This thesis comprises three chapters united by a single theme: development of alkali metal cation sensors based on ion complexing macrocycles. In part 1, benzo-18-crown-6 and cryptand 2.2.2B were immobilised on polyacrylic acid backbone through an amide linkage. The benzo-18-crown-6 and 2.2.2B were functionalised using the Friedal-Crafts acylation reaction with ω-amino acids. The spacer between the polymer backbone and the crown ether was varied by using co-amino acids with varying numbers of methylene groups [special characters omitted]. Attempts to use co-amino acids with an intermediate spacer length [special characters omitted] failed due to formation of a cyclic imine. The amino crown ethers were immobilised on a poly(acryloyl chloride). Polymers 2a, 5ad and 6a failed to give self supporting membranes but a polymer blend with PVC/Plasticizer was employed for membrane fabrication. Ion Selective Electrodes (ISEs) and Coated Wire Electrodes (CWEs) were made from polymer blend membranes and their response to alkali metal cations was tested. The ISEs made with mobile carriers were active, while those prepared from immobilised carriers were inactive. The reverse was the case with CWEs. This dichotomy existed in all cases. The selectivity of the ionophores among the alkali metals was unaffected by linkage to the polymer backbone. However, the alkali metal/alkaline earth metal selectivity was enhanced. The effect of plasticizer and hydrophilic additives on electrode response was insignificant. The spacer length had considerable influence: the longer the spacer, the better the electrode response of the CWEs. In part 2, the mass transport of ions across the polymer blend membrane under a temperature gradient was investigated. The immobilised polymers prepared in part 1 were used here to fabricate membranes from polymer blends with NOMEX. In thermodialysis experiments, a low level of ion transport was detected. These preliminary experiments led to a rediscovery of membrane distillation. The scope of this latter process with hydrophobic membranes was explored in detail. Part 3 was devoted to the design and synthesis of water soluble photoionophores. Three series of molecules were synthesised: captands, bis crown ether compounds and phenol derivatives of tartaro crown ether carboxylic adds. Captand molecules were synthesised by a capping reaction of crown ether tetraacid chloride 14 with 1,3-bis(aminomwthyl) benzene, 1,4- bis(aminomethyl) benzene and 2,2’-bis(aminomethyl) biphenyl. Crystals of meta- and para xylene capped molecules were grown and their structures solved to establish the conformation of the molecules. Fluorescence quenching studies of these molecules were done in 0.3% methanol:water (v/v). Quenching due to alkali metal ions was insignificant ( < 20%) while copper and mercury cations quenched the emission significantly ( > 90%). Stern-Volmer analysis showed an upward curvature indicating association between the ligand and the cations [special characters omitted] cations, but dynamic and static components of the quenching could not be separated. Potentiometric titration with a potassium selective electrodes was carried out to obtain the stability constants for these ligands with potassium ion. The bis crown ethers 28 and 29, designed to increase water solubility, were prepared by the reaction of anhydride 27 with 9,10-bis(ammomethyl) anthracene and 1,2-bis(aminomethyl) benzene. The pKa values of the ligands and their stability constants with alkali and alkaline earth metal ions were determined by potentiometric titration. Fluorescence quenching studies were done in aqueous buffer at pH 10. These compounds also failed to give an emission quenching in the presence of alkali or alkaline earth metal cations, but both copper and mercury cations showed a significant amount of quenching. Stability constants were derived from emission quenching studies for [special characters omitted]. Chromoionophores, phenol derivatives of tartaro crown ethers, were synthesised from the reaction of crown ether anhydrides and 2-aminophenol. The structure of the compound 31 was assigned as the syn isomer based on nmr data in comparison to literature reports. Absorption studies were carried out in water. The absorption spectra of compound 30 were perturbed by alkali metal as well as alkaline earth metal ions, while the absorption spectrum of compound 31 showed no response to varying cation concentration. The lack of response from compound 31 was attributed to the competitive binding of cations among syn carboxylic groups away from the syn phenolic groups. / Graduate

No description available.

Nowadays the necessity for designing and synthesizing novel imaging agents increases rapidly. The long wavelength, and thus, low energy, of excitation and emission, and the good specificity and stability are examples of essential characteristics of ideal diagnostic and therapeutic agents. In this work, the synthesis and photophysical studies of metal complexes for biological applications were performed and evaluated, and it contained the development of (a) a porphyrin probe for imaging and treatment and (b) a tripodal thermal sensor for imaging. The research and study of the two cases of complex is analyzed in the second and third chapters, respectively, which follow the introduction or literature review to the diagnostic and/ or therapeutic agents which is given with examples in the first chapter. The scope of the main project, which is analysed in the second chapter, was the development and synthesis of a porphyrin-based bio-probe capable of bacterial fluorescence imaging. The porphyrin moiety of a complex is also able to generate singlet oxygen and this effect can be used for treatment purposes (PDT, Photodynamic Therapy). Thus, the complex can act as a diagnostic and therapeutic (anti-bacterial in this case) agent simultaneously. A probe with such a dual capability is known as theranostic agent. A theranostic agent is crucial for the enhancement and expansion of personalised medicine. The studies and physical measurements of the proposed, synthesised porphyrin complex have proved its capability to be used as a theranostic probe. Furthermore, after coupling the porphyrin moiety firstly with a small protein part (ampetoid: antimicrobial peptoid) and secondly with a radionuclide (Gallium-68), the in vitro and in vivo studies have to be performed. The aim of the project analysed in the third chapter was the development of a thermal sensor. Coordination of a tripodal ligand with a mixture of two lanthanides in various ratios was achieved and the photophysical measurements of the resulted complexes were evaluated. Lanthanide metals were chosen due to their unique photophysical properties that they offer when they are connected to an organic chomophoric ligand. Additionally, the preferred final luminophore product would obey a thermostable structure over a wide temperature range and it would be capable of effectively sensing the alterations in temperature. These properties were true for the ratio 99.5:0.5 for Terbium: Europium, and thus, the complex with such a consistency clarified the final product. Furthermore, the highly promising results after repeatedly photophysical (especially emission) measurements could conclude that the complex can be served as an ideal thermal sensor. Additional emission measurements at higher temperatures have to be done in order to confirm the ability of the proposed thermal sensor to be used for bio-imaging purposes. In conclusion, two-kind of metal complexes for biological applications were synthesized and their photophysical properties were assessed. Both the bulky porphyrin complex and the smaller tripodal ligand have shown promising results for their proposed applications. Of course, a more detailed assessment is required to verify their capability.

No description available.

No description available.

No description available.

Several series of novel diamido, diamino and diimino ligands containing different spacers and heterocyclic donors have been synthesised. The spacers include the flexible biphenyl, the rigid 1,1 O-phenanthroline and various acyclic moieties, while the heterocyclic donors comprise pyridine, imidazole or benzimidazole groups. These ligands have been designed to complex copper and act as biomimetic models of the active site of the enzyme, tyrosinase, and their complexes with copper, cobalt, nickel and platinum have been analysed using microanalytical, IR, UV-Visible and cyclic voltammetric techniques. Attempted reduction of the biphenyl-based diimino ligands resulted in an unexpected intramolecular cyclisation affording azepine derivatives, the structures of which were elucidated with the aid of single crystal X-ray analysis of cobalt and nickel complexes. Computer modelling methods have been used to explore the conformational options of the copper complexes, and to assess the accessibility of the dinuclear copper site to substrate molecules. Computer modelling has also been used, in conjunction with the available analytical data, to visualise the possible structures of selected ligands and complexes. The copper complexes, although predominantly polymeric, were evaluated as biomimetic catalysts using 3,5-di-t-butylphenol and 3,5-di-t-butylcatechol as substrates. Some of the complexes clearly displayed biomimetic potential, exhibiting both phenolase and catecholase activity.

No description available.

No description available.

This thesis is dedicated to developing novel charged Pt(II) complexes and exploring their applications in electroluminescence, bio-imaging and the preparation of soft salts. At the beginning, a brief introduction about the development of ionic transition metal complexes and an overview of their applications in electroluminescence, bio-imaging and soft salts are presented. In chapter 2, a series of anionic Pt(II) complexes were successfully synthesized and fully characterized for their application in electroluminescence with relatively small current density. All the complexes show highly intense emission from blue to red in the solid state but is almost non-emissive in solution. The obtained single crystal data show that the anionic Pt(II) complexes exhibit very large Pt-Pt separation of over 10 Å in the crystal packings due to the bulky counterion [N(n-C4H9)4]+. The strong interactions between adjacent [Pt(C^N)(CN)2]- is thus absent in the solid state and this is considered as the main reason for the different properties in solution and solid state of these anionic complexes. This kind of Pt(II) anionic complexes has also found application in electroluminescence with relatively small current density. A series of novel water-soluble cationic Pt(II) complexes have also been designed and synthesized in chapter 3. Their photophysical properties in both water solution and solid state were investigated. Some of the cationic Pt(II) complexes have been selected to be applied in cell imaging in both live human hepatoma cells (BEL-7402) and mouse embryonic fibroblast (MEF) cells. The results show that these complexes have a much higher cellular uptake in BEL-7402 cells (tumor cells) than in MEF cells (normal cells), indicating these complexes are promising probes for tumor cell imaging. All of the cationic Pt(II) complexes show very low cytotoxicity at low concentration and the cell viability is still assessed to be high even when the concentration increases to 10 μM. The localization of the complexes turned out to be in the cytoplasm and accumulate near the cell nucleus. Attempts have been made to obtain efficient deep-red or NIR Pt(II) complexes by taking advantages of the Pt-Pt interactions in chapter 4. Two Pt(II) soft salts, SS1 and SS2 with bright emission at 674 and 718 nm, have been successfully prepared and characterized. The crystal packing shows a short separation between the two Pt atoms of 3.476 Å and the average distance of two planes of the cyclometalated ligands is 3.360 Å, indicating the existence of strong intramolecular Pt-Pt and π-π interactions. It is the first examples of Pt(II) soft salts bearing strong Pt-Pt interactions and π-π stacking and this has opened a versatile and facile avenue to prepare efficient NIR Pt(II) emitters by taking advantages of the Pt-Pt interactions. SS2 shows different emission in PEG with different concentration and excitation wavelength, indicating their potential application in optical data storage. The electrochromic properties of SS2 have also been investigated considering that the soft salt consists of ions with opposite charges, which suggests the soft salt could be promising candidate for electrochromic and optoelectronic material. The Pt(II) soft salt has also been used as NIR in-vivo imaging probe. Chapters presents the concluding remarks and points out some further work that could be done in the future. The experimental details are displayed in Chapter 6.