Issue 29, 2011

Synthesis, structural characterization and luminescent properties of a series of Cu(i) complexes based on polyphosphine ligands

Abstract

A series of Cu(I) complexes with a [Cu(NN)(PP)]+ moiety, [Cu(phen)(pba)](BF4) (1a), [Cu2(phen)2(pbaa)](BF4)2 (2a), [Cu2(phen)2(pnaa)](BF4)2 (3a), [Cu2(phen)2(pbbaa)](BF4)2 (4a), [Cu(dmp)(pba)](BF4) (1b), [Cu2(dmp)2(pbaa)](BF4)2 (2b), [Cu2(dmp)2(pnaa)](BF4)2 (3b) and [Cu2(dmp)2(pbbaa)](BF4)2 (4b) (phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, pba = N,N-bis((diphenylphosphino)methyl)benzenamine, pbaa = N,N,N′,N′-tetrakis((diphenylphosphino)methyl)benzene-1,4-diamine, pnaa = N,N,N′,N′-tetrakis((diphenylphosphino)methyl)naphthalene-1,5-diamine and pbbaa = N,N,N′,N′-tetrakis((diphenylphosphino)methyl)biphenyl-4,4′-diamine), were rationally designed and synthesized. These complexes were characterized by 1H and 31P NMR, electrospray mass spectrometry, elemental analysis and X-ray crystal structure analysis. Introduction of different central arene spacers (phenyl, naphthyl, biphenyl) into ligands, resulting in the size variation of these complexes, aims to tune the photophysical properties of the complexes. Each Cu(I) ion in these complexes adopts a distorted tetrahedral geometry constructed by the chelating diimine and phosphine groups. Intermolecular C–H⋯π and/or π⋯π interactions are involved in the solid states. The dmp-containing complex exhibits better emission relative to the corresponding phen complex due to the steric encumbrance of bulky alkyl groups. Furthermore, for complexes with identical diimine but different phosphine ligands, the tendency of increased emission lifetime as well as blue-shifted emission in the solid state follows with the decrease in size of complexes. Intermolecular C–H⋯π interactions have an influence on the final solid state photophysical properties through vibrationally relaxed non-radiative energy transfer in the excited state. Smaller-sized complexes show better photophysical properties due to less vibrationally relaxed behavior related to flexible C–H⋯π bonds. Nevertheless, the tendency for increased quantum yield and emission lifetime, as well as blue-shifted emission in dilute solution goes with the increase in size of complexes. The central arene ring (phenyl, naphthyl or biphenyl) has an influence on the final photophysical properties. The larger the π-conjugated extension of central arene ring is, the better the photophysical properties of complex are. The rigid and large-sized complex 3b, with a high quantum yield and long lifetime, is the best luminophore among these complexes.

Graphical abstract: Synthesis, structural characterization and luminescent properties of a series of Cu(i) complexes based on polyphosphine ligands

Supplementary files

Article information

Article type
Paper
Submitted
02 Mar 2011
Accepted
19 May 2011
First published
24 Jun 2011

Dalton Trans., 2011,40, 7551-7558

Synthesis, structural characterization and luminescent properties of a series of Cu(I) complexes based on polyphosphine ligands

R. Hou, T. Huang, X. Wang, X. Jiang, Q. Ni, L. Gui, Y. Fan and Y. Tan, Dalton Trans., 2011, 40, 7551 DOI: 10.1039/C1DT10358J

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