Electroorganic reactions. Part 55.† Quinodimethane chemistry. Part 3. Transition metal complexes as inter- and intra-molecular redox catalysts for the electrosynthesis of poly(p-xylylene) (PPX) polymers and oligomers‡

Janssen, Robert G.; Utley, James H. P.; Carré, Emmanuelle; Simon, Evelyne; Schirmer, Heike

doi:10.1039/b103274g

Cited by 7 publications

(4 citation statements)

References 27 publications

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“…In recent years several groups have collected data and provided relevant insights into the dynamics of intermolecular DETs, as recently reviewed. ,,,,11b On the other hand, less information is available on the corresponding intramolecular processes. Indeed, interesting results and analyses of the decay of radical anions occurring by fragmentation of a σ bond have been published. ,,,11b,− Except for a few systems, − however, the antibonding orbital initially hosting the electron (most often a π* orbital) is often very strongly coupled to the σ* orbital of the cleaving bond, which makes the description of the overall process in terms of electron uptake followed by intramolecular π* → σ* ET as not quite realistic . On the other hand, it is well known that fascinating results have been obtained in the area of intramolecular nondissociative ETs, leading to the building of a sound experimental−theoretical framework to understand how electrons are transferred through bonds and space. 1c, This knowledge was reached by using well-devised D−Sp−A molecular systems, in which a donor (D) and an acceptor (A) are spatially separated by a spacer (Sp) having specifically tailored properties.…”

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confidence: 99%

Insights into the Free-Energy Dependence of Intramolecular Dissociative Electron Transfers

et al. 2002

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To study the relationship between rate and driving force of intramolecular dissociative electron transfers, a series of donor-spacer-acceptor (D-Sp-A) systems has been devised and synthesized. cis-1,4-Cyclohexanedyil and a perester functional group were kept constant as the spacer and acceptor, respectively. By changing the aryl substituents of the phthalimide moiety, which served as the donor, the driving force could be varied by 0.74 eV. X-ray diffraction crystallography and ab initio conformational calculations pointed to D-Sp-A molecules having the cis-(cyclohexane) equatorial(phthalimido)-axial(perester) conformation and the same D/A orientation. The intramolecular dissociative electron-transfer process was studied by electrochemical means in N,N-dimethylformamide, in comparison with thermodynamic and kinetic information obtained with models of the acceptor and the donor. The intramolecular process consists of the electron transfer from the electrochemically generated phthalimide-moiety radical anion to the peroxide functional group. The electrochemical analysis provided clear evidence of a concerted dissociative electron-transfer mechanism, leading to the cleavage of the O-O bond. Support for this mechanism was obtained by ab initio MO calculations, which provided information about the LUMO of the acceptor and the SOMO of the donor. The intramolecular rate constants were determined and compared with the corresponding intermolecular values, the latter data being obtained by using the model molecules. As long as the effective location of the centroid of the donor SOMO does not vary significantly by changing the aryl substituent(s), the intramolecular dissociative electron transfer obeys the same main rules already highlighted for the corresponding intermolecular process. On the other hand, introduction of a nitro group drags the SOMO away from the acceptor, and consequently, the intramolecular rate drops by as much as 1.6 orders of magnitude from the expected value. Therefore, a larger solvent reorganization than for intermolecular electron transfers and the effective D/A distance and thus electronic coupling must be taken into account for quantitative predictions of intramolecular rates.

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confidence: 99%

Insights into the Free-Energy Dependence of Intramolecular Dissociative Electron Transfers

et al. 2002

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“…Symmetric macrocyclic ligands containing two tetradentate salen coordination sites formed from trans ‐1,2‐diaminocyclohexane, and the corresponding mono‐ and dinuclear nickel( II ) complexes, have been reported 24. With trans ‐1,2‐diaminocyclohexane as the Schiff base counterpart, dissymmetric macrocyclic structures incorporating one nickel( II ) salen unit, which acts as an intramolecular redox catalyst, and a 1,4‐bis(chloromethylarene) function have been prepared by a multistep synthesis 25. A macrocyclic compound characterized by the presence of a salen–uranyl moiety opposite a pyridine group and linked by oxyethyl chains has been reported 23.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of a Novel Heteroditopic Macrocyclic System – Monometallic Nickel(II) and Uranyl Complexes and Their Corresponding Heterobimetallic Carbonylrhodium(I) Complexes

et al. 2006

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A novel heteroditopic macrocyclic ligand system for selective coordination of two different transition metal ions has been obtained in the form of monometallic salen complexes of Ni II (LNi, 1) and uranyl (LUO 2 , 2). The system is characterized by the presence of a dianionic, tetradentate salen donor system (N 2 O 2 ) derived from cis-1,2-diaminocyclohexane and of a neutral, tridentate 2,6-bis(alkylthiomethyl)pyridine group (NS 2 ). The two binding sites are connected by two oxyethyl chains. The synthetic procedure involves the coupling of the disodium salt of 2,6-bis(mercaptomethyl)pyridine with two equivalents of 3-(2-bromoethoxy)-2-(2-propenyloxy)benzaldehyde. Removal of the protecting allyl groups from the reaction product (I) by palladium catalysis yields the ligand synthon 2,6-bis[2-(3-formyl-2-hydroxyphenyl)oxyethyl]thiomethylpyridine (II). The monometallic macrocyclic complexes 1 and 2, obtained by metal-templated synthesis from cis-1,2-diaminocyclohexane, ligson II, and the corresponding Ni II or

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“…It started with the heterofunctionalization of TEG to form the monotosyl derivative 6, which was obtained purified in a yield of 54 %. [32] Conversion of 6 to the respective phthalimide derivative 7 could be performed at higher temperatures and shorter reaction times than conversion of 4 to 5 up to a maximum yield of 27 %. Tosylation of the remaining hydroxyl group afforded 5 in 56 % yield.…”

Section: Synthesismentioning

confidence: 99%

“…Column chromatography using ethyl acetate as eluent gave 6 as a colourless oil (17.6 g, 54 %). 1 (7): [32] Compound 6 (6.6 g, 18.9 mmol) and phthalimide potassium salt (6.3 g, 19.5 mmol) were placed in a dry flask and DMF (60 mL) was added. The mixture was heated to 80 8C during 18 h. DMF was distilled off (at 5 10 À2 mbar) and the residue was taken up in ethyl acetate (125 mL), washed with 1 n HCl (2 50 mL) and saturated NaHCO 3 solution (2 30 mL), and dried over anhydrous sodium sulphate.…”

Section: -{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}ethylmentioning

confidence: 99%

Photoactive Branched and Linear Surface Architectures for Functional and Patterned Immobilization of Proteins and Cells onto Surfaces: A Comparative Study

Stegmaier¹,

Campo²

2009

ChemPhysChem

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Molecular architecture affects the properties of surface layers. Photosensitive silanes with branched architectures allow patterning and coupling of proteins and cells on surfaces while maintaining their biofunctional state. Attachment can be directed to the activated regions of irradiated substrates with high selectivity (see image of mouse fibroblasts). Novel photosensitive silanes with a branched molecular architecture combining three end-functionalized oligoethylene glycol (OEG) and alkyl arms are presented. These molecules are synthesized and applied to the modification of silica surfaces. The resulting layers are tested in their ability for the selective, patterned and functional immobilization of proteins and cells. The results demonstrate and accurately quantify the benefits of branched OEG structures against linear analogues for preventing non-specific interactions with the biological material. Linear structures guarantee high selectivity for the attachment of proteins, however, they fail in the case of cells. Branched structures provide good antifouling properties in both cases and allow the formation of protein patterns with higher densities of the target protein, as well as cell patterns. The results demonstrate the careful balance between surface functionality, composition and architecture that is required for maximizing the performance of any surface-based assay in biology.

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Electroorganic reactions. Part 55.† Quinodimethane chemistry. Part 3. Transition metal complexes as inter- and intra-molecular redox catalysts for the electrosynthesis of poly(p-xylylene) (PPX) polymers and oligomers‡

Cited by 7 publications

References 27 publications

Insights into the Free-Energy Dependence of Intramolecular Dissociative Electron Transfers

Insights into the Free-Energy Dependence of Intramolecular Dissociative Electron Transfers

Synthesis and Characterization of a Novel Heteroditopic Macrocyclic System – Monometallic Nickel(II) and Uranyl Complexes and Their Corresponding Heterobimetallic Carbonylrhodium(I) Complexes

Photoactive Branched and Linear Surface Architectures for Functional and Patterned Immobilization of Proteins and Cells onto Surfaces: A Comparative Study

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