A codimerization of styrene and ethene can be carried out continuously in a nanofiltration membrane reactor with dendritic Pd complexes such as 1. The selectivity of the reaction is increased considerably under continuous conditions. The activity and selectivity of monomeric model complexes and the dendritic catalysts were compared in batch reactions.

The zeroth (Si{(CH2)3SiMe2(C6H4CH2OC(O)CMe2Br)}4), 2, and first (Si{(CH2)3Si((CH2)3-SiMe2(C6H4CH2OC(O)CMe2Br))3}4), 3, generation of 2-bromoisobutyryl functionalized carbosilane dendrimers have been successfully applied as initiators for the copper(I) bromide/N-(n-octyl)-2-pyridylmethanimine-mediated living-radical polymerization of methyl methacrylate. The overall rate of polymerization are comparable for the two dendritic initiators studied, 2 (3.4 × 10 -5 mol L -1 s -1 ) and 3 (4.8 × 10 -5 mol L -1 s -1 ) with the benzylic model compound C6H5CH2OC(O)CMe2Br ( 1) showing a lower rate of polymerization for both dendritic initiators, (7.3 × 10 -5 mol L -1 s -1 ) where [initiator sites] ) 1.87 × 10 -2 mol L -1 . We postulate that this is caused by initial intramolecular termination. The molecular weight distribution is less than 1.3 after 3 h reaction time. Initiator 3, however, produces star-star coupling throughout the polymerization. When the dendritic periphery is partialy functionalized (statistically two and six arms of the first generation dendrimer, respectively, 4 and 5) the control of the molecular weight distribution was lost (PDI > 3) for 4 as a result of too low of a value for [initiator site], i.e., 3.12 × 10 -3 mol L -1 .

Different sizes of core-functionalized metallodendritic wedges were prepared by anchoring sensor-active arylplatinum(II) sites at the focal point of Fréchet-type polyether dendritic wedges of various generations. The strong color of these metallodendrimers in the presence of SO2 was used to assess the permeability of nanofiltration membranes (molecular weight cut-off of 400 dalton) at ambient pressure. A primary result of these studies is that dendrimers do not have to be exceptionally large for successful retention. Hence, nanofiltration, membrane-capped. immersion vials were developed, which operate as sensor devices when loaded with metallodendrimers with good retention properties. Appropriate substitution of the dye site at the focal point of these metallodendritic wedges by a catalytically active group afforded dendritic catalysts that exhibit essentially the same physical properties (shape, retention) as the corresponding dyefunctionalized dendritic wedges. When this homogeneous catalyst is compartmentalized in membrane-capped vials, a unique and convenient method for its retrieval from product solutions is available. Moreover, such immobilized metallodendritic catalysts can be regenerated and stored for months without losing their activity; this provides access for the development of novel sustainable homogeneous catalysts.