Synthetic, structural, and spectroscopic study of luminescent transition metal complexes for use in electronic devices and environmental sensors.

Abstract

This thesis describes the synthesis, structural, and spectroscopic study of ruthenium and iridium complexes for use in environmental sensors or electronic devices. Chapters 1-2 discuss studies of ruthenium polypyridyl (pp) complexes used for detection of oxygen gas. In Chapter 1 the variation of the counterion and its affect on the packing structure and subsequent detection of oxygen is discussed. The anion tfpb - (tetrakis(bis-3,5-trifluoromethylphenylborate) worked particularly well and provided the inefficient packing structure with desired channels of open space. In Chapter 2 optically pure metal complexes were explored to alter the packing structure. Both means of creating void space enabled oxygen diffusion to give sensitive and reproducible crystalline oxygen sensors.

Chapter 3 describes the dual use of a [Ru(pp) 3 ](tfpb) 2 complex for detection of oxygen and the volatile organic, benzene. The crystalline solid undergoes a reversible vapochromic shift of the emission λ max to higher energy in the presence of benzene. Additionally, in the presence of oxygen the solid exhibits linear Stern-Volmer quenching behavior. This crystalline solid was a practical sensor at low concentrations (0.76%) of benzene vapor.

In Chapter 4, the synthesis of new compounds of the general form [( p -cym)Ru(pp)Cl]Cl is discussed. This method allowed the study of a series of Ru(II) complexes, with different polypyridyl and β-diketonate ligands. Modification of the substituent group on the β-diketonate ligand has a pronounced effect on the electronic and electrochemical properties of these complexes. The presence of channels in the crystal structures of two of these molecules as well as the low Ru(III)/Ru(II) redox couple led to their examination as chlorine sensors.

In Chapter 5, a selective low-temperature synthesis of the highly desired fac and mer tris-cyclometalated Ir(III) complexes used in OLEDs is discussed. The bis-acetonitrile species, [Ir(C^N) 2 (NCCH 3 ) 2 ]PF 6 , and hydroxy-bridged dimers, [Ir(C^N) 2 (OH)] 2 for two cyclometalating ligands (C^N) were synthesized.The fac-Ir(C^N) 3 and mer -Ir(C^N) 3 complexeswere synthesized at 100 ºC in o -dichlorobenzene from the [Ir(C^N)2(NCCH3)2]PF6 or [Ir(CN) 2 (OH)] 2 complexesrespectively. A mechanism is proposed that may account for the selectivity observed in the formation of these fac-Ir(CN) 3 and mer-Ir(CN) 3 isomers.