9 research outputs found
Palladium-Mediated One-Step Coupling between Polypyridine Metal Complexes: Preparation of Rigid and Dendritic Nano-Sized Ruthenium Complexes
No full textPhotoluminescence Properties, Molecular Structures, and Theoretical Study of Heteroleptic Silver(I) Complexes Containing Diphosphine Ligands
No full textThe homoleptic complex [Ag(<b>L</b>)<sub>2</sub>]PF<sub>6</sub> (<b>1</b>) and heteroleptic complexes [Ag(<b>L</b>)(<b>L</b><sub><b>Me</b></sub>)]BF<sub>4</sub> (<b>2</b>) and [Ag(<b>L</b>)(<b>L</b><sub><b>Et</b></sub>)]BF<sub>4</sub> (<b>3</b>) [<b>L</b> =
1,2-bis(diphenylphosphino)benzene, <b>L</b><sub><b>Me</b></sub> = 1,2-bis[bis(2-methylphenyl)phosphino]benzene,
and <b>L</b><sub><b>Et</b></sub> = 1,2-bis[bis(2-ethylphenyl)phosphino]benzene]
were synthesized and characterized. X-ray crystallography demonstrated
that <b>1</b>–<b>3</b> possess tetrahedral structures.
Photophysical studies and time-dependent density functional theory
calculations of <b>1</b>–<b>3</b> revealed that
alkyl substituents at the ortho positions of peripheral phenyl groups
in the diphosphine ligands have a significant influence on the energy
and intensity of phosphorescence of the complex in solution at room
temperature. The results can be interpreted in terms of the geometric
preferences of each complex in the ground and excited states. The
homoleptic complex <b>1</b> exhibits weak orange phosphorescence
in solution arising from its flat structure in the triplet state,
while heteroleptic complexes <b>2</b> and <b>3</b> show
strong green phosphorescence from triplet states with tetrahedral
structure. Larger interligand steric interactions in <b>2</b> and <b>3</b> caused by their bulkier ligands probably inhibit
geometric relaxation within the excited-state lifetimes, leading to
higher energy phosphorescence than that observed for <b>1</b>. NMR experiments revealed that <b>2</b> and <b>3</b> in solution possess structures that are much more immobilized than
that of <b>1</b>; fluxional motion is completely suppressed
in <b>2</b> and <b>3</b>. Accordingly, conformational
changes of <b>2</b> and <b>3</b> are expected to be suppressed
by the alkyl substituents not only in the ground state but also in
excited states. Consequently, nonradiative decay of the excited states
of <b>2</b> and <b>3</b> occurs less efficiently than
in <b>1</b>. As a result, the quantum yields of phosphorescence
for <b>2</b> and <b>3</b> are 6 times larger than that
for the homoleptic complex <b>1</b>
Photoluminescence Properties, Molecular Structures, and Theoretical Study of Heteroleptic Silver(I) Complexes Containing Diphosphine Ligands
No full textThe homoleptic complex [Ag(<b>L</b>)<sub>2</sub>]PF<sub>6</sub> (<b>1</b>) and heteroleptic complexes [Ag(<b>L</b>)(<b>L</b><sub><b>Me</b></sub>)]BF<sub>4</sub> (<b>2</b>) and [Ag(<b>L</b>)(<b>L</b><sub><b>Et</b></sub>)]BF<sub>4</sub> (<b>3</b>) [<b>L</b> =
1,2-bis(diphenylphosphino)benzene, <b>L</b><sub><b>Me</b></sub> = 1,2-bis[bis(2-methylphenyl)phosphino]benzene,
and <b>L</b><sub><b>Et</b></sub> = 1,2-bis[bis(2-ethylphenyl)phosphino]benzene]
were synthesized and characterized. X-ray crystallography demonstrated
that <b>1</b>–<b>3</b> possess tetrahedral structures.
Photophysical studies and time-dependent density functional theory
calculations of <b>1</b>–<b>3</b> revealed that
alkyl substituents at the ortho positions of peripheral phenyl groups
in the diphosphine ligands have a significant influence on the energy
and intensity of phosphorescence of the complex in solution at room
temperature. The results can be interpreted in terms of the geometric
preferences of each complex in the ground and excited states. The
homoleptic complex <b>1</b> exhibits weak orange phosphorescence
in solution arising from its flat structure in the triplet state,
while heteroleptic complexes <b>2</b> and <b>3</b> show
strong green phosphorescence from triplet states with tetrahedral
structure. Larger interligand steric interactions in <b>2</b> and <b>3</b> caused by their bulkier ligands probably inhibit
geometric relaxation within the excited-state lifetimes, leading to
higher energy phosphorescence than that observed for <b>1</b>. NMR experiments revealed that <b>2</b> and <b>3</b> in solution possess structures that are much more immobilized than
that of <b>1</b>; fluxional motion is completely suppressed
in <b>2</b> and <b>3</b>. Accordingly, conformational
changes of <b>2</b> and <b>3</b> are expected to be suppressed
by the alkyl substituents not only in the ground state but also in
excited states. Consequently, nonradiative decay of the excited states
of <b>2</b> and <b>3</b> occurs less efficiently than
in <b>1</b>. As a result, the quantum yields of phosphorescence
for <b>2</b> and <b>3</b> are 6 times larger than that
for the homoleptic complex <b>1</b>
Photo-activation of Pd-catalyzed Sonogashira coupling using a Ru/bpyridine complex as energy transfer agent
No full textPhotoluminescent properties and molecular structures of [NaphAu(PPh3)] and [μ-Naph {Au(PPh3)}2] ClO4 (Naph = 2-naphthyl)
No full textPhoto-activation of Pd-catalyzed Sonogashira coupling using a Ru/bipyridine complex as energy transfer agent
No full textSynthesis, Structure and Magnetic Properties of a Linear Trimanganese(III,II,III) Complex Bridged with a (.mu.-Hydroxo)bis(.mu.-acetato) Unit
No full text
