934749-58-3Relevant academic research and scientific papers
Synthesis and self-assembly of spin-labile and redox-active manganese(iii) complexes
Gandolfi, Claudio,Cotting, Tatiana,Martinho, Paulo N.,Sereda, Olha,Neels, Antonia,Morgan, Grace G.,Albrecht, Martin
, p. 1855 - 1865 (2011)
New amphiphilic and spin-labile MnIII complexes based on dianionic N4O2-hexadentate sal2trien or sal2bapen ligands, which contain OC6H13, OC12H25, or OC18H37 alkoxy substituents at different positions of the salicylidene unit were prepared (H2sal2trien = N,N′′′-bis(salicylidene)- 1,4,7,10-tetraazadecane, H2sal2bapen = 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 sal2trien complexes (S = 2) and gradual spin crossover for sal2bapen 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 (C12 or C18) as well as a mutual syn-orientation of these molecular recognition sites were required for the Langmuir monolayers to be stable. The Royal Society of Chemistry 2011.
Improved cooperativity of spin-labile iron(III) centers by self-assembly in solution
Gandolfi, Claudio,Moitzi, Christian,Schurtenberger, Peter,Morgan, Grace G.,Albrecht, Martin
, p. 14434 - 14435 (2008)
Supramolecular principles have been applied for improving the spin crossover activity of metal centers due to cooperative effects in solution. Thus, incorporation of alkyloxy tails at the phenyl group of Fe(sal2trien) 2a provides amphiphilic complexes Fe(sal-OR2trien) 2b-d (b, R = C6H13; c, R = C8H17; d, R = C18H37) comprising an apolar group for supramolecular organization and a polar headgroup with potential spin crossover activity due to the presence of a spin-labile iron(III) center. Self-assembly of these complexes in solution resulted in the formation of microsize and submicrosize particles when the alkyl chain was long enough (2d) but not with shorter chains (2a-c). Solutions of 2d showed enhanced spin crossover activity as compared to complexes 2a-c, both in terms of transition temperature and steepness of the transition. This observation has been correlated to an improved cooperativity of the metal centers in 2d due to self-assembly, thus facilitating a tandem spin transition. Copyright
Organization of spin- and redox-labile metal centers into Langmuir and Langmuir-Blodgett films
Gandolfi, Claudio,Miyashita, Naoko,Kurth, Dirk G.,Martinho, Paulo N.,Morgan, Grace G.,Albrecht, Martin
supporting information; experimental part, p. 4508 - 4516 (2010/08/21)
New sal2(trien) ligands that contain alkoxy substituents of various length in meta position of the phenolate entities were coordinated to electronically and magnetically active iron(III) and cobalt(iii) centers. The electrochemical and spectroscopic properties of these amphiphilic complexes are virtually unaffected upon alteration of the alkoxy substituents, thus providing a system in which the physical behavior and the metal-centered chemical activity can be tailored independently. The amphiphilic character has been exploited for preparing Langmuir monolayers at the air-water interface and for constructing Langmuir-Blodgett films, hence allowing for hierarchical assembling of electronically and magnetically active systems. While Langmuir films were stable, transfer onto solid supports was limited, which restricted the magnetic analysis of the Langmuir-Blodgett assemblies.
