I. Marić, M. Gotic, T. Jurkin, L. Mikac, E. Tronc, M. Ivanda
Iron/Titanium oxide nanoparticles with initial molar ratio Fe/(Fe+Ti) = 0.05 (low loading of Fe in TiO2) and Fe/(Fe+Ti) = 0.15 (high loading of Fe in TiO2) were synthesized by a modified sol-gel procedure using Ti(IV)-isopropoxide, FeSO4 ∙ 7H2O and poly(ethylene glycol) (PEG) as starting material. The amount of doped iron strongly affected structural properties as well as the degree of dispersion of iron in the Fe- Ti-O system. The highly-doped sample contained poorly crystallized hydrated iron(III)- sulphates or basic iron(III)-sulphates in a considerable amount. The lowly-doped Fe-TiO2 sample contained about 22 wt % of brookite that had taken up iron virtually in the same proportion as anatase. Contrary to quasi- homogeneous distributions of iron in the lowly- doped Fe-TiO2 sample, the uptake of iron in the highly-doped Fe-TiO2 sample heated at 500 °C is significant, but anatase is free from iron, thus suggesting a heterogeneous distribution of iron. The photocatalytic activity of the highly-doped Fe-TiO2 sample was better than that of the lowly-doped Fe-TiO2 sample, but still below the photoactivity of Degussa P25 reference photocatalyst.
{"title":"Structural Properties of Iron/Titanium Oxide Nanoparticles Synthesized by Sol-gel Method in the Presence of Poly(ethylene glycol)","authors":"I. Marić, M. Gotic, T. Jurkin, L. Mikac, E. Tronc, M. Ivanda","doi":"10.5562/CCA3441","DOIUrl":"https://doi.org/10.5562/CCA3441","url":null,"abstract":"Iron/Titanium oxide nanoparticles with initial molar ratio Fe/(Fe+Ti) = 0.05 (low loading of Fe in TiO2) and Fe/(Fe+Ti) = 0.15 (high loading of Fe in TiO2) were synthesized by a modified sol-gel procedure using Ti(IV)-isopropoxide, FeSO4 ∙ 7H2O and poly(ethylene glycol) (PEG) as starting material. The amount of doped iron strongly affected structural properties as well as the degree of dispersion of iron in the Fe- Ti-O system. The highly-doped sample contained poorly crystallized hydrated iron(III)- sulphates or basic iron(III)-sulphates in a considerable amount. The lowly-doped Fe-TiO2 sample contained about 22 wt % of brookite that had taken up iron virtually in the same proportion as anatase. Contrary to quasi- homogeneous distributions of iron in the lowly- doped Fe-TiO2 sample, the uptake of iron in the highly-doped Fe-TiO2 sample heated at 500 °C is significant, but anatase is free from iron, thus suggesting a heterogeneous distribution of iron. The photocatalytic activity of the highly-doped Fe-TiO2 sample was better than that of the lowly-doped Fe-TiO2 sample, but still below the photoactivity of Degussa P25 reference photocatalyst.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"577-588"},"PeriodicalIF":0.3,"publicationDate":"2018-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49007111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Katarina Marušić, H. O. Ćurković, Ema Supnišek Lisac, H. Takenouti
Two different imidazole based molecules were investigated as corrosion inhibitors for Cu-6Sn bronze in a sulphate/carbonate solution at pH 3 and 5 which simulate a mild and strong polluted urban environment. The tested corrosion inhibitors were 4-methyl-1-phenylimidazole (PMI) and 4- methy1-1-p- tolylimidazole (TMI). The difference between structures is in the additional para positioned methyl, -CH3, group in the phenyl ring of the TMI molecule. Their protective effect was investigated by different electrochemical methods: polarization in wide and narrow potential range and electrochemical impedance spectroscopy. The investigations have shown that both molecules give good protection to the bronze at pH 3, but only TMI showed a good effect at pH 5. Indicating that the para positioned methyl group serves as a link between the inhibitor molecule and substrate bronze.
{"title":"Two Imidazole Based Corrosion Inhibitors for Protection of Bronze from Urban Atmospheres","authors":"Katarina Marušić, H. O. Ćurković, Ema Supnišek Lisac, H. Takenouti","doi":"10.5562/CCA3440","DOIUrl":"https://doi.org/10.5562/CCA3440","url":null,"abstract":"Two different imidazole based molecules were investigated as corrosion inhibitors for Cu-6Sn bronze in a sulphate/carbonate solution at pH 3 and 5 which simulate a mild and strong polluted urban environment. The tested corrosion inhibitors were 4-methyl-1-phenylimidazole (PMI) and 4- methy1-1-p- tolylimidazole (TMI). The difference between structures is in the additional para positioned methyl, -CH3, group in the phenyl ring of the TMI molecule. Their protective effect was investigated by different electrochemical methods: polarization in wide and narrow potential range and electrochemical impedance spectroscopy. The investigations have shown that both molecules give good protection to the bronze at pH 3, but only TMI showed a good effect at pH 5. Indicating that the para positioned methyl group serves as a link between the inhibitor molecule and substrate bronze.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"435-446"},"PeriodicalIF":0.3,"publicationDate":"2018-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45839000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. El-Sharief, S. Abbas, Z. Moussa, E. El-Gammal, A. El‐Sharief
1,3-Disubstituted-4-thioxoimidazolidin-2-one derivatives with various substituents at N1 and N3 were synthesized with high yields and excellent purity by the reaction of various N-arylcyanothioformamide derivatives with isocyanate derivatives. The activity of these products as antibacterial and antifungal agents was studied to through some light on structural activity relationship. Some of synthesized compounds showed significant antibacterial and antifungal activities. Most of the imidazole derivatives possess significant antifungal activity aginst S. cerevisiae (MIC 1–10 μg mL–1). As comparision with ketoconazole, most of the imidazole derivatives showed activity ranging from 50 % less activity to fourfold activity.
{"title":"Synthesis and Evaluation of Antibacterial and Antifungal Activities of 1,3-Disubstituted-4-thioxoimidazolidin-2-one Derivatives","authors":"M. El-Sharief, S. Abbas, Z. Moussa, E. El-Gammal, A. El‐Sharief","doi":"10.5562/CCA3354","DOIUrl":"https://doi.org/10.5562/CCA3354","url":null,"abstract":"1,3-Disubstituted-4-thioxoimidazolidin-2-one derivatives with various substituents at N1 and N3 were synthesized with high yields and excellent purity by the reaction of various N-arylcyanothioformamide derivatives with isocyanate derivatives. The activity of these products as antibacterial and antifungal agents was studied to through some light on structural activity relationship. Some of synthesized compounds showed significant antibacterial and antifungal activities. Most of the imidazole derivatives possess significant antifungal activity aginst S. cerevisiae (MIC 1–10 μg mL–1). As comparision with ketoconazole, most of the imidazole derivatives showed activity ranging from 50 % less activity to fourfold activity.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"335-340"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3354","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46728106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Jablan, M. Rajković, S. Inić, R. Petlevski, A. Domijan
The aim of this study was to compare zinc (Zn) level in EDTA, heparin, citrate plasma and serum. The blood samples from the same healthy volunteers (n
本研究的目的是比较EDTA、肝素、柠檬酸盐血浆和血清中锌的水平。来自相同健康志愿者的血液样本（n
{"title":"Impact of anticoagulants on assessment of zinc in plasma","authors":"J. Jablan, M. Rajković, S. Inić, R. Petlevski, A. Domijan","doi":"10.5562/CCA3321","DOIUrl":"https://doi.org/10.5562/CCA3321","url":null,"abstract":"The aim of this study was to compare zinc (Zn) level in EDTA, heparin, citrate plasma and serum. The blood samples from the same healthy volunteers (n","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"317-321"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3321","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48570033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sadanand N. Shringare, H. Chavan, Pravin S. Bhale, Sakharam B. Dongare, Yoginath B. Mule, Nishikant D. Kolekar, B. Bandgar
{"title":"Synthesis and Pharmacological Evaluation of Pyrazoline and Pyrimidine Analogs of Combretastatin-A4 as Anticancer, Anti-inflammatory and Antioxidant Agents","authors":"Sadanand N. Shringare, H. Chavan, Pravin S. Bhale, Sakharam B. Dongare, Yoginath B. Mule, Nishikant D. Kolekar, B. Bandgar","doi":"10.5562/CCA3393","DOIUrl":"https://doi.org/10.5562/CCA3393","url":null,"abstract":"","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"357-366"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45272596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Gilja, L. K. Krehula, Z. Katančić, S. Krehula, Z. Hrnjak-Murgić, J. Travas-sejdic
Titanium catalysts (TiO2) were synthesized by three different methods. Their photocatalytic activity was validated through photodegradation of Reactive Red 45 (RR45) azo dye and Acid Blue 25 (AB25) anthraquinone dye in an aqueous solution under UV irradiation. TiO2 photocatalysts were characterized by FTIR, XRD and SEM. Photosensitivity and TiO2 activity range were characterized by UV/Vis spectroscopy. Photocatalytic validation has been made by way of determining the degree of RR45 and AB25 removal. TOC was determined as a measure of the mineralization of RR45 and AB25 by photocatalysis. The stability of TiO2 catalysts and a possibility of using them in consecutive photocatalysis cycles have also been studied. The results show that the photocatalytic efficiency depends on the crystal structure of TiO2. The size of crystallites depends on synthesis conditions. From the results of photocatalytic efficiency it is concluded that the chemical interaction between a catalyst and a dye strongly depends on the dye chemical structure.
{"title":"Influence of Titanium Dioxide Preparation Method on Photocatalytic Degradation of Organic Dyes","authors":"V. Gilja, L. K. Krehula, Z. Katančić, S. Krehula, Z. Hrnjak-Murgić, J. Travas-sejdic","doi":"10.5562/CCA3292","DOIUrl":"https://doi.org/10.5562/CCA3292","url":null,"abstract":"Titanium catalysts (TiO2) were synthesized by three different methods. Their photocatalytic activity was validated through photodegradation of Reactive Red 45 (RR45) azo dye and Acid Blue 25 (AB25) anthraquinone dye in an aqueous solution under UV irradiation. TiO2 photocatalysts were characterized by FTIR, XRD and SEM. Photosensitivity and TiO2 activity range were characterized by UV/Vis spectroscopy. Photocatalytic validation has been made by way of determining the degree of RR45 and AB25 removal. TOC was determined as a measure of the mineralization of RR45 and AB25 by photocatalysis. The stability of TiO2 catalysts and a possibility of using them in consecutive photocatalysis cycles have also been studied. The results show that the photocatalytic efficiency depends on the crystal structure of TiO2. The size of crystallites depends on synthesis conditions. From the results of photocatalytic efficiency it is concluded that the chemical interaction between a catalyst and a dye strongly depends on the dye chemical structure.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"323-334"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3292","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46408366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Ristić, Jasenka Štajdohar, Ivana Mitar, S. Musić
Precipitations by the forced hydrolysis of 0.2 M FeCl3 aqueous solutions between 2 and 72 hours in the presence of 1% sodium n-dodecyl sulphate (SDS) were investigated. In the absence of SDS a direct phase transformation b- FeOOH → a-Fe2O3 via dissolution/ recrystallization occurred in the precipitation system. In the presence of SDS small amounts (traces) of a-FeOOH as an intermediate phase precipitated, and with a prolonged time of forced hydrolysis a-FeOOH also transformed to a-Fe2O3 via the dissolution/recrystallization mechanism. On the basis of Mossbauer spectra it was concluded that in the presence of SDS the a-Fe2O3 phase exhibited a lower degree of crystallinity. During the precipitation process in the presence of SDS the competition between the stability of Fe(III)-dodecyl sulphate on one side and the formation of iron oxide phases on the other also played an important role. Thermal field emission scanning electron microscopy (FE SEM) revealed that the big a- Fe2O3 particles possessed a substructure. The elongation of primary a-Fe2O3 particles produced in the presence of SDS was noticed. This effect can be assigned to the preferential adsorption of sulphate groups on nuclei and crystallites of FeOOH and a-Fe2O3 phases during the forced hydrolysis of FeCl3 solutions.
{"title":"Monitoring of the Forced Hydrolysis of FeCl3 Solutions in the Presence of Sodium Dodecyl Sulphate","authors":"M. Ristić, Jasenka Štajdohar, Ivana Mitar, S. Musić","doi":"10.5562/CCA3412","DOIUrl":"https://doi.org/10.5562/CCA3412","url":null,"abstract":"Precipitations by the forced hydrolysis of 0.2 M FeCl3 aqueous solutions between 2 and 72 hours in the presence of 1% sodium n-dodecyl sulphate (SDS) were investigated. In the absence of SDS a direct phase transformation b- FeOOH → a-Fe2O3 via dissolution/ recrystallization occurred in the precipitation system. In the presence of SDS small amounts (traces) of a-FeOOH as an intermediate phase precipitated, and with a prolonged time of forced hydrolysis a-FeOOH also transformed to a-Fe2O3 via the dissolution/recrystallization mechanism. On the basis of Mossbauer spectra it was concluded that in the presence of SDS the a-Fe2O3 phase exhibited a lower degree of crystallinity. During the precipitation process in the presence of SDS the competition between the stability of Fe(III)-dodecyl sulphate on one side and the formation of iron oxide phases on the other also played an important role. Thermal field emission scanning electron microscopy (FE SEM) revealed that the big a- Fe2O3 particles possessed a substructure. The elongation of primary a-Fe2O3 particles produced in the presence of SDS was noticed. This effect can be assigned to the preferential adsorption of sulphate groups on nuclei and crystallites of FeOOH and a-Fe2O3 phases during the forced hydrolysis of FeCl3 solutions.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"403-410"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44148323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyurethane (PUs) are present in many aspects of everyday lives such as the rigid foam insulation panel in construction, seat cushion in automotive and elastomeric materials in medical industries. Conventional PUs are made from petrochemical based starting materials which raised severe health and environmental concerns. The substitution of petro-based polyols with carbohydrate polyols have shown to improve biodegradability and mechanical properties of PUs. Reaction pathways were examined with density functional theory to design novel environmental friendly polyurethanes. Based on the calculated thermodynamic properties, the reactivity of sugars towards isocyanates was compared. Fructose was found to be the most reactive as the corresponding fructose-isocyanate reaction has the lowest energy barrier of 135.6 kJ/mol. Therefore, the results obtained have encouraged the synthesis of fructose-based polyurethane foam. The synthesis was successful, and the produced fully fructose-based foam was stable with minimal sign of shrinkage.
{"title":"Molecular Design of Sugar-Based Polyurethanes","authors":"Min Lu, Attila Surányi, B. Viskolcz, Béla Fiser","doi":"10.5562/CCA3328","DOIUrl":"https://doi.org/10.5562/CCA3328","url":null,"abstract":"Polyurethane (PUs) are present in many aspects of everyday lives such as the rigid foam insulation panel in construction, seat cushion in automotive and elastomeric materials in medical industries. Conventional PUs are made from petrochemical based starting materials which raised severe health and environmental concerns. The substitution of petro-based polyols with carbohydrate polyols have shown to improve biodegradability and mechanical properties of PUs. Reaction pathways were examined with density functional theory to design novel environmental friendly polyurethanes. Based on the calculated thermodynamic properties, the reactivity of sugars towards isocyanates was compared. Fructose was found to be the most reactive as the corresponding fructose-isocyanate reaction has the lowest energy barrier of 135.6 kJ/mol. Therefore, the results obtained have encouraged the synthesis of fructose-based polyurethane foam. The synthesis was successful, and the produced fully fructose-based foam was stable with minimal sign of shrinkage.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"299-307"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3328","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46846926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Gulaboski, Pavlinka Kokoskarova, Sofija Petkovska
: Protein-film voltammetry is recognized as a very efficient tool in mechanistic enzymology, but it is also seen as a relevant approach to gain thermodynamic and kinetic information related to the redox chemistry of many enzymes. This technique requires a small amount of redox enzyme, whose molecules form monomolecular film on the working electrode surface. In this paper we present a simple and time - independent cyclo-voltammetric method for the determination of kinetics of the chemical step of an electrochemical-catalytic (EC’) mechanism in protein- film scenario. Theoretical results of a surface EC’ mechanism show that the limiting cyclo -voltammetric catalytic current, measured at large overpotentials, depends solely on the rate of the chemical regenerative re action. At large overpotentials, the limiting current of the steady-state cyclic voltammograms is independent on all kinetics and thermodynamic parameters related to the electrode reaction of adsorbed enzyme. The approach proposed relies on the dependence of the magnitude of limiting current of the experimental cyclic steady-state voltammograms as a function of the substrate concentration.
{"title":"Time-Independent Methodology to Access Michaelis-Menten Constant by Exploring Electrochemical-Catalytic Mechanism in Protein-Film Cyclic Staircase Voltammetry","authors":"R. Gulaboski, Pavlinka Kokoskarova, Sofija Petkovska","doi":"10.5562/CCA3383","DOIUrl":"https://doi.org/10.5562/CCA3383","url":null,"abstract":": Protein-film voltammetry is recognized as a very efficient tool in mechanistic enzymology, but it is also seen as a relevant approach to gain thermodynamic and kinetic information related to the redox chemistry of many enzymes. This technique requires a small amount of redox enzyme, whose molecules form monomolecular film on the working electrode surface. In this paper we present a simple and time - independent cyclo-voltammetric method for the determination of kinetics of the chemical step of an electrochemical-catalytic (EC’) mechanism in protein- film scenario. Theoretical results of a surface EC’ mechanism show that the limiting cyclo -voltammetric catalytic current, measured at large overpotentials, depends solely on the rate of the chemical regenerative re action. At large overpotentials, the limiting current of the steady-state cyclic voltammograms is independent on all kinetics and thermodynamic parameters related to the electrode reaction of adsorbed enzyme. The approach proposed relies on the dependence of the magnitude of limiting current of the experimental cyclic steady-state voltammograms as a function of the substrate concentration.","PeriodicalId":10822,"journal":{"name":"Croatica Chemica Acta","volume":"91 1","pages":"377-382"},"PeriodicalIF":0.3,"publicationDate":"2018-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.5562/CCA3383","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45334963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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