Exciton coupling in coordination compounds

Abstract

This Perspective reviews the impact of exciton coupling on the spectroscopic properties of coordination compounds. Exciton coupling features arise in electronic absorption and circular dichroism spectra when chromophores are brought into close spatial proximity, for example by coordination to a metal centre. The analysis of these features can reveal much information such as the geometry of a complex and its absolute configuration. The extension of the exciton coupling model to polynuclear metallosupramolecular arrays is discussed.

Copper Active Sites in Biology

“…316 Each peroxide π * orbital makes CT transitions to each of the two Cu(II) ions in the peroxide bridged site. In zeroth order, these transitions are degenerate.…”

Exciton Coupling of Surface Complexes on a Nanocrystal Surface

“…[49][50][51][52][53] Albrecht et al reported a lanthanum complex with three Q ligands showing exciton coupling of the coordinated Q at 280, 295, 350, and 480 nm in the absorption spectrum. [54] Telfer et al and Kwong et al [31,[55][56][57] also found exciton coupling in dinuclear and polynuclear complexes with structures that resemble those of neighboring surface complexes on an NC surface. All of these observations give support to the exciton-coupling model proposed for the ZnS-Q NCs.…”

“…This suggests that the PL redshift is probably due to exciton coupling, and not simply caused by Fçrster (or fluorescence) resonance energy transfer (FRET) between the surface complexes. [31,32] Further evidence comes from the PLE spectrum (Figure 2 C). At low surface density of the surface complex, the excitation spectrum has two peaks at 310 and 368 nm.…”

“…400 nm) observed in the absorption/PLE of the ZnQ 2 complex. [30,31,46] Exciton coupling of uncoordinated 7-hydoxyquinoline or quinoline-derived chromophores in organic compounds [47,48] and of coordinated quinoline chromophores in Cu/Zn complexes has been observed. [49][50][51][52][53] Albrecht et al reported a lanthanum complex with three Q ligands showing exciton coupling of the coordinated Q at 280, 295, 350, and 480 nm in the absorption spectrum.…”

“…The intensities of Q*'' and Q*' are approximately equal (see Figure 2 C). Unlike for a specific complex with a given structure, for which information on the molecular geometry can be derived from the intensity ratio of the higher-and lower-energy excited states of coupled chromophores, [31] no specific geometrical information can be extracted in this case, because the NCs offer surface coordination sites with diverse local fields. The apparent Q*'' and Q*' intensities should be the statistical result of coupled surface complexes with various structures.…”