Thermo- and photo-induced electron transfer in a series of [Fe 2 Co 2 ] capsules.

Recently, a family of [Fe 2 Co 2 ] molecular capsules that display tunable electron transfer-coupled spin transition (ETCST) behavior were reported via a smart approach through Schiff-base condensation of aldehyde-functionalized 2,2-bipyridines (bpy CHO ) and 1,7-heptanediamine (H 2 N(CH 2 ) 7 NH 2 ). Here, three more capsule complexes {[(Tp R )Fe(CN) 3 ] 2 [Co(bpy CN(CH 2 ) n NC bpy)] 2 [ClO 4 ] 2 }· n (solvent) (1, Tp R = Tp*, n = 5, sol = 8DMF; 2, Tp R = Tp Me , n = 9, sol = 5MeCN; and 3, Tp R = Tp*, n = 11, sol = 5MeCN), where Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate and Tp Me = hydridotris(3-methylpyrazol-1-yl)borate are reported, demonstrating a successful extension of such an approach with other alkyldiamines of different lengths. Combined X-ray crystallographic, infrared spectroscopic and magnetic studies reveal incomplete electron transfer with either changing temperature or upon light exposure.