Oxidative Ring Research Articles

Mechanistic Insights into Pyridine Ring Degradation Catalyzed by 2,5-Dihydroxypyridine Dioxygenase NicX.

2,5-Dihydroxypyridine dioxygenase (NicX) from Pseudomonas putida KT2440 is a mononuclear non-heme iron oxygenase that can catalyze the oxidative pyridine ring cleavage. Recently, the reported crystal structure of NicX has lent support to an apical dioxygen catalytic mechanism, while the mechanistic details remain unclear. In this work, we constructed a Fe(II)-O2-substrate complex model and performed a series of combined quantum mechanics/molecular mechanics (QM/MM) calculations to illuminate the catalysis of NicX. Our results reveal that although the substrate does not directly coordinate with the central iron ion, there is an electron transfer from the substrate to the Fe-coordinated dioxygen, and the active form of the reactant complex can be described as DHP•+-Fe(II)-O2•-, which is different from other similar mononuclear non-heme iron. The NicX-catalyzed pyridine ring degradation contains three parts, including the attack of Fe(II)-superoxo on the activated pyridine ring, the dissociation of the Op-Od bond, and the ring-opening of the seven-membered-ring lactone. Owing to the radical characteristic of the pyridine ring, the first attack of Fe(II)-superoxo on the C6 of the pyridine ring was calculated to be quite easy. In the second step of the reaction, the dissociation of the Op-Od bond leads to the incorporation of the first oxygen atom into the substrate, which is the rate-limiting step of the overall reaction with an energy barrier of 18.0 kcal/mol. The resultant intermediate then undergoes an arrangement by the intramolecular attack of Od• on the carbonyl C5, forming the seven-membered-ring lactone. Finally, the Fe(III)-oxo attacks the carbonyl C5 of lactone, accompanied by the ring-opening to generate N-formylmaleamic acid. His105 can promote reactivity by donating a proton to Fe(III)-oxo, but it is not a necessary residue. In addition to the ligated residues of iron, other pocket residues such as Glu177, His189, and His105 mainly play roles in anchoring the substrate.

Cascade proton relays facilitate electron transfer across hydrogen‐bonding network

AbstractFunctioning as both hydrogen‐bonding donor and acceptor, the imidazole group of histidine holds a unique position in the proton transfer cascade of biological systems. For example, a histidine residue in the oxygen‐evolving photosystem II participates in the proton‐coupled electron transfer (PCET) reaction to facilitate light‐triggered one‐electron oxidation of a nearby tyrosine residue. As a minimalist synthetic model of such His–Tyr functional diad, three structural variants of benzimidazole–phenol conjugate were studied. We found that an increasing number of hydrogen bonds facilitate reversible one‐electron oxidation of the phenol ring. The reaction coordinates of this intriguing PCET process were mapped out by density functional theory computational studies to reveal oxidation‐driven conformational switching as an entry point to cascade proton relays stabilizing the phenoxyl radical. Strategic placement of hydrogen bonds thus tightly regulates the energy windows of electron transfer, which is an effective strategy for biological redoxphores of seemingly limited structural diversity.

Bacteria are better predictive biomarkers of environmental estrogen transmission than fungi

The heavy reliance on estrogens in the food industry worldwide greatly contributes to the environmental release of these compounds, begetting serious public concern of their fate. Various microorganisms capable of estrogen degradation, and their catabolic pathways, have been isolated, suggesting that they can eliminate estrogens in both engineered and natural environments. Nonetheless, it remains little understood as to how potential estrogen-degrading microorganisms are distributed within those habitats. An estrogen transmission chain from swine manure to compost, compost-amended soil, and neighboring agricultural soil was investigated in five suburban areas of Beijing, China. The concentrations of major estrogen classes decreased by > 90% from manure to soils, which did not co-vary with environmental antibiotics and heavy metal concentrations. Many bacterial taxa, such as Lactobacillus and Bacteroides, could serve as potential biomarkers of estrogen concentrations, while fungi were only occasionally accurate. To explain this phenomenon, stochasticity was found to be dominant in shaping the fungal communities across all samples, while deterministic selection, arising from biotic interactions, was important for bacterial communities. Metabolic genes involved in oxidizing phenol and catalyzing oxidative ring cleavage of catechol were detected, co-varying with estrogen concentrations. These findings are important as identifying microbial biomarkers of estrogen dynamics, spanning the levels of both taxonomy and functional genes, provides valuable information for assessing estrogen bioavailability and biomarking of estrogen fate in the environment.

Understanding the factors governing the water oxidation reaction pathway of mononuclear and binuclear cobalt phthalocyanine catalysts.

The rational design of efficient catalysts for electrochemical water oxidation highly depends on the understanding of reaction pathways, which still remains a challenge. Herein, mononuclear and binuclear cobalt phthalocyanine (mono-CoPc and bi-CoPc) with a well-defined molecular structure are selected as model electrocatalysts to study the water oxidation mechanism. We found that bi-CoPc on a carbon support (bi-CoPc/carbon) shows an overpotential of 357 mV at 10 mA cm−2, much lower than that of mono-CoPc/carbon (>450 mV). Kinetic analysis reveals that the rate-determining step (RDS) of the oxygen evolution reaction (OER) over both electrocatalysts is a nucleophilic attack process involving a hydroxy anion (OH−). However, the substrate nucleophilically attacked by OH− for bi-CoPc is the phthalocyanine cation-radical species (CoII–Pc–Pc˙+–CoII–OH) that is formed from the oxidation of the phthalocyanine ring, while cobalt oxidized species (Pc–CoIII–OH) is involved in mono-CoPc as evidenced by the operando UV-vis spectroelectrochemistry technique. DFT calculations show that the reaction barrier for the nucleophilic attack of OH− on CoII–Pc–Pc˙+–CoII–OH is 1.67 eV, lower than that of mono-CoPc with Pc–CoIII–OH nucleophilically attacked by OH− (1.78 eV). The good agreement between the experimental and theoretical results suggests that bi-CoPc can effectively stabilize the accumulated oxidative charges in the phthalocyanine ring, and is thus bestowed with a higher OER performance.

Late-stage modification of π-electron systems based on asymmetric oxidation of a medium-sized sulfur-containing ring.

The asymmetric oxidation of a sulfur-containing nine-membered heterocycle was achieved for the late-stage introduction of chirality to the substituents of π-electron systems. The oxidation of the sulfur atom considerably influenced the phase-transition behaviour and crystallinity of the resulting π-electron systems.

Atomically dispersed Ag on δ-MnO2viacation vacancy trapping for toluene catalytic oxidation

Atomic dispersion of Ag on δ-MnO2was achievedviaH2O2-induced Mn vacancy trapping. Single-atom Ag could activate adjacent lattice oxygen, facilitating methyl oxidation and benzene ring cleavage to improve toluene oxidation activity.

Studies of GenK and OxsB, two B12-dependent radical SAM enzymes involved in natural product biosynthesis.

The B12-dependent radical SAM enzymes are an emerging subgroup of biological catalysts that bind a cobalamin cofactor in addition to the canonical [Fe4S4] cluster characteristic of radical SAM enzymes. Most of the B12-dependent radical SAM enzymes that have been characterized mediated methyltransfer reactions; however, a small number are known to catalyze more diverse reactions such as ring contractions. Thus, Genk is a methyltransferase from the gentamicin C biosynthetic pathway, whereas OxsB catalyzes the oxidative ring contraction of 2'-deoxyadenosine 5'-phosphates to generate an oxetane aldehyde during the biosynthesis of oxetanocin A. The preparation and in vitro characterization of such enzymes is complicated by the presence of two redox sensitive cofactors in addition to challenges in obtaining soluble protein for study. This chapter describes expression, purification and assay methodologies for GenK and OxsB highlighting the use of denaturation/refolding protocols for solubilizing inclusion bodies as well as the use of cluster assembly and cobalamin uptake machinery during in vivo expression.

A concise synthesis of herbertenolide.

A concise synthesis of (±)-herbertenolide has been accomplished herein. The strategy relies on a H2O2-mediated oxidative ring contraction of all-substituted cyclic α-formyl ketones for the stereospecific construction of contiguous quaternary carbon centers (CQCCs). Furthermore, a Sc(OTf)3/chiral N,N'-dioxide catalyzed asymmetric Michael addition of benzofuranone to MVK has been optimized for forging a chiral aromatic quaternary carbon center, which enables the formal synthesis of (+)-ent-herbertenolide.

Acceleration of levofloxacin degradation by combination of multiple free radicals via MoS2 anchored in manganese ferrite doped perovskite activated PMS under visible light

The nanocomposite of MoS2 embedded manganese ferrite doped perovskite (SrCoO3/MnFe2O4/MoS2, abbreviated as SMM) was successfully synthesized for peroxymonosulfate (PMS) activation under visible-light. It was optimized that the SMM-3 (mass ratio of MoS2 modified nanocomposite was 0.3) exhibited excellent catalytic performance to activate PMS for levofloxacin (LVF) degradation, with the degradation efficiency of 95.1% in 20 min. Besides, SMM-3 was able to efficiently degrade LVF under real water matrix. The quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that SO4•- and HO• played a dominant role in reaction. Due to the photocatalytic property of nanocomposites, the visible light could excite electrons to react with oxygen and form O2•-, which further reacted with HO• to produce 1O2. In the reaction process, the rapid redox cycle of metal ions (including Co, Mn, Fe and Mo) boosted the activation of PMS and promoted the degradation of LVF in a short time. The Density functional theory (DFT) calculation and LC-MS/MS further revealed that oxidation of piperazine ring, decarboxylation and defluorination processes were the main LVF degradation pathways. Finally, the toxicity analysis based on Toxicity Estimation Software Tool (T.E.S.T) verified the ecological risks of transformation residues.

Combination of high specific activity carbon-14 labeling and high resolution mass spectrometry to study pesticide metabolism in crops: Metabolism of cycloxaprid in rice.

The study of pesticide metabolism in crops is critical for assessing the mode of action and environmental risks of pesticides. However, the study of pesticide metabolism in crops is usually complicated and it is often a daunting challenge to accurately screen the metabolites of novel pesticides in complex matrices. This study demonstrated a combined use of high-specific activity carbon-14 labeling and high-resolution mass spectrometry (HSA-14C-HRMS) for metabolism profiling of a novel neonicotinoid cycloxaprid in rice. By generating the characteristic radioactive peaks on the liquid chromatogram, the use of 14C can eliminate the severe interference of complex matrices and quickly probe target compounds; by producing ion pairs with unique abundance ratios on HRMS, high-specific activity labeling can effectively exclude false matrix positives and promote the elucidation of metabolite structure. The structures of 15 metabolites were identified, three of which were further confirmed by authentic standards. Based on these metabolites, a metabolic profile of cycloxaprid was established, which includes denitrification, demethylation, imidazolidine hydroxylation and ring cleavage olefin formation, oxidation and carboxylation reactions. The strategy of combining high-specific activity 14C labeling and HRMS offers unique advantages and provides a powerful solution for profiling unknown metabolites of novel pesticides in complex matrices, especially when traditional non-labeling methods are not feasible.

Photodegradation of norfloxacin in ice: Role of the fluorine substituent

Ice is an important medium in cold regions, because it regulates the environmental behaviors and the fate of pollutants. The photodegradation of fluoroquinolone (FQ) antibiotics as emerging contaminants of concern in ice remains poorly understood. Here, the photodegradation of fluorine-containing norfloxacin (NOR) as one model of FQs in ice formed from freezing solutions was investigated. Pipemidic acid (PPA) as a structural analogue of NOR was selected to compare the effect of molecular structure on the antibiotic photodegradation in the ice. Results suggested that the photodegradation rate constant of NOR in ice relative to pure water increased by 40.0%. Both the absorbance in the absorption spectra and quantum yields of NOR in ice over water increased by 1.4 times. Direct photodegradation mainly caused the defluorination of NOR, which was more important than cleavage and oxidation of the piperazine ring by self-sensitized photooxidation in ice. The defluorination rate of NOR in the ice relative to water increased by about 12.7%. The fluorine substituent played a more important role in the NOR photodegradation in the ice, resulting in a 1.6-fold increase in the photodegradation rate constant of NOR relative to PPA. This work provides a new insight into the role of fluorine substituents in the photodegradation of fluorinated pharmaceuticals in cold regions.

An NADPH-Dependent Ketoreductase Catalyses the Tetracyclic to Pentacyclic Skeletal Rearrangement in Chartreusin Biosynthesis.

Redox tailoring enzymes play key roles in generating structural complexity and diversity in type II polyketides. In chartreusin biosynthesis, the early 13 C-labeling experiments and bioinformatic analysis suggest the unusual aglycone is originated from a tetracyclic anthracyclic polyketide. Here, we demonstrated that the carbon skeleton rearrangement from a linear anthracyclic polyketide to an angular pentacyclic biosynthetic intermediate requires two redox enzymes. The flavin-dependent monooxygenase ChaZ catalyses a Baeyer-Villiger oxidation on resomycin C to form a seven-membered lactone. Subsequently, a ketoreductase ChaE rearranges the carbon skeleton and affords the α-pyrone containing pentacyclic intermediate in an NADPH-dependent manner via tandem reactions including the reduction of the lactone carbonyl group, Aldol-type reaction, followed by a spontaneous γ-lactone ring formation, oxidation and aromatization. Our work reveals an unprecedented function of a ketoreductase that contributes to generate structural complexity of aromatic polyketide.

An NADPH‐Dependent Ketoreductase Catalyses the Tetracyclic to Pentacyclic Skeletal Rearrangement in Chartreusin Biosynthesis

AbstractRedox tailoring enzymes play key roles in generating structural complexity and diversity in type II polyketides. In chartreusin biosynthesis, the early 13C‐labeling experiments and bioinformatic analysis suggest the unusual aglycone is originated from a tetracyclic anthracyclic polyketide. Here, we demonstrated that the carbon skeleton rearrangement from a linear anthracyclic polyketide to an angular pentacyclic biosynthetic intermediate requires two redox enzymes. The flavin‐dependent monooxygenase ChaZ catalyses a Baeyer–Villiger oxidation on resomycin C to form a seven‐membered lactone. Subsequently, a ketoreductase ChaE rearranges the carbon skeleton and affords the α‐pyrone containing pentacyclic intermediate in an NADPH‐dependent manner via tandem reactions including the reduction of the lactone carbonyl group, Aldol‐type reaction, followed by a spontaneous γ‐lactone ring formation, oxidation and aromatization. Our work reveals an unprecedented function of a ketoreductase that contributes to generate structural complexity of aromatic polyketide.

Application of Oxidative Ring Opening/Ring Closing by Reductive Amination Protocol for the Stereocontrolled Synthesis of Functionalized Azaheterocycles

AbstractThe current Account gives an insight into the synthesis of some N-heterocyclic β-amino acid derivatives and various functionalized saturated azaheterocycles accessed from substituted cycloalkenes via ring C=C bond oxidative cleavage followed by ring closing across double reductive amination. The ring-cleavage protocol has been accomplished according to two common approaches: a) Os-catalyzed dihydroxylation/NaIO4 vicinal diol oxidation and b) ozonolysis. A comparative study on these methodologies has been investigated. Due to the everincreasing relevance of organofluorine chemistry in drug research as well as of the high biological potential of β-amino acid derivatives several illustrative examples to the access of various fluorine-containing piperidine or azepane β-amino acid derivatives are also presented in the current Account.1 Introduction2 Olefin-Bond Transformation by Oxidative Ring Cleavage3 Synthesis of Saturated Azaheterocycles via Oxidative Ring-Opening/Ring-Closing Double Reductive Amination3.1 Importance of Fluorine-Containing Azaheterocycles in Pharmaceutical Research3.2 Synthesis of Azaheterocyclic Amino Acid Derivatives with a Piperidine or Azepane Framework through Oxidative Ring Opening/Reductive Amination3.2.1 Synthesis of Piperidine β-Amino Esters3.2.2 Synthesis of Azepane β-Amino Esters3.2.3 Synthesis of Fluorine-Containing Piperidine γ-Amino Esters3.3 Synthesis of Tetrahydroisoquinoline Derivatives through Oxidative Ring Opening/Reductive Amination Protocol3.4 Synthesis of Functionalized Benzazepines through Reductive Amination3.4.1 Synthesis of Benzo[c]azepines3.4.2 Synthesis of Benzo[d]azepines3.5 Synthesis of Various N-Heterocycles via Ozonolysis/Reductive Amination3.5.1 Synthesis of Compounds with an Azepane Ring3.5.2 Synthesis of Piperidine β-Amino Acids and Piperidine-Fused β-Lactams3.5.3 Synthesis of γ-Lactams with a Piperidine Ring3.5.4 Synthesis of other N-Heterocycles4 Summary and Outlook5 List of Abbreviations

Effects of Constant Electric Field on Biodegradation of Phenol by Free and Immobilized Cells of Bradyrhizobium japonicum 273

It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation than in a free culture. The application of a constant electric field during cultivation led to enhanced phenol biodegradation in a free culture and in immobilized cells on granulated activated carbon. The highest phenol removal efficiency was observed for an anode potential of 1.0 V/S.H.E. The effect was better pronounced in a free culture. The enzyme activities of free cells for phenol oxidation and benzene ring cleavage were very sensitive to the anode potential in the first two steps of the metabolic pathway of phenol biodegradation catalyzed by phenol hydroxylase—catechol-1,2-dioxygenase and catechol-2,3-dioxygenase. It was observed that at an anode potential of 0.8 V/S.H.E., the meta-pathway of cleavage of the benzene ring catalyzed by catechol-2,3-dioxygenase became competitive with the ortho-pathway, catalyzed by catechol-1,2-dioxygenase. The obtained results showed that the positive effect of constant electric field on phenol biodegradation was rather due to electric stimulation of enzyme activity than electrochemical anode oxidation.

Performance evaluation and mechanism analysis of halotolerant bacterial strains and cerium oxide nanoparticle to degrade Benzo[a]pyrene

The key source for Benzo[a]pyrene (B[a]P) and various other Polyaromatic hydrocarbon (PAH) is partial ignition of crude oil, and several other by-products of petroleum and its components. Moreover, industries that utilises coal and further when coal is burnt during various natural and anthropogenic activities also leads B[a]P to cause great threat to the environment by getting mixed in the air. The PAH compounds are highly enduring, bio-toxic, cytotoxic, and cancerous. The aqua-phobic property of these hydrocarbons makes these stable and unreactive. Among various other environments marine environment is under great threat due to various anthropogenic activities like an oil leak accidents and industrial emission, specifically from factories. Due to the rapidly varying industrial trends the harmful pollutants get released into the saline and hypersaline environment. Thus, it is the need of the hour to find a way to degrade these toxic chemicals in the environment. Many physicochemical techniques to remediate B[a]P include chemical oxidation, photo-dissociation, burning, landfilling, volatilisation, and adsorption. The by-products from all the techniques cause severe harm to the environment. Here we describe the Benzo[a]pyrene degradation by employing two techniques, first through biodegradation and second using cerium oxide nanoparticles synthesised employing sol gel method. This current work aims to compare the degradation of B[a]P using both bacterial cocultures (Biological) and CeO2 nanoparticle (Chemical method). Mechanism of Biodegradation of B[a]P is proposed to take place by the hydroxylation through oxidation of aromatic ring, tracked by cis-dihydrodiol intermediates formation, finally resulting in cleavage to simple alcohols, carbonyl compounds, phenolics and carboxylic acids. The interpretation of the Mass spectrum also revealed some non-reported low molecular weight compounds like cyclopentadienyl, cyclobutadienyl cations, diacetylene and DHP, along with O-Cresol, Benzaldehyde, Benzoic acid, Naphthalene, Naphthol, Diacetylene and Dihydropyran. On comparing with biodegradation, the degradation using cerium oxide nanoparticles gave many simple, and fewer toxic by-products. • Halotolerant B[a]P degrading bacterial strains were isolated from marine environment. • Strains were screened and optimised for enhanced degradation of B[a]P. • Synthesis (citrate–nitrate sol–gel route) & characterisation of CeO 2 nanoparticles. • Degradation of benzo[a]pyrene of CeO 2 NP in the visible light. • Comparative study on bio and CeO 2 nanoparticle B[a]P degradation.

AN INNOVATIVE METHOD FOR PROCESSING OF USED VANADIUM CATALYSTS FOR OBTAINING VANADIUM PENTOXIDE

All in all, there are about 60 million vanadium deposits in the world, 90% of which are localized in the territory of the five countries: Russia, South Africa, Venezuela, the United States and China. Sulfuric acid production is the main consumer of vanadium in the form of vanadium catalysts (V2 O5 pentoxide). The demand for vanadium and its compounds keeps growing every year, as a result of the increased interest in processing of secondary vanadium-containing raw materials. One of the main sources of vanadium are the spent vanadium catalysts – SVC. About 100 thousand tons of spent vanadium catalysts are formed throughout the country, which are considered to be potentially hazardous for the environment and local population. Disposal of spent vanadium catalysts used for oxidizing of sulfur dioxide represents a serious environmental threat due to the lack of effective technologies for their processing. This work is devoted to a method for processing of spent vanadium catalysts to obtain a stuff that will be suitable for modifying of steels. The pyrometallurgical method of processing of technogenic raw materials by oxidative fi ring has been investigated and the parameters of firing – optimal fi ring time and temperature for extracting vanadium from the material – have been identified.

Rapid detection and structural characterization of methysticin metabolites generated from rat and human liver microsomes and hepatocytes using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry.

Methysticin is a naturally occurring ingredient isolated from Piper methysticum Forst. The metabolic profile of methysticin is unknown. The goal of this study was to elucidate the metabolism of methysticin using rat and human liver microsomes and hepatocytes. The incubation samples were analyzed using ultra-high-performance liquid chromatography coupled with quadrupole/orbitrap high-resolution mass spectrometry (UHPLC-HRMS). The structures of the metabolites were characterized based on the elemental composition, exact mass, and product ions. A total of 10 metabolites were detected and identified. Among these metabolites, M4 (ring opening of 1,3-benzodioxole) was the predominant metabolite in rat and human liver microsomes. M4 and its glucuronide conjugate (M2) were the major metabolites in rat and human hepatocytes. The metabolic pathways of methysticin are summarized as follows: (a) oxidative ring opening of 1,3-benzodioxole forms the catechol derivative (M4), which subsequently undergoes glucuronidation (M1 and M2), methylation (M8), and sulfation (M7). (b) Demethylation to yield desmethyl methysticin (M6), followed by glucuronidation (M3 and M5). (c) Hydroxylation (M9 and M10). For the first time, this study provides new information on the in vitro metabolic profiles of methysticin, which facilitates an understanding of the disposition of this bioactive ingredient.

Innovative antimicrobial substances based on uracil S-derivatives.

The problem of antimicrobial resistance is an important global public health challenge. We propose that a development of new antibiotic compounds around known natural substances is a solution to this problem. We investigate reengineer natural products into potent antibiotics. Uracil fragment is abundant in nature and significant to treat infectious diseases due to its affection to the replication of the bacterial chromosome. 12 new uracil S-derivatives were obtained and tested for their in vitro antimicrobial properties. N3 -(thietan-3-yl)- and N3 -(1,1-dioxothietan-3-yl)uracils derivatives were synthesized by thietanylation of 6-methyluracil with 2-chloromethylthiirane and subsequent oxidation of the thietan ring. A method of their alkylation with ethyl-2-chloroacetate was developed and acetohydrazides containing 3-(thietan-3-yl)- and 3-(1,1-dioxothietan-3-yl)uracilyls fragments in the acetyl group were obtained by hydrazinolysis of 2-(thietanyluracil-1-yl)acetic acid ethyl esters. Their interaction with β-dicarbonyl compounds, anhydride of mono- and dicarboxylic acids was studied. Antimicrobial activity was determined by the agar diffusion method on test organisms: S. aureus, E. coli, P. vulgaris, K. pneumoniae, C. diversus, E. aerogenes, P. aeruginosa, S. abosit. N-acyl-5-hydroxypyrazolines and N,N'-diacylhydrazines of 6-methyluracil thietanyl- and dioxothietanyl derivatives showed high antimicrobial activity, which is consistent with the results of structure activity relationship analysis (MIC 0.1-10μg/ml).

Synthesis of Cu(II) complexes by N,O‐donor ligand transformation and their catalytic role in visible‐light‐driven alcohol oxidation

AbstractVisible‐light‐driven photoreactions using metal complexes as catalysts are currently a research hotspot in terms of the development of environmentally friendly sustainable processes. To develop potential copper‐based photocatalysts, a Mannich base ligand, namely, 2,4‐dichloro‐6‐((4‐(2‐hydroxyethyl)piperazin‐1‐yl)methyl)phenol (H2L), has been synthesized and characterized. Two copper complexes [Cu (HL1)] (1) and [Cu (HL2)] (2) have been obtained from H2L, where the ligand undergoes an unprecedented transformation plausibly via oxidation of piperazine ring to ketone, subsequent oxidation of enol and nucleophilic attack of methanol followed by hydrolysis of amide bond, resulting piperazine ring cleavage. Under the irradiation of visible light, these catalysts can oxidize primary alcohols into corresponding aldehydes with very good conversion and high selectivity in the presence of molecular oxygen. The photocatalysts could be recovered almost quantitatively after completion of the catalytic cycle and recycled at least four times without much depreciation of catalytic activity. A plausible mechanistic pathway for alcohol oxidation has been explored through electrospray ionization mass spectrometry (ESI‐MS) spectrometric, cyclic voltammetry, UV–vis, and computational study.