Photochemical Degradation Research Articles

CNCs and CeO2 as organic–inorganic additives to enhance HPC bio-polymer wood coatings against photochemical degradation

CNCs and CeO2 as organic–inorganic additives to enhance HPC bio-polymer wood coatings against photochemical degradation

How Pharmaceutical Residues Occur, Behave, and Affect the Soil Environment.

Many pharmaceuticals (PhMs), compounds for the treatment or prevention of diseases in humans and animals, have been identified as pollutants of emerging concern (PECs) due to their wide environmental distribution and potential adverse impact on nontarget organisms and populations. They are often found at significant levels in soils due to the continuous release of effluent and sludge from wastewater treatment plants (WWTPs), the release of which occurs much faster than the removal of PhMs. Although they are generally present at low environmental concentrations, conventional wastewater treatment cannot successfully remove PhMs from influent streams or biosolids. In addition, the soil application of animal manure can result in the pollution of soil, surface water, and groundwater with PhMs through surface runoff and leaching. In arid and semiarid regions, irrigation with reclaimed wastewater and the soil application of biosolids are usual agricultural practices, resulting in the distribution of a wide number of PhMs in agricultural soils. The ability to accurately study the fate of PhMs in soils is critical for careful risk evaluation associated with wastewater reuse or biosolid return to the environment. The behavior and fate of PhMs in soils are determined by a number of processes, including adsorption/desorption (accumulation) to soil colloids, biotic (biodegradation) and abiotic (chemical and photochemical degradation) degradation, and transfer (movement) through the soil profile. The sorption/desorption of PhMs in soils is the main determinant of the amount of organic chemicals taken up by plant roots. The magnitude of this process depends on several factors, such as crop type, the physicochemical properties of the compound, environmental properties, and soil-plant characteristics. PhMs are assumed to be readily bioavailable in soil solutions for uptake by plants, and such solutions act as carriers to transport PhMs into plants. Determining microbial responses under exposure conditions can assist in elucidating the impact of PhMs on soil microbial activity and community size. For all of the above reasons, soil remediation is critical when soil pollutants threaten the environment.

Thermal and photochemical degradation of CsGeI3 and CsGeBr3: XPS and optical studies

The toxicity of complex lead halides significantly limits the commercialization and practical application of perovskite solar cells. In recent days, lead-free complex lead halides with a perovskite structure have become increasingly popular, among which germanium systems are the least studied. Here we present for the first time a systematic study of the thermal and photochemical stability of perovskite thin films of CsGeI3 and CsGeBr3. The measurements of optical absorbance and X-ray photoelectron spectra (XPS) of core levels and valence bands of Ge-based halide perovskites after light soaking and heat stress were thoroughly performed. It has been found the effect of thermal and photochemical degradation of Ge perovskites which is accompanied by reduction of I:Ge and Br:Ge ratios and appearance of tetravalent metal species fixed in XPS Ge 2p and Ge 3d spectra. The XPS O 1s measurements of irradiated and annealed Ge-based perovskites and their comparison with spectra of GeO2 have shown that formation of Ge4+-species is not due to metal oxidation but owing to defect-mediated hole-doping. While the Ge2+→Ge4+ process lowers the thermal and photochemical stability of Ge-based perovskites and limits their use in photovoltaics, the temperature induced hole doping is favorable for thermoelectric applications.

Photochemical degradation of antibiotics: real-time investigation by aerodynamic thermal breakup droplet ionization mass spectrometry.

A method is proposed for studying photochemical reactions in solution in real time using aerodynamic/thermal breakup droplet ionization mass spectrometry. Capabilities of the method were demonstrated by analyses of photodegradation processes of three antibiotics (thiamphenicol, ciprofloxacin, and ofloxacin) by means of aqueous solutions. The method rapidly provided information about photochemical changes for understanding the photochemical processes.

Quality assessment of common anti-malarial medicines marketed in Gambella, National Regional State, South Western-Ethiopia

BackgroundOver the past years, there has been a growing concern that a considerable amount of anti-malarial supply in the underdeveloped world particularly in the private sector, is of poor quality. The World Health Organization (WHO) has received about 1500 reports that mentions instances of substandard and falsified products since 2013. The majority of the reports concerned antibiotics and anti-malarials. The majority of reports (42%) originate from the WHO African region.ObjectiveThis study intends to assess the quality of the most widely used anti-malarial medications [artemether-lumefantrine tablets, chloroquine phosphate tablets, primaquine phosphate tablets, artesunate, and artemether injections] in Gambella, South-West, Ethiopia.MethodsA total of 52 samples were collected on June 2022 from Gambella National Regional State, Ethiopia. Half of the districts (six) located in the four zones of the region were chosen using simple random sampling technique. All drug retail outlets available in the selected districts (locally known as woredas) were included. The samples were subjected to visual inspection with a tool adopted from the joint WHO/FIP/ USP checklist. The pharmacopeial tests for identification, uniformity of dosage forms, assay, thickness, diameter, hardness, friability, disintegration test, dissolution, and sterility tests were carried out according to the USP 44-NF 39 and International Pharmacopoeia 11th edition, 2022 monographs.Results and DiscussionOnly 25% of the samples were registered on the Ethiopian Food and Drug Authority (EFDA’s) electronic regulatory/ registration system (ERIS). Besides, 88.8% of artemether injection products were presented in clear glass ampoules. This might expose the products to photochemical degradation that leads to in loss of anti-plasmodial activity. In addition, 50% of the artemether products assessed were not bioequivalent with the comparator product in the in vitro dissolution comparison tests. Overall, the study findings reveal a high prevalence (58.3%) of substandard anti-malarial drugs in the region. The stated percent of the samples had failed in one or more of the quality test parameters assessed in this study.ConclusionThe study findings reveal a high prevalence (58.3%) of substandard anti-malarial drugs in the region. Only a quarter were registered and 38% of the unregistered products failed the quality tests. Hence, the national, regional medicine regulatory bodies and other stake holders should perform the required roles to circumvent presence of Substandard and Falsified (SF) anti-malarial drugs in the study sites.

Photodegradation in terrestrial ecosystems.

The first step in carbon (C) turnover, where senesced plant biomass is converted through various pathways into compounds that are released to the atmosphere or incorporated into the soil, is termed litter decomposition. This review is focused on recent advances of how solar radiation can affect this important process in terrestrial ecosystems. We explore the photochemical degradation of plant litter and its consequences for biotic decomposition and C cycling. The ubiquitous presence of lignin in plant tissues poses an important challenge for enzymatic litter decomposition due to its biological recalcitrance, creating a substantial bottleneck for decomposer organisms. The recognition that lignin is also photolabile and can be rapidly altered by natural doses of sunlight to increase access to cell wall carbohydrates and even bolster the activity of cell wall degrading enzymes highlights a novel role for lignin in modulating rates of litter decomposition. Lignin represents a key functional connector between photochemistry and biochemistry with important consequences for our understanding of how sunlight exposure may affect litter decomposition in a wide range of terrestrial ecosystems. A mechanistic understanding of how sunlight controls litter decomposition and C turnover can help inform management and other decisions related to mitigating human impact on the planet.

Photodegradation Processes and Weathering Products of Microfibers in Aquatic Environments.

Microplastics, particularly microfibers (MFs), pose a significant threat to the environment. Despite their widespread presence, the photochemical reactivity, weathering products, and environmental fate of MFs remain poorly understood. To address this knowledge gap, photodegradation experiments were conducted on three prevalent MFs: polyester (POL), nylon (NYL), and acrylic (ACR), to elucidate their degradation pathways, changes in surface morphology and polymer structure, and chemical and colloidal characterization of weathering products during photochemical degradation of MFs. The results showed that concentrations of dissolved organic carbon, chromophoric dissolved organic matter (DOM), and fluorescent components consistently increased during weathering, exhibiting a continuous release of DOM. Scanning electron microscopy and Raman spectroscopy revealed changes in the surface morphology and polymer spectra of the MFs. During the weathering experiments, DOM aromaticity (SUVA254) decreased, while spectral slope increased, indicating concurrent DOM release and degradation of aromatic components. The released DOM or nanoplastics were negatively charged with sizes between 128 and 374 nm. The production rate constants of DOM or the photochemical reactivity of MFs followed the order ACR > NYL ≥ POL, consistent with their differences in chemical structures. These findings provide an improved understanding of the photochemical reactivity, degradation pathways, weathering products, and environmental fate of microfibers in the environment.

Validación de un método de cromatografía líquida (HPLC-UV/Vis) para la cuantificación de aldehídos en agua de lluvia y aire

Aldehydes are compounds in the atmosphere formed by the photochemical degradation of other organic compounds in the troposphere and can be emitted by natural or anthropogenic sources. [Objective] An analytical method was implemented to quantify aldehyde samples in matrices such as air and rainwater. [Methodology] Aldehyde sampling and analysis were conducted using method TO-11 from the United States Environmental Protection Agency (EPA). Sampling was carried out by using adsorption cartridges coated with a 2,4-DNPH solution, forming a hydrazone with the aldehydes present in the rainwater and the air, which were tested using a liquid chromatograph coupled to a UV-visible detector (HPLC-UV/Vis). To validate the analysis technique and the analytical quality of the results, the following was determined: linearity, sensitivity, quantification limits, detection limits, repeatability, reproducibility, and recovery percentage. In the case of repeatability, the comparison of the Horwitz coefficient of variation was used with the percentages of relative standard deviation (% RSD) of the samples. [Results] The detection and quantification limits obtained range between 0.18 μg/m3 and 3.20 μg/m3 for acetaldehyde and acrolein, respectively, while quantification limits are between 0.62 μg/m3 for acetaldehyde and 4.70 μg/m3 for heptanal, data that characterizes the method’s analytical quality. [Conclusions] In general, the analysis method for aldehydes showed linearity, with R2 values equal to or greater than 0.9991 for each calibration curve, and relative deviation percentage values less than 2.25 %, indicating good precision in the analysis.

Comparison of the differences in photochemical degradation of dissolved organic matter in rivers, lakes, and ponds by adding nanoparticles TiO2.

This study examines the photolysis of Dissolved Organic Matter (DOM) in urban rivers, lakes, and ponds using photocatalysis experiments. Employing a photochemical reactor and UV spectrophotometer, we investigated the precise effects of TiO2 nanoparticles and illumination duration on the degradation efficiency, rate, and kinetics in water bodies. Simultaneously, an analysis was conducted on the photochemical degradation process of DOM from various sources. The results demonstrate that the photocatalyst TiO2 can effectively improve DOM degradation and light absorption degradation efficiency, with longer illumination durations inversely correlating with DOM content. Both Dissolved Organic Carbon (DOC) and 254 nm absorbance degradation kinetics follow pseudo-first-order degradation kinetics. Notably, the pond exhibited the most significant change in degradation efficiency, reaching 96.7%. Our findings suggest that degradation efficiency in water bodies may be influenced by surrounding vegetation, population density, and rainfall conditions. This study contributes to a deeper understanding of DOM degradation processes by photocatalysts and provides a feasible method to effectively mitigate water pollution.

Photolytic Degradation of Water‐Soluble Organic Carbon in Snowmelts: Changes in Molecular Characteristics, Brown Carbon Chromophores, and Radiative Effects

AbstractWater‐soluble organic carbon (WSOC) deposited in ambient snowpack play key roles in regional carbon cycle and surface energy budget, but the impacts of photo‐induced processes on its optical and chemical properties are poorly understood yet. In this study, melted samples of the seasonal snow collected from northern Xinjiang, northwestern China, were exposed to ultraviolet (UV) radiation to investigate the photolytic transformations of WSOC. Molecular characteristics and chemical composition of WSOC and its brown carbon (BrC) constituents were investigated using high‐performance liquid chromatography interfaced with a photodiode array detector and a high‐resolution mass spectrometer. Upon illumination, formation of nitrogen‐ and sulfur‐containing species with high molecular weight was observed in snow samples influenced by soil‐ and plant‐derived organics. In contrast, the representative sample collected from remote region showed the lowest molecular diversity and photolytic reactivity among all samples, in which no identified BrC chromophores decomposed upon illumination. Approximately 65% of chromophores in urban samples endured UV irradiation. However, most of BrC composed of phenolic/lignin‐derived compounds and flavonoids disappeared in the illuminated samples containing WSOC from soil‐ and plant‐related sources. Effects of the photochemical degradation of WSOC on the potential modulation of snow albedo were estimated. Apparent half‐lives of WSOC estimated as albedo reduction in 300–400 nm indicated 0.1–0.4 atmospheric equivalent days, which are shorter than typical photolysis half‐lives of ambient biomass smoke aerosol. This study provides new insights into the roles of WSOC in snow photochemistry and snow surface energy balance.

Judicious Fluorination of Perovskite Quantum Wells Enables Over 25% Efficiency in Inverted Solar Cells

AbstractThe photovoltaic performance of inverted perovskite solar cells (PSCs) is often hindered by trap‐induced non‐radiative recombination and photochemical degradation occurring at the upper interfaces and the grain boundaries of perovskite films. Herein, ortho‐, meta‐, and para‐isomers of fluorophenylethylammonium iodine (F‐PEAI) organic spacer molecules are evaluated for the construction of perovskite quantum wells (2D or quasi‐2D, PQWs) to encapsulate 3D perovskites. Among the three variants, p‐F‐PEAI leads to the most symmetric charge distribution and the weakest steric hindrance which resulting in reinforced interactions with PbI2 and perovskite, the enhanced out‐of‐plane orientation is confirmed by Grazing incidence wide‐angle X‐ray scattering (GIWAXS) results. Density functional theory and crystal orbital Hamilton population (COHP) calculations further confirm that p‐F‐PEAI engages most strongly with the perovskite structure. Moreover, transmission electron microscopy (TEM) characterization is used to illustrate that p‐F‐PEAI‐assisted 2D PQWs effectively passivate both the grain boundaries and surfaces of perovskites. This configuration facilitates effective surface passivation, improves charge carrier transport, and significantly suppresses non‐radiative recombination. The resultant inverted PSCs achieve an excellent power conversion efficiency (PCE) of 25.03% with a fill factor (FF) of 85.11%. The unencapsulated devices exhibit enhanced long‐term stability under ambient environments and continuous light illumination.

Four decades of changing dissolved organic matter quality and stoichiometry in a Swedish forest stream

Dissolved organic matter (DOM) concentrations have risen by a factor of two or more across much of Europe and North America during recent decades. These increases have affected the carbon cycle, light regime, drinking water treatability, and the energy and nutrient budgets of lakes and streams. However, while trends in DOM quantity are well characterised, information on how/whether qualitative properties of DOM have changed are scarce. Here, we describe over 40 years of monitoring data from a forested headwater stream in the Gårdsjön experimental catchment, southwest Sweden, which provides a unique record of biogeochemical change, including optical and stoichiometric DOM quality metrics, spanning the entire period of recovery from acidification. For the period 1980–2020 we find a 71% reduction in decadal mean sulphate concentrations, and a similar reduction in inorganic aluminium concentrations, alongside a 64% increase in dissolved organic carbon (DOC) concentrations. Over the same period, colour (absorbance at 420 nm) increased almost twice as much as DOC, whereas dissolved organic nitrogen (DON) increased by only one third as much. These results demonstrate a shift in stream water composition, with DOM becoming dominated by highly coloured, complex, nitrogen-poor compounds. This material is likely more resistant to biological degradation, but more susceptible to photochemical degradation. Changes in DOM stoichiometry could lead to intensified nitrogen and/or phosphorus limitation in surface waters, while increased colour/DOC ratios could intensify light-limitation of primary production beyond that expected from DOC increases alone. We observed increases in organic matter associated metals (iron 117%, organically complexed aluminium 85%) that exceeded the increase in DOC, consistent with their increased mobilisation by more aromatic organic matter. All observed changes are consistent with recovery from acidification being the primary driver of change, implying that past acidification, and ongoing recovery, have profoundly affected terrestrial and aquatic biogeochemistry, ecology and the carbon cycle.

Photochemical degradation of bisphenol S and its tetrahalogenated derivatives in water

Bisphenol S (BPS), a widely used plasticizer, is known to have potential endocrine disrupting effects to organisms. Its tetrahalogenated derivatives, tetrachlorobisphenol S (TCBPS) and tetrabromobisphenol S (TBBPS), are flame retardants exhibiting high neurodevelopmental toxicity and cytotoxicity. Halogen substitution has been shown to significantly affect the optical and photochemical properties of organic compounds. In this study, we conducted a comparative investigation into the photochemical behaviors of BPS, TCBPS, and TBBPS in aqueous solutions under both laboratory UV and natural sunlight irradiation. Spectroscopic titration results indicated that the pKa of TCBPS (4.16) and TBBPS (4.13) are approximately 3.7 units smaller than that of BPS (7.85), indicating that the halogenated derivatives are mainly present as the phenolate anions under circumneutral conditions. The halogen substituents also cause a significant bathochromic shift in the absorption spectra of TCBPS and TBBPS compared to BPS, leading to the enhanced absorption of sunlight. Meanwhile, TCBPS and TBBPS showed higher quantum yields than BPS, attributed to the "heavy atom" effect of halogen substituents. GCSOLAR modeling predicted half-lives for BPS, TCBPS, and TBBPS in surface water in Nanjing (32°2′7.3′′N, 118°50′21′′E) under noon sunlight in clear mid-autumn days as 810.2, 3.4, and 0.7 min, respectively. Toxicity evaluation suggest potential ecological risks of BPS/TCBPS/TBBPS and their photoproducts to aquatic organisms. Our findings highlight direct photolysis as an important mechanism accounting for the attenuation of tetrahalogenated bisphenols in both sunlit surface waters and UV based water treatment processes.engineered (e.g., UV disinfection) and natural aquatic environments (e.g., surface fresh waters).

The ability of photochemical decomposition products of the Roundup to induce oxidative stress in bacterial cells

BACKGROUND: A common non-selective systemic herbicide Roundup (Glyphosate, active ingredient N-phosphonomethylglycine, N-PMG) is used to control perennial weeds. It is necessary to assess the hazard of the products of photochemical decomposition of N-FMG formed under the influence of solar UV and ozone. AIM: Using lux-biosensors based on Escherichia coli, studying the ability of N-FMG photochemical degradation products to induce oxidative stress in bacterial cells. MATERIALS AND METHODS: The work used the active substance of the herbicide Roundup N-phosphonomethylglycine (N-PMG), biosensors E. coli (pSoxS-lux), E. coli (pKatG-lux). UV radiation, Mass spectrometry. RESULTS: Using biosensors, it was shown that the products of photochemical decomposition of N-PMG (2-(N-hydroxymethyl-hydroxyamine) ethanoic acid) cause an increase in the concentration of superoxide anion radical and H2O2 in E. coli cells, which induces oxidative stress in the bacterial cell. CONCLUSIONS: The photochemical decomposition product of N-PMG (2-(N-hydroxymethyl-hydroxyamine) ethanoic acid) induces the formation of superoxide anion radical and H2O2 in bacterial cells.

Environmental Assessment of Narmada River Tributary I. E Ganjal River Water and its Photo Chemical Degradation using TiO2 Nanocatalyst

Environmental Assessment of Narmada River Tributary I. E Ganjal River Water and its Photo Chemical Degradation using TiO2 Nanocatalyst

Photochemical and Oxidative Degradation of Chamazulene Contained in Artemisia, Matricaria and Achillea Essential Oils and Setup of Protection Strategies.

Chamazulene (CA) is an intensely blue molecule with a wealth of biological properties. In cosmetics, chamazulene is exploited as a natural coloring and soothing agent. CA is unstable and tends to spontaneously degrade, accelerated by light. We studied the photodegradation of CA upon controlled exposure to UVB-UVA irradiation by multiple techniques, including GC-MS, UHPLC-PDA-ESI-MS/MS and by direct infusion in ESI-MSn, which were matched to in silico mass spectral simulations to identify degradation products. Seven byproducts formed upon UVA exposure for 3 h at 70 mW/cm2 (blue-to-green color change) were identified, including CA dimers and CA benzenoid, which were not found on extended 6 h irradiation (green-to-yellow fading). Photostability tests with reduced irradiance conducted in various solvents in the presence/absence of air indicated highest degradation in acetonitrile in the presence of oxygen, suggesting a photo-oxidative mechanism. Testing in the presence of antioxidants (tocopherol, ascorbyl palmitate, hydroxytyrosol, bakuchiol, γ-terpinene, TEMPO and their combinations) indicated the highest protection by tocopherol and TEMPO. Sunscreens ethylhexyl methoxycinnamate and particularly Tinosorb® S (but not octocrylene) showed good CA photoprotection. Thermal stability tests indicated no degradation of CA in acetonitrile at 50 °C in the dark for 50 days; however, accelerated degradation occurred in the presence of ascorbyl palmitate.

Photocatalytic Degradation of Naproxen: Intermediates and Total Reaction Mechanism.

Photochemical and photocatalytic oxidation of naproxen (NPX) with UV-A light and commercial TiO2 under constant flow of oxygen have been investigated. Adsorption experiments indicated that 90% of the solute remained in the solution. Combined chemical analysis of samples on the photochemical degradation indicated that NPX in an aqueous solution (20 ppm) is efficiently transformed into other species but only 18% of the reactant is mineralized into CO2 and water after three hours of reaction. Performing the photocatalytic oxidation in the presence of TiO2, more than 80% of the organic compounds are mineralized by reactive oxidation species (ROS) within four hours of reaction. Analysis of reaction mixtures by a combination of analytical techniques indicated that naproxen is transformed into several aromatic naphthalene derivatives. These latter compounds are eventually transformed into polyhydroxylated aromatic compounds that are strongly adsorbed onto the TiO2 surface and are quickly oxidized into low-molecular-weight acids by an electron transfer mechanism. Based on this and previous studies on NPX photocatalytic oxidation, a unified and complete degradation mechanism is presented.

Sodium copper chlorophyllin conjugated with Ag plasmonic nanoparticles as efficient nanostructure for application in photodynamic therapy

Photodynamic therapy (PDT) is a method that uses light-sensitive photosensitizers to stimulate cells with specific wavelengths. Nanoparticles (NPs) are an emerging technology in PDT, offering advantages over classical photosensitizers. The amalgamation of silver NPs and photosensitizer drugs has gained significant attention in PDT. We conjugated Ag NPs to sodium-copper chlorophyllin (SCC) in this research. The binding of Ag NPs to SCC was examined using X-ray diffraction, SEM, EDS, DLS, Zeta potential, and FTIR analyses. The optical properties of SCC before and after binding toAg NPs were performed through Photoluminescence (PL) analysis and UV–visible spectroscopy, as well as the production of reactive oxygen species (ROS) and free radicals (hydroxyl radical) before and after binding through the photobleaching phenomenon of methylene blue and photochemical degradation of anthracene. SCC exhibits high absorption in the visible spectrum violet-blue (350–470 nm) and red (570–710 nm) regions. HeLa cells and red LED were used to investigate the cytotoxicity (MTT assay) of SCC attached to Ag NPs.

Impact of ultraviolet aging on the composition and characteristics of multifunctional composite coatings

AbstractMultifunctional composite coatings exposed to environmental conditions are prone to aging and potential functional failure due to ultraviolet (UV) radiation. This study investigates the impact of UV radiation on the structure and properties of low infrared emissivity composite coatings, comprising ethylene propylene diene monomer (EPDM) as the matrix and antistatic carbon fiber (CF) and flaky floating aluminum powder as fillers. In addition to analyzing the photochemical degradation reactions of the composite coating under UV irradiation, the role of fillers in resisting UV aging is elucidated. The performance parameters examined include infrared (IR) emissivity, surface resistivity, mechanical properties, and dielectric properties. The results indicate that after UV aging, EPDM undergoes the most significant changes, leading to the formation of carbonyl groups. CFs experience mild UV aging and an increase in resistivity. Aluminum powder, on the other hand, remains largely unchanged after UV aging and its addition significantly reduces the UV aging rate of the composite coating, resulting in a low IR emissivity of as low as 0.2 after UV aging. Among them, Coating 4 exhibits the best overall performance after UV aging.Highlights The UV aging mechanism of EPDM and the role of fillers were revealed. The UV aging of the coating significantly reduced the infrared emissivity (Reduced from 0.5 to 0.2). Al powder effectively reduced the UV degradation rate of the coating by reflecting UV light. The properties of the double‐formulated coating perform best after UV aging.

Synthesis and characterization of mixed ligands based Co(II)-based coordination polymers and study their photochemically antibiotic degradation

Two Co(II)-based coordination polymers （CPs）, denoted as [Co4(NPDA)4(bmb)2·3H2O]n (1) and [Co(CHDA)(bmb)]n (2) (bmb = 4, 4́-bis(2-methylimidazol-3-ium-1-yl) biphenyl; H2NPDA = 1,4-naphthalenedicarboxylic acid; H2CHDA = 1,4-cyclohexanedicarboxylic acid), were obtained from mixtures of Co(NO3)2·6H2O and H2NPDA and bmb for 1 or H2CHDA and bmb for 2 with good yields (67 % and 53 %). Single crystal XRD shows a quadruply acetate-bridged Co(II)···Co(II) center for 1 with distorted triangular bipyramid surrounding of Co atom, while 2 shows a cis-configured octahedral N2O4 coordination for Co. Thermal gravimetric analysis confirms the water content of 1 and shows remarkable thermal stabilities, with a decomposition for 1 at around 400 °C and 450 °C for 2. 1 and 2 were used as catalysts for the photochemical degradation of the antibiotics secnidazole (SIZ), nitrofurazone (NFZ), sulfasalazine (SLA), and furazolidone (FZD). Using 1 at a dosage of 10 mg/L allowed a degradation efficiency of 92.3 % for 30 ppm NFZ at 6.5 pH. A proposed photodegradation mechanism was investigated through radical trapping experiments.