No abstract

A novel approach is developed to address the requirement of multiple stamps and inks for microcontact printing (microCP) onto different substrate surfaces. This approach relies on microCP one divalent molecule, which is able to form Janus self-assembled monolayers (JSAMs) with a labile cleavable centre, thus providing a facile method for the chemical derivatization of different substrate surfaces. This study presents an answer to the challenges presented within a highly versatile application, microCP. N-(3-diethylphosphatoxy)propyl-11-mercaptoundecanamide is used for the first time as an ink for microCP onto both gold and titanium oxide surfaces, utilizing the same polydimethylsiloxane stamp. Following printing, the JSAMs are enzymatically treated on these two different substrates to reveal different functional groups. The newly formed surfaces are subjected to additional surface reactions and used for the chemisorption of bovine serum albumin. At each stage, these JSAMs are characterized by X-ray photoelectron spectroscopy and dynamic water-contact-angle measurements. Confocal laser scanning microscopy is used for the characterization of the adsorbed proteins.

Summary: We report the synthesis, characterisation and photophysical properties of mixed alkyl‐ and alkoxy‐substituted poly[(phenylene ethynylene)‐alt‐(phenylene vinylene)] hybrid polymers with the general constitutional unit: (PhCCPhCCPhCHCHPhCHCH)n (7). The polymers were obtained through the Horner‐Wadsworth‐Emmons olefination reaction of alkyl‐substituted luminophoric dialdehydes, 5a–b, and alkoxy‐substituted bisphosphonates. Contrary to their alkoxy‐substituted congeners, 10a–b, which exhibit solution fluorescence quantum yields close to unity, dialdehydes (5a–b) fluoresce poorly at room temperature, but show phosphorescence at 77 K. High molecular weight polymers were obtained showing poor solubility compared to solely alkoxy‐substituted polymers (11) of the same backbone constitutional units. The presence of alkyl side groups in 7 leads to a 15 nm blue shift of their absorption spectra relative to 11. Both types of polymers show however identical emission spectra with only a slight blue shift (3–4 nm) of the emission peak of 7 relative to 11. This clearly proves that the chromophore system responsible for the emission in both types of compounds is located around the lower‐energy, alkoxy‐substituted phenylene‐vinylene portion of the polymers as confirmed by fluorescence kinetics investigations. magnified image

Self-assembled monolayers (SAMs) of N-(3-diethylphosphatoxy)propyl-11-mercaptoundecanamide (PPMA) were prepared on gold surfaces. The SAMs, consisting originally of a phosphonate surface functionality, were subjected to step-by-step acidic hydrolysis to reveal two different functional groups: (a) a hydroxyl and (b) a carboxylic group. At each stage these SAMs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and water contact angle measurements. To our best knowledge, for the first time a methodical approach was used to obtain three different surface functionalities from one type of molecule on the surface of gold. These SAMs could provide a novel approach for conducting high-throughput investigations, for instance for cell adhesion. The present study contributes toward the understanding of reactions at interfaces as it demonstrates the influence of step-by-step hydrolysis on SAMs.

Back Cover: The Cover shows the absorption and emission spectra of alkyl-and alkoxysubstituted dialdehydes, and their respective poly[(phenylene ethynylene)-alt-(phenylene vinylene)] hybrid polymers, obtained by the polycondensation of the dialdehydes with alkoxy-substituted bisphosphonates. Photophysical investigations and quantum chemical calculations reveal remarkable differences between alkyl-and alkoxy-substituted dialdehydes. On the contrary, their polymers exhibit similar photophysical properties, indicating an identical fluorophore system located around the lower energy phenylene-vinylene segment of the polymers.Further details can be found in the Full Paper by D. A. M. Egbe,* S. Sell, C. Ulbricht, E. Birckner, and U.-W. Grummt on page 2105.