Origin of Ubiquitous Stripes at the Graphite–Water Interface

The investigation of solid-liquid interfaces is pivotal for understanding processes like wetting, corrosion, and mineral dissolution and growth. The graphite-water interface constitutes a prime example for studying the water structure at a seemingly hydrophobic surface. Surprisingly, in a large number of atomic force microscopy (AFM) experiments, well-ordered stripes have been observed at the graphite-water interface. Although many groups have reported on the observation of stripes at this interface, fundamental properties and, in particular, the origin of the stripes are still under debate. Proposed origins include contamination, interplanar stacking of graphene layers, formation of methan…

Monadic second-order logic over pictures and recognizability by tiling systems

We show that a set of pictures (rectangular arrays of symbols) is recognized by a finite tiling system if and only if it is definable in existential monadic second-order logic. As a consequence, finite tiling systems constitute a notion of recognizability over two-dimensional inputs which at the same time generalizes finite-state recognizability over strings and matches a natural logic. The proof is based on the Ehrenfeucht-FraIsse technique for first-order logic and an implementation of “threshold counting” within tiling systems.

Preparation, Properties, and Reactivity of (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)chromium(0) as Bulky Isolobal Trimetallo-amide

Nucleophilic substitution of the ethoxy substituent in the Fischer carbene complex (ethoxy)(ferrocenyl)carbene(pentacarbonyl)chromium(0) (1) by ferrocenyl amide [Fc-NH]– [2-H]– gives the hetero trimetallic complex (aminoferrocenyl)(ferrocenyl)carbene (pentacarbonyl)chromium(0) (3). As the Cr(CO)5 fragment is isolobal to oxygen or sulfur 3 can be viewed as an isolobal metallo analogue to diferrocenylamide (Fc)(FcNH)C=O (4) and diferrocenylthioamide (Fc)(FcNH)C=S (5). The impact of the formal replacement of O/S by Cr(CO)5 in 3 is studied with respect to steric and electronic consequences as well as reactivity by spectroscopic, diffraction, electrochemical and theoretical methods.

Unexpected C–C bond formation with a ferrocenyl Fischer carbene complex

Monadic Second-Order Logic over Rectangular Pictures and Recognizability by Tiling Systems

Abstract It is shown that a set of pictures (rectangular arrays of symbols) is recognized by a finite tiling system iff it is definable in existential monadic second-order logic. As a consequence, finite tiling systems constitute a notion of recognizability over two-dimensional inputs which at the same time generalizes finite-state recognizability over strings and also matches a natural logic. The proof is based on the Ehrenfeucht–Fraisse technique for first-order logic and an implementation of “threshold counting” within tiling systems.

CCDC 1962440: Experimental Crystal Structure Determination

Related Article: Philipp Veit, Sebastian Seibert, Christoph Förster, Katja Heinze|2020|Z.Anorg.Allg.Chem.|646|940|doi:10.1002/zaac.201900350

CCDC 1962439: Experimental Crystal Structure Determination

Related Article: Philipp Veit, Sebastian Seibert, Christoph Förster, Katja Heinze|2020|Z.Anorg.Allg.Chem.|646|940|doi:10.1002/zaac.201900350

CCDC 1409670: Experimental Crystal Structure Determination

Related Article: Philipp Veit, Christoph Förster, Sebastian Seibert and Katja Heinze|2015|Z.Anorg.Allg.Chem.|641|2083|doi:10.1002/zaac.201500562