The author of 《Vapochromic luminescent proton conductors: switchable vapochromism and proton conduction of luminescent Pt(II) complexes with proton-exchangeable sites》 were Kobayashi, Atsushi; Imada, Shin-ichiro; Shigeta, Yasuhiro; Nagao, Yuki; Yoshida, Masaki; Kato, Masako. And the article was published in Journal of Materials Chemistry C: Materials for Optical and Electronic Devices in 2019. Formula: C20H14N4 The author mentioned the following in the article:
Two luminescent and highly proton-conductive Pt(II) complexes [PtCl(tpypy)]Cl and [PtCl(tpypyH)]Cl2 (1 and 1·HCl, resp.; tpypy = 2,2′: 6′,2”-terpyridine-4′,4”’-pyridine) were successfully synthesized. X-ray anal. revealed that the intermol. Pt···Pt interaction was ineffective in the monohydrated form of 1·H2O but effective in dihydrate and hexahydrate forms, 1·HCl·nH2O (n = 2 and 6). Yellow luminescence (λem = 519 nm and Φ = 0.016) assigned to intraligand 3π-π* phosphorescence was observed for 1·H2O, whereas a stronger red emission ascribable to the phosphorescence from the triplet metal-metal-to-ligand charge transfer (3MMLCT) state was observed for the HCl adduct 1·HCl·nH2O (λem = 741 nm, Φ = 0.06 for n = 2, λem = 642 nm, and Φ = 0.10 for n = 6). Both complexes exhibited strong relative humidity (RH)-dependent proton conductivity, while surprisingly high conductivity was observed for 1·HCl (6.8 × 10-3 S cm-1) at 95% RH at 298 K. The reversible transformation between 1 and 1·HCl was achieved upon exposure to humid HCl gas and heating and their vapochromic behavior was completely different owing to the presence of acidic N-H protons and the addnl. hydrophilic Cl- counteranions in 1·HCl. To the best of the authors’ knowledge, these complexes are the first switchable vapochromic and highly proton conductive materials that can be employed to visualize the proton conducting state by color and luminescence. The results came from multiple reactions, including the reaction of 4′-(4-Pyridyl)-2,2′:6′,2”-terpyridine(cas: 112881-51-3Formula: C20H14N4)
4′-(4-Pyridyl)-2,2′:6′,2”-terpyridine(cas: 112881-51-3) belongs to pyridine derivatives. The ring atoms in the pyridine molecule are sp2-hybridized. The nitrogen is involved in the π-bonding aromatic system using its unhybridized p orbital. Formula: C20H14N4The lone pair is in an sp2 orbital, projecting outward from the ring in the same plane as the σ bonds.