Luminescent main group and transition metal complexes with N,N'- and N,N',N'-chelate ligands and their electroluminescent applications

The objective of my PhD research is to develop a new class of luminescent main group and transition metal complexes based on N,N' - or N,N',N″-chelate ligands and to investigate their uses in electroluminescent devices. Five classes of new materials have been developed and investigated.; The first class are fluorescent organoboron complexes with the general formula of BPh2(N^N) (N^N = bidentate chelate ligand with one -1charged N donor and one neutral N donor). It is demonstrated that the emission color of this class of organoboron complexes could be easily tuned to the blue (450 nm) or red (612 nm) region by modifying the substituent of the N,N'-chelate ligand, or by enlarging the conjugation system of the N,N'-chelate ligand. Molecular orbital calculations revealed that the origin of the fluorescence of the boron complexes is from ligand based charge transfer. Blue, green, and red organic-light-emitting devices (OLEDs) were fabricated successfully using three of the organoboron complexes as emitters and electron transport materials.; The second class of materials investigated are phosphorescent mononuclear metal complexes with N,N',N″-tridentate chelate ligands, 2,6-bis(2'-indolyl)pyridine (H 2bip) and 2,6-bis[2'-(7-azaindolyl)]pyridine (H 2bap). This class of molecules include both main group metal complexes MLPh2 (M = Sn or Pb, L = bip or bap) and Pt(II) complexes PtLX (L = bip, X = Py or SMe2). The Sn(IV) and Pb(IV) complexes display orange phosphorescence at 77 K, while the Pt(II) complexes exhibit orange/red phosphorescence at room temperature. Orange-red electrophosphorescence was achieved using 4.2 as an emitter.; The third class are polynuclear Pt(II) complexes based on linear or starburst 2,2'-dipyridylamino (dpa) functionalized ligands of the form Ar[Pt(dpa)Ph2]n (n = 2, 3, Ar = aromatic groups that connect the Pt(dpa)Ph2 units). This class of molecule displayed blue-green ligand based phosphorescence at 77K.; The fourth class are mono- or polynuclear Pt(II) complexes based on linear or starburst 2-(2'-pyridyl)benzimidazolyl (pbm) functionalized ligands of the form Ar[Pt(pbm)Ph2)n (n = 1, 2, 3, Ar = aromatic groups that connect the Pt(pbm)Ph2 units). Orange-red metal-to-ligand charge transfer (MLCT) emissions were observed for this class of molecules. Fluxional phenomena were also observed for three of the complexes.; The fifth class are phosphorescent transition metal complexes based on 4,4'-diphenyl-6,6'-dimethyl-2,2 '-bipyrimidine (pmbp), with formula [Zn(pmbp)2]ClO 4 and M(pmbp)X2 (M = Zn, Pt, or Hg; X = Cl- or phenyl). The different origins of the luminescence is found to be responsible for the different colors of the Zn(II) and Pt(II) complexes with pmbp. The Hg(Il) complex with pmbp was found to be non-emissive.