Magnetic observation of above room-temperature spin transition in vesicular nano-spheres. Issue 34 (15th August 2016)

• Record Type: Journal Article
• Authors: Luo, Yang-Hui; Liu, Qing-Ling; Yang, Li-Jing; Sun, Yu; Wang, Jin-Wen; You, Chao-Qun; Sun, Bai-Wang
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 34(2016)
• Page Start: 8061
• Page End: 8069
• Publication Date: 2016-08-15
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6tc02796b
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Above room-temperature spin-transition behavior has been achieved in a series of vesicular nano-spheres, which were prepared via a liposomal self-assembly strategy. Abstract : Nano-scale materials are acquiring a leading role in the fabrication of new generation devices, especially for the practical application of molecular bi-stability. However, the preparation of purely bi-stable nano-objects without the use of surfactants/polymers remains a challenging task. Here, we present a new approach to prepare spin-crossover (SCO) vesicular nano-spheres with single-external diameters of approximately 100 nm using a CHCl3 –H2 O mixture. The nano-spheres are based on a series SCO complexes, [Fe(H2 Bpz2 )2 (dialkyl-bipy)] (H2 Bpz2 = dihydrobis(1-pyrazolyl)borate, dialkyl-bipy = N 4, N 4 ′-dialkyl-(2, 2′-bipyridine)-4, 4′-dicarbo-xamide, alkyl = propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and cetyl), and are prepared through a self-assembly process that is similar to liposomal assembly, with the dialkyl-bipy moiety acting as the hydrophobic tail and the Fe(H2 Bpz2 ) moiety acting as the hydrophilic head. This study reveals that the alkyl chain length plays a key role in the formation of these nano-spheres and the determination of their spin transition temperatures. The spin transition temperatures for the bulk materials are centered at around 160 K, and show a positive correlation with the alkyl chain length. Meanwhile, for the vesicular nano-spheres in the solid state, their transition temperatures are above room-temperature, and the correlation with the alkyl chain length is negative. These results provide an effective strategy for the design of new metal–organic materials for nano-technological applications.