Copper is an essential trace element present in all living systems and is important for the function of many cellular enzymes. It ranks third in intracellular abundance behind only zinc and iron and plays a very important role as a catalytic cofactor in various cellular processes such as mitochondrial respiration, iron uptake, and the redox processes of a number of enzymes, including superoxide dismutase, lysyl oxidase, or tyrosinase. Any abnormality in copper trafficking pathways can lead to serious diseases such as Wilsons disease, Menkes syndrome and has been implicated in the neurodegenerative diseases amyotropic lateral sclerosis (ALS) and Alzheimers disease. While free copper in the cytoplasm would prove toxic, there is compelling evidence for the existence of a labile pool of copper that remains kinetically accessible. In order to investigate the existence of such a pool the development of Cu(I) selective probes is necessary. Chapter I provides the background for the role of copper in biology and elucidates the main trafficking pathways discovered to date. This chapter also provides recent developments of fluorescent sensors for selective visualization of biologically relevant metals. Chapter II discusses the exploration of a phenanthroline-based ligand for the selective detection of Cu(I). A series of derivatives incorporating chelating substituents in the 2- and 9-positions to enforce a 1:1 binding stoichiometry were synthesized and the properties of their respective Cu(I) complexes were characterized by x-ray structural analysis, and their photophysical properties were investigated by absorption and emission spectroscopy. Visible light excitation yielded metal-to-ligand charge-transfer (MLCT) excited states with luminescence lifetimes up to 155 ns. Electrochemical measurements further indicate that coordinative rearrangements are involved in nonradiative deactivation of the excited states. According to time-dependent density functional theory calculations (B3LYP/6-31G**), the major MLCT transitions are polarized along the C2 axis of the complex and originate predominantly from the dxz orbital. In chapter III, the development of a ratiometric Cu(I) sensor based on a donor-acceptor functionalized biphenyl fluorophore platform is discussed. The fluorescence emission energy for such fluorophores is highly dependent upon the interannular twist angle and this property was harnessed to provide a ratiometric sensor selective for Cu(I). Coordination of Cu(I) leads to a flattening of the biphenyl backbone and was confirmed by absorbance and emission spectroscopy as well as 2D NOESY experiments. The peak emission energy was shifted by 39 nm towards higher energy upon metal cation binding with a concomitant 7 bathochromic shift in absorption energy. The photophysical data accompanied by 1H NMR analysis confirms a well-defined 1:1 binding stoichiometry between metal and ligand. The findings from this study showed ratiometric behavior for this probe, albeit with a lowered quantum yield. While the quantum yield for the fluorophore discussed in chapter III was low (8.0%), the focus of chapter IV was the elucidation of the fluorescence quenching mechanism. To investigate the possibility of a twisted intramolecular charge transfer (TICT) state a donor-acceptor biphenyl fluorophore was synthesized incorporating a conformationally restricted amine donor group incapable of rotating out of plane in the excited state. Analysis of this derivative, as well as the sensor discussed in chapter III, reveals that fluorescence quenching is most likely due to hydrogen bonding to the acceptor subunit in they excited state. Finally, in chapter V, a pyrazoline fluorophore library with varying numbers of fluorine substituents was synthesized. The photophysical and electrochemical properties of these fluorophores were measured in order to determine if careful tuning of the excited state electron transfer thermodynamics is possible. The compounds cover a broad range of excited state energies and reduction potentials, and the data suggest that selective and differential tuning of both the reduction potential of the acceptor as well as the excited state equilibrium energy. These findings show that the individual parameters involved in excited state electron transfer can be tuned by the modular architecture of the pyrazoline fluorophore.

M. tuberculosis copper-sensitive operon repressor (Mtb CsoR) is the founding member of a new metalloregulatory protein family in prokaryotes that regulates the transcription of the cso operon in response to copper toxicity. Mtb CsoR tetramer binds 1 monomer mol equiv of Cu(I) with very high affinity (log KCu=18.0) via three conserved residues, Cys36, His61' and Cys65'. Binding of Cu(I) allosterically inhibits the CsoR binding to the DNA operator (CsoO) overlapping the cso promoter (DeltaGc=+3.6 kcal/mol, pH 7.0, 25 oC). These findings are consistent with a role of CsoR as a transcriptional repressor with Cu(I) binding inducing transcriptional derepression. To explore the mechanism of this regulation, His61 was substituted with 1-methylhistidine (MeH) or Beta- (2-thiazolyl)-alanine (Thz) using a native chemical ligation strategy. The CsoO binding affinities of the resultant H61MeH and H61Thz CsoRs are both refractory to inhibition by Cu(I) binding despite the fact that each forms a high affinity 3-coordinate complex with Cu(I). This suggests that while Cu(I) is coordinated by the N?11 atom of His61, the N?22 atom plays an critical role in driving this allosteric switch. Evidence in support of a formation of a hydrogen bonding network involving the N?1 face of His61 and two conserved "second coordination shell" residues, Glu81' and Tyr35, is presented. Remarkably, this mechanism is analogous to that proposed for the Zn(II) sensor CzrA from S. aureus. To test this, we employed the same native chemical ligation approach to substitute the key Zn(II) ligand His97 with 1-methylhistidine; with the preliminary findings fully consistent with an intersubunit allosteric switch involving the N?2 face of this key His97 residue in CzrA. Two predicted homologs of Mtb CsoR were also biochemically characterized to obtain additional support for the hypothesis that CsoR is a key Cu(I) regulatory protein in many bacterial species. B. subtilis CsoR, known to regulate the transcription of the copZA operon, was found to have biochemical properties similar to those of Mtb CsoR as to Cu(I) binding, DNA binding and Cu(I)-dependent allosteric regulation. Interestingly, Bsu CsoR also binds other divalent metal ions (Zn, Ni) with high affinity but with metal coordination geometries distinct from that of Cu(I). Binding of these divalent metal ions only weakly regulates copZA operator binding in vitro, suggesting that coordination number and geometry are most closely related to the allosteric regulation. Finally, a putative CsoR from the pathogenic S. aureus Newman strain was identified and characterized, and was found to exhibit biochemical properties similar to those of Mtb and Bsu CsoRs. Parallels between Cu(I)-sensing CsoRs and functional orthologs in the CsoR/RcnR family are further discussed in the context of the mechanism and evolutionary divergence of this new family of regulatory proteins.

Membrane separations provide a potentially attractive technology over conventional processes due to their advantages, such as low capital cost and energy consumption. The goal of this thesis is to design hybrid membranes that facilitate specific gas separations, especially olefin/paraffin separations. This thesis focuses on the designing dendrimer-based hybrid membranes on mesoporous alumina for reverse-selective separations, synthesizing Cu(I)-dendrimer hybrid membrane to facilitate olefin/paraffin separations, particularly ethylene/methane separation, and investigating the influence of solvent, stabilizing ligands on facilitated transport membrane. Reverse-selective gas separations have attracted considerable attention in removing the heavier/larger molecules from gas mixtures. In this study, dendrimer-based chemistry was proved to be an effective method by altering dendrimer structures and generations. G6-PIP, G4-AMP and G3-XDA are capable to fill the alumina mesopores and slight selectivity are observed. Facilitated transport membranes were made to increase the olefin/paraffin selectivity based on their chemical interaction with olefin molecules. Two approaches were explored, the first was to combine facilitator Cu(I) with dendrimer hybrid membrane to increase olefin permeance and olefin/paraffin selectivity simultaneously, and second was to facilitate transport membrane functionality by altering solvents and stabilizing ligands. Promising results were found by these two approaches, which were: 1) olefin/paraffin selectivity slightly increased by introducing facilitator Cu(I), 2) the interaction between Cu(I) and dendrimer functional groups are better known.

No description available.

A plethora of novel scientific phenomena and practical applications, such as solid-state molecular solar cells and other optoelectronic devices for energy harvesting and lighting technologies, have catalyzed us to synthesize novel compounds with tunable properties. Synthetic routes, single crystal structures, and spectral and materials properties are described. Reactions of Ag(I) and Cu(I) precursors with various types of ligands -- including the azolates, diimines, and diiphosphines -- lead to the corresponding complexes in high yield. Varying the metal ions, ligands, synthetic methods, solvents, and/or stoichiometric ratio can change the properties including the molecular geometry or packing structure, reactivity, photophysical and photochemical properties, semiconducting behavior, and/or porosity of the functional coordination polymers obtained. For solar cells purposes, the absorption energy can be extended from the ultraviolet (UV) region, through the entire visible (Vis) region, onto a significant portion of the near-infrared (NIR) portion of the solar spectrum with high absorption coefficients due to the infinite conjugation of Cu(I) with diimine ligands. Twenty-eight crystal structures were obtained by conventional crystal growth methods from organic solvents, whereas their bulk product syntheses also included "green chemistry" approaches that precluded the use of hazardous organic solvents. The resulting products are characterized by powder x-ray diffraction (PXRD), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), UV/Vis/NIR absorption/diffuse reflectance/photoluminescence spectroscopies, and thermogravimetric analysis (TGA). Regarding the scientific phenomena investigated, the highlighting work in this dissertation is the discovery of novel bonding/photophysical/optoelectronic properties of the following materials: a black absorber with absorption from 200- 900 nm, a very stable compound with a bright green luminescence obtained by a solventless reaction, and a novel coordination polymer showing uncommon interaction of Ag(I) with three different types of diimine ligands simultaneously.

A comparative investigation of electrochemical characteristics of two complex systems, viz. Cu|Cu(II), glycine and Cu|Cu(II), maleic acid, was carried out. The equations were obtained for quantitative description of pH-metric and spectrophotometric data, which were used for determination of equilibrium characteristics in Cu(II)-maleic acid solutions. Thermodynamic analysis shows that deep changes are possible in this system resulting in 90 % transform of Cu(II) into Cu(I). The rates of Cu corrosion and Cu2O formation are estimated to be of the same order (nmol cm-2 s-1). Regularities of formal electrochemical kinetics, which account for the mass transport of chemically interacting particles and for step-wise charge transfer process, are suitable for interpretation of voltammetric data of the Cu|Cu(II), glycine system. Kinetic parameters Cu(II) glycinate complex depend on the nature of the supporting electrolyte: the exchange current density decreases and the cathodic charge transfer coefficient increases in the sequence: Li+ - Na+ - K+ - Cs+. To enhance the Cu(I) generation in maleic acid system, the pre-electrolysis procedure was applied. It was found that its effect depends on solution pH. Applied theoretical model describes satisfactorily the steady-state voltammetric characteristics of Cu|Cu(II), maleic acid system, but some contradictory results were obtained in the case of time-dependent processes. Theoretical and experimental problems to be solved are discussed. / Atliktas palyginamasis dviejų kompleksinių sistemų - Cu|Cu(II), glicinas ir Cu|Cu(II), maleino rūgštis - elektrocheminių charakteristikų tyrimas. Nustatytos maleino rūgšties tirpalų pusiausvyrinės charakteristikos. Kiekybiniam titravimo kreivių aprašymui išvestos lygtys, kuriose įvertinti medžiagų bei krūvių balansai bei atsižvelgta į praskiedimo efektus. Jų taikymas pH-metrinių duomenų analizei davė tokias maleato anijonų protonizacijos konstantų reikšmes: log = 6,05, log = 7,48. Nustatyta, kad tirpaluose su 0,3 M K2SO4 priedu protonizuotų ligando formų stabilumas sumažėja (log = 5,75, log = 7,30). Cu(II) maleatinių kompleksų stabilumui nustatyti panaudotas spektrofotometrijos metodas ir pasiūlyta duomenų analizės procedūra. Ji remiasi kiekybiniu absorbcijos spektrų aprašymu, taikant lygtis, išplaukiančias iš valdomo harmoninio osciliatoriaus teorijos. Išanalizavus įvairių sudėčių tirpalų absorbcijos maksimumo dydžius, prieita išvados, kad rūgščiose terpėse vyrauja monoligandinis kompleksas, kurio koncentracinė stabilumo konstanta log b1 = 2,2. Atlikta sistemos Cu|Cu(II), maleino rūgštis pusiausvyrų termodinaminė analizė. Nustatyta, kad esant metalinio vario ir tirpalų sąlyčiui, sistemoje galimi gilūs virsmai, kurių metu iki 90 % Cu(II) transformuojasi į Cu(I). Teorines išvadas patvirtina eksperimentiniai duomenys, gauti spektrofotometrijos ir elektrocheminės kvarco kristalo mikrogravimetrijos metodais. Įvertinti Cu korozijos bei fazinių Cu2O sluoksnių susidarymo... [toliau žr. visą tekstą]

Atliktas palyginamasis dviejų kompleksinių sistemų - Cu|Cu(II), glicinas ir Cu|Cu(II), maleino rūgštis - elektrocheminių charakteristikų tyrimas. Nustatytos maleino rūgšties tirpalų pusiausvyrinės charakteristikos. Kiekybiniam titravimo kreivių aprašymui išvestos lygtys, kuriose įvertinti medžiagų bei krūvių balansai bei atsižvelgta į praskiedimo efektus. Jų taikymas pH-metrinių duomenų analizei davė tokias maleato anijonų protonizacijos konstantų reikšmes: log = 6,05, log = 7,48. Nustatyta, kad tirpaluose su 0,3 M K2SO4 priedu protonizuotų ligando formų stabilumas sumažėja (log = 5,75, log = 7,30). Cu(II) maleatinių kompleksų stabilumui nustatyti panaudotas spektrofotometrijos metodas ir pasiūlyta duomenų analizės procedūra. Ji remiasi kiekybiniu absorbcijos spektrų aprašymu, taikant lygtis, išplaukiančias iš valdomo harmoninio osciliatoriaus teorijos. Išanalizavus įvairių sudėčių tirpalų absorbcijos maksimumo dydžius, prieita išvados, kad rūgščiose terpėse vyrauja monoligandinis kompleksas, kurio koncentracinė stabilumo konstanta log b1 = 2,2. Atlikta sistemos Cu|Cu(II), maleino rūgštis pusiausvyrų termodinaminė analizė. Nustatyta, kad esant metalinio vario ir tirpalų sąlyčiui, sistemoje galimi gilūs virsmai, kurių metu iki 90 % Cu(II) transformuojasi į Cu(I). Teorines išvadas patvirtina eksperimentiniai duomenys, gauti spektrofotometrijos ir elektrocheminės kvarco kristalo mikrogravimetrijos metodais. Įvertinti Cu korozijos bei fazinių Cu2O sluoksnių susidarymo... [toliau žr. visą tekstą] / A comparative investigation of electrochemical characteristics of two complex systems, viz. Cu|Cu(II), glycine and Cu|Cu(II), maleic acid, was carried out. The equations were obtained for quantitative description of pH-metric and spectrophotometric data, which were used for determination of equilibrium characteristics in Cu(II)-maleic acid solutions. Thermodynamic analysis shows that deep changes are possible in this system resulting in 90 % transform of Cu(II) into Cu(I). The rates of Cu corrosion and Cu2O formation are estimated to be of the same order (nmol cm-2 s-1). Regularities of formal electrochemical kinetics, which account for the mass transport of chemically interacting particles and for step-wise charge transfer process, are suitable for interpretation of voltammetric data of the Cu|Cu(II), glycine system. Kinetic parameters Cu(II) glycinate complex depend on the nature of the supporting electrolyte: the exchange current density decreases and the cathodic charge transfer coefficient increases in the sequence: Li+ - Na+ - K+ - Cs+. To enhance the Cu(I) generation in maleic acid system, the pre-electrolysis procedure was applied. It was found that its effect depends on solution pH. Applied theoretical model describes satisfactorily the steady-state voltammetric characteristics of Cu|Cu(II), maleic acid system, but some contradictory results were obtained in the case of time-dependent processes. Theoretical and experimental problems to be solved are discussed.

In this research, a method for site-selective attachment of synthetic molecules into glycoproteins using Boronic acid (BA)-directed tosyl chemistry is proposed. The synthetic BA-tosyl chemical probes are composed of boronic asid as a affinity ligand, a tosyl group as a reactive group and a terminal alkyne group for reporting. In neutral and alkaline environment, boronic acid can act as a targeting head to react with the cis-diol of carbohydrates and therefore forms a covalently reversible boronic diester ring. The newly formed boronate ring can withdraw the probe moeular close to the molecular surface of glycoproteins of interest. Followed by a SN2 reaction with the nucleophilic residues of labeled glycoproteins, the report alkyne group can covalently shift to the protein surface apart from the BA-tosyl skeleton. With the competition of polyols, the BA modified carbohydrates can be recovered to the native glycan structures. The traceless labeling strategy developed in the work has been demonstrated in the specific interaction with a known glycoprotein feutin with negatives controls. We believe that the successful development of this methodology can certainly accelerate the study of glycoproteomics and glycobiology.

The objective of this thesis is to explore new reactivities and to improve luminescent properties of 7-azaindole-containing metal complexes. Selectivity for the activation of toluene and ethyl benzene has been investigated with two cationic Pt(II)(N,N-L) complexes, where N,N-L = 1,2-bis(1-N-7-azaindolyl)benzene (BAB) or bis(1-N-7-azaindolyl)methane (BAM). A high regioselectivity toward toluene and ethyl benzene benzylic C-H activation and a distinct diastereoselectivity for ethyl benzene benzylic C-H activation are demonstrated. Detailed mechanistic studies have been performed, leading to the establishment of both the intermediacy of the η3-benzylic Pt(II) complexes in the reactions and the ligand steric impacts as origins for the distinct diastereoselectivity. A PtMe2 complex of 1-N-(pyridin-2-yl)-7-azaindole (NPA) has been synthesized and found to undergo facile transformation at ambient temperature, resulting in the quantitive formation of a neutral Pt4 molecular square. The mechanism of the transformation process has been examined, establishing a distinct intramolecular C-H driven self-assembly process. The geometrical impacts of the BAB and BAM ligands on the structure and stability of their fac-Pt(IV)Me3 complexes has been investigated. The BAB ligand is more effective than the BAM ligand in stabilizing the five-coordinate Pt(IV)Me3 complexes. With the BAB ligand, a five-coordinate fac-Pt(IV)Me3 complex is obtained; with the BAM ligand, two six-coordinate fac-Pt(IV)Me3 complexes are obtained. In solution, the methyl groups in the BAB complex exchange slowly, but those in the BAM complexes exchange rapidly. Several new 7-azaindolyl derivative ligands via either modifying or altering the BAM and BAB bridging groups have been developed. The syntheses, structures and reactivities of their Pt(II) complexes have been examined, leading to the finding of an unconventional C-Sn oxidative addition reaction. The modification of the NPA ligand via the incorporation of a triarylboron group has been carried out. Several novel Pt(II) and Cu(I) complexes have been synthesized and studied. A Cu(I) complex is found to display exceptionally bright ambient temperature phosphorescence. A series of dinuclear Cu(I) compounds of the 1,2,3,4-tetra(1-N-7-azaindolyl)benzene (TTAB) ligand have been synthesized and examined. The close contacts between the TTAB bridging phenyl ring and the Cu(I) centers are present in the complexes. / Thesis (Ph.D, Chemistry) -- Queen's University, 2008-05-21 18:10:58.628

The objective of this thesis is to examine the photophysical and structural properties of Cu(I) complexes of 2-(2’-pyridyl)benzimidazolyl based ligands and Cu(I), Pd(II) and Pt(II) complexes of 2-(2’-pyridyl)indolyl based ligands, for possible use as phosphorescent emitters in OLEDs. The discovery of the atropisomeric 3,3’-bis(2-(2’-pyridyl)indolyl based ligands led to the examination of C-C coupling reactions and the investigation of the new chiral ligands with transition metal ions. Cu(I) complexes of 2-(2’pyridyl)benzimidazolyl-benzene with varying phosphine ligands were prepared. The structures were studied with X-ray crystallography and NMR. Experimental and computational results established that steric and electronic properties of the phosphine ligands influence the photophysical properties of the Cu(I) complexes. Polynuclear Cu(I) complexes with 2-(2’-pyridyl)benzimidazolyl based ligands and two PPh3 ancillary ligands were synthesized, the photoluminescent and electroluminescent properties were examined. A series of 2-(2’-pyridyl)indolyl based ligands; 2-(2’-pyridyl)indolyl-benzene (pib), 1,4-bis[2-(2’-pyridyl)indolyl]benzene (bib) and 1,3,5-tris[2-(2’-pyridyl)indolyl]benzene) (tib) and the corresponding C-C coupled dimers bis[3,3’(2-(2’-pyridyl)indolyl-benzene)] (bpib), bis[3,3’(1,4-bis[2-(2’-pyridyl)indolyl]benzene (bbib) and bis[3,3’(1,3,5-tris[2-(2’-pyridyl)indolyl]benzene)] (btib) were synthesized in a one-pot reaction with the formation of both C-N and C-C bonds. The photophysical properties of these new molecules were investigated. The dimers display intramolecular exciplex formation. The rotation barrier around the C-C bond in the 3 position of the bis-indole was calculated using DFT which support that bpib is an atropisomeric ligand. Cu(I), Pd(II) and Pt(II) complexes were synthesized with pib and bpib. [Cu(pib)(PPh3)2]+ contains a three-coordinate Cu(I) ion and doesn’t display MLCT but rather 3π-1π phosphorescence. In Pd(pib)(acac) and Pt(pib)(DMSO)Cl the pib ligand forms C,N chelated neutral complexes that display red emission in frozen solution and in solid state. The X-ray crystal structure for [Cu(bpib)2]+ revealed a homo-chiral crystal and for Pd(bpib)Cl2 and Pt(bpib)Cl¬2 show a trans-chelating geometry around the metal centre. Frozen solutions of [Cu(bpib)2]+ and Pd(bpib)Cl2 display MCLT phosphorescence. Finally the atropisomeric ligands bpib and bbib were examined as sensors to determine the enantiomeric excess of Zn(2-bromo-3-methylbutyrate)2 by CD spectroscopy. CD and fluorescent titration experiments verified that these ligands have selective interactions with different Zn(II) carboxylates. DFT computations showed that diastereomeric excess caused by chiral discrimination leads to the CD spectral-response of the atropisomeric ligands toward chiral Zn(II) carboxylates. / Thesis (Ph.D, Chemistry) -- Queen's University, 2008-09-25 09:54:21.464