Concomitant ferro- and antiferromagnetic interactions in an H-bonded molecular ribbon duplex

Abstract

The title architecture is formed by self-association of a nitronyl aminoxyl substituted triazole derivative designed for multi-center H-bonding; moreover close -stacking of the resulting network produces duplex structures, as found by X-ray analysis, in which both ferro-and antiferromagnetic interactions take place.

4-(5-Amino-1H-1,2,4-triazol-3-yl)pyridinium chloride monohydrate

“…The pyridine and triazole rings are almost coplanar, the dihedral angle between the planes of the rings is 2.3 (1)°. Bond lengths and angles in the triazole cycle are within the normal ranges and are comparable with those found in the other 3-substituted 5-amino-1H-1,2,4-triazoles (Rusinov et al, 1991;Daro et al, 2000;Boechat et al, 2004;Dolzhenko et al, 2009b,c). The nitrogen atom of the amino group is in a trigonal pyramidal configuration (sum of valence angles is 356.0° and deviates from the triazole plane by only 0.020 (3)Å. Conjugation between the unshared electron pair of N21 and the π-system of the triazole fragment leads to a shortening of the N21-C2 bond (1.330 (2)Å) relative to the standard length of a purely single Nsp 2 -Csp 2 bond (1.43-1.45Å) (Burke-Laing & Laing, 1976;Allen et al, 1987).…”

“…For typical NMR chemical shifts of 3-substituted 5-amino-1,2,4-triazoles and their salts, see: Chernyshev et al (2010). For the crystal structures of 3substituted 5-amino-1H-1,2,4-triazoles, see: Rusinov et al (1991); Daro et al (2000); Boechat et al (2004); Dolzhenko et al (2009b,c). For the crystal structures of 3(5)-pyridyl-substituted 1,2,4-triazoles protonated at the pyridine ring, see: Ren & Jian (2008); Xie et al (2009); Du et al (2009).…”

Crystal packing and physical properties of pyridinium tetrabromocuprate(II) complexes assembled via hydrogen bonds and aromatic stacking interactions

“…In this respect, weak magnetic couplings across aromatic (pyrazolyl and 2,2@-bipyridine rings) p-stacking interactions were reported37 and hydrogen bonding has been extensively demonstrated to be a powerful tool for generating magnetic interactions and for propagating them in both inorganic38 and organic solids. 39 In the case of 3 the product remains practically con-s m T stant up to around 50 K, and it increases sharply at lower temperatures to attain a value of 0.48 cm3 mol~1 K at 2 K (Fig. 6).…”

A family of multi-spin rare-earth complexes based on a triazole nitronyl nitroxide radical: synthesis, structure and magnetic properties

“…Up to now, only four triazole nitronyl nitroxide radicals have been reported. 17 All of the free radicals exhibit ferromagnetic interactions at low temperature, which proves that the π system and the N atoms in the triazole ring are good units for transferring effective magnetic interactions. Now we are interested in a nitronyl nitroxide radical based on a triazole ring, named 2-[3-(4-methyl-l,2,4-triazolyl)]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (4-Me-3-NITtrz) ( Scheme 1 ).…”