Infrared Research Articles

Crystal Structure, Photophysical Properties and Antibacterial Activity of a Cd(II) Complex with Trans-2,3,4-Trimethoxycinnamic Acid and 4,4'-Bipyridine Ligands.

A new coordination polymer {[Cd(C12H13O5)2(4,4'-bpy)(H2O)2]}n (Cd-Tmca-bpy) was constructed with trans-2,3,4-Trimethoxycinnamic acid (HTmca) and 4,4'-Bipyridine (4,4'-bpy) ligands. This complex was structurally characterized on the basis of elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction and thermogravimetric analyses. X-ray crystallography revealed that the complex was monoclinic, space group C2/c. The Cd(II) ion in the complex was six coordinated, adopting an octahedron geometry. The neighboring Cd(II) ions linked linear ligand 4,4'-bpy molecules to form an infinite 1D chain. The 1D chain was further interlinked by O-H···O and C-H···O hydrogen bonds, resulting in a 3-D supramolecular framework. Meanwhile, the photoluminescence spectrum of the Cd(II) complex at room temperature exhibited an emission maximum at 475 nm. Using the time-dependent density functional theory (TD-DFT) method, the electronic absorption spectra of the Cd(II) complex was predicted. A good agreement was achieved between the predicted spectra and the experimental data. Bioactivity studies showed that the complex exhibited significant inhibition halos against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus).

Infrared Spectra Prediction for Functional Group Region Utilizing a Machine Learning Approach with Structural Neighboring Mechanism.

Infrared (IR) spectroscopy is a pivotal technique in chemical research for elucidating molecular structures and dynamics through vibrational and rotational transitions. However, the intricate molecular fingerprints characterized by unique vibrational and rotational patterns present substantial analytical challenges. Here, we present a machine learning approach employing a structural neighboring mechanism tailored to enhance the prediction and interpretation of infrared spectra. Our model distinguishes itself by honing in on chemical information proximal to functional groups, thereby significantly bolstering the accuracy, robustness, and interpretability of spectral predictions. This method not only demystifies the correlations between infrared spectral features and molecular structures but also offers a scalable and efficient paradigm for dissecting complex molecular interactions.

NIR‐Triggered Cu2O/Cu2‐xS Heterostructure as an “All‐In‐One” Functional Nanoplatform for Efficient Synergistic Tumor Therapy

AbstractThe fabrication of synergistic multifunctional anti‐tumor nanoplatforms is challenging due to the urgent requirement to activate different therapeutic modalities. Although the multi‐modal treatments can be achieved by carrying out the activation with different exogenous and endogenous stimulations in sequence, this tedious manner is not applicable to the ideal synergistic cancer treatment. Herein, a simple heterojunction of Cu2O/Cu2‐xS modified with gambogic acid and hyaluronic acid (CCS@GA@HA) is ingeniously fabricated for the synergistic cancer treatment combining photothermal therapy (PTT), photocatalytic therapy (PCT), chemodynamic therapy (CDT) and potential ferroptosis just activated by the single near infrared (NIR) light irradiation. Cu2O/Cu2‐xS heterostructure (CCS) with promoted separation and transfer efficiency of photogenerated charge carriers exhibits excellent photocatalytic performance. The intervention of gambogic acid (GA) downregulates the overexpression of heat shock protein 90 (HSP90), which make it possible to execute the mild PTT. And the CDT performance is efficiently improved by the heat generated from PTT. Specifically, CCS appears to accelerate the accumulation of lipid peroxides (LPO) and inactivate glutathione peroxidase 4 (GPX4) that directly induce ferroptosis. In brief, CCS@GA@HA exhibits prominent NIR‐triggered synergistic effect involving PCT, mild PTT, enhanced CDT and ferroptosis for an effective multi‐modal tumor treatment.

Evaluation of RMS Current in AC Power Wires Using a High-Speed Infrared System

This paper presents a new method of the effective value (RMS) of alternating current (AC) in power wires based on infrared radiation (IR) measurement using a high-speed medium wavelength infrared (MWIR) camera. The method called “2-ω” involves measurement of the 100 Hz harmonic of temperature (T100) and is supported by signal analysis in the frequency domain. The article discusses the issue of non-sinusoidal alternating current, which causes much more difficult analyzes compared to sinusoidal current with a frequency of 50/60 Hz. The simulation and measurement results for different current shapes obtained in typical power systems like: a phase-controlled switching regulator, half-wave and full-wave rectifiers, and finally the nonlinear distortion of the AC current due to saturation of the magnetic core, are presented and confirm the linear relation of T100 ~ I2RMS. The main advantage of proposed method is the independence of the measurement results from environmental conditions.

Design, Synthesis, and Antimicrobial Evaluation of Novel Schiff Bases Derived from Thymol

Schiff bases, a significant class of organic compounds, are synthesized through the reaction of a primary amine with an aldehyde or ketone under specific conditions. In this study, we report the synthesis of novel Schiff bases derived from thymol (2-Isopropyl-5-methylphenol). The synthesis began with the esterification of thymol to produce (2-Isopropyl-5-methylphenoxy)-acetic acid ethyl ester (1), followed by hydrazination to yield (2-Isopropyl-5-methylphenoxy)-acetic acid hydrazide (2). The hydrazide (2) was then treated with various aromatic aldehydes to synthesize a series of Schiff bases (3A-J). The chemical structures of these compounds were elucidated using infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H-NMR), and mass spectrometry. The synthesized Schiff bases were evaluated for their antibacterial and antifungal activities using standard screening methods. The results indicated that all synthesized compounds exhibited varying degrees of antimicrobial activity. Among the series, compound 3C showed the highest antibacterial and antifungal potency, suggesting it could be a promising candidate for further development. This study highlights the potential of Schiff bases as bioactive compounds with broad-spectrum antimicrobial properties. The structure-activity relationship (SAR) suggests that the presence of specific substituents on the aromatic aldehyde moiety could enhance biological activity. Further investigation into the mechanisms of action and optimization of these Schiff bases could contribute to the development of novel antimicrobial agents

A zero-dimensional 1-butylpiperazine-cadmium(II) hybrid material: Synthesis, structural analysis, and DFT studies

This study reports the synthesis and characterization of an organoammonium-cadmium(II) hybrid material, (BPH₂)₂[Cd₂Cl₈] (BP = 1-butylpiperazine), using a combination of experimental and theoretical techniques. Single-crystal X-ray diffraction shows a centrosymmetric crystal structure in the P1¯ space group, featuring a zero-dimensional (0D) arrangement where binuclear [Cd₂Cl₈]⁴⁻ anions and (C₈H₂₀N₂⁺) cations are linked by N—H···Cl and C—H···Cl hydrogen bonds. Hirshfeld surface analysis further elucidates these intermolecular noncovalent interactions, highlighting the dominant role of H···Cl contacts in the molecular packing. The crystal morphology is further investigated via the Bravais-Friedel-Donnay-Harker (BFDH) model. Infrared (IR) spectroscopic analysis was conducted to identify vibrational modes, confirm structure, and elucidate bonding features. Additionally, Experimental UV–visible study indicates an optical band gap energy of 4.75 eV, and density functional theory (DFT) calculations corroborate these findings, predicting a direct band gap of 4.45 eV. Moreover, theoretical calculations, including the complex dielectric function, band structure, and total density of states (DOS), were performed to explore the electrical and optical properties. Finally, the chemical reactivity was evaluated using conceptual-DFT descriptors at the B3LYP/SDD/aug-cc-pVTZ level of theory.

Microwave-Assisted Synthesis and Characterization of Novel 1,3,4-Oxadiazole Derivatives and Evaluation of In Vitro Antimycobacterial Activity.

Objective The study's goal was to come up with and make a new group of 1,3,4-oxadiazole derivatives (3a-3e) and test how well they could kill Mycobacterium tuberculosis (Mtb) H37Rv strain. Additionally, molecular docking and pharmacokinetic properties were analyzed using computational software to identify potential inhibitors, followed by in vitro antimycobacterial assays. Methods A group of 1,3,4-oxadiazoles was prepared by reacting acyl hydrazides with alanine, an N-protected α-amino acid, and a small amount of POCl3. This was carried out under microwave treatment. The structural characterization of the newly synthesized compounds was performed using infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and mass spectrometry. The in vitro antimycobacterial activity of the 1,3,4-oxadiazole derivatives (3a-3e) was assessed using the microplate Alamar Blue assay against the Mtb H37Rv strain. The synthesized compounds were subjected to molecular docking investigations in order to gain insights into their interaction mechanisms with the mycobacterial enzyme InhA (enoyl-acyl carrier protein reductase). Computational analysis of pharmacokinetic properties was performed to predict the oral bioavailability and drug-likeness of the compounds. Results All synthesized compounds inhibited the growth of Mtbat concentrations of 50 and 100 μg/mL. At a concentration of 50 μg/mL, compounds 3c and 3d exhibited the most prominent antimycobacterial action. Molecular docking results revealed that compound 3d exhibited the highest binding energy interaction with the InhA enzyme (-9.1 kcal/mol). Pharmacokinetic predictions indicated that all compounds possess favorable drug-like properties suitable for oral administration. Conclusion This study successfully synthesized a novel series of oxadiazole derivatives (3a-3e) using a microwave-assisted method with high yields. The synthesized compounds demonstrated significant antimycobacterial activity, particularly compounds 3c and 3d. Molecular docking and pharmacokinetic analyses further confirmed the potential of these compounds as promising leads for the development of anti-tubercular agents.

Experimental Determination of Slag Emissivities for Enhanced Slag Control by Infrared‐Based Systems

For today's high‐quality steel production, good control of slag composition is essential in secondary steelmaking. However, the conventional slag analysis practice, involving sampling, sample preparation, and analysis, is very time‐consuming. This work is the first step toward an investigation of infrared (IR)‐based systems and can be used for online slag composition monitoring using the principle that different slag compositions have different emissivities in the IR wavelength range. Therefore, this work experimentally determines emissivity values of slags as a function of composition at steelmaking temperature, since available data for slags are very limited in the literature. The emissivities of three different slag compositions belonging to the Al2O3–CaO–SiO2–MgO system are investigated at 1773 K. The investigated emissivities are in the range of 0.75–0.87, with the best repeatability seen in the slag which is fully liquid at 1773 K. Variations in emissivities are observed within the other slags due to the presence of solid phases. Although the data clearly indicate a difference of emissivities as a function of slag composition, further experiments must be performed to evaluate the emissivities of other characteristic slags at different temperatures in order to further assess the applicability of IR‐based systems for slag composition control.

Gambogic acid and IR780 self-assembled nanoparticles for combined chemo-phototherapy

Combined chemo-phototherapy has shown considerable advantages and potential in cancer treatment. For this purpose, self-assembled nanoparticles by gambogic acid (GA) and IR780 (referred to as GA-IR780 NPs) were prepared. Herein, GA, an active compound derived from Garcinia hanburyi Hook.f, was selected as a chemo-agent. IR780 was used as a photothermal agent as well as a photosensitizer, which could kill tumor cells via photothermal effect and photodynamic effect. The obtained GA-IR780 NPs were uniform spheres with particle size of ca. 50 nm. The drug loading efficiency of GA and IR780 was 38.42 % and 56.64 %, respectively. The GA-IR780 NPs exhibited excellent photothermal properties as well as photodynamic effect when irradiated by near infrared (NIR) light (808 nm, 2.0 W/cm2). Moreover, the GA-IR780 NPs showed enhanced cytotoxicity with NIR light activation. Results of animal experiments showed that GA-IR780 NPs had the most significant tumor inhibition when irradiated by laser, and the results of H&E, Ki-67 and TUNEL staining confirmed that the GA-IR780 NPs+Laser group caused the most severe tumor tissue damage. The above results indicated that GA-mediated chemotherapy combining with IR780-based phototherapy could significantly improve the anti-tumor efficacy.

Evaluating efficiency of foreign object detection technology based on the use of passive infrared thermography

A new method for detecting subsurface solid objects buried in farmlands, such as plastic bottles, wasted cans, etc., has been proposed by applying the technique of infrared (IR) thermography to monitor the temperature of soil surface subjected to solar irradiation. Through both experimentation and simulation, this study parameterizes the influence of environmental factors on IR images and validates the detection capabilities of the method. To verify the feasibility of IR thermography testing, the experimental section of the work is devoted to monitoring aluminum and polyethylene terephthalate cans buried in sand with varying grades of moisture. The dependencies between the efficiency of foreign object detection and their depth are derived. A restoring pseudothermal flux algorithm was used to reduce the impact of lateral diffusion on IR thermographic detection of foreign objects buried in soil. Variations of soil temperature caused by varying solar radiation during multiple day-night cycles are used to improve the detectable diameter-depth ratio. The described technique is efficient and provides no harm to human beings.

TB-mBJ for doping concentration effects on magneto-optical properties in [formula omitted] spintronics materials

An investigation for electronic, magnetic, and optical properties of Mn-doped ZnSnAs2 compound performed using advanced computational methods. Using spin-polarized density functional theory (DFT) calculations with local orbital linearized augmented plane wave (lo-LAPW) method and Tran–Blaha’s modified Becke–Johnson (TB-mBJ) functional, Mn-doped n-type chalcopyrite semiconductor ZnMnxSn(1−x)As2, studied within varying Mn doping concentration range 0≤x≤0.5. Doping of Mn to Sn site in pure ZnSnAs2 creates a strong spin effect, which makes it useful spintronic materials. We observed with increase the Mn concentration in ZnSnAs2, energy bandgap changes while the magnetic strength of the unit cell remains unchanged, showing stability of system’s magnetism. Optical properties of the Mn doped ZnSnAs2 compounds analysed in term of dielectric function, absorption spectra, and refractive index. Optical properties show, compound is optically low active in the Infrared (IR) region and more active in visible and ultraviolet (UV) region. The electronic and optical properties of Mn-doped ZnSnAs2, offer potential technological advancements in semiconductor device design technology and engineering.

Effects of cross-sectional shape on the low observability of double serpentine nozzles

When unmanned combat aerial vehicles (UCAVs) egress from the battlefield after attacking the target, the defensive radar systems detect signals reflected by the cavity structure of the nozzle and engine of the UCAVs, threatening their survivability. Infrared (IR) guided missiles can also threaten them by detecting the gaseous plume and hot engine parts. We present a comprehensive investigation of the effects of the cross-sectional shape of double serpentine nozzles on thrust, IR signature, and radar cross section (RCS), which are associated with propulsive performance and low observability. The fillet radius and cross-sectional shape of the nozzles were considered as the main design variables. The thermal flow field was analyzed using the compressible Navier-Stokes equations, while the IR signature was analyzed with the radiative heat transfer equation with a narrow band model. The RCS was calculated using a multi-level fast multipole method of full Maxwell's equations instead of the approximate methods often employed. The double serpentine (DS) nozzle with an elliptical cross-section showed high pressure recovery and a 9.66 % lower IR signature than the DS nozzle with a rectangular cross section. The maximum RCS and mean RCS were lowest for the DS nozzle with an elliptical cross section, with a maximum difference in maximum RCS of 383 % and mean RCS of 90 % compared with the DS nozzle with a rectangular cross section. The DS nozzle with an elliptical cross section distributes the current more evenly across the central part of the engine than the DS nozzle with a rectangular cross section. The DS nozzle with an elliptical cross-section showed excellent nozzle performance with a negligible difference in thrust. In addition, the results show that the cross-sectional shape of the nozzles has different levels of impact on thrust and pressure recovery (negligible), IR signature (limited), and RCS (significant).

Photothermal-assisted magnetic recoverable Cd0.9Zn0.1S/NiCoB heterojunction with extraordinary photocatalytic hydrogen evolution

Easily recyclable photocatalysts hold great potential in the field of photocatalysis. Guided by rational theoretical predictions, this study designs a novel tetrapod-like Cd0.9Zn0.1S/NiCoB (CZS/NCB) Schottky heterojunction with magnetic and photothermal properties, and demonstrates its excellent photocatalytic hydrogen evolution performance. Under the combined effects of the photothermal properties and the Schottky heterojunction, the photocatalytic hydrogen evolution rate extraordinarily reaches 108.39 mmol g−1 h−1 after 3 h of visible light irradiation, which is 4.69 times that of pure CZS. Additionally, photocatalytic hydrogen evolution tests conducted using infrared thermography and alternating visible and visible plus infrared light irradiation have confirmed the material’s outstanding photothermal properties. In-depth density functional theory (DFT) calculations reveal potential charge transfer pathways and confirm the formation of the Schottky heterojunction. This work provides guidance for the rational construction of magnetic recoverable photocatalysts with practical application.

5-D spatial-temporal information-based infrared small target detection in complex environments

Recently, infrared (IR) small target detection problem has attracted increasing attention. Tensor component analysis-based techniques have been widely utilized, while they are faced with challenges such as tensor structures, background and target estimation, and real-time performance. In this paper, we propose a 5-D spatial–temporal factor-based completion model (5D-STFC) for IR small target detection. Specifically, a 5-D whitened spatial–temporal patch-tensor is constructed. Then, we devise a spatial–temporal factor-based low-rank background estimation norm and a Moreau envelope-derived sparsity estimation norm based on joint spatial–temporal knowledge. Furthermore, we establish a comprehensive completion model for component analysis. To efficiently solve this model, we design a multi-block alternating direction method of multipliers (multi-block ADMM)-based optimization scheme. Extensive experiments conducted on five real IR sequences demonstrate the superiority of 5D-STFC over nine state-of-the-art competitive methods. It can be concluded that 5D-STFC is excellent and practical in target detectability, background suppressibility, overall performance, and real-time performance.

Mineral Interface Doping: Hydroxyapatite Deposited on Silicon to Trigger the Electronic Properties

AbstractDoping silicon wafers without using highly toxic or corrosive chemical substances has become a critical issue for semiconductor device manufacturing. In this work, ultra‐thin films of hydroxyapatite (Ca5(PO4)3OH) are prepared by tethering by aggregation and growth (T‐BAG), and further processed by spike annealing. Via in situ infrared (IR), the decomposition of hydroxyapatite and intermixing with the native silicon oxide is observed already at temperatures as low as 200 °C. Phosphate transport through the native silicon oxide is driven by a phase transformation into a more stable thermal oxide. At 700 °C, diffusion of phosphorus into the sub‐surface region of oxide‐free silicon is observed. In situ IR combined with electrical impedance spectroscopy (EIS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), and X‐ray photoelectron spectroscopy (XPS) measurements allows to conclude that the phosphorus is: i) transported through the silicon oxide barrier, ii)) diffused inside the oxide‐free silicon, and iii) finally modified the electrical activity of the silicon wafer. To further explain the experimental findings, density‐functional theory (DFT) is used to demonstrate the extent of the effect of phosphorus doping on the electronic nature of silicon surfaces, showing that even small amounts of doping can have a measurable effect on the electrical performance of semiconductor wafers.

Polyphosphate-Mediated Crystallographic and Colloidal Stabilization of CuS Nanoparticles: Enhanced NIR-Responsive Chemo-Photothermal Efficacy.

Photothermal therapy (PTT) is an emerging treatment modality for cancer management. However, the photothermal agents (PTAs) used in PTT should have sufficient biocompatibility, water dispersibility, and good photoresponsive. In this aspect, water-dispersible and biocompatible linear polyphosphate (LP)-functionalized CuS nanoparticles (LP-CuS NPs) were developed using sodium tripolyphosphate (LP molecule) as a surface passivating agent. The successful formation of the green covellite CuS phase was confirmed by X-ray diffraction and TEM analyses, and its surface functionalization with the LP ligand was evident from X-ray photoelectron spectroscopy, Fourier transform infrared, thermogravimetric analysis, and light scattering measurements. It has been found that the use of LP not only stabilizes the crystallographic covellite CuS phase by overcoming the requirement of a soft ligand but also provides long-term aqueous colloidal stability, which is essential for PTT applications. The aqueous suspension of LP-CuS NPs showed excellent heating efficacy under near infrared (NIR) light irradiation (980 nm) and has a strong binding affinity towards anticancer drug, doxorubicin hydrochloride (DOX). The drug-loaded systems (DOX@LP-CuS NPs) revealed a pH-dependent drug release behavior with higher concentrations in a mild acidic environment. The in vitro studies showed substantial cellular uptake of DOX-loaded systems in cancer cell lines and enhanced toxicity towards them upon irradiation of NIR light through apoptotic induction, suggesting their potential application in chemo-photothermal therapy.

Formation of Uranyl Peroxide Compounds via Dissolution of Studtite, [(UO2)(O2)(H2O)2](H2O)2, in Ionic Liquids.

Four uranyl peroxide compounds with novel structures were formed following the dissolution of studtite, [(UO2)(O2)(H2O)2](H2O)2, in imidazolium-based ionic liquids. The compounds were characterized using single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Raman and infrared (IR) spectroscopy, and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The ionic liquids used in the experiments were 1-ethyl-3-methylimidazolium (EMIm) diethyl phosphate, EMIm ethyl sulfate, and EMIm acetate. Each of the four uranyl peroxide compounds contain components from the ionic liquids as terminal ligands on uranyl peroxide molecular units, bridging ligands in uranyl peroxide sheet structures, or charge balancing cations located in the interstitial space. The studtite dissolved in and reacted with the ionic liquids, producing unique crystal structures depending on the anionic component of the ionic liquid, the temperature at which the synthesis was performed, and the introduction of additional ionic species into the solution. This is the first report of studtite dissolving in and reacting with ionic liquids to form uranyl peroxide compounds, which has the potential to vastly increase the number of synthetic routes for the formation of uranyl peroxide clusters and uranyl peroxide cage clusters.

Discrimination of Explosive Residues by Standoff Sensing Using Anodic Aluminum Oxide Microcantilever Laser Absorption Spectroscopy with Kernel-Based Machine Learning.

Standoff laser absorption spectroscopy (LAS) has attracted considerable interest across many applications for environmental safety. Herein, we propose an anodic aluminum oxide (AAO) microcantilever LAS combined with machine learning (ML) for sensitive and selective standoff discrimination of explosive residues. A nanoporous AAO microcantilever with a thickness of <1 μm was fabricated using a micromachining process; its spring constant (18.95 mN/m) was approximately one-third of that of a typical Si microcantilever (53.41 mN/m) with the same dimensions. The standoff infrared (IR) spectra of pentaerythritol tetranitrate, cyclotrimethylene trinitramine, and trinitrotoluene were measured using our AAO microcantilever LAS over a wide range of wavelengths, and they closely matched the spectra obtained using standard Fourier transform infrared spectroscopy. The standoff IR spectra were fed into ML models, such as kernel extreme learning machines (KELMs), support vector machines (SVMs), random forest (RF), and backpropagation neural networks (BPNNs). Among these four ML models, the kernel-based ML models (KELM and SVM) were found to be efficient learning models able to satisfy both a high prediction accuracy (KELM: 94.4%, SVM: 95.8%) and short hyperparameter optimization time (KELM: 5.9 s, SVM: 7.6 s). Thus, the AAO microcantilever LAS with kernel-based learners could emerge as an efficient sensing method for safety monitoring.

Cascaded nanocavity-shaped metasurfaces for realizing an intensive radiation absorption in the mid-to-long infrared region based on electromagnetic wavefield resonance response and accumulation

A type of cascaded metal-insulator-metal nanocavity-shaped (CMNM) metasurface has been developed for realizing an intensive radiation absorption in the mid-to-long infrared (IR) region. The radiation absorption characteristics are analyzed according to the impedance matching mechanism. By evaluating the electromagnetic wavefield properties at several wavelength points selected, the spatial resonance morphology of the electric field and magnetic field components excited mainly by the resonance of the free electrons over the surfaces of the metasurface are simulated effectively. The stimulating and redistributing behaviors of the conductive electric-currents, including the surface equivalent eddy-currents surrounding a couple of dielectric films configurated in the cascaded nanocavities, and the net charges distributed over three Ti films, which will induce a resonant accumulation enhancement of the wavefields in the metasurfaces corresponding to the incident IR radiation, are exhibited. An average absorption level of more than 85% in the 3–14µm wavelength region is already achieved. Due to the IR responding and manipulating approaches proposed by us, the CMNM samples also exhibit an insensitivity of the beam incident angle for some typical applications in uncooled infrared imaging and thermal radiation detection.

Linear electronic relationship of surface functionalized fly ash and substituted phenols on bactericidal activity with the computational study

AbstractFly ash is a solid waste by‐product obtained from coal‐burning power plants. It is a silico‐aluminate material with an admixture of several metal oxides, which finds an application in geopolymers, zeolites, cement, catalysts, etc. The present article aims to assess the antibacterial activity of fly ash and substituted phenols against Escherichia coli and Staphylococcus in broth and agar cultures, respectively. High‐Temperature Activated Fly Ash (TAFA) shows significant bactericidal activity against gram positive (+) and negative (−) bacteria as compared to Mechanically Activated Fly Ash (MAFA) and Waste Polyethylene Coated Fly Ash (WPCFA), which attribute to the augmentation of mullite phase (lacking charge balancing cation) of fly ash at high temperature. These modified fly ash (TAFA, MAFA, and WPCFA) were characterized by Fourier Transform Infra Red (FT‐IR), Scanning Electron Microscope (SEM), and X‐Ray Diffraction (XRD) techniques. The substituted phenols further explored the significance of charge on the antibacterial properties. The para‐substituted phenols with groups having (+) mesomeric effect M &gt; (−) I Inductive effect and ortho substituents with (+) I effect shows a linear electronic relationship with antibacterial properties with gram (+) bacteria, owing to charge augmentation at oxygen atom of phenoxide ion due to electronic effects. Further, the bactericidal efficacy was less significant on gram (−) bacteria. Small energy gap (Egap) values corroborated the chemical reactivity of phenols and substituted phenols. The antimicrobial potential of phenol/substituted phenols can be correlated with global descriptors. Molecular Electrostatic Potential (MEP) maps obtained through Density Functional Theory (DFT) indicate the nucleophilic centers in the molecular structure.