A series of new emissive group 11 transition metal d(10)-complexes 1-8 bearing functionalized 2-pyridyl pyrrolide together with phosphine ancillary such as bis[2-(diphenylphosphino)phenyl] ether (POP) or PPh(3) are reported. The titled complexes are categorized into three classes, i.e. Cu(I) complexes (1-3), Ag(I) complexes (4 and 5), and Au(I) metal complexes (6-8). Via combination of experimental and theoretical approaches, the group 11 d(10)-metal ions versus their structural variation, stability, and corresponding photophysical properties have been investigated in a systematic and comprehensive manner. The results conclude that, along the same family, how much a metal d-orbital is involved in the electronic transition plays a more important role than how heavy the metal atom is, i.e. the atomic number, in enhancing the spin-orbit coupling. The metal ions with and without involvement of a d orbital in the lowest lying electronic transition are thus classified into internal and external heavy atoms, respectively. Cu(I) complexes 1-3 show an appreciable metal d contribution (i.e., MLCT) in the lowest lying transition, so that Cu(I) acts as an internal heavy atom. Despite its smallest atomic number among group 11 elements, Cu(I) complexes 1-3 exhibit a substantially larger rate of intersystem crossing (ISC) and phosphorescence radiative decay rate constant (k(r)(p)) than those of Ag(I) (4 and 5) and Au(I) (6-8) complexes possessing pure π → π* character in the lowest transition. Since Ag(I) and Au(I) act only as external heavy atoms in the titled complexes, the spin-orbit coupling is mainly governed by the atomic number, such that complexes associated with the heavier Au(I) (6-8) show faster ISC and larger k(r)(p) than the Ag(I) complexes (4 and 5). This trend of correlation should be universal and has been firmly supported by experimental data in combination with empirical derivation. Along this line, Cu(I) complex 1 exhibits intensive phosphorescence (Φ(p) = 0.35 in solid state) and has been successfully utilized for fabrication of OLEDs, attaining peak EL efficiencies of 6.6%, 20.0 cd/A, and 14.9 lm/W for the forward directions.

Novel ter(9,9-diarylfluorene)s were synthesized by a Suzuki-coupling reaction of 2-bromofluorene (1) and 2,7-fluorenediboronic ester derivatives (3) with high isolated yields (63-86%). The X-ray structure analysis of ter(9,9'-spirobifluorene) (4aa) revealed that the conjugated chromophore adopts a helical conformation. This conformation effectively releases the steric interaction between the fluorene moieties and prevents inter-chromophore interactions. The introduction of aryl groups at the C9 position of fluorene was highly beneficial to the thermal and morphological stability of these oligomers. These terfluorenes exhibit intense blue fluorescence with excellent quantum yields both in solution ( approximately 100%) and in solid state (66-90%), and possess interesting reversible redox properties. Highly efficient blue light-emitting OLED devices were fabricated using 4aa and 4cc as emitters as well as hole transporters. The devices exhibit low turn-on voltage ( approximately 3 V) and high EL external quantum efficiency (2.5-3%).

Green fluorescence protein (GFP), which serves as an energy acceptor and emitter for bioluminescence in the sea pansy Renilla reniformis and the jellyfish Aequorea Victoria, has drawn much attention because of its applications in molecular biology and biochemistry. 1 GFP takes advantage of the presence of a chromophore that is anchored both covalently and via a hydrogen-bond network, 4-(4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (p-HBDI, see Scheme 1), which undergoes excited-state proton transfer (ESPT) 2 via the proton relay of water molecules and a remote residue such as E222, 3 resulting in a very effective and intense anion fluorescence.Nevertheless, studies reveal a strong cutoff between the properties of wild type GFP (or certain GFP mutants) and the synthetic analogue chromophores of p-HBDI. 4 In view of photophysics, the fluorescence yield of the protein-free chromophore in fluid solvents is much weaker and strongly temperature dependent. The results suggest an efficient radiationless transition operating in p-HBDI, most probably induced by conformational relaxation along torsional deformation of the two exocyclic C-C bonds to a nonfluorescent twisted intermediate. 5 More recently, it has been proposed that the shallow potential energy surface of the intermediates may conically intersect with that of the ground state, inducing the dominant radiationless deactivation. 4c-d,6 Such a conformational relaxation is greatly suppressed in GFP by its proton relay, rigid environment.In view of chemistry, most of the research has been focused on the chemical modification of p-HBDI analogues at the C(1) position. 4c,7 Conversely, in this study, we are interested in the derivatization on the phenyl ring. As an ingenious approach, switching the hydroxyl group from the C(8) position to the C(6) position (see Scheme 1), forming 4-(2-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (o-HBDI), a structural isomer of p-HBDI may reveal several novel features with respect to p-HBDI. The geometry optimization (B3LYP/cc-pVDZ and aug-cc-pVDZ, see ESI) of o-HBDI unveils the existence of a seven-memberedring intramolecular hydrogen bond between -OH and the N(2) atom. This intramolecular hydrogen-bonding configuration should, in part, hinder the exocyclic torsional deformation such that the radiationless deactivation may be reduced. More importantly, theoretical approaches also predict that excited-state intramolecular proton transfer (ESIPT) from the OH proton to the N(2) atom is thermally favorable (vide infra), forming a zwitterionic tautomer species (see Table of Content, TOC).In light of these perspectives, we have thus expended great effort to make a facile synthesis of o-HBDI. Briefly, the o-methoxybenzaldehyde was used as a starting reactant (see Scheme 1). Because of the lack of the o-hydroxyl group and hence the intramolecular lactonation, 3 was obtained with a good yield (70%). Subsequent reaction of 3 with methylamine, followed by deprotection of the methyl group of o-MBDI by BBr 3 , afforded o-H...

Organic light-emitting diodes with external quantum efficiency of 38.8% are realized using a Pt-based thin-film emitting layer with photoluminescence quantum yield of 96% and transition dipole ratio of 93%. The emitting dipole orientation of the thin films fabricated using Pt complexes is investigated and the structural relationship between X-ray structural analysis and the structures in thin films are discussed based on quantum chemical calculations.

A new class of neutral bis-tridentate Ir(III) metal complexes that show nearly unitary red, green, and blue emissions in solution is prepared and employed for the fabrication of both monochrome and white-emitting organic light-emitting diodes, among which a green device gives external quantum efficiency exceeding 31%.