for NAC detection is elucidated using Density Functional Theory (DFT) calculations conducted using the Gaussian 09 software. The examination of energy gaps existing between molecular orbitals, namely the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), provides a valuable understanding of electron-transfer processes and electronic interactions. Smaller energy gaps are indicative of heightened selectivity resulting from favorable electron-transfer processes, whereas bigger gaps suggest less selectivity attributable to weaker electronic contacts. This work integrates experimental and computational methodologies to provide a full understanding of the selective binding behavior of DNOC. As a result, DNOC emerges as a viable chemical sensor for detecting nitroaromatic explosives.

Propyl-phthalimide Cyclotricatechylene-Based Chemosensor for Sulfosulfuron Detection: Hybrid Computational and Experimental Approach

The detection of trace amounts of sulfosulfuron, a pesticide of increasing importance, has become a pressing issue, prompting the development of effective chemosensors. In this study, we functionalized cyclotricatechylene (CTC) with propyl-phthalimide due to the presence of electronegative oxygen and nitrogen binding sites. Our optimized ligand displayed the highest docking score with sulfosulfuron, and experimental studies confirmed a significant fluorescence enhancement upon its interaction with sulfosulfuron. To gain a deeper understanding of the binding mechanism, we introduced density functional theory (DFT) studies. We carried out binding constant, Job's plot, and limit of detection (LOD) calculations to establish the effectiveness of our chemosensor as a selective detector for sulfosulfuron. These findings demonstrate the potential of our chemosensor for future applications in the field of pesticide detection.

A Highly Selective Pyrene Appended Oxacalixarene Receptor for MNA and 4-NP Detection: an Experimental and Computational Study

A novel pyrene-substituted oxacalixarene was designed and synthesized as a selective probe for the simultaneous detection of MNA and 4-NP. Utilizing 1H-NMR, 13C-NMR, and FT-IR analysis techniques, its structure was characterized. The binding property of BPOC to a variety of NACs, including 1,3-DNB, 2,3-DNT, 2,4-DNT, 2,6-DNT, 4-NP, 4-NT, and PA, revealed that the sensor binds to MNA and 4-NP with remarkable selectivity. Binding constant reveals lower detection limits of MNA is 0.2 µM and 0.3 µM for 4-NP. Using docking and density functional theory (DFT), computational insights were provided for investigating the stability and spectroscopic analysis of the inclusion complex. From molecular docking study, we observed the best docking score of BPOC with 4-NT and MNA complex. The calculations supplement the findings significantly and clarify the structural geometry and mode of interactions in supramolecular complexation. In an MTT experiment on human PBMC to check for cytotoxicity, this chemical was found to influence 1 × 105 cell viability dose-dependently.

Fluorescent cyclophanes and their applications

With the serendipitous discovery of crown ethers by Pedersen more than half a century ago and the subsequent introduction of host-guest chemistry and supramolecular chemistry by Cram and Lehn, respectively, followed by the design and synthesis of wholly synthetic cyclophanes-in particular, fluorescent cyclophanes, having rich structural characteristics and functions-have been the focus of considerable research activity during the past few decades. Cyclophanes with remarkable emissive properties have been investigated continuously over the years and employed in numerous applications across the field of science and technology. In this Review, we feature the recent developments in the chemistry of fluorescent cyclophanes, along with their design and synthesis. Their host-guest chemistry and applications related to their structure and properties are highlighted.

A versatile enrichment of functionalized calixarene as a facile sensor for amino acids

Amino acids have become the most important part of the human biological system due to their roles in the living processes. Role of amino acids stretches beyond their traditional role as a building block for proteins, deficiency of the same could lead to decreased immunity, digestive problems, depression, fertility issues, lower mental alertness, slowed growth in children, and many other health issues. The acute detection of amino acids is necessary to determine the human health domain. Here in this review, we summarize and study the calixarenes as a complex detailed being of an immeasurable value and its utilization for the amino acids' detection. The key factors responsible such as noncovalent forces, LOD and supramolecular chemistry of calixarenes with amino acids are described well. This study presents the most recent efforts made for the development of potential and highly efficient calixarene based sensors for the detection of amino acids.

Recent Advancements for the Recognization of Nitroaromatic Explosives Using Calixarene Based Fluorescent Probes

In this era, explosives are easily available compared to the early days. Thus, more effective detection of explosives has become the main concern of homeland security. In the past decades, a large number of sensing materials have been developed for the detection of explosives in solid, vapor, and solution states through fluorescence methods. In recent years, great efforts have been devoted to developing new fluorescent materials with various sensing mechanisms for detecting explosives in order to achieve super-sensitivity, ultra-selectivity, as well as fast response time. Modified calixarenes have high potentials to detect nitroaromatic compounds (NACs) due to their favorable structural properties. It summarizes the detection of NACs by the modified calixarene system formed by the complex. Various methodologies responsible for complex formation and binding mechanisms (PET, FRET, EE, etc.) are the centerpiece of this review. Finally, conclusions and future outlook are presented and discussed.

A Cu2+-selective colorimetric-fluorometric sensor based on an anthracenyl-modified oxacalix[4]arene

An anthracenyl-modified oxacalix[4]arene with imine linkages exhibits highly selective and sensitive detection of Cu2+via drastic colour change and enhanced FL.

Interpol review of detection and characterization of explosives and explosives residues 2016-2019

This review paper covers the forensic-relevant literature for the analysis and detection of explosives and explosives residues from 2016-2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/Resources/Documents#Publications.

An oxacalix[4]arene derived dual sensing fluorescent probe for the detection of As(v) and Cr(vi) oxyanions in aqueous media

An oxacalix[4]arene-Ce(iii) complex viz. L-Ce(III) has been introduced for the selective detection of As(v) and Cr(vi) oxyanions in aqueous medium. The binding mode of L-Ce(III) + AsO₄^3-/CrO₄^2- was completely investigated with fluorometric titration, time resolve fluorescent decay and FTIR analyses. Photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) play an important role in the sensing of these oxyanions. The characteristic fluorescence of the L-Ce(III) complex has been quenched by AsO₄^3- and CrO₄^2- through cascading the ligating sites. Cyclic voltammetry (CV) experiments with various scan rates suggest that the electrochemical processes on the electrodes were controlled by diffusion. Both the analytes exhibit a lower limit of detection (LOD) below their standard EPA permissible limits. Moreover, the probe successfully detects the oxyanions in environmental real samples with excellent recovery ranging from 97 to 101%.

A DFT study of inclusion complexes of substituted calix[n]arenes with dasatinib and lapatinib

Herein, we have presented the results of Density Functional Theory (DFT) based calculations of inclusion complexes of lapatinib and dasatinib with calix[n]arene macrocycles. A total of 48 calix [n]arene complexes were modeled via considering varied ring sizes (n = 4,5,6,8) and upper-rim functionalization viz. SO₃H, tert-Butyl, iso-Propyl, COOH, C₂H₅OH, and C₂H₅NH₂. From the results of multilevel molecular docking, DFT energetics, and reactivity descriptors; it has been demonstrated that dasatinib form optimal complexes with calix 4f, 3f (-35 to -40 kcal/mol). Moreover, for lapatinib, hosts 3f, 4a, 1f, 3d have the capability to generate promising complexes (>35 kcal/mol). Based on counterpoise corrected binding energies (E_bind) and global reactivity descriptors, we anticipate that the proposed complexes can vitally be used as analogous to carrier-mediated-drug-delivery.

A one-step synthesized acridine-based fluorescent chemosensor for selective detection of copper(ii) ions and living cell imaging

A highly selective and sensitive fluorescence quenching chemosensor (ACC) for Cu²⁺ detection in HEPES buffer and living cell imaging was developed.

Sensing of Ce(iii) using di-naphthoylated oxacalix[4]arene via realistic simulations and experimental studies

Here, we report a fluorescent sensor for the detection of Ce(iii) using di-naphthoylated oxacalix[4]arene (DNOC).

Dual in vitro and in silico analysis of thiacalix[4]arene dinaphthalene sulfonate for the sensing of 4-nitrotoluene and 2,3-dinitrotoluene

A newly synthesized thiacalix[4]arene dinaphthalene sulfonate, i.e., TCDNS, has been used as a fluorescence quencher for 2,3-DNT as well as 4-NT. The complex was analyzed by ESI-MS and ¹H-NMR titration, which has been further confirmed by the in silico study.