Light-Emitting Cyclopalladated Complexes of 6-Phenyl-2,2'-bipyridines with Hydrogen-Bonding Functionality
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- 作者：Francesco Neve ; Alessandra Crispini ; Cinzia Di Pietro ; and Sebastiano Campagna
- 刊名：Organometallics
- 出版年：2002
- 出版时间：August 19, 2002
- 年：2002
- 卷：21
- 期：17
- 页码：3511 - 3518
- 全文大小：164K
- 年卷期：v.21,no.17(August 19, 2002)
- ISSN：1520-6041
文摘
The tridentate ligand 4-carboxy-6-phenyl-2,2'-bipyridine (HL1) was used to prepare thecyclometalated Pd(II) complex [Pd(L1)Cl] (1). Similar ligands were effective in the formationof [Pd(L2)Cl] (2) and [Pd(L3)Cl] (3) (where HL2 = 4-carboxyphenyl-6-phenyl-2,2'-bipyridineand HL3 = 4-hydroxyphenyl-6-phenyl-2,2'-bipyridine). The crystal structure of [Pd(L1)Cl]·H2O has been determined by X-ray diffraction, revealing a variegated array of H-bondingmotifs and 
-stacking. The [Pd(L1)Cl] molecules are associated in dimers with an intradimerPd···Pd distance of 3.27 Å, while dimers are separated by interdimer Pd···Pd contacts of5.41 Å. All complexes 1-3 exhibited intense luminescence at 77 K, with lifetimes in the10-200 
s range. The luminescence is assigned to metal-perturbed triplet ligand-centered(LC) excited states for 1 and 3 (partially mixed with an upper-lying metal-to-ligand chargetransfer (MLCT) level) and to an excimeric excited state for 2. Room-temperature solid-state luminescence was also revealed by 1 (emission energy and lifetime of 650 nm and 1s, respectively), which has been assigned to oligomeric species. Differences in thephotophysical properties of 1-3 are addressed with reference to the chemical structure andelectronic properties of their polypyridine ligands.
-stacking. The [Pd(L1)Cl] molecules are associated in dimers with an intradimerPd···Pd distance of 3.27 Å, while dimers are separated by interdimer Pd···Pd contacts of5.41 Å. All complexes 1-3 exhibited intense luminescence at 77 K, with lifetimes in the10-200 s range. The luminescence is assigned to metal-perturbed triplet ligand-centered(LC) excited states for 1 and 3 (partially mixed with an upper-lying metal-to-ligand chargetransfer (MLCT) level) and to an excimeric excited state for 2. Room-temperature solid-state luminescence was also revealed by 1 (emission energy and lifetime of 650 nm and 1s, respectively), which has been assigned to oligomeric species. Differences in thephotophysical properties of 1-3 are addressed with reference to the chemical structure andelectronic properties of their polypyridine ligands.