This thesis is concerned with the synthesis of diazo compounds for the introduction of various functional groups on the surface of polymers by means of carbene insertion and diazonium coupling. Characterisation and investigation of their properties were conducted. A library of functionalised polystyrene beads containing pyridine rings has been established for the coordination of metal ions and metal complexes. The pyridyl system on the surface has demonstrated its capability to bind with zinc complexes of bis(thiosemicarbazones) and release the corresponding copper complexes upon transmetallation. A spiropyran derivative has been introduced onto the surface of polystyrene and polyethylene terephthalate. The chromophore on both polymers exhibited photoswitchability as determined from colour change and wettability. Polystyrenes with either pyridine or spiropyran units have been investigated for reversible immobilisation of bioactive species. Materials coated with penicillin V gave significant inhibition zones in antibacterial assays, showing efficacy in drug delivery. Finally, a range of diazo compounds with different substituents has been synthesised and their thermal stabilities have been assessed by differential scanning calorimetry technique.

Οι εξαιρετικά καλές μηχανικές ιδιότητες που εμφανίζουν οι νανοσωλήνες άνθρακα τους καθιστούν ιδανικό ενισχυτικό μέσο για πολυμερικές μήτρες με σκοπό την παραγωγή σύνθετων πολυμερικών υλικών υψηλής αντοχής. Για την παρασκευή όμως τέτοιων υλικών είναι αναγκαία η τροποποίηση της επιφάνειας των νανοσωλήνων με σκοπό την δημιουργία «ενεργούς» διεπιφάνειας αλληλεπίδρασης μεταξύ αυτών και της πολυμερικής μήτρας. Σε αυτό το πλαίσιο, στο πρώτο μέρος της παρούσας εργασίας, έγινε συστηματική μελέτη της χημικής και ηλεκτροχημικής τροποποίησης της επιφάνειας νανοσωλήνων άνθρακα, έτσι ώστε να βρεθεί το καλύτερο οξειδωτικό μέσο και οι καταλληλότερες συνθήκες οξείδωσης για να επιτευχθεί η ενσωμάτωσή τους σε πολυμερική μήτρα. Για την μελέτη αυτή χρησιμοποιήθηκαν η Φασματοσκοπία Φωτοηλεκτρονίων από ακτίνες-Χ και Υπεριώδες (XPS, UPS), η Φασματοσκοπία Raman και η θερμοσταθμική ανάλυση TGA. Αρχικά τροποποιήθηκαν νανοσωλήνες άνθρακα πολλαπλού τοιχίου σε μορφή υμενίου (φιλμ) με την τεχνική της ηλεκτροχημικής οξείδωσης χρησιμοποιώντας ως ηλεκτρολύτη διάλυμα χλωριούχου νατρίου (ΝaCl). Οι νανοσωλήνες είχαν τοποθετηθεί στη θέση της ανόδου σε σταθερή βάση στήριξης. Τα αποτελέσματα από την φασματοσκοπία XPS έδειξαν ότι αν και επιτυγχάνεται οξείδωση, υπάρχει δυσαναλογία ως προς τα ποσοστά των λειτουργικών ομάδων που επάγωνται στην επιφάνεια του υμενίου σε σχέση με την ένταση της οξειδωτικής διαδικασίας. Στη συνέχεια, μελετώντας υμένια που οξειδώθηκαν σε σταθερή βάση χρησιμοποιώντας HNO3 ως ηλεκτρολύτη, παρατηρήθηκε ότι δεν επιτυγχάνεται ομοιόμορφη ηλεκτροχημική οξείδωση και στις δύο πλευρές των υμενίων. Έτσι σχεδιάστηκε περιστροφικό σύστημα για την άνοδο (περιστροφική βάση), η οποία και χρησιμοποιήθηκε περαιτέρω. Έχοντας κάνει αυτή την αλλαγή στο ηλεκτροχημικό κελί έγιναν μελέτες όπου χρησιμοποιήθηκαν ως ηλεκτρολύτες διαλύματα νιτρικού οξέος (ΗΝΟ3), υδροχλωρικού οξέος (ΗCl) και καυστικής ποτάσας (ΚΟΗ). Βρέθηκε ότι το νιτρικό οξύ οδηγεί (υπό κατάλληλες συνθήκες) σε ικανοποιητική αλλά και ελεγχόμενη τροποποίηση της επιφάνειας. Το υδροχλωρικό οξύ, όπως αναμενόταν, λειτούργησε ως ένα αποτελεσματικό οξειδωτικό μέσο για τον καθαρισμό των νανοσωλήνων από επικαθίσεις άμορφου άνθρακα, ενώ η καυστική ποτάσα έδειξε ότι είναι ισχυρό οξειδωτικό μέσο δημιουργώντας λειτουργικές ομάδες στην επιφάνεια του φιλμ νανοσωλήνων άνθρακα σε λιγότερο χρόνο οξείδωσης. Στην συνέχεια μελετήθηκε η απλή χημική οξείδωση σκόνης νανοσωλήνων άνθρακα χρησιμοποιώντας ως οξειδωτικά μέσα μείγμα θεϊκού οξέος (Η2SO4) και υπεροξειδίου του υδρογόνου (Η2Ο2) γνωστό και ως piranha, διάλυμα υδροχλωρικού οξέος και νιτρικού οξέος αλλά και μείγμα υδροξείδιου του αμμωνίου με υπεροξείδιο του υδρογόνου. Βρέθηκε ότι η οξείδωση με piranha δημιουργούσε σχετικά χαμηλό αριθμό δομικών ατελειών στην επιφάνεια των νανοσωλήνων ενώ ταυτόχρονα οδηγούσε σε ικανοποιητικού βαθμού τροποποίηση επάγοντας επιφανειακές λειτουργικές ομάδες. Έτσι η διαδικασία τροποποίησης με piranha ήταν αυτή που επιλέχθηκε για τη προετοιμασία των υμενίων νανοσωλήνων που θα αποτελούσαν το ενισχυτικό υλικό στο σύνθετο πολυμερικό υλικό. Η μελέτη των δειγμάτων σύνθετων πολυμερικών υλικών σε διάφορα ποσοστά εποξειδικής ρητίνης έγινε με XPS. Στα φάσματα που προήλθαν από τα σύνθετα υλικά εντοπίστηκαν χαρακτηριστικά που αποτελούν ενδείξεις ότι η χημική συγγένεια μεταξύ του υμενίου και της πολυμερικής μήτρας είχε επιτευχθεί. Αξιοσημείωτη είναι όμως και η επιφανειακή ανομοιομορφία που παρατηρήθηκε στα συγκεκριμένα υλικά. Στο δεύτερο μέρος της εργασίας μελετήθηκαν δύο υβριδικά μόρια που προήλθαν από προσάρτηση πολυμερικών αλυσίδων στην επιφάνεια νανοσωλήνων άνθρακα μονού τοιχίου. Οι πολυμερικές αλυσίδες προήλθαν από το μονομερές του μεθακρυλικού μεθυλεστέρα (ΜΜΑ) και του ακρυλικού οξέως (ΑΑ). Τα αποτελέσματα τον μετρήσεων με XPS έδειξαν ότι η πολυμερική αλυσίδα και στις δύο περιπτώσεις περιβάλλει την επιφάνεια του νανοσωλήνα στον οποίο έχει προσαρτηθεί. Επιπλέον εντοπίστηκαν φασματοσκοπικά χαρακτηριστικά που αποτελούν ενδείξεις ότι αλυσίδες έχουν προσαρτηθεί χημικά στην επιφάνεια των νανοσωλήνων. Αλλά και η φασματοσκοπία Raman πιστοποίησε ότι η προσάρτηση των πολυμερικών αλυσίδων έχει επιτευχθεί και στις δύο περιπτώσεις. Μέσω της θερμοσταθμικής ανάλυσης TGA φαίνεται μάλιστα το υβριδικό μόριο με προσαρτημένες αλυσίδες PAA να είναι μεγαλύτερου μοριακού βάρους από το αντίστοιχο υβριδικό μόριο με προσαρτημένες αλυσίδες PMMA. / The excellent mechanical properties of carbon nanotubes render them as ideal reinforcing materials for the development of polymer-based composite materials of high mechanical strength. However, for the production of such composites, the surface modification of carbon nanotubes appears to be a necessary step in order to form an “active” interface with the polymeric matrix. In this context, within the first part of this work, a systematic study of the chemical and electrochemical surface modification of carbon nanotubes took place. The scope was to identify the proper oxidation conditions that lead to the maximum number of surface functional groups while, at the same time, keeping the graphitic lattice intact by preventing defect formation. Two surface sensitive techniques, X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS) as well as Raman Spectroscopy and Thermogravimetric Analysis (TGA) were employed for this study. Multi-wall carbon nanotubes in the form of buckypapers were initially modified by electrochemical oxidation, using NaCl. In the electrochemical cell, the buckypapers were placed at the anode position on an immovable holder. XPS showed that the surface functionalisation was achieved. Nevertheless, quantitative analysis demonstrated that the quantity of the functional groups was not related to the intensity of the oxidation conditions. Studying both sides of buckypapers, oxidised in the same way by HNO3 clearly proved that the side of the film that “faces” the procedure is more affected. For this reason a new electrochemical cell was designed, where the film holder (anode) was able to rotate during the oxidation procedure. Using this new cell, buckpaper electrochemical oxidation was studied in ΗΝΟ3, ΗCl and ΚΟΗ solutions. It was found that HNO3 (under proper conditions) can lead to successful surface modification in a controllable manner. As expected HCl had a very mild effect, mainly cleaning the film surface from amorphous carbon contamination. Finally, KOH was found to act as a fast oxidising surface agent but in a less controllable way. Multi-wall carbon nanotubes in the form of powder were modified by a wet oxidation method using Η2SO4-Η2Ο2 (piranha), HCl, HNO3 and HNO4-Η2Ο2 solutions. The treatment with piranha solution was found to lead to the formation of a relatively low number of structural defects while, at the same time, it was inducing a moderate number of surface functional groups. Thus, piranha solution was selected to be used for the preparation of the reinforcing material (in the form of a buckypaper) for the composite polymer that was the final product of these efforts. The XPS study of the produced composite polymeric materials was performed on samples prepared with different quantities of epoxy resin (polymeric matrix). The spectra originating from the composite samples had both the spectroscopic features of the nanotubes and the polymer. Although surface inhomogeneity was observed, there was evidence of an active interface between the nanotubes and the matrix. The second and shorter part of this work was dedicated to the study of two hybrid molecules prepared by grafting polymeric chains on the surface of single wall carbon nanotubes. The polymer chains originated from the methacrylic methylester (MMA) and acrylic oxide (AA) monomers. XPS measurements showed that in both cases the polymer chains wrap around the nanotubes. Furthermore, there was spectroscopic evidence that the chains have been chemically attached to the nanotubes. This was also supported by Raman spectroscopy measurements. Thermogravimetric analysis showed that the hybrid molecule with the PAA chains attached was of higher molecular weight compared to that with PMMA chains.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [87]-90.

The principle aims of this thesis have been to develop well-defined heterogeneous catalysts for potential applications in tandem hydrocarbon upgrading. Catalysts for olefin oligomerisation and metathesis of &alpsha;-olefins and transfer hydrogenation of alkanes based on tungsten mono-imido and PCP pincer iridium complexes have been synthesised and immobilised on solid supports. The reactivity of the immobilised catalysts has been tested and compared with the precursor complexes. Co-immobilisation of the two complexes on the same support has been undertaken. <b>Chapter One</b> provides a background to the olefin metathesis reaction and the development of highly active tungsten mono-imido and ruthenium alkylidene complexes. A summary of the implementation of the olefin oligomerisation reaction by industry and the development of highly active systems based on group 6 metals is discussed, along with a mechanistic discussion. The SOMC grafting procedure is considered and the immobilisation of catalysts for alkane and olefin metathesis and oligomerisation discussed; with focus on support materials: silica, sMAO and AMO-LDHs. Finally, tandem catalysis and its use in hydrocarbon upgrading and copolymerisation are presented. <b>Chapter Two</b> details the synthesis of W(NR)Cl₄(THF) complexes and their conversion to W(NR)Me₃Cl complexes employing TMA. The products are characterised by single crystal X-ray diffraction, NMR and FTIR spectroscopy. W(NR)Me₃Cl complexes are shown to be active for the selective dimerisation of ethylene to 1-butene. Attempted formation of possible intermediates in the reaction is presented, and efforts to form mimics for silica supported species are also discussed. <b>Chapter Three</b> describes the preparation of AMO-LDHs for use as catalyst supports. The effect on the surface hydroxyl content and structural properties of these materials by thermally treating them under vacuum is analysed. Their capability to act as supports for ethylene polymerisation after impregnation with MAO and (ⁿBuCp)₂ZrCl₂ is described. <b>Chapter Four</b> investigates the immobilisation and characterisation of synthesised tungsten mono-imido complexes on sMAO, AMO-LDHs and silica, utilising SSNMR, FTIR and X-ray absorption spectroscopy. The reactivity of the grafted complexes towards ethylene oligomerisation is discussed. For the immobilised species effects of varying the imido ligand, temperature and solvent medium are reported. Attempts to immobilise ruthenium carbene complexes on AMO-LDHs and sMAO is detailed. <b>Chapter Five</b> gives an account of the immobilisation of Ir(^tBuPCP)HCl on sMAO which is characterised by SSNMR and FTIR spectroscopy. Molecular analogues of the supported species are synthesised and reactivity for the hydrogenation of ethylene compared. Transfer hydrogenation reaction with sMAO-Ir(^tBuPCP)HCl and COA or ethane with TBE as a sacrificial H₂ acceptor are discussed. Finally, co-immobilisation of W{N(2,6-F-C₆H₃)}Cl₄(THF) and Ir(^tBuPCP)HCl on sMAO was carried out and the solid characterised by SSNMR spectroscopy. <b>Chapter Six</b> provides experimental details and characterising data for the preceding chapters. An <b>Appendices</b> with crystallographic data, and characterising spectra for each chapter is provided, while the <b>Electronic Appendix</b> contains a combined CIF and checkcif for all the molecular structures presented.

In this research various techniques were used to study surface groups on carbon electrodes, including the spectroscopic techniques UV-Vis-NIR, FTIR, PAS, XPS and XAS, as well as the Boehm titration. The methods determined to give the best insight to the surface functionalities on the carbon were XPS, XAS and the Boehm titration. The Boehm titration methodology was standardized before use. An in situ method of examining surface groups using spectroscopy during electrochemistry was attempted. Spectroelectrochemistry is a useful way to gain information on how electrochemistry affects electrodes during experimentation; however, it was unsuccessful for the carbon used and remains to be developed. Polymerization of the copolymer of PANI and PPy as a potential electrode material for ECs was achieved by electrochemical cycling and was studied through spectroelectrochemical measurements. Overall, the research completed included the initial stages to studying electrodes for electrochemical capacitors using analytical, non-electrochemistry techniques in conjunction with electrochemistry.

Surface catalysed reactions play an important role in chemical productions. Developments of catalyst requiring high activity whilst improving on product selectivity can potentially have a profound effect in the chemical industry. Traditional catalyst modifications were focused on tuning the size, shape and foreign metal doping to form well defined metal nanoparticles of unique functionalities. Here, we show new approach to engineering of metal nanocatalysts via a subsurface approach can modify the chemisorption strength of adsorbates on the surface. Carbon modified nanoparticles were synthesised using glucose to stabilise Pd nanoparticles at a molecular level. Upon heat treatment, the carbonised glucose encapsulated the Pd nanoparticles with carbon atoms take residence in the octahedral holes (15 at.%). These materials were tested in liquid phase stereoselective hydrogenations of 3-hexyn-1-ol and 4-octyne. The former has importance in the fragrance industry towards the production of leaf fragrance alcohol. It was shown for the first time that the geometrically and electronically modified Pd with interstitial carbon atoms reduced the adsorption energy of alkenes, ultimately leading to higher reaction selectivity. Boron modified Pd nanoparticles was synthesised using BH₃.THF in the liquid phase. The material possess high B interstitial saturation (20 at.%), which can be synthesised for the first time below 100°C. These materials were tested in the liquid phase selective hydrogenation of various alkynes and 2-chloronitrobenzene, of which the latter has importance in the pesticides industry. Kinetic modelling on the hydrogenation of 4-octyne suggests these subsurface occupied B does play a pivotal role on increasing the reaction selectivity, as removal of these species lead to decreased selectivity. Au nanoparticles were synthesised and characterised using H¹³COOH NMR. The new liquid NMR characterisation method is successfully applied to examine the chemisorption strength of metal nanoparticles. An attempt to synthesise PVP capped B modified Pd nanoparticles with the above NMR characterisation was investigated. It is believed the examples of subsurface atom modifications as shown here may offer future catalyst developments in this area.

Zethrenes are model diradicaloids with potential applications in spintronics and optoelectronics. Despite a rich chemistry in solution, on-surface synthesis of zethrenes has never been demonstrated. We report the on-surface synthesis of super-heptazethrene on Au(111). Scanning tunneling spectroscopy investigations reveal that super-heptazethrene exhibits an exceedingly low HOMO–LUMO gap of 230 meV and, in contrast to its open-shell singlet ground state in the solution phase and in the solid-state, likely adopts a closed-shell ground state on Au(111).