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1.
A new approach to micropatterning is demonstrated. The approach is based on driving an electrochemical process at the solid-liquid interface through the formation of a flux of ions from a micropipet that is held in close proximity to the surface. The flux of ions is generated by the so-called potential assisted ion transfer at the interface between two immiscible electrolyte solutions (ITIES). As a model system, the local deposition of silver was examined. Specifically, a constant potential, which was applied to a micropipet filled with an aqueous solution of silver ions, caused the transfer of Ag(+) into the outer nitrobenzene (NB) solution that consisted of an electrolyte, tetrabutylammonium tetrakis[4-chlorophenyl]borate (TBATPBCl). To facilitate the transfer of silver ions a macrocyclic ligand, that is, dibenzo-24-crown-8 (DB24C8), was added to the organic phase. The Faradaic current of this micro-ITIES was used as a means of controlling the tip-surface distance in scanning electrochemical microscopy (SECM) and depositing silver microstructures on a gold substrate. 相似文献
2.
Yael Diskin‐Posner Goutam Kumar Patra Israel Goldberg 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):m344-m346
The title compound, [5,10,15,20‐meso‐tetrakis(4‐hydroxyphenyl)porphyrinato‐κ4N]zinc(II) tris(dibenzo‐24‐crown‐8) methanol tetrasolvate, [Zn(C44H28N4O4)]·3C24H32O8·4CH4O, was synthesized and its molecular structure precisely characterized by low‐temperature single‐crystal analysis. All the components are involved in hydrogen bonding with each other, thus forming an extensively hydrogen‐bonded supramolecular lattice. The functionalized porphyrin moiety coordinates both equatorially and axially to the neighboring species. 相似文献
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Dr. Ori Gidron Dr. Yael Diskin‐Posner Prof. Michael Bendikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13140-13150
The extent of charge delocalization and of conjugation in oligofurans and oligothiophenes was studied by using mixed valence systems comprising oligofurans and oligothiophenes capped at both ends by ferrocenyl redox units. Using electrochemical, spectral, and computational tools, we find strong charge delocalization in ferrocene‐capped oligofurans which was stronger than in the corresponding oligothiophene systems. Spectroscopic studies suggest that the electronic coupling integral (Hab) is roughly 30–50 % greater for oligofuran‐bridged systems, indicating better energy matching between ferrocene units and oligofurans. The distance decay constant (damping factor), β, is similar for oligofurans (0.066 A?1) and oligothiophenes (0.070 A?1), which suggests a similar extent of delocalization in the bridge, despite the higher HOMO–LUMO gap in oligofurans. Computational studies indicate a slightly larger extent of delocalization in furan‐bridged systems compared with thiophene‐bridged systems, which is consistent with oligofurans being significantly more rigid and less aromatic than oligothiophenes. High charge delocalization in oligofurans, combined with the previously reported strong fluorescence, high mobility, and high rigidity of oligofuran‐based materials makes them attractive candidates for organic electronic applications. 相似文献
6.
Iron Dicarbonyl Complexes Featuring Bipyridine‐Based PNN Pincer Ligands with Short Interpyridine CC Bond Lengths: Innocent or Non‐Innocent Ligand? 下载免费PDF全文
7.
Eyal Jakobs Yael Hanein 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,290(1-3):33-40
A novel method for fabricating micrometer sized gel patterns is described. The presented method involves spin-coating a pre-gel solution on a surface that was chemically treated to modulate its surface energy, creating highly hydrophobic areas on a hydrophilic substrate. Following spin-coating, the gel solution self organizes on the hydrophilic sites. This method offers the advantages of high resolution, self-alignment to pre-patterned electrodes, and a simple straightforward fabrication process. Minimum feature size achieved was approximately 20 μm. The characteristic shrinking and swelling times of gel patterns were measured and found to be around 0.6 s for swelling and 2 s for shrinking (for a 60 μm diameter gel) in agreement with the reduced response time expected for scaled down gel patterns. These results suggest the suitability of these gel patterns as valves or actuators in microfluidic devices. Micron-size gel patterns were also incorporated into microfluidic channels thus demonstrating a new approach to create simple, affordable, microfluidic devices, which incorporate “smart” hydrogels as building elements in a simple fashion. 相似文献
8.
Yael S. Balazs Lynmarie K. Thompson 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,139(2):371-376
Simple modifications of the rotational resonance experiment substantially reduce the total experimental time needed to measure weak homonuclear dipolar couplings, a critical factor for achieving routine internuclear distance measurements in large biomolecular systems. These modifications also address several problems cited in the literature. Here we introduce a constant-time rotational resonance experiment that eliminates the need for control spectra to correct for effects from variable RF heating, particularly critical for accurate long-distance measurements. This reduces the total number of experiments needed by as much as a factor of 2. Other improvements incorporated include achieving selective inversion with a delay rather than a weak pulse (P. R. Costa et al., J. Am. Chem. Soc. 119, 10487-10493, 1997), which we observe results in the elimination of oscillations in peak intensities for short mixing time points. This reduces the total experiment time in two ways. First, there is no longer a need to average different "zero"-time points (S. O. Smith et al., Biochemistry 33, 6334-6341, 1994) to correct for intensity variations. Second, short-mixing-time lineshape differences observed in large membrane-bound proteins only appear with the weak-pulse inversion and not when using the delay inversion. Consistent lineshapes between short and long mixing times permit the use of a single spectrum for subtraction of natural abundance background signals from all labeled-protein time points. Elimination of these effects improves the accuracy and efficiency of rotational resonance internuclear distance measurements. 相似文献
9.
Vigalok A Rybtchinski B Gozin Y Koblenz TS Ben-David Y Rozenberg H Milstein D 《Journal of the American Chemical Society》2003,125(51):15692-15693
An unprecedented metal-stabilized phenoxonium cation was prepared by a process involving dearomatization of a phenoxy complex. The unique eta2 C=O-metal (iridium) coordination mode leaves the positive charge delocalized within the former aromatic ring. The X-ray structure and conversion into eta2 C=O-coordinated metal-quinone complex are described. 相似文献
10.
Diskin-Posner Y Patra GK Goldberg I 《Chemical communications (Cambridge, England)》2002,(13):1420-1421
Targeted synthesis of new supramolecular motifs of metalloporphyrins in crystals by a concerted mechanism of molecular recognition in three dimensions, aided by organic ligands, is presented; it involves induced assembly of [tetrakis(4-hydroxyphenyl)porphyrinato]zinc species by a combination of axial coordination through bridging bipyridyls and of lateral hydrogen bonding. 相似文献