Azo dyes demonstrate dose-dependent carcinogenic and mutagenic effects in exposed
cells. Among remediation approaches, microbial adsorption is the most sustainable and
environmentally friendly method for eliminating azo dyes. A novel Aspergillus terreus silica
composite was developed as a sustainable adsorbent for crystal violet dye (CVD) removal.
The fungal strain was isolated from dye wastewater and was genetically identified by 18S
rRNA gene sequencing. Dried mycelia of A. terreus (PX920301) were combined with SiO2
(1:1 w/w) through iterative hydration-drying cycles, yielding a composite characterized by
FTIR analyses. Removal CVD %, adsorption capacity, and CVD residual were calculated,
and the adsorption process was optimized using Box–Behnken design (four factors, 25 runs).
The biosafety of the composite was assessed for phytotoxicity and microbial toxicity. The
composite was also applied to real dyes wastewater collected from the bacteriological
laboratory. Aspergillus terreus-silica composite showed the highest CVD removal percentage
by 85.4%, adsorption capacity (qe) 121.1 mg/L, and lowest CVD residual by 7.26 mg/L,
followed by the dried active mycelia (DA-mycelia) with CVD removal 40.23%, adsorption
capacity (qe) 57.05 mg/L, and CVD residual by 29.73 mg/L. Optimization data cleared that
the maximum experimental values of CVD removal (%) was 99.59% (predicted value 100%)
obtained in run number (4) using initial CVD concentration (200 mg/L), pH (8), adsorbent
composite weight (0.1 g), and contact time (48 h). Biosafety evaluation demonstrated
negligible phytotoxicity against Triticum aestivum seedlings post-treatment, with restored
germination and growth comparable to controls. Microbial toxicity assays via well-diffusion
to seven microbial isolates confirmed no toxic activities against the tested bacteria, yeast,
and fungi, underscoring the composite’s environmental safety. The composite could
decolorize the real dye wastewater of laboratories by 95.37%. In conclusion, A. terreus
mycelial-silica composite offers a cost-effective, sustainable, and eco-friendly alternative
solution for dye bioremediation.

In the current industrial scenario, cobalt (Co) as a metal is of great importance but poses a major threat to the ecosystem because of its toxicity, but fewer studies have been conducted on its effects and alleviation strategies by using plant growth-promoting rhizo-bacteria (PGPR) and nanoparticles (NPs). Taking into consideration the positive effects of silver nanoparticles (Ag−NPs) and Bacillus cereus in reducing Co toxicity in plants, the present study was conducted. A pot experiment was conducted to determine the effects of individual application of different levels (10 and 20 µL) of B. cereus and Ag−NPs (25 and 40 mg L^⁻1) on Co accumulation, morpho-physio-biochemical attributes of Sorghum bicolor L. exposed to severe Co stress [0 (without Co stress), 15 and 25 mg kg⁻¹ in soil]. The research outcomes indicated that elevated levels of Co stress in the soil significantly (P ≤ 0.05) decreased plant growth and biomass, photosynthetic pigments, and gas exchange attributes. However, Co stress also induced oxidative stress in the plants by increasing malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), which also induced increased compounds of various enzymatic and non-enzymatic antioxidants, organic acids, and also the gene expression and sugar content. Furthermore, a significant (P ≤ 0.05) increase in proline metabolism, was observed. Although, the application of B. cereus showed a significant (P ≤ 0.05) increase in plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds, and their gene expression and also decreased oxidative stress and also organic acid exudation pattern. The application of B. cereus and Ag−NPs decreased the proline metabolism in S. bicolor plants. Research findings, therefore, suggest that the application of B. cereus and Ag−NPs can ameliorate Co toxicity in S. bicolor, resulting in improved plant growth and composition under metal stress, as depicted by balanced antioxidant defense mechanism. These findings highlight the potential of nanotechnology and beneficial microbes as sustainable strategies for mitigating heavy metal toxicity and improving crop performance in contaminated soils, thereby contributing to environmentally resilient agricultural systems

Highly active catalysts for oxygen evolution reaction (OER) derived from transition metals are crucial for boosting the performance of catalytic electrolysis of water, a key technology for sustainable hydrogen production. This research highlights the design and synthesis of FeM@Co layered double hydroxide (LDH) nanoflowers, where M represents Co, Mn, or Ni, prepared through a facile two-step electrodeposition method. Introducing diverse transition metals significantly modulates the interfacial synergy between the nanostructured Co LDH and the FeM decoration, thereby tuning the electronic structure and electrocatalytic efficiency. Comparative evaluation of the hybrid structures revealed that FeNi@Co LDH nanoflowers exhibit the most remarkable OER activity, with an overpotential of only 266 mV at 100 mA∙cm⁻², a minimal Tafel slope of 21 mV∙dec⁻¹, and excellent durability over 50 h under prolonged operation at 100 mA∙cm⁻². Beyond half-cell studies, a full-cell electrolyzer employing FeNi@Co LDH serving as the anode, with Pt/C functioning as the cathode, delivered 10 mA∙cm⁻² at only 1.43 V, underscoring its high energy efficiency and practical viability. These findings highlight the promise of tailored FeM@Co LDH architectures as high-performance catalysts, contributing valuable knowledge to the purposeful design of advanced materials for efficient water-splitting and clean energy applications.

A simple one-pot protocol is described for the synthesis of dispiro[fluorene-9,3′-pyrazole-5′,4″-pyrazolidines] via a [3 + 2] cycloaddition reaction between 9-diazo-9H-fluorene (DF) and a series of (E/Z)-4-arylidene-1-phenylpyrazolidine-3,5-diones (APPs). In all cases, the cycloaddition proceeds with complete regioselectivity, affording a single regioisomeric framework as a pair of diastereomers through an endo approach. The structures and regiochemical outcomes of the cycloadducts were established by comprehensive 1D and 2D NMR spectroscopic analyses (¹H, ¹³C, DEPT-135, COSY, ¹H-HSQC, HMBC, and ROESY). The regiochemistry and mechanism of the cycloaddition reaction were investigated using density functional theory (DFT) calculations at the B3LYP/cc-pVTZ level of theory, supported by analysis of global and dual local electrophilicity and nucleophilicity descriptors. To rationalize the observed stereoselectivity, the relevant transition-state structures were located and optimized using a QST3-based transition-state search at the same level of theory. Global electron density transfer (GEDT) analysis revealed that the cycloaddition reactions are highly polar, with electron density flowing from 9-diazo-9H-fluorene (DF) toward the (E/Z)-4-arylidene-1-phenylpyrazolidine-3,5-dione (APP) framework. Consistently, molecular electrostatic potential surface (MESP) analysis showed that, in the energetically favored transition states, the reacting partners approach through regions of opposite electrostatic potential, leading to stabilizing electrostatic interactions between the two fragments. The computational results are consistent with the experimental observations and support a polar, synchronous one-step cycloaddition mechanism. The developed protocol affords the desired dispiro compounds in good to excellent yields (59–91%) with complete regioselectivity, providing a single regioisomeric framework as a pair of diastereomers. This work provides valuable insights into diazo-based cycloaddition chemistry and is expected to stimulate further research in the synthesis of structurally complex spiroheterocycles. Compared to previously reported approaches, the present method offers a simple one-pot strategy with high efficiency, complete regioselectivity, and operational simplicity.

Acetylation of 1-amino-5-(piperidin-1-yl)-N-phenyl-6,7,8,9-tetrahydrothieno[2,3-c]isoquinoline-2-carboxamide (3) with acetic anhydride afforded unexpected [1,3]oxazinothienoisoquinolinone derivative in an excellent yield instead of the expected N-phenylpyrimidothienoisoquinolinone. Diazotization of 3 using sodium nitrite in acetic acid and sulfuric acid yielded the corresponding triazinothienoisoquinoline, while the reaction with triethyl orthoformate in acetic acid produced N-phenylpyrimidine derivative 7. Chloroacetylation of compound 3 with chloroacetyl chloride in dioxane at 60–70°C yielded chloroacetamido compound 8, which underwent ring closure upon reflux in acetic anhydride to produce the chloromethyl oxazinone derivative 9. Oxazinone derivatives 5 and 9 underwent nucleophilic substitution upon treatment with ammonium acetate/acetic acid mixture and hydrazine hydrate to afford pyrimidinone …