Crowded Cu(I) complexes involving benzo[h]quinoline: pi-stacking effects and long-lives excited states.
The Friedländer condensation was employed to synthesize two series of 3,3'-polymethylene bridged ligands, L, based on 2-(2'-pyridyl)-benzo[h]quinoline and 2,2'-bibenzo[h]quinoline (BHQ) along with the fully aromatic naphtho[1,2-b]-1,10-phenanthroline. Complexes [Cu(L)(2)](+) were prepared as their perchlorate or hexafluorophosphate salts. The solution state structures were analyzed by NMR and shielding effects reflected significant interligand pi-stacking interaction in the complexes. Solid-state structures of the complexes where L = 3,3'-tetramethylene-2,2'-bibenzo[h]quinoline or naphtho[1,2-b]-1,10-phenanthroline were determined by X-ray analysis. The tetramethylene bridged complex showed a highly distorted coordination geometry with the BHQ rings of opposing ligands pi-stacked at a interplanar distance of about 3.37 A. Complexes of the BHQ series showed a pronounced MLCT absorption maximum which shifted bathochromically from 496 to 610 nm as the 3,3'-bridge decreased from 4 to 2 carbons. The BHQ complexes luminesced strongly in CH(2)Cl(2) solution and the tetramethylene-bridged system showed the longest yet recorded excited-state lifetime for a copper MLCT excited state, tau = 5.3 micros and Phi = 0.10.
Riesgo
E C
EC
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Hu
Y Z
YZ
Bouvier
F
F
Thummel
R P
RP
Scaltrito
D V
DV
Meyer
G J
GJ
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D049449:Luminescence; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011804:Quinolines / Q000737:chemistry*
D007202:Indicators and Reagents; D011804:Quinolines; C039107:benzo(h)quinoline; D003300:Copper