Ru(II) complexes of crowded delocalized diimine ligands
摘要:
The ligands 3,3'-dimethylene-2,2'-bibenzo[g]quinoline and bisbenzo[2,3:9,8]-1,10-phenanthroline have been coordinated with Ru(II) to form both tris- and mixed ligand complexes. These species are highly congested about the metal center but can be formed through the use of microwave irradiation. Shielding and deshielding effects on the chemical shifts of the aryl as well as the bridge protons reveal important conformational effects. Bathochromic shifts are observed in the electronic absorption spectra, associated with increased delocalization of the ligand and lowering of the pi*-energy level. Similar effects are observed for the reduction potentials while the oxidation potentials are much less sensitive to ligand structure. (C) 2002 Elsevier Science B.V. All rights reserved.
Synthesis and Properties of Ligands Based on Benzo[g]quinoline
摘要:
The preparation of 3-amino-2-naphthaldehyde is described. Ammonolysis of 3-hydroxy-8-naphthoic acid affords the corresponding amino acid which can be esterified and then reduced with LAH. Protection of the amino group, MnO2 oxidation of the primary alcohol to an aldehyde, and deprotection gave the amino aldehyde which is an excellent Friedlander synthon for benzo[g]quinolines. Dimethylene-bridged analogues of 2,2'-bipyridine and 2,2';6,2''-terpyridine were prepared as well as orthocyclophanes derived from tetracyclo[6.3.0.0(4,11).0(5,9)]undecane-2,7-dione (TCU-2,7-dione). The absorption and emission spectra of these species are consistent with the parent benzo[g]quinoline where bathochromic shifts result from increased delocalization. The TCU derivative evidences exciplex formation so that its benzo[g]quinoline emission is almost completely quenched and an exciplex emission appears at 525 nm. Electrochemical analysis indicates that both reduction and UV absorption involve the same pi(*) orbital.
Synthesis and Properties of Ligands Based on Benzo[g]quinoline
作者:Emmanuelle Taffarel、Sarah Chirayil、Randolph P. Thummel
DOI:10.1021/jo00083a024
日期:1994.2
The preparation of 3-amino-2-naphthaldehyde is described. Ammonolysis of 3-hydroxy-8-naphthoic acid affords the corresponding amino acid which can be esterified and then reduced with LAH. Protection of the amino group, MnO2 oxidation of the primary alcohol to an aldehyde, and deprotection gave the amino aldehyde which is an excellent Friedlander synthon for benzo[g]quinolines. Dimethylene-bridged analogues of 2,2'-bipyridine and 2,2';6,2''-terpyridine were prepared as well as orthocyclophanes derived from tetracyclo[6.3.0.0(4,11).0(5,9)]undecane-2,7-dione (TCU-2,7-dione). The absorption and emission spectra of these species are consistent with the parent benzo[g]quinoline where bathochromic shifts result from increased delocalization. The TCU derivative evidences exciplex formation so that its benzo[g]quinoline emission is almost completely quenched and an exciplex emission appears at 525 nm. Electrochemical analysis indicates that both reduction and UV absorption involve the same pi(*) orbital.
Ru(II) complexes of crowded delocalized diimine ligands
作者:Feiyue Wu、Randolph P Thummel
DOI:10.1016/s0020-1693(01)00684-3
日期:2002.1
The ligands 3,3'-dimethylene-2,2'-bibenzo[g]quinoline and bisbenzo[2,3:9,8]-1,10-phenanthroline have been coordinated with Ru(II) to form both tris- and mixed ligand complexes. These species are highly congested about the metal center but can be formed through the use of microwave irradiation. Shielding and deshielding effects on the chemical shifts of the aryl as well as the bridge protons reveal important conformational effects. Bathochromic shifts are observed in the electronic absorption spectra, associated with increased delocalization of the ligand and lowering of the pi*-energy level. Similar effects are observed for the reduction potentials while the oxidation potentials are much less sensitive to ligand structure. (C) 2002 Elsevier Science B.V. All rights reserved.