We report the stereospecific ring-opening metathesis polymerization (ROMP) of endodicyclopentadiene (DCPD) by various well-defined molybdenum-based and tungsten-based alkylidene initiators. Tungsten MAP (MonoAryloxide Pyrrolide) initiators with the general formula W(X)(CHCMe 2 Ph)(Me 2 Pyr)(OAr) (X = arylimido, alkylimido, or oxo; Me 2 Pyr = 2,5dimethylpyrrolide; OAr = an aryloxide) yield cis,syndiotactic-poly(DCPD), while biphenolate alkylidene complexes with the general formula M(NR)(CHCMe 2 Ph)(biphen) (M = Mo or W; R = alkyl or aryl, biphen = (e.g.) 3,3′-(t-Bu) 2 -5,5′-6,6′-(CH 3 ) 4 -1,1′-biphenyl-2,2′-diolate) yield cis,isotactic-poly(DCPD). Subtle changes in the initiator can greatly alter the structure of the poly(DCPD)s that are formed. Cis,syndiotactic or cis,isotactic poly(DCPD)s (made with 50-1000 equiv of DCPD) are accessible within seconds to minutes in dichloromethane at room temperature. No isomerization or cross-linking reactions are observed, and addition of a chain transfer reagent (1-hexene) or the use of THF as a solvent does not decrease the stereospecificity of the polymerizations. Cis,syndiotactic and cis,isotactic poly(DCPD)s can be distinguished readily from each other by 13 C NMR spectroscopy. Hydrogenation of each stereoregular poly(DCPD) produces crystalline H-poly(DCPD)s that have melting points between 270 and 290 °C.

In this paper we report the synthesis of >98% cis,isotactic and cis,syndiotactic polynorbornene (poly(NBE)) and poly(endo,anti-tetracyclododecene) (poly(TCD)). Cis,isotactic poly(NBE) and poly(TCD) were prepared employing Mo-based biphenolate imido alkylidene initiators, Mo(NR)(CHCMe2Ph)(Biphen)

Intracellular uptake of nanoparticles is highly interesting for labeling of cells, drug delivery, or non-viral gene delivery. In this study we have synthesized a wide variety of poly(alkyl methacrylate) nanoparticles with the same size and investigated their uptake into cells. The nanoparticles were prepared from alkylmethacrylates with different linear and branched ester chains as well as from benzylmethacrylate using the miniemulsion polymerizaiton technique. By adding a fluorescent dye as a marker, the internalization of the nanoparticles could be investigated quantitatively with flow cytometry and qualitatively with confocal laser scanning microscopy. With increasing side chain of the ester and therefore increasing hydrophobicity and at glass transition temperature (T(g)), below the incubation temperature of 37 degrees C the uptake of the nanoparticles into cells is favored.

A dicationic ruthenium-alkylidene complex [Ru(dmf)(3)(IMesH(2))(=CH-2-(2-PrO)-C(6)H(4))][(BF(4))(2)] (1; IMesH(2) =1,3-dimesitylimidazolin-2-ylidene) has been prepared and used in continuous metathesis reactions by exploiting supported ionic-liquid phase (SILP) technology. For these purposes, ring-opening metathesis polymerization (ROMP)-derived monoliths were prepared from norborn-2-ene, tris(norborn-5-ene-2-ylmethyloxy)methylsilane, and [RuCl(2)(PCy(3))(2)(CHPh)] (Cy=cyclohexyl) in the presence of 2-propanol and toluene and surface grafted with norborn-5-en-2-ylmethyl-N,N,N-trimethylammonium tetrafluoroborate ([NBE-CH(2)-NMe(3)][BF(4)]). Subsequent immobilization of the ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BDMIM][BF(4)]), containing ionic catalyst 1 created the SILP catalyst. The use of a second liquid transport phase, which contained the substrate and was immiscible with the IL, allowed continuous metathesis reactions to be realized. High turnover numbers (TONs) of up to 3700 obtained in organic solvents for the ring-closing metathesis (RCM) of, for example, N,N-diallyltrifluoroacetamide, diethyl diallylmalonate, diethyl di(methallyl)malonate, tert-butyl-N,N-diallylcarbamate, N,N-diallylacetamide, diphenyldiallylsilane, and 1,7-octadiene, as well as in the self-metathesis of methyl oleate, could be further increased by using biphasic conditions with [BDMIM][BF(4)]/heptane. Under continuous SILP conditions, TONs up to 900 were observed. Due to the ionic character of the initiator, catalyst leaching into the transport phase was very low (<0.1 %). Finally, the IL can, together with decomposed catalyst, be removed from the monolithic support by flushing with methanol. Upon reloading with [BDMIM][BF(4)]/1, the recycled support material again qualified for utilization in continuous metathesis reactions.

Partial bromination or epoxidation has been used to prove the tacticities of several stereoregular polymers made through ROMP methods with well-defined Mo or W initiators. Tacticities were proven for cis,isotactic and cis,syndiotactic poly(norbornene), poly(3-methyl-3phenylcyclopropene), and poly(endo,anti-tetracyclododecene). Various limitations can prevent application of these proofs in general to stereoregular polymers prepared through ROMP.

A novel ionic metathesis catalyst, [Ru(1‐CH3‐4‐CO2Py+)2(IMesH2)(CH‐2‐{2‐PrO}‐5‐NO2C6H3)][OTf−]2 (3 b; IMesH2=1,3‐dimesitylimidazolin‐2‐ylidene, Py=pyridine), has been prepared. 3 b and the Grubbs–Hoveyda catalysts [Ru(1‐CH3‐4‐CO2Py+)2(IMesH2)(CH‐2‐{2‐PrO}C6H4)][OTf−]2 (3 a) and [RuCl(1‐CH3‐4‐CO2Py+)(IMesH2)(CH‐2‐{2‐PrO}C6H4)][OTf−] (5 a) were used for ring‐opening metathesis polymerization (ROMP) reactions under both homogeneous and biphasic liquid–liquid conditions by using the ionic liquid 1‐butyl‐2,3‐dimethylimidazolium tetrafluoroborate ([BDMIM+][BF4−]) and toluene. All catalysts were active in the ROMP of norborn‐2‐ene‐based monomers, with cis‐cyclooctene and dicyclopentadiene providing good yields under homogeneous conditions and complex 5 a the most active catalyst. With all catalysts, the use of a chain transfer agent (CTA) allowed for the synthesis of polymers with low metal contents between 10 and 80 ppm, corresponding to a ruthenium removal of 98–99.8 % without any additional purification step. In addition, the use of a CTA allowed for recycling experiments under biphasic conditions, in which 3 a and 5 a were particularly active for several cycles.

The reactivity of the dicationic Ru–alkylidene complex [Ru(DMF)3(IMesH2)(—CH—2—(2—PrO)—C6H4)]2+(BF4−)2] (1, IMesH2 = 1,3‐dimesitylimidazolin‐2‐ylidene) in the ring‐opening metathesis polymerization (ROMP) of various functional norborn‐2‐enes as well as in the cyclopolymerization of different 1,6‐heptadiynes is reported. Due to its dicationic character, complex 1 is highly electrophilic and possesses high reactivity towards alkenes and 1,6‐heptadiynes. Generally, a pronounced difference in reactivity between monomers bearing coordinating groups and those that lack such moieties is observed. In the presence of ionic monomers containing coordinating anions such as Br− and I−, a rapid change in the nature of the propagating alkylidene from a dicationic to a neutral one is observed.

The synthesis of the novel ionic Ru–alkylidenes [Ru[(4‐CO2)(1‐CH3)Py+)]2(IMesH2)(CH‐2‐(2‐PrO)‐C6H4)][OTf−]2 (1, IMesH2=1,3‐dimesitylimidazolin‐2‐ylidene, Py=pyridine, OTf−=triflate) and [RuCl[(4‐CO2)(1‐CH3)Py+)](IMesH2)(CH‐2‐(2‐PrO)‐C6H4)][OTf−] (2) is reported. Catalysts 1 and 2 were successfully used in various metathesis reactions under biphasic liquid–liquid conditions using 1‐butyl‐2,3‐dimethylimidazolium tetrafluoroborate and heptane as liquid phases. Ruthenium leaching into the heptane phase was very low (<0.4 %), translating into Ru contamination of the products between 0.3 and 2.5 ppm. Both 1 and 2 exhibited comparable reactivity in organic solvents and under biphasic conditions. Catalyst 1 and 2 were also successfully used in the continuous metathesis of methyl oleate and 1,7‐octadiene under supported liquid–liquid conditions. Finally, the disproportionation of the monocarboxylato monochloro substituted Ru–alkylidene 2 was traced by 1H NMR analysis at 40 °C, thereby demonstrating the formation of complex 1 and the neutral complex [RuCl2(IMesH2)(CH‐2‐(2‐PrO)‐C6H4)].