H. Spikes, Shelby J. Jarrett-Noland, Stephan M. Germann, W. Olivas, J. Braddock-Wilking, C. M. Dupureur
Fluorescent compounds have been shown to be useful in probing lipid dynamics, and there is ongoing interest in nontoxic, photostable, and sensitive dyes. Recently, we evaluated a number of 2,7-disubstituted-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenyl sila- and germafluorenes for their potential as cellular fluorescent probes. These compounds exhibit remarkable quantum yields in hydrophobic environments and dramatic increases in emission intensity in the presence of surfactants. Here, we show that they exhibit significant emission enhancements in the presence of small unilamellar vesicles and are nontoxic to E. coli, S. aureus, and S. cerevisiae. Furthermore, they luminesce in S. cerevisiae cells with strong photostability and colocalize with the lipid droplet stain Nile Red, demonstrating their promise as lipid probes.
{"title":"Group 14 Metallafluorenes for Lipid Structure Detection and Cellular Imaging","authors":"H. Spikes, Shelby J. Jarrett-Noland, Stephan M. Germann, W. Olivas, J. Braddock-Wilking, C. M. Dupureur","doi":"10.3390/csac2021-10455","DOIUrl":"https://doi.org/10.3390/csac2021-10455","url":null,"abstract":"Fluorescent compounds have been shown to be useful in probing lipid dynamics, and there is ongoing interest in nontoxic, photostable, and sensitive dyes. Recently, we evaluated a number of 2,7-disubstituted-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenyl sila- and germafluorenes for their potential as cellular fluorescent probes. These compounds exhibit remarkable quantum yields in hydrophobic environments and dramatic increases in emission intensity in the presence of surfactants. Here, we show that they exhibit significant emission enhancements in the presence of small unilamellar vesicles and are nontoxic to E. coli, S. aureus, and S. cerevisiae. Furthermore, they luminesce in S. cerevisiae cells with strong photostability and colocalize with the lipid droplet stain Nile Red, demonstrating their promise as lipid probes.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86270557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aged distilled beverages (cognac and brandy) contain phenolic antioxidants as their quality markers. Voltammetric sensors based on the carbon nanotubes and electropolymerized pyrocatechol violet (PCV) or p-aminobenzoic acid (ABA) were developed for the simultaneous determination of the phenolic antioxidants in cognac and brandy. The polymerization conditions of PCV and ABA were optimized. Sensors allow for the simultaneous sensitive determination of gallic and ellagic acids as well as syringaldehyde and vanillin. The analytical characteristics are improved vs. other modified electrodes. The sensors show selectivity in the presence of typical interferences and other natural phenolics. The sensors that were developed were tested on cognac and brandy samples.
{"title":"Sensitive and Selective Voltammetric Sensors for the Simultaneous Quantification of Natural Phenolic Antioxidants in Cognac and Brandy","authors":"G. Ziyatdinova, E. Guss","doi":"10.3390/csac2021-10420","DOIUrl":"https://doi.org/10.3390/csac2021-10420","url":null,"abstract":"Aged distilled beverages (cognac and brandy) contain phenolic antioxidants as their quality markers. Voltammetric sensors based on the carbon nanotubes and electropolymerized pyrocatechol violet (PCV) or p-aminobenzoic acid (ABA) were developed for the simultaneous determination of the phenolic antioxidants in cognac and brandy. The polymerization conditions of PCV and ABA were optimized. Sensors allow for the simultaneous sensitive determination of gallic and ellagic acids as well as syringaldehyde and vanillin. The analytical characteristics are improved vs. other modified electrodes. The sensors show selectivity in the presence of typical interferences and other natural phenolics. The sensors that were developed were tested on cognac and brandy samples.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82708744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Edgar G. Mendez-Lopez, Jersson X. Leon-Medina, D. Tibaduiza
Electronic tongue type sensor arrays are made of different materials with the property of capturing signals independently by each sensor. The signals captured when conducting electrochemical tests often have high dimensionality, which increases when performing the data unfolding process. This unfolding process consists of arranging the data coming from different experiments, sensors, and sample times, thus the obtained information is arranged in a two-dimensional matrix. In this work, a description of a tool for the analysis of electronic tongue signals is developed. This tool is developed in Matlab® App Designer, to process and classify the data from different substances analyzed by an electronic tongue type sensor array. The data processing is carried out through the execution of the following stages: (1) data unfolding, (2) normalization, (3) dimensionality reduction, (4) classification through a supervised machine learning model, and finally (5) a cross-validation procedure to calculate a set of classification performance measures. Some important characteristics of this tool are the possibility to tune the parameters of the dimensionality reduction and classifier algorithms, and also plot the two and three-dimensional scatter plot of the features after reduced the dimensionality. This to see the data separability between classes and compatibility in each class. This interface is successfully tested with two electronic tongue sensor array datasets with multi-frequency large amplitude pulse voltammetry (MLAPV) signals. The developed graphical user interface allows comparing different methods in each of the mentioned stages to find the best combination of methods and thus obtain the highest values of classification performance measures.
{"title":"Development of a Pattern Recognition Tool for the Classification of Electronic Tongue Signals Using Machine Learning","authors":"Edgar G. Mendez-Lopez, Jersson X. Leon-Medina, D. Tibaduiza","doi":"10.3390/csac2021-10447","DOIUrl":"https://doi.org/10.3390/csac2021-10447","url":null,"abstract":"Electronic tongue type sensor arrays are made of different materials with the property of capturing signals independently by each sensor. The signals captured when conducting electrochemical tests often have high dimensionality, which increases when performing the data unfolding process. This unfolding process consists of arranging the data coming from different experiments, sensors, and sample times, thus the obtained information is arranged in a two-dimensional matrix. In this work, a description of a tool for the analysis of electronic tongue signals is developed. This tool is developed in Matlab® App Designer, to process and classify the data from different substances analyzed by an electronic tongue type sensor array. The data processing is carried out through the execution of the following stages: (1) data unfolding, (2) normalization, (3) dimensionality reduction, (4) classification through a supervised machine learning model, and finally (5) a cross-validation procedure to calculate a set of classification performance measures. Some important characteristics of this tool are the possibility to tune the parameters of the dimensionality reduction and classifier algorithms, and also plot the two and three-dimensional scatter plot of the features after reduced the dimensionality. This to see the data separability between classes and compatibility in each class. This interface is successfully tested with two electronic tongue sensor array datasets with multi-frequency large amplitude pulse voltammetry (MLAPV) signals. The developed graphical user interface allows comparing different methods in each of the mentioned stages to find the best combination of methods and thus obtain the highest values of classification performance measures.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78123573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ashutosh Kumar, H. Heidari-Bafroui, Amer Charbaji, Nasim Rahmani, C. Anagnostopoulos, M. Faghri
Microfluidic paper-based analytical devices (μPADs) have witnessed a great extent of innovation over the past decade, developing new components and materials assisting the diagnosis of different diseases and sensing of a wide range of biological, chemical, optical, and electrochemical phenomena. The novel paper-based cantilever (PBC) actuator is one the major components that allows autonomous loading and control of multiple fluid reagents required for the accurate operation of paper-based microfluidic devices. This paper provides an extensive overview of numerical and experimental modeling of fluidically controlled PBC actuators for automation of the paper-based assay. The PBC model undergoing hygro-expansion utilizes quasi-static 2D fluid loaded structure governed by the Euler–Bernoulli beam theory for small and moderately large deflections. The solution for the model can avail the response of paper-based actuators for response deflection θ, within 0° to 10° under the assumption of insignificant cross-sectional deformation. The actuation of PBC obtained using a quasi-static theory shows that our results are consistent with quantitative experiments demonstrating the adequacy of models.
{"title":"Numerical and Experimental Modeling of Paper-Based Actuators","authors":"Ashutosh Kumar, H. Heidari-Bafroui, Amer Charbaji, Nasim Rahmani, C. Anagnostopoulos, M. Faghri","doi":"10.3390/csac2021-10468","DOIUrl":"https://doi.org/10.3390/csac2021-10468","url":null,"abstract":"Microfluidic paper-based analytical devices (μPADs) have witnessed a great extent of innovation over the past decade, developing new components and materials assisting the diagnosis of different diseases and sensing of a wide range of biological, chemical, optical, and electrochemical phenomena. The novel paper-based cantilever (PBC) actuator is one the major components that allows autonomous loading and control of multiple fluid reagents required for the accurate operation of paper-based microfluidic devices. This paper provides an extensive overview of numerical and experimental modeling of fluidically controlled PBC actuators for automation of the paper-based assay. The PBC model undergoing hygro-expansion utilizes quasi-static 2D fluid loaded structure governed by the Euler–Bernoulli beam theory for small and moderately large deflections. The solution for the model can avail the response of paper-based actuators for response deflection θ, within 0° to 10° under the assumption of insignificant cross-sectional deformation. The actuation of PBC obtained using a quasi-static theory shows that our results are consistent with quantitative experiments demonstrating the adequacy of models.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89741481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Limonium brasiliense (Boiss.) Kuntze (Plumbaginaceae) is a medicinal plant that is popularly used in the folk medicine. In this study, we examined xanthine oxidase (XO) inhibitory activity of the aqueous fraction of Limonium brasiliense extract and its polar bioactive constituents using the enzymatic hypoxanthine (HX)–XO system in vitro. Seven active compounds isolated from the aqueous extract proved to be strong XO inhibitors. Prodelphinidin B1-3,3′-digallate (1) showed the most potent inhibitory activity with an IC50 value of 6.61 µM, comparable to allopurinol. This study provides basis for the potential use of the aqueous fraction of L. brasiliense against hyperuricemia, displaying potent XO inhibitory activity with an IC50 value of 48.3 µg/mL. This inhibitory effect is compatible with the presence of (1) in this extract.
{"title":"Xanthine Oxidase Inhibition by Aqueous Extract of Limonium brasiliense (Plumbaginaceae)","authors":"S. Rodriguez, A. Murray, J. Leiro","doi":"10.3390/ECSOC-24-08410","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08410","url":null,"abstract":"Limonium brasiliense (Boiss.) Kuntze (Plumbaginaceae) is a medicinal plant that is popularly used in the folk medicine. In this study, we examined xanthine oxidase (XO) inhibitory activity of the aqueous fraction of Limonium brasiliense extract and its polar bioactive constituents using the enzymatic hypoxanthine (HX)–XO system in vitro. Seven active compounds isolated from the aqueous extract proved to be strong XO inhibitors. Prodelphinidin B1-3,3′-digallate (1) showed the most potent inhibitory activity with an IC50 value of 6.61 µM, comparable to allopurinol. This study provides basis for the potential use of the aqueous fraction of L. brasiliense against hyperuricemia, displaying potent XO inhibitory activity with an IC50 value of 48.3 µg/mL. This inhibitory effect is compatible with the presence of (1) in this extract.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77955676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Bálint, Nóra Popovics-Tóth, Ádám Tajti, Bettina Rávai, K. Szabó, F. Perdih
Organophosphorus compounds play an important role in the medicinal- or agricultural industry, and in the human body as well. Over the last years, heterocyclic phosphonates have received growing interest due to their potential biological activity. An efficient tool for the preparation of such derivatives is their synthesis via multicomponent reactions. These transformations possess several criteria of an “ideal synthesis”, such as high atom economy, fast and simple accomplishment, energy efficiency, and environmentally friendliness. A number of heterocyclic phosphonates were prepared by us utilizing multicomponent syntheses. In this proceeding, the synthesis of the diethyl (2-amino-3-cyano-4H-chromen-4-yl)phosphonate by the condensation of salicylaldehyde, malononitrile and diethyl phosphite is briefly introduced. The reaction was optimized in respect of the catalyst type, the catalyst amount, the reaction time, and the temperature.
{"title":"Microwave-Assisted Multicomponent Syntheses of Heterocyclic Phosphonates","authors":"E. Bálint, Nóra Popovics-Tóth, Ádám Tajti, Bettina Rávai, K. Szabó, F. Perdih","doi":"10.3390/ECSOC-24-08548","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08548","url":null,"abstract":"Organophosphorus compounds play an important role in the medicinal- or agricultural industry, and in the human body as well. Over the last years, heterocyclic phosphonates have received growing interest due to their potential biological activity. An efficient tool for the preparation of such derivatives is their synthesis via multicomponent reactions. These transformations possess several criteria of an “ideal synthesis”, such as high atom economy, fast and simple accomplishment, energy efficiency, and environmentally friendliness. A number of heterocyclic phosphonates were prepared by us utilizing multicomponent syntheses. In this proceeding, the synthesis of the diethyl (2-amino-3-cyano-4H-chromen-4-yl)phosphonate by the condensation of salicylaldehyde, malononitrile and diethyl phosphite is briefly introduced. The reaction was optimized in respect of the catalyst type, the catalyst amount, the reaction time, and the temperature.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76970811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anamika Sharma, Z. Almarhoon, Rotimi Sheyi, Rakia Abd Alhameed, B. G. Torre, F. Albericio, Ayman Al-Faham
2,4,6-Trichloro-1,3,5-triazine (TCT) offers the unique ability to undergo sequential nucleophilic substitution reactions using regular nucleophiles (first Cl replacement at 0 °C, second at RT, and third at >90 °C), making s-triazine a privileged scaffold-finding application in drug development with an extension towards the development of new materials. This selective chemical property of TCT fulfills the goal of chemists to control organic structures and make them react in the required conditions for achieving each objective. In this regard, orthogonality and chemoselectivity are two modern organic chemistry concepts which have been exploited in various areas of research, ranging from supramolecular chemistry to organic/bioconjugation chemistry. We have demonstrated the fusion of these two concepts using TCT as “Orthogonal Chemoselectivity” and defined it as discrimination between reactive sites in any order. The usage of azide as one of the nucleophiles modulated the reactivity of the s-triazine core for the last Cl replacement. This allowed us to overcome the barrier of higher temperature (>90 °C) for the last Cl replacement which happened at RT, taking advantage of side chains of Cys, Tyr and Lys in a biological context. In this presentation, we revise the chemistry developed in our laboratories to manipulate the TCT core for application in our medicinal chemistry programs and in bioconjugation.
{"title":"s-Triazine: A Multidisciplinary and International Journey","authors":"Anamika Sharma, Z. Almarhoon, Rotimi Sheyi, Rakia Abd Alhameed, B. G. Torre, F. Albericio, Ayman Al-Faham","doi":"10.3390/ECSOC-24-08502","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08502","url":null,"abstract":"2,4,6-Trichloro-1,3,5-triazine (TCT) offers the unique ability to undergo sequential nucleophilic substitution reactions using regular nucleophiles (first Cl replacement at 0 °C, second at RT, and third at >90 °C), making s-triazine a privileged scaffold-finding application in drug development with an extension towards the development of new materials. This selective chemical property of TCT fulfills the goal of chemists to control organic structures and make them react in the required conditions for achieving each objective. In this regard, orthogonality and chemoselectivity are two modern organic chemistry concepts which have been exploited in various areas of research, ranging from supramolecular chemistry to organic/bioconjugation chemistry. We have demonstrated the fusion of these two concepts using TCT as “Orthogonal Chemoselectivity” and defined it as discrimination between reactive sites in any order. The usage of azide as one of the nucleophiles modulated the reactivity of the s-triazine core for the last Cl replacement. This allowed us to overcome the barrier of higher temperature (>90 °C) for the last Cl replacement which happened at RT, taking advantage of side chains of Cys, Tyr and Lys in a biological context. In this presentation, we revise the chemistry developed in our laboratories to manipulate the TCT core for application in our medicinal chemistry programs and in bioconjugation.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82873763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An efficient and sustainable copper-catalyzed protocol has been developed for the preparation of amidines via nucleophilic addition of amines into nitriles. The reaction proceeded smoothly at 100 °C in the presence of CuCl, Cs2CO3, and 2,2/-bipyridine under oxygen (O2) atmosphere in 2,2,2-trifluoroethanol (TFE) solvent. Moreover, a straightforward synthetic method for the synthesis of substituted pyrimidouracils via PhI(OAc)2-mediated oxidative coupling of N-uracil amidines and methylarenes has been developed. The starting materials N-uracil amidines were synthesized from 6-chlorouracil and amidines via nucleophilic substitution reactions.
{"title":"Synthesis of Amidines and Its Application to Pyrimidouracil Synthesis","authors":"P. Debnath","doi":"10.3390/ECSOC-24-08503","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08503","url":null,"abstract":"An efficient and sustainable copper-catalyzed protocol has been developed for the preparation of amidines via nucleophilic addition of amines into nitriles. The reaction proceeded smoothly at 100 °C in the presence of CuCl, Cs2CO3, and 2,2/-bipyridine under oxygen (O2) atmosphere in 2,2,2-trifluoroethanol (TFE) solvent. Moreover, a straightforward synthetic method for the synthesis of substituted pyrimidouracils via PhI(OAc)2-mediated oxidative coupling of N-uracil amidines and methylarenes has been developed. The starting materials N-uracil amidines were synthesized from 6-chlorouracil and amidines via nucleophilic substitution reactions.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81162932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rubén López-Cortés, A. Vazquez, Alberto Fernández, R. Estévez, J. Estévez
Iminosugars are sugar mimetics present in plants and microorganisms that were first reported in the 1960s. [...]
亚氨基糖是20世纪60年代首次报道的存在于植物和微生物中的糖模拟物。[…]
{"title":"An Improved Stereoselective Synthesis of (1R,2S,3S,4R,5R)-4-Amino-5-(hydroxymethyl)-cyclopentane-1,2,3-triol","authors":"Rubén López-Cortés, A. Vazquez, Alberto Fernández, R. Estévez, J. Estévez","doi":"10.3390/ECSOC-24-08474","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08474","url":null,"abstract":"Iminosugars are sugar mimetics present in plants and microorganisms that were first reported in the 1960s. [...]","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77940539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexandra I. Costa, Patrícia D. Barata, J. V. Prata
The sensing behavior of a calix[4]arene-oxacyclophane-carbazole conjugate (1) towards Cu(I) ions was investigated. Contrary to the noteworthy sensitivity and selectivity previously found for Cu(II), the affinity of 1 for Cu(I) cations is much lower. Through fluorescence titration assays, the apparent binding constants (Ka) for the two ions were determined, showing that an affinity of over thirteen fold was displayed for Cu(II). Two Cu(I) counter-ions were used to determine possible effects on the binding event. It was found that acetate and iodide ions behave similarly, yielding Ka of the same magnitude. Formation of a ground-state supramolecular complex between 1 and Cu(I) ions was not observed on UV-Vis titrations, in contrast to what was previously reported for Cu(II) using the same host. The affinity of 1 for Fe(III), a major biological competitor, was also assessed. The fluorescence of host 1 is quenched by Fe(III) ions although to a lesser extent (32% less efficient than Cu(II)). The study demonstrates that calixarene 1 is able to differentiate copper ions in two common oxidation states using fluorescence techniques, thereby suggesting its application for redox-active centers in biomimetic chemistry.
{"title":"Fluorescent Calix[4]arene-Oxacyclophane Sensor for Transition Metal Cations","authors":"Alexandra I. Costa, Patrícia D. Barata, J. V. Prata","doi":"10.3390/ECSOC-24-08453","DOIUrl":"https://doi.org/10.3390/ECSOC-24-08453","url":null,"abstract":"The sensing behavior of a calix[4]arene-oxacyclophane-carbazole conjugate (1) towards Cu(I) ions was investigated. Contrary to the noteworthy sensitivity and selectivity previously found for Cu(II), the affinity of 1 for Cu(I) cations is much lower. Through fluorescence titration assays, the apparent binding constants (Ka) for the two ions were determined, showing that an affinity of over thirteen fold was displayed for Cu(II). Two Cu(I) counter-ions were used to determine possible effects on the binding event. It was found that acetate and iodide ions behave similarly, yielding Ka of the same magnitude. Formation of a ground-state supramolecular complex between 1 and Cu(I) ions was not observed on UV-Vis titrations, in contrast to what was previously reported for Cu(II) using the same host. The affinity of 1 for Fe(III), a major biological competitor, was also assessed. The fluorescence of host 1 is quenched by Fe(III) ions although to a lesser extent (32% less efficient than Cu(II)). The study demonstrates that calixarene 1 is able to differentiate copper ions in two common oxidation states using fluorescence techniques, thereby suggesting its application for redox-active centers in biomimetic chemistry.","PeriodicalId":9815,"journal":{"name":"Chemistry Proceedings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76772077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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