Animal lectins as cell adhesion molecules

Protein-carbohydrate interaction is exploited in cell adhesion mechanisms besides the recognition of peptide motifs. The sugar code thus significantly contributes to the intriguing specificity of cellular selection of binding partners. Focusing on two classes of lectins (selectins and galectins), it is evident that their functionality for mediation of adhesive contacts is becoming increasingly appreciated, as is the integration of this type of interaction with other recognition modes to yield the noted specificity. The initial contact formation between leukocytes and activated endothelium makes use of selectins to guide lymphocyte trafficking. In addition to the three selectins which bind a distinct array of ligands, galectin-1 and galectin-3 and possibly other members of this family are involved in cell-cell or cell-matrix interactions. This review summarizes structural and functional aspects of these two classes of endogenous lectins relevant for cell adhesion

Copper(II) Dicyanamide Complexes with N ‐Substituted Tetrazole Ligands – Energetic Coordination Polymers with Moderate Sensitivities

Following the useful concept of energetic coordination compounds (ECC), copper(II) dicyanamide was used as a building block for the synthesis of eight new complexes. As ligands, six different N ‐substituted tetrazoles were applied, leading to the formation of high‐nitrogen containing complexes. The obtained compounds were characterized in detail by single crystal as well as powder XRD, IR, EA, DTA, and TGA. In addition, the sensitivities towards impact and friction were determined with BAM standard techniques as well as the sensitivity towards electrostatic discharges. All compounds show moderate sensitivities (IS >6, FS >80 N) and energetic properties but differ in their polymeric structures forming polymeric chains or layers up to 3D networks

1-(Azidomethyl)-5H-Tetrazole: A Powerful New Ligand for Highly Energetic Coordination Compounds

Highly energetic 1-(azidomethyl)-5H-tetrazole (AzMT, 3) has been synthesized and characterized. This completes the series of 1-(azidoalkyl)-5H-tetrazoles represented by 1-(azidoethyl)-5H-tetrazole (AET) and 1-(azidopropyl)-5H-tetrazole (APT). AzMT was thoroughly analyzed by single-crystal X-ray diffraction experiments, elemental analysis, IR spectroscopy and multinuclear (H-1, C-13, N-14, N-15) NMR measurements. Several energetic coordination compounds (ECCs) of 3d metals (Mn, Fe, Cu, Zn) and silver in combination with anions such as (per)chlorate, mono- and dihydroxy-trinitrophenolate were prepared, giving insight into the coordination behavior of AzMT as a ligand. The synthesized ECCs were also analyzed by X-ray diffraction experiments, elemental analysis, and IR spectroscopy. Differential thermal analysis for all compounds was conducted, and the sensitivity towards external stimuli (impact, friction, and ESD) was measured. Due to the high enthalpy of formation of AzMT (+654.5 kJ mol(-1)), some of the resulting coordination compounds are extremely sensitive, yet are able to undergo deflagration-to-detonation transition (DDT) and initiate pentaerythritol tetranitrate (PETN). Therefore, they are to be ranked as primary explosives

Refinement of Copper(II) Azide with 1‐Alkyl‐5H‐tetrazoles: Adaptable Energetic Complexes

A concept for stabilizing highly sensitive and explosive copper(II) azide with 1‐N‐substituted tetrazoles is described. It was possible to stabilize the system by the use of highly endothermic, nitrogen‐rich ligands. The sensitivities of the resulting energetic copper coordination compounds can be tuned further by variation of the alkyl chain of the ligands and by phlegmatization of the complexes with classical additives during the synthesis. It is demonstrated, using the compound based on 1‐methyl‐5H‐tetrazole ([Cu(N3)2(MTZ)], 1) that this class of complexes can be applied as a potential replacement for both lead azide (LA) and lead styphnate (LS). The complex was extensively investigated according to its chemical (elemental analysis, single‐crystal and powder X‐ray diffraction, IR spectroscopy, scanning electron microscopy) and physico‐chemical properties (differential thermal analysis, sensitivities towards impact, friction, and electrostatic discharge) compared to pure copper(II) azide

Salts of Picramic Acid – Nearly Forgotten Temperature‐Resistant Energetic Materials

Thermally stable explosives are becoming more and more important nowadays due to their important role in the oil and mining industry. The requirements of these explosives are constantly changing. Picramate‐based compounds are poorly investigated towards their energetic properties as well as sensitivities. In this work, 13 different salts of picramic acid were synthesized as potential energetic materials with high thermal stability in a simple one‐step reaction and compared with commercially used lead picramate. The obtained compounds were extensively characterized by e. g. XRD, IR, EA, DTA, and TGA. In addition, the sensitivities towards impact and friction were determined with the BAM drop hammer and the BAM friction tester. Also, the electrostatic discharge sensitivity was explored. Calculations of the energetic performance of selected compounds were carried out with the current version of EXPLO5 code. Therefore, heats of formation were computed and X‐ray densities were converted to room temperature. Some of the synthesized salts show promising characteristics with high exothermic decomposition temperatures. Especially, the water‐free rubidium, cesium, and barium salts 5 , 6 and 10 with decomposition temperatures of almost 300 °C could be promising candidates for future applications

Urazine – a Long Established Heterocycle and Energetic Chameleon

The five‐membered heterocycle urazine is investigated as a useful precursor of energetic materials. A variety of salt and complexes as well as a trinitroethyl derivative is presented. The compounds were thoroughly characterized including their thermal stability and sensitivity values. Furthermore, for potential applications, small‐scale shock reactivity test (SSRT), hot needle, hot plate, and laser ignition tests were performed

Less sensitive oxygen-rich organic peroxides containing geminal hydroperoxy groups

Tetranitratoethane (C2H2N4O12), which has an oxygen content of 70.1% was synthesized by nitration of monomeric glyoxal using N2O5 and purified by sublimation. Single crystals could be grown from CH2Cl2/pentane and were used to determine the structure by X-ray diffraction. Several energetic parameters and values were also established

Less sensitive oxygen-rich organic peroxides containing geminal hydroperoxy groups

Tetranitratoethane (C2H2N4O12), which has an oxygen content of 70.1% was synthesized by nitration of monomeric glyoxal using N2O5 and purified by sublimation. Single crystals could be grown from CH2Cl2/pentane and were used to determine the structure by X-ray diffraction. Several energetic parameters and values were also established