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[en] This paper presents results of several years of experimental and theoretical work on a library of oligo(ethylene glycol)-containing self-assembled monolayers (OEG SAMs) on gold. The library consists of 15 different thiol compounds, which all contain alkyl and OEG portions of different length, as well as amide moieties forming a stabilizing lateral hydrogen bonding network. We have investigated the quality, conformation, orientation, defect structure and infrared (IR) signatures of these OEG SAMs prepared by spontaneous adsorption from dilute solutions. It is shown that solution concentration and incubation time are important factors to obtain high quality SAMs, in particular for those containing long OEG chains. Further on, the thiol compounds should contain a sufficiently long alkyl spacer to provide in plane van der Waals interactions strong enough to govern the formation of a densely packed alkylthiolate overlayer on the Au(1 1 1) surface. Such a highly ordered alkyl support, which is additionally stabilized by the lateral hydrogen bonds, enables us to vary the length of the terminal OEG portion from 1 to at least 12, without affecting the integrity and conformational characteristics of the supporting (alkyl) part of the SAM. Also, we discuss the importance of appropriate modeling tools to advance the understanding of IR signatures of the OEG SAMs. Finally, we demonstrate the generality of our 'modular approach' by analyzing the structure of OEG SAMs formed by compounds extended with an additional terminal amide and an alkyl tail. Thus, the SAMs discussed herein provide an attractive platform for construction of advanced nanoarchitectures on surfaces, not only limited to biomaterials and fouling applications.
[en] In order to reduce the photosensitivity of scintillator fluids, stabilizing organic compounds of bivalent sulfur are added. A mercaptan whose dissociation constant is higher than that of phenol is a suitable substance. (DG)
[de]Um die Lichtempfindlichkeit der Szintillator-Fluessigkeiten herabzusetzen, werden ihnen stabilisierende organische Verbindungen des zweiwertigen Schwefels zugegeben. Geeignet ist ein Mercaptan, dessen Dissoziationskonstante groesser ist als jene des Phenols. (DG)
[en] Synthesis of 2-alkylaminoethanethiols with a tertiary group fixed to the nitrogen atom has been achieved. A very convenient method of access to such 2-alkylaminoethanethiols with one, two, and three allyl substituents is the reaction between allylic organomagensium compounds and thiazolidines, 2-alkylthiazolines, and 2-methylthiothiazolines respectively
[en] Poly(vinyl chloride) (PVC) is one of the most important medical plastics. Recently, however, the safety of flexible PVC containing the common plasticizer, di(2-ethylhexyl) phthalate, has been called into question. Widely used heat stabilizers for PVC that incorporate toxic heavy metals also have fallen into disfavor. In order to address these problems, we have synthesized and tested, as potential replacements, several organic thiols that contain one or more carboxylate ester functions and thus are highly compatible with the polymer. When introduced into PVC at high loading levels (e.g., 30-35 parts by weight), the ester thiols are extremely effective as heat stabilizers and also useful as primary plasticizers. When used at a low loading level (e.g., 3 parts by weight), they still are excellent heat stabilizers for both plasticized and rigid PVC. Importantly, their high potency is achieved in the absence of any costabilizers that incorporate heavy metals. Their syntheses are simple and straightforward, and their odors are not offensive, because their volatilities are low. Described here are some typical results obtained with this new additive technology, which was licensed for commercialization in 2005