The coordination chemistry of functionalised poly(pyrazol-1-yl)borate ligands and the photophysical properties of cyanide-bridged d-f hybrids
The content of this thesis is concerned with two distinctly independent areas of research: (i) the synthesis and study of new poly(pyrazol-1-yl)borate ligands and their metal complexes; (ii) crystallographic and photophysical studies of new d-f hybrid complexes. Chapter One is divided into three parts: Part one gives a general introduction to poly(pyrazol-1-yl)borate chemistry along with a concise and up-to-date review of those ligands containing substituents in the C3 position of the pyrazolyl ring; part two provides a brief introduction into the physical properties of lanthanide(III) metal ions, as well as describing the practical applications of their individual spectroscopic properties; and part three contains a brief review on the structural chemistry of cyanide-bridged coordination polymers. Chapter Two describes the syntheses of four new scorpionates: dihydrobis[3-(4-pyridyl)pyrazol-1-yl]borate (Bp4py); dihydro-bis[3-(3-pyridyl)pyrazol-1- yl]borate (Bp3py); hydro-tris[3-(4-pyridyl)pyrazol-1-yl]borate (Tp4py) and hydrotris[3-(3-pyridyl)pyrazol-1-yl]borate (Tp3py). A series of X-ray crystallographic studies reveals a range of mononuclear, dinuclear and polymeric coordination complexes with various metal ions. Chapter Three describes a range of structural and photophysical studies on lanthanide(III) complexes of poly(pyrazol-1-yl)borate ligands. New mixed-ligand lanthanide(III) complexes with various combinations of the anionic ligands Tp2py , Bp2py and dibenzoylmethane (dbm) were prepared and structurally characterised. Photophysical studies on the isostructual series [Ln(Bp2py)(dbm)2] (Ln = Pr, Nd, Er, Yb) show characteristic near-IR luminescence from the lanthanide ion. Near-IR luminescence was also demonstrated from the complexes [Ln(Bp2py) 2(NO3)] and [Ln(Tp2py)(NO3) 2] (Ln = Pr, Er), upon suitable excitation of the ligand chromophores. Chapter Four describes the structural and photophysical properties of new cyanide-bridged d-f coordination polymers. Structural and photophysical studies are presented for a series of Ru-Ln complexes based on the [Ru(bipy)(CN)4] 2- donor unit connected to a Ln(III) energy-acceptor via cyanide bridges (where bipy is 2,2’- bipyridine and Ln = Pr, Nd, Er, Yb). Structural and photophysical studies were also performed on [Cr(CN)6][Ln(DMF)4(H2 O)2] complexes, in which the lanthanide ion (Ln = Nd, Yb) acts as the energy acceptor from the hexacyanochromate chromophore. The structures of [Cr(CN)6][Ln(H2 O)2] (Ln = Gd, Yb) and K2[Ru(phen)(CN)4] (where phen = 1,10-phenanthroline) are also presented. Chapter Five gives a brief review of the field of X-Ray Crystallography with analysis of the history and theory of the technique, as well as an overview of its practical aspects used in this work. A few crystal structures solved by the author, and independent of the topics in this thesis, are also reported.