Stimuli-Responsive Luminescent Bis-Tridentate Ru(II) Complexes toward the Design of Functional Materials

Abstract

We report here the synthesis, characterization, and photophysics of two bis-tridentate Ru­(II) complexes based on a heteroditopic ligand and thoroughly studied their stimuli-responsive behaviors toward the design of functional materials. Both complexes display emission at room temperature having lifetimes in the range of 0.5–70.0 ns, depending on coligand and solvent. Substantial modulations of absorption and emission spectral behaviors of the complexes were done upon interaction with anions, and anion-induced changes in the properties lead to recognition of selected anions in both organic and aqueous media. Photophysical properties of the complexes were also tuned by changing the pH of the medium, and pK a values in both ground and excited states were determined. The presence of free pyridine-imidazole motifs in the complexes leads to substantial modulation of the optical properties and switching of the emission properties upon interaction with selected cations as well as with protons. Fe2+, Co2+, Ni2+, and Cu2+ trigger emission quenching, while Zn2+ induces finite enhancement of the emission intensity in the complexes. In essence, modulation of the optical properties and switching of luminescence properties of the complexes were accomplished by a variety of the external stimuli such as anions, cations, protons, and pH, as well as solvent polarity. Importantly, the optical outputs in response to an appropriate set of stimuli were utilized to mimic the functions of two-input IMPLICATION, NOR, and XNOR logic gates.

Selective oxidation of alcohols and sulfides via O2 using a Co(ii) salen complex catalyst immobilized on KCC-1: synthesis and kinetic study

“…Then, the smooth interaction among peroxy acid and Co(II) salen complex (a) should initiate the reaction to produce Co(II)-OOH (b). 47,48 Then, Co-oxo (c) is formed from the heterolytic cleavage of the O-O bond of species (b). The production of a carbonyl compound corresponds to the reaction of the Co-oxo species with alcohol via a transition species (d), because of the electrophilic character of Co-oxo (c) followed by b-hydride elimination.…”

Novel Ru(II)/Os(II)‐Exchange Homo‐ and Heterometallic Polypyridyl Complexes with Effective Energy Transfer

“…These deficiencies in terpyridine Ru(II) complexes severely limits their application as photosensitizers [3c,4] . Therefore, tpy‐type complexes have been replaced by bpy‐tpy‐type (bpy=2,2′‐bipyridine, tpy=2,2′:6′,2′′‐terpyridine) complexes or substituted tpy‐type complexes or variation of the bound metal centers, [5] providing directional control of the photoinduced intercomponent processes between metal‐to‐ligand charge‐transfer ( 3 MLCT) and metal‐centered ( 3 MC) state [2d,6] . Intramolecular energy transfer takes place from the Ru(II)‐based center to the lowest 3 MLCT excited state of the Os(II)‐based center to provide a multichannel optical sensor [7]…”

Stimuli-Responsive Near-Infrared Emissive Os(II)–Terpyridine Complexes with a Sense of Logic

“…44,46 tpy-Hbzim-dipy = 4′-[4-(4,5-dipyridin-2-yl-1H-imidazol-2-yl)-phenyl]-[2,2′:6′,2″]terpyridine, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, tpy-PhCH 3 = 4′-(4-methylphenyl)-2,2′:6′,2″-terpyridine, H 2 pbbzim = 2,6-bis(benzimidazol-2-yl)- pyridine. 38,49,76 bpy = 2,2′-bipyridine and HL = 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline). 77 bpy = 2,2′-bipyridine and Htppip = 2-(4-(2,6-di(pyridin-2-yl)pyridin-4-yl)phenyl)-1Himidazo[4,5-f] [1,10] phenanthroline.…”

“…21−25 Moreover, the materials based on transition metals are superior compared with pure organic framework as the former have the ability to better tune the structural, photophysical, and redox properties, and thus, there remains a huge prospect for tuning of absorption and emission wavelength, excited-state lifetime, and quantum efficiency in the complexes by proper selection of ligand and metal. 26−38…”