The formation of the conductive TTF‐TCNQ (tetrathiafulvalene–tetracyanoquinodimethane) charge‐transfer salt via rupture of microencapsulated solutions of its individual components is reported. Solutions of TTF and TCNQ in various solvents are separately incorporated into poly(urea‐formaldehyde) core–shell microcapsules. Rupture of a mixture of TTF‐containing microcapsules and TCNQ‐containing microcapsules results in the formation of the crystalline salt, as verified by FTIR spectroscopy and powder X‐ray diffraction. Preliminary measurements demonstrate the partial restoration of conductivity of severed gold electrodes in the presence of TTF‐TCNQ derived in situ. This is the first microcapsule system for the restoration of conductivity in mechanically damaged electronic devices in which the repairing agent is not conductive until its release.

We report the use of microcapsules containing suspensions of polymer-stabilized carbon nanotubes and/or graphene flakes for the autonomic restoration of conductivity in fractured gold lines. Multilayered samples were prepared in which microcapsules were embedded in layers of epoxy above and below a glass slide patterned with gold lines. Upon sample fracture, conductivity was lost as a crack formed in the gold line. Simultaneous release of carbon nanotubes and/or graphene suspensions from capsule cores restored conductivity in minutes. We suggest a healing mechanism in which the released carbon nanomaterials bridge gaps in the gold lines. V

The oxidation products of selenomethionine (SeMet) have been studied via experimental (77)Se NMR and theoretical (77)Se chemical shifts. Four signals are observed: a diastereomeric pair of selenoxides at 840 ppm and two unidentified resonances at 703 and 716 ppm. Theoretical DeltaG and chemical shifts suggest the 703 and 716 ppm resonances correspond to hypervalent selenium heterocycles, called selenuranes, formed by reaction with the amine or acid group of the amino acid and the selenoxide. To identify which of these selenuranes is formed, the amine and acid groups were individually protected. The N-formyl SeMet formed only the selenoxide pair at 840 ppm. The oxidized SeMet methyl ester produced signals at 703 and 716 ppm which are assigned as the Se-N selenurane.

A method for fabricating chemical gradients on planar and nonplanar substrates using grayscale lithography is reported. Compliant grayscale amplitude masks are fabricated using a vacuum‐assisted microfluidic filling protocol that employs dilutions of a carbon‐black‐containing polydimethylsiloxane emulsion (bPDMS) within traditional clear PDMS (cPDMS) to create planar, fully self‐supporting mask elements. The mask is then placed over a surface functionalized with a hydrophobic coumarin‐based photocleavable monolayer, which exposes a polar group upon irradiation. The mask serves to modulate the intensity of incident UV light, thereby controlling the density of molecules cleaved. The resulting molecular‐level grayscale patterns are characterized by condensation microscopy and imaging mode time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS). Due to the inherent flexibility of this technique, the photofuse as well as the gradient patterns can be designed for a wide range of applications; in this paper two proof‐of‐concept demonstrations are shown. The first utilizes the ability to control the resulting contact angle of the surface for the fabrication of a passive pressure‐sensitive microfluidic gating system. The second is a model surface modification process that utilizes the functional groups deprotected during the photocleavage to pattern the deposition of moieties with complementary chemistry. The spatial layout, resolution, and concentration of these covalently linked molecules follow the gradient pattern created by the grayscale mask during exposure. The programmable chemical gradient fabrication scheme presented in this work allows explicit engineering of both surface properties that dictate nonspecific interactions (surface energy, charge, etc.) and functional chemistry necessary for covalent bonding.

This article reports a set of two homework assignments that can be used in a second-year undergraduate organic chemistry class. These assignments were designed to help reinforce concepts of molecular geometry and to give students the opportunity to use a technological database and data mining to analyze experimentally determined chemical structures.