title: Synthesis and self-assembly of spin-labile and redox-active manganese(III) complexes.
abstract: New amphiphilic and spin-labile Mn(III) complexes based on dianionic N(4)O(2)-hexadentate sal(2)trien or sal(2)bapen ligands, which contain OC(6)H(13), OC(12)H(25), or OC(18)H(37) alkoxy substituents at different positions of the salicylidene unit were prepared (H(2)sal(2)trien = N,N'''-bis(salicylidene)-1,4,7,10-tetraazadecane, H(2)sal(2)bapen = N,N'''-bis(salicylidene)-1,5,8,12-tetraazadodecane). According to electrochemical measurements, these complexes undergo two (quasi)reversible redox processes. Temperature-dependent magnetic measurements revealed a high-spin configuration for all sal(2)trien complexes (S = 2) and gradual spin crossover for sal(2)bapen complexes from high to low spin (S = 1). The chain length strongly influences the spin crossover, as C(18)-functionalization stabilizes the low spin state at much higher temperatures than shorter alkyl chains. Moreover, long alkyl chains allow for spontaneous self-assembly of the molecules, which was investigated in single crystals and in Langmuir-films at the air-water interface. Long alkyl chains (C(12) or C(18)) as well as a mutual syn-orientation of these molecular recognition sites were required for the Langmuir monolayers to be stable.
authors.affiliation: Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700, Fribourg, Switzerland.
authors.forename: Claudio
authors.initials: C
authors.lastname: Gandolfi
authors.forename: Tatiana
authors.initials: T
authors.lastname: Cotting
authors.forename: Paulo N
authors.initials: PN
authors.lastname: Martinho
authors.forename: Olha
authors.initials: O
authors.lastname: Sereda
authors.forename: Antonia
authors.initials: A
authors.lastname: Neels
authors.forename: Grace G
authors.initials: GG
authors.lastname: Morgan
authors.forename: Martin
authors.initials: M
authors.lastname: Albrecht