Efficacy of 2-nitrobenzylidene-hydrazine-based selective and rapid sensor for Cu2+ ions, histidine, and tyrosine: Spectral and computational study

The biotic effects of lignite on humic acid components conversion during chicken manure composting

Targeted regulation of composting to convert organic matter into humic acid (HA) holds significant importance in compost quality. Owing to its low carbon content, chicken manure compost often requires carbon supplements to promote the humification progress. The addition of lignite can increase HA content through biotic pathways, however, its structure was not explored. The Parallel factor analysis revealed that lignite can significantly increase the complexity of highly humified components. The lignite addition improved phenol oxidase activity, particularly laccase, during the thermophilic and cooling phases. The abundance and transformation functions of core bacteria also indicated that lignite addition can influence the activity of microbial transformation of HA components. The structural equation model further confirmed that lignite addition had a direct and indirect impact on enhancing the complexity of HA components through core bacteria and phenol oxidase. Therefore, lignite addition can improve HA structure complexity during composting through biotic pathways.

Computational choreography: dissecting the dance of hydrogen bonding and π-π stacking in the fluorescence discrimination mechanism of ciprofloxacin with supramolecular assembly

The detailed binding insight between the fluorophore and analyte plays a pivotal role in the design of an efficient chemosensor for water pollution. In this study, we designed a picolinic acid-functionalized calix[4]pyrrole ligand (PCACP). When testing out the fluorescence study with selected antibiotics, we observed remarkable enhancement of fluorescence spectra in the presence of ciprofloxacin, singling out the PCACP_Ciprofloxacin complex. The detailed binding mechanism is explored via computational methods including molecular docking and dynamics, DFT (density functional theory) and NBO (Natural Bonding Orbital) analysis. The result of this study provides the comprehensive insight into the involvement of functionalized group of PCACP and ciprofloxacin antibiotic. The results of the computational findings are further explored through NMR complexation study, which corroborate the computational findings. With the limit of detection calculated at 18 µM, we carried out the water sample analysis, which shows promising results. The outcome of this research provides a new, effortless fluorescence approach to monitor the presence of ciprofloxacin in water.In the presence of the ciprofloxacin antibiotic, the fluorescence spectra of PCACP experience remarkable enhancements. This complexation phenomenon is studied through different computational and experimental methods.Communicated by Ramaswamy H. Sarma.

Designing of efficient two-armed colorimetric and fluorescent indole appended organosilicon sensors for the detection of Al(III) ions: Implication as paper-based sensor

Metal ions have significant roles in diagnosis, industry, human health, and the environment. To design and develop new lucid molecular receptors for the selective detection of metal ions is important for environmental and medical applications. In the present work, two-armed indole appended Schiff bases conjoined with 1,2,3-Triazole bis-organosilane and bis-organosilatrane skelton sensors for naked eye colorimetric and fluorescent detection sensors for Al(III) are developed. The introduction of Al(III) in sensor 4 and 5 show red shift in UV-visible spectra, changes in fluorescence spectra and immediate color change from colorless to dark yellow. Furthermore, the pH and time response studies were explored for both sensors 4 & 5. The sensors 4 and 5 exhibited significantly low detection limit (LOD) in nano-molar range 1.41 × 10-9 M and 0.17 × 10-9 M respectively from emission titration. The LOD form absorption titration was found to be 0.6 × 10-7 M for sensor 4 and 0.22 × 10-7 M for sensor 5. In addition, the sensing model is developed as paper based sensor for its practical applicability. The theoretical calculations were performed on Gaussian 03 program by relaxing the structures using Density functional theory.

Fluorescence Naphthalene Cationic Schiff Base Reusable Paper as a Sensitive and Selective for Heavy Metals Cations Sensor: RSM, Optimization, and DFT Modelling

Heavy metals are particularly damaging contaminants in the environment, and even trace concentrations represent a risk to human health due to their toxicity. To detect the heavy metals of Mn2+ and Co2+ ions, a novel selective reusable paper-based Fluorescence naked-eye sensor based on naphthalene cationic Schiff base (NCSB) was synthesized and confirmed using FT-IR, 1 H-NMR, and MS tools. Based on a blue to colorless color change in the aqueous solution, the NCSB sensor is utilized to Mn2+ and Co2+ cations selectively among other metal ions (Fe2+, Cu2+, Mg2+, Ni2+, Zn2+, Cd2+, Hg2+, Pb2+, Sn2+ and Cr3+). In the aqueous medium, the NCSB sensor displayed high sensitivity, with limits of detection (LOD) values of 0.014 µM (14.08 nM) and 0.041 µM (41.47 nM) for Mn2+ and Co2+ cations, respectively. The paper-based sensor naked-eye detected Mn2+ and Co2+ cations in water at concentrations as low as 0.65 µM (65 nM) and 0.086 µM (86 nM), respectively. It was discovered that 5 min of incubation time and a pH range of 7 to 11 were optimal for the complexation reaction between the Mn2+ and Co2+ ions and the NCSB sensor. Through a static quenching process, the interaction of the different metal ions with the Schiff base group in the NCSB molecule results in the development of a ground-state non-fluorescent complex. NCSB sensor was also successfully applied in analysis of Mn2+ and Co2+ in environmental water with good recoveries of 94.8-105.9%. The theoretical calculations based on density functional theory (DFT) studies are in support of experimental interpretations. The links between the input factors and the anticipated response were evaluated using the quadratic model of the response surface methodology (RSM) modeling.

Development of piperazine conjoined 1,2,3-triazolyl-γ-propyltriethoxysilanes: Fluorometric detection of Cr3+ ions and computational study

Chromium is essential for some biochemical processes, and excess is a big concern that shows adverse effects on human health and the environment. Therefore, it is urgent to design new sensors to detect chromium ions rapidly. The present study discusses the synthesis of piperazine conjoined 1,2,3-triazolyl-γ-propyltriethoxysilanes (4a-4b) and development of 4a as fluorescence turn-on sensor for the detection of Cr³⁺ ions. The mechanistic insights reveal to the restricted CN rotation and inhibited intramolecular charge transfer (ICT) process. In addition, Job's plot and Benesi-Hildebrand plot justify the 1:1 binding affinity with a binding constant of 9.96 × 10⁵ M^-1 for [ligand 4a + Cr³⁺] complex and the limit of detection for Cr³⁺ ions is observed as 6.06 × 10^-8 M. The fluorescence spectral changes, ¹H NMR spectra and DFT studies provide evidences for ligand 4a and Cr³⁺ ions interactions. Further, the reversibility of the ligand 4a from [ligand 4a + Cr³⁺] complex on the addition of EDTA can be used in the construction of molecular logic gate where Cr³⁺ and EDTA are considered as inputs and the fluorescence intensity at 398 nm as output. Further, compounds 4a-4b were then evaluated for their antibacterial activity against bacterial strains (Escherichia coliand Staphylococcus aureus), revealing a modest activity. The binding mode of ligand 4a to Staphylococcus aureus (PDB ID - 3U2K) and Escherichia coli (PDB ID - 5Z4O) was investigated using an in-silico molecular docking technique, which revealed that the triazole ring and silanyl group are involved in hydrogen bonding with proteins and may be the cause of the ligand's antibacterial activity. The ligand 4a demonstrated a high affinity for binding within the active sites of proteins with binding energies of -7.97 kcal/mol (3U2K) and -8.68 kcal/mol (5Z4O).

Tactile Sensors: Hydroxyl Decorated Silver Metal-Organic Frameworks for Detecting Cr2O72-, MnO4-, Humic Acid, and Fe3+ Ions

Anionic, acidic, and metal ions are common contaminants in water and cause serious concerns for human and aquatic life. With the goal of rapid detection of analytes, we herein design a new array of ligand 5-(4H-1,2,4-triazol-4-yl)pyridin-3-ol-linked silver coordinated metal-organic frameworks Ag-MOFs as a promising sensor for Cr₂O₇^2-, MnO₄^-, humic acid (HA), and Fe³⁺ ions down to the micro level. Furthermore, as evidenced by luminescence, excitation-emission matrix (EEM) spectroscopic, and PXRD measurements, designed metal-organic frameworks (MOFs) can be fast, stable, and reusable for analyte detection in water.

Colorimetric Cu2+ Detection of (1E,2E)-1,2-Bis((1H-pyrrol-2-yl)methylene)hydrazine Using a Custom-Built Colorimeter

The compound (1E,2E)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (1) was investigated for its chemosensor application. The colorimetric response of 1 with various ions was investigated, and the selective optical change upon mixing with Cu²⁺ was found. The Cu²⁺ binding stoichiometry of 1 derived from Job's plot and the in silico study give us the tentative structural detail of the binding mode of 1 and Cu²⁺ being 1:1. The binding constant between 1 and Cu²⁺ from the Benesi-Hildebrand plot was 1.49 × 10⁴ M^-1. The limit of detection of 1 in Cu²⁺ detection was 0.64 μM (0.040 ppm), which is much lower than the WHO and US EPA maximum allowable Cu²⁺ level in drinking water (2 and 1.3 ppm, respectively). The custom-built colorimeter demonstrates a good linear relationship between Cu²⁺ concentration and electrical resistance (Ω) upon 1-Cu²⁺ ion binding.

Triazole-Based Cu(I) Cationic Metal-Organic Frameworks with Lewis Basic Pyridine Sites for Selective Detection of Ce3+ Ions

A highly symmetric bis-triazole-pyridine-based organic ligand, i.e., 3,5-di(4H-1,2,4-triazol-4-yl)pyridine (L), and Cu(II) salts were used to synthesize three cationic Cu(I) metal-organic frameworks (MOFs), namely, {[Cu(L)]·(NO₃)·(H₂O)}_n (1), {[Cu(L)]·(BF₄)·0.5H₂O}_n (2), and {[Cu_1.25(L)]·1.25(ClO₄)·H₂O}_n (3). All three MOFs have nonbonded anions situated inside the pore spaces. Both 1 and 2 have a two-dimensional network structure, while 3 has a three-dimensional structure. All three MOFs were characterized using Fourier transform infrared spectroscopy, elemental (C, H, and N) analysis, thermogravimetric analysis, and powder and single-crystal X-ray diffraction. Due to the presence of a Lewis basic pyridine moiety, these MOFs could serve as luminescent probes for the selective detection of Ce³⁺ ions with excellent efficiency (10^-7 M). The synthesis of Cu(I)-based MOFs and their use to detect Ce³⁺ ions in water via a turn-on fluorescence process have rarely been reported. These MOFs are highly stable in water, are recyclable, and function efficiently at different pH values.

Tetrazole conjoined organosilane and organosilatrane via the ‘click approach’: a potent Mycobacterium tuberculosis enoyl ACP reductase inhibitor and a dual sensor for Fe(iii) and Cu(ii) ions

This article includes the synthesis and characterization of tetrazole-allied organosilane and organosilatrane. The tetrazole-allied silatrane was explored for molecular docking and optical aspects.