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Although synthetic efforts to prepare carboxylato-bridged tetranuclear iron(III) clusters have been well preformed, introducing of functional groups on the coordination ligands to tune the structural, spectroscopic and physical properties of the cluster remains unstudied. Using amino functionalized ligands bipy-NH 2 and O 2 CPh-NH 2 , we have prepared a new cluster 1 ([Fe 4 O 2 (O 2 CPh-NH 2 ) 7 (bipy-NH 2 ) 2 ]·HO 2 CPh-NH 2 ·(CH 3 CN) 3 ·C 2 H 5 OH·OH) via a new precise orientated strategy starting from iron(II) compound. The cluster was characterized by UV–Vis, IR and Mossbauer spectroscopy, X-ray crystallography, cyclic voltammetric and magnetic studies. Results have shown that the [Fe 4 (μ 3 -O) 2 ] 8+ core was disposed in a bent “butterfly” arrangement, and the adjacent cores were connected into 1-D chain via hydrogen-bonding contacts involving lattice OH − anion, HO 2 CPh-NH 2 and solvent molecules. This 1D chain exhibits strong antiferromagnetic interactions, and irreversible electron reduction of one iron(III) ion to iron(II) at EP.C = −1.77 V vs SCE. Remarkably, color change from reddish violet to bluish green have been observed for this cluster upon protonating the amino functional groups. [ABSTRACT FROM AUTHOR]

The spin-crossover (SCO) can be triggered by light or pressure changes, making it a promising system for multifunctional switches and memory devices at the molecular level. In this work, we have reported a NIR-responsive spin state switching system via doping layered Co(pyridine) 2 Ni(CN) 4 (Co-MOF) into the stable polyvinylidene fluoride matrix for the first time. The layered Co-MOF has shown a rapid response of color change between gray-white and blue, which could be attributed to the SCO behavior triggered by NIR illumination. The new system ensures the soft network structures of the matrix to facilitate the homogeneous distribution of layered Co-MOF, both of which contribute to outstanding reversibility performance, including fast response, coloration in a short period, and decoloration in the ambient environment. This work provides a viable strategy to construct a new NIR-triggered SCO system for molecular switches and spintronic devices. • A NIR-responsive spin state switching system was successfully constructed. • A rapid response of color change between gray-white and blue has been triggered by NIR illumination. • Outstanding reversibility and stability performance has been demonstrated. [ABSTRACT FROM AUTHOR]

Developing versatile printing inks with good biocompatibility is essential for the fabrication of functional colored contact lenses. In this work, by employing a new kind of printing ink that shows humidity-induced discoloration, multifunctional colored contact lenses have been constructed. The obtained products have displayed distinct and stable all-weather humidity-triggered discoloration under ambient conditions. More importantly, combined with a smartphone, the quantitative and qualitative relationship between the discoloration of colored contact lenses and environmental humidity has been established, which is expected to realize the early prediction of humidity-related eye diseases in a portable, economical, and in-situ manner. • A new kind of printing ink that shows humidity-induced discoloration has been prepared. • The colored contact lens with all-weather humidity-triggered discoloration has been constructed. • The quantitative and qualitative relationship between the discoloration of colored contact lenses and environmental humidity has been established. [ABSTRACT FROM AUTHOR]