A meso-tetraaryl ruthenium porphyrin complex having four polymerizable vinylbenzoxy groups (2) has been synthesized by reaction of pyrrole with 4-(vinylbenzoxy)benzaldehyde and subsequent metalation with [Ru3(CO)12]. The porphyrin complex was immobilized by copolymerization with ethylene glycol dimethacrylate. The resulting polymer P2 was found to catalyze the oxidation of alcohols and alkanes with 2,6-dichloropyridine N-oxide without activation by mineral acids. Under similar conditions, the homogeneous catalyst 2 was completely inefficient. By using diphenylaminomethane and 1-aminoadamantane as coordinatively bound templates during the polymerization procedure, the molecularly imprinted polymers P3 and P4 have been synthesized. Compared with the polymer P2, the imprinted catalysts displayed a significantly increased activity with rate enhancements of up to a factor of 16.

An [(arene)RuCl 2 ] 2 complex with a methacrylate side chain (2) has been prepared in two steps using commercially available starting materials. This complex reacts with PPh 3 , pyridine, or toluidine to give the corresponding mononuclear adducts (3-5). The structure of 4 was determined by single-crystal X-ray diffraction. Complex 2 and the PPh 3 adduct 3 were immobilized by copolymerization with divinylbenzene (DVB) or ethyleneglycol dimethacrylate (EGDMA). The resulting EGDMA copolymer was tested as a catalyst in asymmetric transfer hydrogenations. Using (1R,2R)-(-)-N-p-tosyl-1,2-diphenylethylenediamine as the chiral ligand and azeotropic NEt 3 /HCO 2 H as the reducing agent, aromatic ketones were converted to the corresponding alcohols with selectivities between 87 and 97% ee.

A series of [n]dendralenes (n 3, 4, 8, 3b ± d (Fig. 1)) expanded with buta-1,3-diynediyl moieties between the CC bonds were prepared by repetitive acetylenic scaffolding of 3-(cyclohexylidene)penta-1,4-diyne building blocks (Scheme). These remarkably unstable iso-poly(triacetylene) (iso-PTA) oligomers were characterized by 1 H-and 13 CÀNMR ( Fig. 3 and Table 1), IR, and UV/VIS (Figs. 4 and 6 and Table 2) spectroscopy, as well as mass spectrometry (Fig. 2). The expanded [8]dendralene contains 40 C(sp)-and C(sp 2 )-atoms in the backbone and represents the longest iso-PTA oligomer prepared to date. HOMO-LUMO Gap energies were determined as a function of oligomeric length ( Fig. 5 and Table 3), providing insight into the degree of p-electron delocalization in these cross-conjugated chromophores. A continous drop in the HOMO-LUMO gap with increasing number of monomeric repeating units provides evidence that cross-conjugation along the oligomeric backbone is effective to some extent. The limiting HOMO-LUMO gap energy for an infinitely long, buta-1,3-diynediyl-expanded dendralene was extrapolated to about 3.3 ± 3.5 eV. The conformational preferences of the expanded dendralenes were analyzed in semi-empirical calculations, revealing energetic preferences for planar or slightly twisted s-cis and −U-shaped× geometries.1. Introduction. ± Dendralenes are polyene hydrocarbons in which CC bonds are aligned in a cross-conjugated arrangement [1a]. This requires the presence of at least three CC bonds, and the simplest dendralene, therefore, is 3-(methylidene)penta-1,4-diene (a [3]dendralene). Novel synthetic approaches to dendralenes are currently being developed [1d,e], and these chromophores are increasingly investigated for their structural, electronic, and advanced materials properties [1]. Upon insertion of one or more acetylene units between the CC bonds, series of expanded dendralenes are obtained (Fig. 1). Diederich and co-workers [2] reported in 1995 the synthesis of the iso-poly(triacetylene)s 1a ± d by acetylenic scaffolding starting from appropriate tetraethynylethene (TEE, 3,hex-3-ene-1,5-diyne) precursors. Compounds 1c and 1d in this series are the first examples of expanded dendralenes, with buta-1,3-diynediyl bridges inserted between the CC bonds. More recently, Tykwinski and coworkers [3] introduced a new class of expanded dendralenes 2c ± i with the isopoly(diacetylene) backbone, featuring ethynediyl spacers between the CC bonds (the names iso-poly(diacetylene) (iso-PDA) and iso-poly(triacetylene) (iso-PTA) were introduced by Tykwinski and co-workers [3b]). In addition to compounds 2a ± i, with peripheral isopropylidene moieties, derivatives with peripheral cyclohexylidene and adamantylidene fragments were also reported [3d].

A ruthenium meso-tetra [4-(vinylbenzoxy)benzyl]porphyrin catalyst with four polymerizable side chains was synthesized in three steps from commercially available starting materials. The polymerizable side chains allowed the incorporation of this complex in highly cross-linked mesoporous co-polymers. A block polymer and a molecularly imprinted polymer were prepared by co-polymerization with ethyleneglycol dimethacrylate using chloroform as the porogen. The imprinted polymer was prepared in the presence of aminodiphenylmethane as a template. Subsequent removal of the template created a substrate pocket next to the catalytically active center. Both polymers displayed a high catalytic activity for the oxidation of alcohols and alkanes with 2,6-dichloropyridine-N-oxide as the oxidant while the homogeneous catalyst was completely inactive. Furthermore, the imprinted polymer displayed a significant increase in activity compared to the block co-polymer.

A ruthenium porphyrin catalyst with styrene side chains was incorporated into a highly cross-linked polymer by co-polymerization with ethylene glycol dimethacrylate in the presence of a chloroform porogen. Oxidation reactions catalyzed by the resulting polymer were accelerated when perfluoromethylcyclohexane (PFMC) was used as a cosolvent. Moreover, the PFMC co-solvent was found to change the substrate selectivity of the catalytic reactions. Both effects could be explained by a PFMCinduced partitioning of substrates and oxidant into the polymeric, catalyst containing matrix.