Role of moelcular packing and structural defects in reactions of gases with surfaces of organic solids: Ammonia and acenaphthylene 1-carboxylic acid

The marked anisotropy of the rate of reaction between NH₃ and the (001), (010) and (100) facesof acenaphthylene 1-carboxylic acid, and the novel influence of mechanical deformation on reactivity, is discussed in terms of the nature of the molecular packing within the perfect structure.     

Naked eye detection of anions by alkynyl-ruthenium exo-receptors: selective recognition of fluoride anion

Alkynyl-ruthenium complexes bearing terminal hydrogen-bonding receptors act as efficient anion sensors exhibiting large guest-induced colour changes and show unexpectedly high selectivity to fluoride ions.     

Synthesis of 2,3-substituted tetracenes and evaluation of their self-assembling properties in organic solvents

[structure: see text] Rod-shaped 2,3-di-alkoxytetracenes, soluble in common organic solvents, have been synthesized and studied for their gelling ability in organic solvents and their unusual UV-visible spectroscopic properties.     

Photochemistry of bichromophoric systems. Silicon guided intramolecular 9, 10 : 1′, 2′ anthracene photodimerization in bis(9-anthryl) dimethylsilane.

Irradiation of bis(9-anthryl)dimethylsilane ($\text{1}$) generates a single photocyclomer formed by (4π + 2π) intramolecular 9,10 : 1′,2′ anthracene photodimerization. The influence of the silicon atom was investigated by reaction quantum yield determination and fluorescence study (stationary state and lifetimes).     

2,3‐Diethoxy‐9,10‐anthraquinone

Anthraquinone derivatives form an important class of dyes and are also known for their medicinal properties. Recently, 2,3‐disubstituted anthraquinones have been shown unexpectedly to jellify various organic solvents. No information on the packing mode of these derivatives was known. Here, the first X‐ray structure of a 2,3‐disubstituted anthraquinone is reported, namely 2,3‐diethoxy‐9,10‐anthraquinone, C₁₈H₁₆O₄. The merit of this study lies in the observation of significant differences between the packing in 9,10‐anthraquinone, which displays a herring‐bone arrangement, and that in the title 2,3‐diethoxy derivative, in which the molecules lie on parallel crystallographic morror planes separated by a distance of 3.4081 (1) Å, reminiscent of the graphite layer architecture.     

Structural effects on the ground and excited-state properties of photoswitchable hydrogen-bonding receptors

The ground- and excited-state properties of a series of photochromic barbiturate receptors (N,N'-bis{6-[omega-(anthracen-9-yloxy)alkanoylamino]pyridin-2-yl}-5-t-butyl-isophthalamide, Tn), in which anthracene chromophores are tethered via (CH2)n (n = 1, 3-6) polymethylene linkers to the H-bond receptor moiety, are described. In these systems, the thermally reversible [4pi + 4pi] photodimerization of the anthracenes yields macrocyclic receptors (TnC) that possess significantly reduced affinity toward barbital as compared to their acyclic counterparts. The length of the tether not only determines the overall binding ability of the cyclized receptor but also has a profound influence on the photochemical and photophysical properties of the anthracene chromophores. The reduced mobility experienced by the covalently bound anthracenes controls the reactivity of a fluorescent excimer that is proposed to be an intermediate in the photocyclization process.