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Issue 6, 2014
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Protonation, coordination chemistry, cyanometallate “supercomplex” formation and fluorescence chemosensing properties of a bis(2,2′-bipyridino)cyclophane receptor

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Abstract

A new polyazamacrocycle (L) containing two 2,2′-bipyridino (bpy) units, where the heteroaromatic nitrogen atoms point outwards from the macrocyclic cavity, was synthesized and characterized by elemental analysis, ESI-MS, 1H and 13C NMR, FTIR and TGA. Five protonation constants involving aliphatic nitrogens with log K in the range 9.39–3.07 were determined by potentiometry and NMR and a sixth protonation (log K = 2.2) involving a bipyridine moiety could be detected by UV-Vis and NMR titrations. The interaction of L with the cyanometallate anions [Pt(CN)4]2− and [Co(CN)6]3− was studied by potentiometry yielding respectively log K values in the ranges 4.0–6.4 and 5.2–10.5, covering protonation degrees from 1 to 5. Studies on L with [Ru(CN)6]4− led to early precipitation preventing potentiometry, but crystals of [H4L][Ru(CN)6]·10H2O and also of [H2L](ClO4)2·4H2O suitable for X-ray diffraction could be obtained and the crystalline structures are described. The interaction of L with Zn2+ was investigated by potentiometry and UV-Vis showing the formation of mono- and dinuclear complexes involving the bipyridines. The macrocycle was used as a bridging ligand for the successful synthesis of a new dinuclear [(Ru(bpy)2)2(L)](PF6)4·4HPF6 complex that was fully characterized. The protonation (log K in the range 9.9–1.6) and coordination features of this compound towards Cu2+ and Zn2+ were explored by UV-Vis absorption and emission spectroscopies.

Graphical abstract: Protonation, coordination chemistry, cyanometallate “supercomplex” formation and fluorescence chemosensing properties of a bis(2,2′-bipyridino)cyclophane receptor

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Publication details

The article was received on 30 Jul 2013, accepted on 13 Nov 2013 and first published on 04 Dec 2013


Article type: Paper
DOI: 10.1039/C3DT52061G
Citation: Dalton Trans., 2014,43, 2437-2447
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    Protonation, coordination chemistry, cyanometallate “supercomplex” formation and fluorescence chemosensing properties of a bis(2,2′-bipyridino)cyclophane receptor

    S. Gago, J. González, S. Blasco, A. J. Parola, M. T. Albelda, E. García-España and F. Pina, Dalton Trans., 2014, 43, 2437
    DOI: 10.1039/C3DT52061G

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