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A C2-symmetric internally conjugated 1,3-dialkyne system 5, containing phenolphthalein as a fluorophore and ferrocene as a redox moiety, has been synthesized via a microwave-assisted synthetic procedure. Compound 5 was synthesized by Cu-catalyzed Glaser–Hay coupling using a microwave reactor in neat condition for the first time. Compound 5 was found to be highly selective toward Fe3+, Cu2+, and Hg2+ ions via multichannels. Interestingly, Fe3+ and Cu2+ ions simply promote the oxidation of ferrocene unit to ferrocenium ion without binding to the receptor, whereas Hg2+ binds with the receptor 5 (ΔE 1/2 = 71 mV). The oxidation and binding phenomena were investigated by optical and electrochemical analyses. Furthermore, the binding site of Hg2+ ion with our designed probe was confirmed by 1H, 13C NMR and IR titrations, which indicated that conjugated dialkyne unit interacts with Hg2+ ion by a favorable soft–soft interaction. Both receptor 5 and its metal complex, [5·2Hg2+], are stable in the physiological pH range (pH = 6–7) and thermally stable up to 78 °C. The experimental results of metal binding have been further supported by quantum chemical calculations (DFT), which explore the favorable geometry of the free ligand as well as its Hg2+ complex.

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A feasible one-pot synthesis of dimerized arene and heteroarene systems was achieved by employing 2 mol% of Co(II) catalyst 1 along with Zn dust, at room temperature for 2-4 h....

The C 2-symmetric photochromic molecule 3, containing dithienylethene (DTE) and ferrocene units connected by an alkyne bridge, represents a unique probe where a metal (Hg2+) binds with the central DTE moiety. Both photoisomerized states of 3 (open, 3o; closed, 3c) are found to interact with Hg2+ ion by the S atoms of the DTE core; however, the binding constants (from a UV–vis study) and DFT calculations suggest that the open isomer (3o) binds with the metal ion more strongly than that of the closed isomer (3c). Notably, the course of metal binding does not perturb the inherent photoisomerization properties of the DTE core and the photoswitchability persists even in the metal-coordinated form of 3, however, with a comparatively slower rate. The quantum yields for photocyclization (Φo→c) and photocycloreversion (Φc→o) in the free form are 0.56 and 0.007, respectively, whereas the photocyclization quantum yield in the Hg2+ complexed species is 0.068, 8.2 times lower than the photocyclization quantum yield (Φo→c) of free 3o. Thus, the rate of photoisomerization can be modulated by a suitable metal coordination to the DTE core. The dynamics of photoswitchability in the metal-coordinated form of DTE has been explored by experimental means (UV–vis and electrochemical studies) as well as quantum chemical calculations.

We described that quinoline-based NNN-pincer Cu(II) complex acts as an air stable superior catalyst for the oxidative cross coupling of allyl sp3 C-H bond with acid for the synthesis of...

Alkyne is a versatile functional group in organic chemistry, and is able to undergo a wide variety of reactions and interactions. Featuring a reactive functional group, alkyne participates in many...