摘要:

1IntroductionElectronic transitions are inhomogeneously broadened in condensed phases due to the variation of local fields. This broadening obscures valuable spectroscopic information at low temperatures. Often it can be overcome by the application of laser techniques such as fluorescence line narrowing (FLN) and spectral hole-burning (SHB).1–3Laser techniques facilitate investigations of subtle details of the electronic structure of molecules or molecular ions.3,4Non-photochemical spectral hole-burning is a general phenomenon in amorphous systems. It is based on some rearrangement of host–guest interactions upon photoexcitation, resulting in a slight shift of the transition frequency of the laser-selected subset of chromophores.Recently, metal complexes of the 2,2′:6′,2″-terpyridine ligand (abbreviated as terpy in the following) and its derivatives have obtained a great deal of attention.5The [Cr(terpy)2]3+complex displays a very strong nephelauxetic effect in comparison with very similar systems such as [Cr(bpy)3]3+(bpy = 2,2′-bipyridine). This follows from the 760 cm−1shift of theRlines from ≈729 nm for [Cr(bpy)3]3+to 772 nm for [Cr(terpy)2]3+.6The latter complex assumes a distorted meridional geometry, resulting in interligand pockets which facilitate a solvation of the chromium(iii) ion.7Efficient non-photochemical hole-burning processes can be expected due to the interaction of the solvent molecules with the terpy ligands.Terpy, like bpy, can stabilise the +2 oxidation state of chromium and hence its complexes have some potential as optical recording materials. Here we present preliminary results of fluorescence line-narrowing (FLN) and spectral hole-burning (SHB) studies of the2E←4A2spin–flip transition in [Cr(terpy)2]3+.

ISSN:1460-2733    

DOI:10.1039/b209460f

出版商:RSC    

年代:2002

数据来源: RSC