Triazole, benzotriazole, and naphthotriazole as copper corrosion inhibitors: I. Molecular electronic and adsorption properties

Exposure to benzotriazoles and benzothiazoles in Czech male population and its associations with biomarkers of liver function, serum lipids and oxidative stress

INTRODUCTION

Benzotriazoles and benzothiazoles (BTs) are high-production volume chemicals as well as widely distributed emerging pollutants with potential health risk. However, information about human exposure to BTs and associated health outcomes is limited.

OBJECTIVE

We aimed to characterise exposure to BTs among Czech men, including possible occupational exposure among firefighters, its predictors, and its associations with liver function, serum lipids and oxidative stress.

METHODS

165 participants (including 110 firefighters) provided urine and blood samples that were used to quantify the urinary levels of 8 BTs (high-performance liquid chromatography-tandem mass spectrometry), and 4 liver enzymes, cholesterol, low-density lipoprotein, and 8-hydroxy-2'-deoxyguanosine. Linear regression was used to assess associations with population characteristics and biomarkers of liver function, serum lipids and oxidative stress. Regression models were adjusted for potential confounding variables and false discovery rate procedure was applied to account for multiplicity.

RESULTS

The BTs ranged from undetected up to 46.8 ng/mL. 2-hydroxy-benzothiazole was the most predominant compound (detection frequency 83%; median 1.95 ng/mL). 1-methyl-benzotriazole (1M-BTR) was measured in human samples for the first time, with a detection frequency 77% and median 1.75 ng/mL. Professional firefighters had lower urinary 1M-BTR compared to non-firefighters. Urinary 1M-BTR was associated with levels of γ-glutamyl transferase (β = - 17.54%; 95% CI: - 26.127, - 7.962).

CONCLUSION

This is the first study to investigate BT exposure in Central Europe, including potentially exposed firefighters. The findings showed a high prevalence of BTs in the study population, the relevance of 1M-BTR as a new biomarker of exposure, and an urgent need for further research into associated adverse health outcomes.

Assessment of Hydrazone Derivatives for Enhanced Steel Corrosion Resistance in 15 wt.% HCl Environments: A Dual Experimental and Theoretical Perspective

This study evaluates the corrosion inhibition capabilities of two novel hydrazone derivatives, (E)-2-(5-methoxy-2-methyl-1H-indol-3-yl)-N'-(4-methylbenzylidene)acetohydrazide (MeHDZ) and (E)-N'-benzylidene-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HHDZ), on carbon steel in a 15 wt.% HCl solution. A comprehensive suite of analytical techniques, including gravimetric analysis, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM), demonstrates their significant inhibition efficiency. At an optimal concentration of 5 × 10-3 mol/L, MeHDZ and HHDZ achieve remarkable inhibition efficiencies of 98% and 94%, respectively. EIS measurements reveal a dramatic reduction in effective double-layer capacitance (from 236.2 to 52.8 and 75.3 µF/cm2), strongly suggesting inhibitor adsorption on the steel surface. This effect is further corroborated by an increase in polarization resistance and a significant decrease in corrosion current density at optimal concentrations. Moreover, these inhibitors demonstrate sustained corrosion mitigation over extended exposure durations and maintain effectiveness even under elevated temperatures, highlighting their potential for diverse operational conditions. The adsorption process of these inhibitors aligns well with the Langmuir adsorption isotherm, implying physicochemical interactions at the carbon steel surface. Density functional tight-binding (DFTB) calculations and molecular dynamics simulations provide insights into the inhibitor-surface interaction mechanism, further elucidating the potential of these hydrazone derivatives as highly effective corrosion inhibitors in acidic environments.

Computational Exploration of Phenolic Compounds in Corrosion Inhibition: A Case Study of Hydroxytyrosol and Tyrosol

The corrosion of materials remains a critical challenge with significant economic and infrastructural impacts. A comprehensive understanding of adsorption characteristics of phytochemicals can facilitate the effective design of high-performing environmentally friendly inhibitors. This study conducted a computational exploration of hydroxytyrosol (HTR) and tyrosol (TRS) (potent phenolic compounds found in olive leaf extracts), focusing on their adsorption and reactivity on iron surfaces. Utilizing self-consistent-charge density-functional tight-binding (SCC-DFTB) simulations, molecular dynamics (MD) simulations, and quantum chemical calculations (QCCs), we investigated the molecules' structural and electronic attributes and interactions with iron surfaces. The SCC-DFTB results highlighted that HTR and TRS coordinated with iron atoms when adsorbed individually, but only HTR maintained bonding when adsorbed alongside TRS. At their individual adsorption, HTR and TRS had interaction energies of -1.874 and -1.598 eV, which became more negative when put together (-1.976 eV). The MD simulations revealed parallel adsorption under aqueous and vacuum conditions, with HTR demonstrating higher adsorption energy. The analysis of quantum chemical parameters, including global and local reactivity descriptors, offered crucial insights into molecular reactivity, stability, and interaction-prone atomic sites. QCCs revealed that the fraction of transferred electron ∆N aligned with SCC-DFTB results, while other parameters of purely isolated molecules failed to predict the same. These findings pave the way for potential advancements in anticorrosion strategies leveraging phenolic compounds.

Studies of Benzotriazole on and into the Copper Electrodeposited Layer by Cyclic Voltammetry, Time-of-Flight Secondary-Ion Mass Spectrometry, Atomic Force Microscopy, and Surface Enhanced Raman Spectroscopy

Benzotriazole (BTA) is an important compound that demonstrates the strongest anticorrosion properties of copper and plays a role as a leveler and an additive to the electroplating bath for control of the roughness and corrosion resistance of the electrodeposited copper layer. In this paper, we combined cyclic voltammetry (CV), time-of-flight secondary-ion mass spectrometry (TOF-SIMS), surface enhanced Raman spectroscopy (SERS), and atomic force microscopy (AFM) to study the interaction of BTA with copper surfaces at varied concentrations with and without the presence of chloride ions. We identified the most relevant molecular copper and its complex forms with BTA on the copper electrodeposited layer. BTA is adsorbed and incorporated into the copper surface in monomeric, dimeric, trimeric, tetrameric, and pentameric forms, inhibiting the copper electrodeposition. The addition of chloride ions diminishes the inhibiting properties of BTA. The Cu-BTA-Cl complexes were identified in the forms C12H8N6Cu2Cl- and C6H4N3CuCl-. Coadsorption of chloride ions and BTA molecules depends on their concentration and applied potential. Chloride ions are replaced by BTA molecules. BTA and chloride ions, depending on their concentration and applied potential, control the copper nucleation processes at the micro- and nanoscales. We compared the abilities and limitations of TOF-SIMS and SERS for studies of the interactions of benzotriazole with copper and chloride ions at the molecular level.

New Application of 1,2,4-Triazole Derivatives as Antitubercular Agents. Structure, In Vitro Screening and Docking Studies

A series of 1,2,4-triazole derivatives were synthesized and assigned as potential anti-tuberculosis substances. The molecular and crystal structures for the model compounds C1, C12, and C13 were determined using X-ray analysis. The X-ray investigation confirmed the synthesis pathway and the assumed molecular structures for analyzed 1,2,4-triazol-5-thione derivatives. The conformational preferences resulting from rotational degrees of freedom of the 1,2,4-triazole ring substituents were characterized. The lipophilicity (logP) and electronic parameters as the energy of frontier orbitals, dipole moments, NBO net charge distribution on the atoms, and electrostatic potential distribution for all structures were calculated at AM1 and DFT/B3LYP/6-311++G(d,p) level. The in vitro test was done against M. tuberculosis H37Ra, M. phlei, M. smegmatis, and M. timereck. The obtained results clearly confirmed the antituberculosis potential of compound C4, which turned out to be the most active against Mycobacterium H37Ra (MIC = 0.976 μg/mL), Mycobaterium pheli (MIC = 7.81 μg/mL) and Mycobacerium timereck (62.6 μg/mL). Satisfactory results were obtained with compounds C8, C11, C14 versus Myc. H37Ra, Myc. pheli, Myc. timereck (MIC = 31.25-62.5 μg/mL). The molecular docking studies were carried out for all investigated compounds using the Mycobacterium tuberculosis cytochrome P450 CYP121 enzyme as molecular a target connected with antimycobacterial activity.

On-surface condensation of low-dimensional benzotriazole-copper assemblies

The reactivity of benzotriazole with copper on a gold surface has been studied by a combination of surface sensitive methods with support from DFT (density functional theory) calculations. For some time benzotriazole has been known to enhance the corrosion resistance of copper at the monolayer level, although the exact mechanism is still a matter of discussion and disagreement in the literature. A single crystal Au(111) surface allows evaluation of the interaction of weakly physisorbed, intact benzotriazole molecules with copper atoms dosed to sub-monolayer amounts. These interactions have been characterised, in the temperature range ca. 300-650 K, by scanning tunnelling microscopy, high resolution electron energy loss spectroscopy and synchrotron-based X-ray photoemission spectroscopy and near-edge X-ray absorption fine structure studies. Supporting DFT calculations considered the stability of isolated, gas-phase, benzotriazole/Cu species and their corresponding spectroscopic signature at the N K absorption edge. In agreement with previous investigations, benzotriazole physisorbs on a clean Au(111) surface at room temperature forming a hydrogen-bonded network of flat-lying BTAH molecules, relatively weakly bonded to the underlying gold surface. However, in the presence of co-adsorbed copper atoms, proton removal from the molecules leads to species better described as BTA^- interacting directly with Cu atoms. In these situations the molecules adopt a more upright orientation and Cu(BTA)₂ and -[Cu(BTA)]_n- species are formed, depending on temperature and coverage of the adsorbed species. These species are stable to relatively high temperatures, 550-600 K.

Copper/Epoxy Joints in Printed Circuit Boards: Manufacturing and Interfacial Failure Mechanisms

Printed circuit boards (PCBs) have a wide range of applications in electronics where they are used for electric signal transfer. For a multilayer build-up, thin copper foils are alternated with epoxy-based prepregs and laminated to each other. Adhesion between copper and epoxy composites is achieved by technologies based on mechanical interlocking or chemical bonding, however for future development, the understanding of failure mechanisms between these materials is of high importance. In literature, various interfacial failures are reported which lead to adhesion loss between copper and epoxy resins. This review aims to give an overview on common coupling technologies and possible failure mechanisms. The information reviewed can in turn lead to the development of new strategies, enhancing the adhesion strength of copper/epoxy joints and, therefore, establishing a basis for future PCB manufacturing.

Adsorption Behavior of Organic Molecules: A Study of Benzotriazole on Cu(111) with Spectroscopic and Theoretical Methods

The adsorption of organic molecules on solid substrates is important to applications in fields such as catalysis, photovoltaics, corrosion inhibition, adhesion, and sensors. The molecular level description of the surface-molecule interaction and of the adsorption structures in these complex systems is crucial to understand their properties and function. Here, we present an investigation of one such system, benzotriazole (BTAH) on single-crystal Cu(111) in vacuum conditions. BTAH is the most widely used corrosion inhibitor for copper and thus a molecule of great industrial relevance. We show that the co-application of a wide range of spectroscopic techniques with theoretical methods provides unique insight in the description of the atomistic details of the adsorbed structures. Specifically, spectroscopic photoemission, absorption, and standing wave experiments combined with ab initio computational modeling allowed us to identify that benzotriazole forms overlayers of intact BTAH when deposited at low temperature, and it dissociates into BTA and H at room temperature and above. The dissociated molecule then forms complex structures of mixed chains and dimers of BTA bound to copper adatoms. Our work also reveals that copper adatoms at low concentrations, such as the theoretically predicted superstructures, cannot be resolved by means of current X-ray photoelectron spectroscopy as the modeled Cu 2p spectra are practically indistinguishable from those for a Cu surface without adatoms. Overall this study significantly deepens understanding of BTAH on Cu, a system studied for more than 50 years, and it highlights the benefits of combining spectroscopic and computational methods to obtain a complete picture of a complex adsorption system.