A series of new dispiro[fluorene-9',6,9'',12-indeno[1,2b]fluorenes] (DSF-IFs) has been synthesised. These new building blocks for blue-light-emitting devices and electroactive polymers combine indenofluorene (IF) and spirobifluorene (SBF) properties. We report here our synthetic investigations towards these new structures and their thermal, structural, photophysical and electrochemical properties. These properties have been compared to those of IF and SBF. We also report the anodic oxidation of DSF-IFs that leads to the formation of non-soluble transparent three-dimensional polymers. The structural and electrochemical behaviour of these polymers has been studied. The first application of these building blocks as new blue-light-emitting materials in organic light-emitting diodes (OLED) is also reported.

[reaction: see text] A series of new dispiro[fluorene-9',6,9' ',12-indeno[1,2b]fluorenes] (DSFIFs) that combine indenofluorene (IF) and spirobifluorene (SBF) architectural specificities have been prepared. Their anodic oxidations lead to the formation of nonsoluble transparent polymers. The photophysical and electrochemical properties of these new molecules have been evaluated for further blue OLED applications.

Since their first isolation by Arduengo and co-workers in 1991, N-heterocyclic carbenes (NHCs) have been widely used as versatile ligands in organometallic chemistry and homogeneous catalysis.[1] Due to their strong s-donor characteristics, these compounds are known to form robust transition-metal complexes. As a consequence, the use of NHCs as ligands allows the synthesis of highly functionalised organometallic complexes that combine catalytic properties of the metal center with a variety of other functional group properties.[2] The stability of NHC carbene complexes has attracted our interest from the viewpoint of catalyst immobilisation, where loss of functional metal sites from the construct by metal leaching should be minimal.We and others have previously proven the utility of carbosilane [3] and polycationic dendrimers [4] as supports for the immobilisation of transition-metal complexes through covalent and non-covalent attachment, respectively. In particular, the use of polycationic dendrimers allows the easy (reversible) loading of dendrimers with larger numbers of functional molecules and renders the synthesis of catalytically active and recoverable dendritic assemblies feasible. Following these investigations we have turned our attention to the synthesis of functionalised NHC complexes that are suitable for the preparation of non-covalently immobilised homogeneous catalysts. Here, we report on the development of an in situ transmetallation-immobilisation strategy for the construction of non-covalent NHC-metallodendrimers starting from a common polycationic dendrimer in combination with an anion-tethered NHC ligand and different metal precursors.The zwitterionic imidazolium 1 was synthesised in a single-step procedure by nucleophilic addition of mesityl imidazole to 1,4-butane sultone (Scheme 1) and was obtained in excellent yield.[5] Treatment of 1 with an excess of Ag 2 O in acetonitrile at reflux temperature for 6 h resulted in the formation of the corresponding bis-carbene silver complex 2, which was isolated in 87 % yield. H} NMR spectroscopy confirmed coordination of silver to the ligand by the presence of a typical signal at d = 180.2 ppm for the C 2 carbon. Single crystals of complex 2 suitable for X-ray structure determination were grown by slow evaporation of a solution of 2 in dichloromethane/benzene. The molecular structure shows that 2 is a bis(imidazol-2-ylidene)silver complex, in which a linear Ag bis-carbene fragment is present (C11-Ag1-C12 178.55(14)8; Figure 1).[10] The silver-carbon bond lengths (range 2.073-2.083 , the individual s.u.s are 0.004 ) in this moiety are consistent with those reported in literature, which are normally found in the range of 2.067-2.117 for bis-carbene silver complexes with non-coordinating anions.[6b]The overall charge neutrality in crystals of 2 is achieved by way of a second silver ion (Ag2). This counterion is bound to three sulfonate groups from three different Agbis-carbene moieties through AgÀO bridges to form one-dimensional (1D) polymeric chains al...