Shape-Memory Platinum(II) Complexes: Intelligent Vapor-History Sensor with ON-OFF Switching Function

• Published in: Chemistry : a European journal 2016-02, Vol.22 (8), p.2682-2690
• Main Authors: Shigeta, Yasuhiro, Kobayashi, Atsushi, Ohba, Tadashi, Yoshida, Masaki, Matsumoto, Takeshi, Chang, Ho-Chol, Kato, Masako
• Format: Article
• Language: English
• Subjects: Chemistry; chromophores; Collapse; Crystal structure; Detection; Grinding; Manuals; mechanochromism; Platinum; Shape memory; shape-memory effects; Switching; Synthesis; Three dimensional; Transformations; Transformations (mathematics); vapochromism; Vapors
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201503247

A novel platinum(II)–diimine complex, [Pt(CN)2(H2dcphen)] (1; H2dcphen=4,7‐dicarboxy‐1,10‐ phenanthroline), was synthesized and its vapochromic shape‐memory behavior was evaluated. The as‐synthesized amorphous purple solid, [Pt(CN)2(H2dcphen)]⋅2 H2O (1 P), exhibited vapochromic behavior in the presence of alcoholic vapors through transformation to a red, crystalline, porous, vapor‐adsorbed form, 1 R⊃vapor. The obtained 1 R⊃vapor complex released the adsorbed vapors upon heating without collapse of the porous structure. The vaporfree, porous 1 R⊃open could detect water or n‐hexane vapor, although these vapors could not induce 1 P‐to‐1 R⊃vapor transformation, and 1 R⊃open could easily be converted to the initial 1 P by manual grinding. These results indicate that 1 is a new shape‐memory material that functions through formation and collapse of the porous framework with an emission change upon vapor‐adsorption and grinding; this enables it to exhibit vapor history and ON–OFF switching sensing functions. Molecule‐based shape‐memory behavior of a newly synthesized PtII complex, [Pt(CN)2(H2dcphen)] (H2dcphen=4,7‐ dicarboxy‐1,10‐phenanthroline), is reported. A three‐dimensional flexible network constructed of one‐dimensional intermolecular Pt⋅⋅⋅Pt interactions and two‐dimensional hydrogen bonds enables the complex to exhibit not only vapor‐history sensing functions, but also ON–OFF switching of the vapor sensing function (see scheme; G1 and G2 represent guest molecules).