From a spin-crossover molecule to the bulk electronic behaviour of a material: the paramount role of hydrogen bonds in molecular electronics

The exact role of the hydrogen bond network in a spin-crossover material is unambiguously shown: changing the -N-H ... O(nitro)salicylidene- 'communic ation wire' between adjacent Fe-II ions in the unidimensional chains of a t wo-step spin-transition material to the poorer -N-C-H ... O(nitro)salicylid ene- pathway results in a gradual and partial spin conversion of Fe-II in o therwise similar unidimensional chains of complex molecules. Cooperativity in the spin-crossover phenomenon indeed results from the effectiveness of t he intermolecular communication. (C) Academie des sciences/Elsevier, Paris.