title: Photochromism emergence in N-salicylidene p-aminobenzenesulfonate diallylammonium salts.
abstract: N-Salicylidene p-aminobenzenesulfonate salts were prepared by in situ condensation of p-aminobenzenesulfonate diallylammonium salt and salicylaldehyde. Modulation of thermo- and photochromism was achieved by varying the alkyl chain length of the diallylammonium counter-cation. A structural-optical properties investigation reveals that both crystal packing and dihedral angle between aromatic rings of the N-salicylidene aniline switch are not sufficient to predict the occurrence of photochromism in the solid state. The available free space around the N-salicylidene p-aminobenzenesulfonate, in addition to the flexibility of the nearby environment, is shown to be of major importance for the cis→trans isomerisation to occur as well as for the stabilisation of the trans-keto form. Emergence of photochromic properties was determined from the diallylhexylammonium cation within the series of investigated counter-cations. High stability is observed for the trans-keto form of one polymorph of N-salicylidene p-aminobenzenesulfonate diallylhexylammonium salt (k = 2.4×10(-7)  s(-1)).
authors.affiliation: Institute of Condensed Matter and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium), Fax: (+32) 1047-2330.
authors.forename: Pierre-Loïc
authors.initials: PL
authors.lastname: Jacquemin
authors.forename: Koen
authors.initials: K
authors.lastname: Robeyns
authors.forename: Michel
authors.initials: M
authors.lastname: Devillers
authors.forename: Yann
authors.initials: Y
authors.lastname: Garcia
mesh_terms: D018360:Crystallography, X-Ray; D007536:Isomerism; D008958:Models, Molecular; D015394:Molecular Structure; D010777:Photochemistry; D000644:Quaternary Ammonium Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013425:Sulfanilic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000644:Quaternary Ammonium Compounds; D013425:Sulfanilic Acids
keywords: isomerization; molecular devices; photochromism; tautomerism; thermochromism