A dicationic organoplatinum(II) complex containing a bridging 2,5-bis-(4-ethynylphenyl)-[1,3,4]oxadiazole ligand behaves as a phosphorescent gelator for organic solvents

Abstract

A dicationic platinum(II) terpyridyl complex, [(tBu 3tpy)Pt(OXD) Pt-(tBu 3tpy)](PF 6) 2 (tBu 3tpy=4, 4′,4″-tri-tert-butyl-2,2′:6′,2″-terpyridyl, OXD= 2,5-bis(4-ethynylphenyl)[1,3,4]oxadiazole) formed phosphorescent organogels in acetonitrile or in a mixture of acetonitrile and alcohol. The structure and properties of these emissive gels were analyzed by polarizing optical and confocal laser scanning microscopy, and by variable-temperature 1H NMR, UV/Vis, and emission spectroscopy. Dry gels were studied by scanning electron microscopy, powder X-ray diffraction (PXRD), and small-angle X-ray scattering (SAXS). SEM images of the dry gel revealed a network of interwoven nanofibers (diameter 12-60 nm, length > 5 μm). Intermolecular π-π interactions between the [(tBu 3tpy)PtC≡C] moieties could be deduced from the variable 1H NMR spectra. The PXRD and SAXS data showed that the assembly of the gelator could be represented by a rectangular 2D lattice of 68 Å x 14 Å. The ability of the complex to gelate a number of organic solvents is most likely due to intermolecular π-π interactions between the [(tBu 3tpy)PtC≡C] moieties. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.