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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies of native and Cd(II)-substituted carbonic anhydrases with special reference to their interaction with inhibitors

Tibell, Lena January 1984 (has links)
The major aim of this work has been to gain further insights into the catalytic mechanism of carbonic anhydrase (carbonate hydro-lyase, EC 4.2.1.1). One approach has been to replace the essential Zn(II) ion by Cd(II) which has favourable spectroscopic properties. The Cd(II)-enzymes have appreciable 4-nitrophenyl acetate hydrolase activities. These activities increase with pH as if dependent on the basic form of a group with pKa near 10. The Cd(II)-carbonic anhydrases also have significant carbon dioxide hydration activities. Jhe Cd(II) derivatives are strongly inhibited by monovalent anions. The 113-Cd(II) derivatives have also been studied by 113-Cd NMR as a function of pH and bicarbonate or inhibitor concentration. Plots of chemical shift versus pH give sigmoidal titration curves in the studied pH range, 10.3. The p«a values vary from 9.2 to 9.7 correlating reasonably well with the activity profiles. When bicarbonate is added to the samples the 113-Cd resonances shift upfield to new characteristic positions. The inhibitors CN", SH", and SCN” bind directly to the metal ion with their C, S, and N atoms, respectively. The results are best explained by assuming a rapid exchange between three species in which the open coordination site of the metal ion is occupied by'hydroxide, water, or bicarbonate. Another approach has been to study kinetic properties of the active en­zyme. A number of monovalent anions were investigated as inhibitors of carbon dioxide hydration catalyzed by human carbonic anhydrase II. Predominantly uncompetitive inhibition patterns were observed at pH near 9 in all cases. The inhibition of human carbonic anhydrase II by the organic compounds tetrazole, 1,2,4-triazole, 2-nitrophenol, and chloral hydrate was also investigated. These inhibitors, together with phenol, can be classified in three groups depending upon the kinetic patterns of inhibition of carbon dioixde hydration at pH near 9. The first group, represented by tetrazole and 2-nitrophenol, yields predominantly uncompetitive inhibition under these conditions in analogy with simple, inorganic anions. The second group, represented by 1,2,4-triazole and chloral hydrate gives rise to essentially noncompetitive inhibition patterns whereas phenol, representing the third group, is a competitive inhibitor of carbon dioxide hydration. These results are analyzed in terms of two rivaling mechanism models, a kinetic scheme originally proposed by Steiner et al. (Eur. 3. Biochem. (1975) 59, 253-259) and a rapid-equilibrium kinetic scheme proposed by Pocker and Deits (3. Am. Chem. Soc. (1982) 104, 2424-2434). It is concluded that the observed steady-state inhibition patterns are compatible with both models, but hat discriminatory data, strongly favouring the model of Stêiner et al., are available in the literature. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1984, härtill 4 uppsatser</p> / digitalisering@umu
2

Cd(II)-, Pb(II)- AND Hg(II)-2-AMINOETHANETHIOLATES

Bharara, Mohan Singh 01 January 2006 (has links)
This theses presents the synthesis and characterization of Cd(II)-, Pb(II)- and Hg(II)-aminoethanethiolates in aqueous media. 2-Aminoethanethiolate, a versatile sulfur andnitrogen (S/N) based ligand was used due to its resemblance to the naturally occurringamino acid, cysteine. The work is presented in four major parts: first, backgroundinformation on the versatile structural chemistry of Cd, Pb and Hg-thiolates with S/Ncontaining ligands; second, synthesis and characterization of Cd(II) with 2-aminoethanethiolates; third, synthesis and characterization and structural chemistry ofPb(II) with 2-aminoethanethiolates; and fourth, synthesis and characterization of Hg(II)-2-aminoethanethiolates in solution- and solid-state with emphasis on the mechanisticpathways for the formation of clusters.The compounds reported here are synthesized by direct addition of the metal saltsand the ligand in deionized water. For Cd(II)-thiolates, insoluble products (77 - 80 and 82- 84) due to the formation of oligomers and polymers were obtained. In Pb(II)-thiolates(85 - 89), the structural chemistry is variable due to the extensive array of coordinationenvironments Pb can acquire. This can be related to the stoichiometry of the reaction aswell as the reaction conditions. The structural trends in Cd(II)- and Pb(II)-thiolates arenot observed in the Hg(II)-thiolates. Rather the halide influences the formation ofmolecular as well as non-molecular structures. Systematic pathways for the formation ofthe compounds based on a variety of commonly observed structural 'building blocks' arepresented. For Cl, Br derivatives, a four-coordinate intermediate, [Hg(SR)2X2] (88 - 96)and for I derivatives three-coordinate intermediates, [HgI(SR)2] and [HgI2(SR)] (97 -100) can be considered as building units. The compounds were characterized withIR/Raman, NMR, MS, Uv-Vis and X-ray crystallography.
3

Μοντελοποίηση της απομάκρυνσης ιόντων καδμίου από απόβλητα με τη χρησιμοποίηση 2-πυρίδυλο οξιμών / Modelling the removal of cadmium ions from wastes using 2-pyridyl oximes

Αγγελίδου, Βαρβάρα 11 July 2013 (has links)
Εξαιτίας των πολλών εφαρμογών του καδμίου στη βιομηχανία αλλά και των ταυτόχρονα τοξικών ιδιοτήτων του στα έμβια όντα, η απομάκρυνση του Cd(II) από υδατικά απόβλητα είναι σήμερα ένα ενδιαφέρον θέμα έρευνας στην Περιβαλλοντική Χημεία. Η υγρή εκχύλιση (εκχύλιση με διαλύτη) είναι μια αποτελεσματική μέθοδος για την απομάκρυνση του Cd(II) από διαλύματα που περιέχουν ιόντα χλωριδίων, θειικά ή φωσφορικά διαλύματα. Κατά την υγρή εκχύλιση το μεταλλοϊόν συμπλοκοποιείται με έναν οργανικό υποκαταστάτη σχηματίζοντας ένα χημικό είδος που μεταφέρεται από την υδατική στην οργανική φάση σε ένα διφασικό σύστημα. Αναφέρθηκε πρόσφατα ότι το κάδμιο(II) μπορεί να εκχυλιστεί από μέσα που περιέχουν ιόντα χλωριδίων ή ιόντα χλωριδίων/νιτρικών χρησιμοποιώντας δύο 2-πυρίδυλο κετονοξίμες, και συγκεκριμένα την 1-(2-πυριδυλο)-δεκατρια-1-όνη οξίμη (2PC12) και την 1-(2-πυριδυλο)-δεκαπεντε-1-όνη (2PC14), ως μέσα εκχύλισης. Ο στόχος αυτής της εργασίας είναι να μοντελοποιήσει την φύση των χημικών ειδών που σχηματίζονται κατα την διαδικασία της υγρής εκχύλισης του Cd(II) χρησιμοποιώντας 2-πυρίδυλο κετονοξίμες ως μέσα εκχύλισης. Έτσι μελετήσαμε τις αντιδράσεις διαφόρων πηγών Cd(II) με 2-πυρίδυλο οξίμες ως υποκαταστάτες (Σχήμα I). Οι υποκαταστάτες που χρησιμοποιήθηκαν ήταν οι 2-πυριδίνη αλδοξίμη (paoH), μέθυλο 2-πυρίδυλο κετονοξίμη (mepaoH), φαίνυλο 2-πυρίδυλο κετονοξίμη (phpaoH) και πυριδινη-2-αμιδοξίμη (ampaoH). Η συστηματική συνθετική μας διερεύνηση οδήγησε στα προϊόντα [CdI2(paoH)2] (1), [Cd(NO3)2(paoH)2] (2), [Cd(NO3)(H2O)(paoH)2](NO3) (3), [Cd(paoH)3](ClO4)2 (4), [Cd(pao)2(paoH)2] (5), [CdI2(mepaoH)2] (6), [Cd(NO3)2(mepaoH)2] (7), [Cd(O2CMe)2(mepaoH)2] (8), [CdCl2(phpaoH)2] (9), [Cd4Br8(phpaoH)4]n (10), [CdI2(phpaoH)2] (11), [Cd(NO3)2(phpaoH)2] (12), [Cd2(Ο2CMe)4(phpaoH)2]n (13), [CdCl2(ampaoH)2] (14), [CdBr2(ampaoH)2] (15), [CdI2(ampaoH)2] (16) και [Cd(NO3)2(ampaoH)2] (17). Οι μοριακές και κρυσταλλικές δομές των συμπλόκων προσδιορίστηκαν με κρυσταλλογραφία ακτίνων Χ επί μονοκρυστάλλων των ενώσεων (Σχήμα II). Τα σύμπλοκα χαρακτηρίσθηκαν με στοιχειακές αναλύσεις και διάφορες φασματοσκοπικές μεθόδους (IR, Raman, NMR, Φωτοφωταύγεια). Τα φασματοσκοπικά δεδομένα μελετήθηκαν σε σχέση με τις γνωστές δομές των ενώσεων. Tα περισσότερα σύμπλοκα είναι μονοπυρηνικά. Οι ενώσεις 10 και 13 είναι 1D πολυμερή ένταξης. Τα μόρια paoH, mepaoH, phpaoH και ampaoH συμπεριφέρονται ως Ν(πυρίδυλο), Ν(οξιμικό)-διδοντικοί χηλικοί υποκαταστάτες. Τα ιόντα CdII στα σύμπλοκα είναι 6-, 7- και 8-ενταγμένα. Οι κρυσταλλικές δομές των περισσοτέρων συμπλόκων σταθεροποιούνται από δεσμούς Η. Τα περισσότερα σύμπλοκα διασπώνται στο DMSO, όπως προκύπτει από τα 1Η ΝΜR φάσματά τους. Τα σύμπλοκα 9, 14 και 12, 17 μοντελοποιούν τα χημικά είδη [CdCl2(μέσο εκχύλισης)2] και [Cd(NO3)2(μέσο εκχύλισης)2] που έχει προταθεί ότι σχηματίζονται κατά τη διαδικασία της υγρής εκχύλισης του Cd(II) με τη χρησιμοποίηση των 2PC12 και 2PC14 σε διαλύματα χλωριδίων και χλωριδίων/νιτρικών, αντίστοιχα. Με επιφύλαξη προτείνουμε ότι η ικανότητα των 2-πυρίδυλο κετοξιμών να απομακρύνουν Cd(II) από υδατικά απόβλητα οφείλεται στην ισχυρά χηλική φύση των μέσων εκχύλισης. / Because of the wide application of cadmium in various industrial facilities and its simultaneous toxic properties for organisms, the removal of Cd(II) from wastewater is a currently hot topic in environmental chemistry. Solvent extraction is an efficient method from the removal of Cd(II) from chloride, sulfate or phosphate solutions. Solvent extraction occurs when a metal ion is coordinated to an organic ligand to form a species that is transferred from the aqueous to the organic phase in a two-phase system. It has recently been reported that cadmium(II) can be extracted from chloride or chloride/nitrate media using two 2-pyridyl ketoximes, namely 1-(2-pyridyl)-trideca-1-one oxime (2PC12) and 1-(2-pyridyl)-pentadeca-one oxime (2PC14), as extractants and chloroform or hydracarbons as organic solvents [A. Parus, K. Wieszczycka, A. Olszanowski (2011) Hydrometallurgy, 105, 284]. The goal of this work is to model the nature of the chemical species that are formed during the solvent extraction of Cd(II) using 2-pyridyl ketoximes as extractants. Thus, we studied the reactions of various Cd(II) sources with 2-pyridyl oximes as ligands (Scheme I). The ligands used were 2-pyridine aldoxime (paoH), methyl 2-pyridyl ketoxime (mepaoH), phenyl 2-pyridyl ketoxime (phpaoH) and pyridine-2-amidoxime (ampaoH). Our systematic investigations gave the products [CdI2(paoH)2] (1), [Cd(NO3)2(paoH)2] (2), [Cd(NO3)(H2O)(paoH)2](NO3) (3), [Cd(paoH)3](ClO4)2 (4), [Cd(pao)2(paoH)2] (5), [CdI2(mepaoH)2] (6), [Cd(NO3)2(mepaoH)2] (7), [Cd(O2CMe)2(mepaoH)2] (8), [CdCl2(phpaoH)2] (9), [Cd4Br8(phpaoH)4]n (10), [CdI2(phpaoH)2] (11), [Cd(NO3)2(phpaoH)2] (12), [Cd2(Ο2CMe)4(phpaoH)2]n (13), [CdCl2(ampaoH)2] (14), [CdBr2(ampaoH)2] (15), [CdI2(ampaoH)2] (16) and [Cd(NO3)2(ampaoH)2] (17). The molecular and crystal structures of the complexes have been determined by single-crystal, X-ray crystallography (Scheme II). The complexes have been characterized by elemental analyses and various spectroscopic techniques (IR, Raman, NMR, Photoluminescence). The spectroscopic data are discussed in terms of the known structures. Most complexes are mononuclear. Compounds 10 and 13 are 1D coordination polymers. The paoH, mepaoH, phpaoH and ampaoH molecules behave as N(pyridyl), N(oxime)–bidentate chelating ligands. The CdII ions in the complexes are 6-, 7- and 8-coordinate. The crystal structures of most complexes are stabilized by H bonds. Most of the complexes decompose in DMSO, as evidenced by 1H NMR spectroscopy. Complexes 9, 14 and 12, 17 model the chemical species [CdCl2(extractant)2] and [Cd(NO3)2(extractant)2] that have been proposed to form during the solvent extraction of Cd(II) using 2PC12 and 2PC14 in chloride and dilute chloride/concentrated nitrate solutions, respectively. We tentatively propose that the ability of 2-pyridyl ketoximes to remove Cd(II) from wastewater is due to the strongly chelating nature of the extractants.
4

Chemical Processes at the Water-Manganite (γ-MnOOH) Interface / Kemiska Processer vid gränsytan mellan vatten och manganit (γ-MnOOH)

Ramstedt, Madeleine January 2004 (has links)
The chemistry of mineral surfaces is of great importance in many different areas including natural processes occurring in oceans, rivers, lakes and soils. Manganese (hydr)oxides are one important group to these natural processes, and the thermodynamically most stable trivalent manganese (hydr)oxide, manganit (γ-MnOOH), is studied in this thesis. This thesis summarises six papers in which the surface chemistry of synthetic manganite has been investigated with respect to surface acid-base properties, dissolution, and adsorption of Cd(II) and the herbicide N-(phosphonomethyl)glycine (glyphosate, PMG). In these papers, a wide range of analysis techniques were used, including X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), potentiometry, electrophoretic mobility measurements and wet chemical techniques, in order to obtain a more complete understanding of the different processes occurring at the manganite-water interface. From the combined use of these techniques, a 1-pKa acid-base model was established that is valid at pH&gt;6. The model includes a Na+ interaction with the surface: =MnOH2+½ --&gt; =MnOH-½ + H+ log β0 (intr.) = -8.20 = -pHiep =MnOH2+½ + Na+ --&gt; =MnOHNa+½ + H+ log β0 (intr.) = -9.64 At pH&lt;6 the manganite crystals dissolve and disproportionate into pyrolusite (β-MnO2) and Mn(II)-ions in solution according to: 2 γ-MnOOH + 2H+ --&gt; β-MnO2 + Mn2+ + 2H2O log K0 = 7.61 ± 0.10 The adsorption and co-adsorption of Cd(II) and glyphosate at the manganite surface was studied at pH&gt;6. Cd(II) adsorption displays an adsorption edge at pH~8.5. Glyphosate adsorbs over the entire pH range, but the adsorption decreases with increasing pH. When the two substances are co-adsorbed, the adsorption of Cd(II) is increased at low pH but decreased at high pH. The adsorption of glyphosate is increased in the entire pH range in the presence of Cd(II). From XPS, FTIR and EXAFS it was found that glyphosate and Cd(II) form inner sphere complexes. The binary Cd(II)-surface complex is bonded by edge sharing of Mn and Cd octahedra on the (010) plane of manganite. Glyphosate forms inner-sphere complexes through an interaction between the phosphonate group and the manganite surface. The largest fraction of this binary glyphosate complex is protonated throughout the pH range. A ternary surface complex is also present, and its structure is explained as type B ternary surface complex (surface-glyphosate-Cd(II)). The chelating rings between the Cd(II) and glyphosate, found in aqueous complexes, are maintained at the surface, and the ternary complex is bound to the surface through the phosphonate group of the ligand.
5

Application of Modified Chitosan for Recovery of Heavy Metals Found in Spent Batteries

Babakhani, Ataollah 11 April 2022 (has links)
Finding economical and environmentally friendly processes to recover heavy metals (HMs) from spent batteries is a research priority to move toward sustainability. Adsorption seems an acceptable procedure to replace the current separation/purification stage of hydrometallurgical techniques. Chitosan is an efficient adsorbent for HM uptake from aqueous solutions. Nevertheless, in practice, chitosan modification is unavoidable to improve its physicochemical properties. Sodium tripolyphosphate is an environmentally benign crosslinker that can be used for chitosan modification. In addition, ion-imprinting technique could potentially enhance the adsorption efficiency and selectivity of crosslinked chitosan. Considering the above, the primary purposes of this research were: investigating the adsorption efficiency of chitosan for heavy metals uptake from synthetic solutions; modifying chitosan by crosslinking alone and combined with ion-imprinting techniques to improve the physicochemical properties as well as adsorption capacity and selectivity of chitosan; evaluating and comparing the adsorption efficiency of modified chitosan beads for the adsorption of Cd(II), Ni(II) and Co(II) in single and multicomponent batch adsorption systems. Chitosan and sodium tripolyphosphate crosslinked chitosan beads were prepared to remove Cd(II) from aqueous solution in the first phase. FTIR and XRD of the synthesized beads showed partial consumption of chitosan amine groups and a decrease in crystallinity of chitosan structure over crosslinking reaction. The isotherm and thermodynamic studies showed that Langmuir isotherm was the best fit to the experimental data of Cd(II) adsorption on crosslinked chitosan and all the adsorption reactions were endothermic and spontaneous. A reduced quadratic model, constructed by the Response Surface Methodology (RSM), indicated that the Cd(II) adsorption uptake of 99.87 (mg/g) was achieved at 55 °C and 2.92 % (w/v) crosslinking degree. Then, chitosan and crosslinked chitosan beads by sodium tripolyphosphate were used for Ni(II) adsorption from aqueous media in the second phase. The BET characterization showed that increasing the crosslinking degree reduced the chitosan beads' surface area and their total pore volume. The Langmuir model described the experimental results best and showed that the maximum adsorption capacity of chitosan (80.00 mg/g) decreased after crosslinking (52.36 mg/g). In addition, a reduced quadratic model with a correlation coefficient of 0.96 was established to correlate the adsorption uptake of Ni(II) with pH and crosslinking degree. In the third phase, the adsorption of Ni(II) and Cd(II) ions from single and binary metal ions solutions onto chitosan and crosslinked chitosan beads was studied. The extended Freundlich model fitted the adsorption equilibrium data in the binary system, implying the existence of preference in the order of Ni(II) > Cd(II). Desorption studies with a mixture of NaCl and H2SO4 were also conducted during this phase, demonstrating a desorption efficiency of greater than 85 %. In the fourth phase, the removal of cadmium from aqueous solution was examined using a novel Cd(II)-imprinted crosslinked chitosan. SEM, FTIR, TGA, and BET characterizations revealed that the ion-imprinted chitosan beads had better physicochemical properties than chitosan beads and superior potential adsorption properties than non-imprinted crosslinked chitosan beads. The isotherm and thermodynamic studies revealed that the Langmuir isotherm fitted the Cd(II) experimental data the best, and the adsorption reactions were spontaneous and endothermic. The kinetics data were also best fitted by the pseudo-second-order equation. Finally, the ion-imprinted crosslinked chitosan beads were employed for the selective adsorption of Cd(II) in a competitive adsorption system of Cd(II)-Ni(II)-Co(II) in phase five. The characterization of the prepared adsorbents was performed using XRD and BET, showing a higher surface area of ion-imprinted crosslinked chitosan than non-imprinted crosslinked chitosan beads. The Extended Langmuir model fitted the experimental results obtained from the multi-component system, indicating that ion-imprinted crosslinked chitosan had a higher total metal uptake with better selectivity toward Cd(II) uptake compared to non-imprinted crosslinked chitosan. Studying the adsorption mechanism in a ternary system showed that the adsorption was governed by chemical binding and ion exchange mechanisms in the ternary system. In conclusion, crosslinking by sodium tripolyphosphate improved chitosan physiochemical properties; however, it resulted in a decrease in HM adsorption uptake. The RSM was used to assess the effect of pH, temperature, and crosslinking degree and optimize the adsorption uptake of chitosan. Also, ion-imprinting was effective in enhancing the adsorption capacity and selectivity of crosslinked chitosan for the ion used as a template (Cd(II)) in preparing ion-imprinted crosslinked chitosan.
6

Sinteza i karakterizacija nekih derivata pirazola i njihove reakcije sa prelaznim metalima / Synthesis and characterization of some pyrazole derivatives and their reactions with transition metals

Holló Berta 22 September 2011 (has links)
<p style="text-align: justify; ">Reactions of 3,5-dimethylpyrazole-1-carboxamidinium&nbsp;nitrate (dpca∙HNO3) and 4-acetyl-3-amino-5-methylpyrazole (aamp) with transition metals under different reaction conditions are presented. The template reaction of aamp with triethyl orthoformate (teof) in the presence of metal ion is described. Besides, condensation of aamp with thiosemicarbazide (tsc) and the coordination of its product to copper(II) ion is also described. Twelve new complex compounds are synthesized and fully characterized. The characterization of two other, already known complexes is significantly enriched. The influence of HSAB interactions between the metal ions and ligators on the structures of obtained compounds is studied. The influence of the reaction conditions on the composition, structure and quality of crystals obtained in the reactions is investigated. Compounds are characterized by structural&nbsp;analysis, elemental analysis, molar conductivity data, infrared spectrometry and thermal analysis. Some selected complexes are characterized by UV-Vis spectra, magnetic measurements and biological activity tests, too.</p> / <p> Reactions of 3,5-dimethylpyrazole-1-carboxamidinium&nbsp;nitrate (dpca∙HNO3) and 4-acetyl-3-amino-5-methylpyrazole (aamp) with transition metals under different reaction conditions are presented. The template reaction of aamp with triethyl orthoformate (teof) in the presence of metal ion is described. Besides, condensation of aamp with thiosemicarbazide (tsc) and the coordination of its product to copper(II) ion is also described. Twelve new complex compounds are synthesized and fully characterized. The characterization of two other, already known complexes is significantly enriched. The influence of HSAB interactions between the metal ions and ligators on the structures of obtained compounds is studied. The influence of the reaction conditions on the composition, structure and quality of crystals obtained in the reactions is investigated. Compounds are characterized by structural<br /> analysis, elemental analysis, molar conductivity data, infrared spectrometry and thermal analysis. Some selected complexes are characterized by UV-Vis spectra, magnetic measurements and biological activity tests, too</p>
7

Χημεία συμπλόκων ενώσεων του καδμίου με το βενζοτριαζόλιο και υποκατεστημένα παράγωγά του ως υποκαταστάτες / Chemistry of cadmium coordination compouunds with benzotriazoles and its substituded derivatives as ligands

Βαλαβάνη, Ιωάννα 31 August 2012 (has links)
Η χημεία ένταξης του βενζοτριαζολίου και των παραγώγων του έχει προσελκύσει το ενδιαφέρον, κυρίως λόγω της ικανότητάς τους να δρουν ως παρεμποδιστές της διάβρωσης για ορισμένα μέταλλα, συμπεριλαμβανομένου του χαλκού και των κραμάτων του. Έκπληξη προκαλεί το γεγονός ότι μέχρι σήμερα είναι γνωστά μόνο δύο σύμπλοκα του Cd(II) με υποκαταστάτες βενζοτριαζόλια. Στην παρούσα Διπλωματική Εργασία έχει μελετηθεί η χημεία ένταξης του Cd(II) με το 1-μεθυλοβενζοτριαζόλιο (Mebta). Οι νέες ενώσεις [CdI2(Mebta)2] (1), trans, trans, trans-[Cd(NO3)2(Mebta)2(H2O)2] (2), [CdBr2(Mebta)]n (3), [CdBr2(Mebta)2] (4), [Cd3(SCN)6 (Mebta)5(H2O)]n (5), [Cd2.5(SCN)5(Mebta)4(H2O)]n (6) και [Cd{N(CN)2}2(Mebta)2]n (7) παρασκευάσθηκαν και μελετήθηκαν. Το σύμπλοκο [CdI2(5MebtaΗ)2] (8) επίσης απομονώθηκε, όπου 5MebtaH είναι το 5-μεθυλοβενζοτριαζόλιο. Οι μοριακές και κρυσταλλικές δομές των συμπλόκων προσδιορίσθηκαν με κρυσταλλογραφία ακτίνων Χ επί μονοκρυστάλλων. Το Mebta καθώς και το 5MebtaH συμπεριφέρονται ως μονοδοντικοί υποκαταστάτες σε όλες τις σύμπλοκες ενώσεις με το άτομο του αζώτου της θέσης 3 του αζολικού δακτυλίου να δρα ως άτομο-δότης. Τα σύμπλοκα 1, 4 και 8 έχουν παραμορφωμένη τετραεδρική γεωμετρία. οι αλόγονο δότες είναι τερματικοί. Η δομή του συμπλόκου 2 περιλαμβάνει τρία ζεύγη trans νιτράτο, βενζοτριαζολικών και ύδατο υποκαταστατών. Το σύμπλοκο 3 είναι 1D πολυμερές ένταξης όπου οι βρώμο υποκαταστάτες είναι μ2. ένα μόριο Mebta συμπληρώνει αριθμό ένταξης 5 για κάθε μεταλλικό κέντρο που έχει παραμορφωμένη τριγωνική διπυραμιδική γεωμετρία. Η κρυσταλλική δομή των 5, 6 και 7 αποτελείται από αλυσίδες, όπου 2 ψευδοαλόγονο ιόντα [SCN-, N(CN)2-] γεφυρώνουν κάθε ζεύγος μεταλλικών κέντρων. Τα σύμπλοκα έχουν ενδιαφέρουσες υπερμοριακές δομές μέσω μη-κλασικών δεσμών υδρογόνου και π-π αλληλεπιδράσεων. Τα σύμπλοκα 1-8 χαρακτηρίσθηκαν με IR και Raman φασματοσκοπίες. Τα δεδομένα μελετήθηκαν σε σχέση με τους τρόπους ένταξης των υποκαταστατών και λαμβάνοντας υπόψη τις δομές των ενώσεων. NMR φάσματα (1Η, 13C για επιλεγμένα σύμπλοκα) σε d6-DMSO πιστοποιούν τη μη-διατήρηση της δομής των συμπλόκων στο διάλυμα. Το σύμπλοκο 2 παρουσιάζει φθορισμό στα 408 nm με μέγιστο διέγερσης στα 338 nm σε θερμοκρασία δωματίου, συμπεριφορά που οφείλεται σε ηλεκτρονική μετάπτωση του Mebta. Επίσης εκτιμήθηκε η τεχνολογική σημασία των αποτελεσμάτων μας. Φαίνεται ότι τα Ν-υποκατεστημένα βενζοτριαζόλια, με ομάδες που δεν περιέχουν άτομα-δότες, δεν μπορούν να οδηγήσουν σε αποτελεσματικούς παρεμποδιστές διάβρωσης. / The coordination chemistry of benzotriazole and its derivatives has been receiving intense attention, mainly due to the anticorrosion properties of such compounds towards certain metals, particularly copper and its alloys. Surprisingly, only two Cd(II) complexes with benzotriazole ligation have been reported to date. The coordination chemistry of 1-methylbenzotriazole (Mebta) with Cd(II) has been studied in the present Diploma Work. The new complexes [CdI2(Mebta)2] (1), trans, trans, trans-[Cd(NO3)2(Mebta)2(H2O)2] (2), [CdBr2(Mebta)]n (3), [CdBr2(Mebta)2] (4), [Cd3(SCN)6(Mebta)5(H2O)]n (5), [Cd2.5(SCN)5(Mebta)4(H2O)]n (6) and [Cd{N(CN)2}2(Mebta)2]n (7) have been prepared and studied. Complex [CdI2(5MebtaΗ)2] (8) has also been isolated, where 5MebtaH is 5-methylbenzotriazole. The molecular and crystal structures of the complexes have been determined by single-crystal, X-ray crystallography. The Mebta and 5MebtaH molecules behave as monodentate ligands in all the complexes with the nitrogen atom of the position 3 of the azole ring being the donor atom. Complexes 1, 4 and 8 have a distorted tetrahedral structure; the halogenido ligands are terminal. Complex 2 has an all trans structures with three pairs of terminal nitrato, Mebta and aqua ligands. Complex 3 is an 1D coordination polymer in which the bromide ligands are μ2; a Mebta molecule completes a coordination number of 5 at each metal ion which has a distorted trigonal bipyramidal geometry. In the crystal structures of 5, 6 and 7 chains form where two pseudohalogenido ions [SCN-, N(CN)2-] bridge each pair of CdII ions. The complexes have interesting supramolecular structures through non-classical hydrogen bonds and π-π stacking interactions. Complexes 1-8 have been characterized by IR and Raman spectroscopies. The data have been discussed in terms of the coordination modes of the ligands and the known structures. NMR spectra (1H, 13C for selected compounds) in d6-DMSO reveal that the solid-state structures are not retained in solution. Complex 2 displays room-temperature photoluminescence at 408 nm, upon maximum excitation at 338 nm, which is attributed to the coordinated ligand. The technological relevance of our results is also discussed. It seems that benzotriazole N-substitution with groups containing non-donor atoms can not lead to effective corrosion inhibitors.

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