Development of hybrid diblock copolypeptide amphiphile/magnetic metal complexes and their spin crossover with lower-critical-solution-temperature(LCST)-type transition

Abstract

Three composites composed of the cobalt terpyridine complex [Co II (MeO-terpy) 2 ] and the diblock copolypeptide amphiphiles 1 and 2 or the polypeptide 3 (including glutamic acid and leucine) were prepared. Supramolecular structures such as rectangular morphologies were obtained from composites of 1 and 2. A perfectly reversible reverse spin transition was successfully generated in the case of composites made with 1.

Spin crossover polymer composites, polymers and related soft materials

“…Kuroiwa et al combined a cobalt(II)-terpyridine [48] as well as the [Fe(ppi)2(NCS)2] (ppi= Nphenyl-2-pyridinalimine) [49] SCO complex with diblock copolypeptydes amphiphiles composed only of glutamic acid and leucine, in which the carboxylate in the glutamic residue is the counter-anion of the SCO complex (Figure 10). They were prepared by simply mixing the copolypeptide and the desired complex in solution, following a precipitation and lyophilization.…”

Supramolecular Control of Spin Crossover Phenomena Using Various Amphiphiles

“…Therefore, it is believed that SCO with an LCST-type transition can result from various nanostructures and aggregated structures formed from the amorphous diblock copolypeptide amphiphiles and the loose packing of the [Fe II (ppi)2(NCS)2] complexes ( Figure 14c). [37] The results presented thus far demonstrate that composites consisting of [Fe II (ppi)2(NCS)2] complexed with diblock copolypeptide amphiphiles generate supramolecular structures in water. The formation of these nanostructures results in the evolution of morphologies ranging in size from sub-nanometer to several micrometers.…”

“…Our group has also demonstrated a new type of nanocomposite based on the iron(II) complex [Fe II (ppi)2(NCS)2] (2-pyridyl-N-(phenyl)methylamine (ppi); Figure 11) [59][60][61] with a low critical solution temperature (LCST), using diblock copolypeptide amphiphiles and SCO complexes. This work demonstrated the possibility of synthesizing multifunctional nanocomposites with metastable properties as well as the formation of cooperative nanocomposites that change spin state switching in solution [37]. Composites of polypeptides 4-6 with [Fe II (ppi)2(NCS)2] were synthesized by mixing solutions of the respective compounds, followed by dispersion of hydrophobic [Fe II (ppi)2(NCS)2], and by dissolution of the resulting composites in water.…”

“…0.7 nm, as estimated by the CPK model; Figure 14b) when polyleucine partially forms a β sheet with an all-trans conformation. Therefore, it is believed that SCO with an LCST-type transition can result from various nanostructures and aggregated structures formed from the amorphous diblock copolypeptide amphiphiles and the loose packing of the [Fe II (ppi) 2 (NCS) 2 ] complexes (Figure 14c) [37]. Supramolecular structures on the sub-nanometer to micrometer scale were observed using TEM, DLS, and SAXS, indicating that the hydrophobic interactions of the Leu moieties (Figure 14a) determine the intermolecular interactions of the composites.…”

A flexible polymer–nanoparticle hybrid material containing triazole-based Fe(ii) with spin crossover properties for magneto-optical applications

“…[38][39][40] The engineering of composite materials is a promising way to address this ultimate goal. In this frame, SCO compounds have been encapsulated within polymer matrices of synthetic [41][42][43][44][45][46][47][48][49] and biological 38,[50][51][52][53] origin, providing nanoscale confinement suitable for maintaining cooperativity between SCO complexes. Sol-gel techniques were also used for encapsulation.…”