Macrometallocycle binuclear NHC silver(I) complexes: synthesis, structure and recognition for o-phenylenediamine
Two bis-benzimidazolium salts 1,4-bis[n'-(N-benzyl-benzimidazolium-N'-yl)alkoxy]-9,10-anthraquinone hexafluorophosphate (L1H2•(PF6)2 and L3H2•(PF6)2) and two bis-imidazolium salts 1,4-bis[n'-(N-benzyl-imidazolium-N'-yl)alkoxy]-9,10-anthraquinone hexafluorophosphate (L2H2•(PF6)2 and L4H2•(PF6)2) (n = 2 or 3), as well as their four macrometallocycle binuclear N-heterocyclic carbene silver(I) complexes [(L1Ag)2](PF6)2 (1), [(L2Ag)2](PF6)2 (2), [(L3Ag)2](PF6)2 (3) and [(L4Ag)2](PF6)2 (4) were prepared and characterized. In complexes 1-4, each macrometallocycle (30-membered macrometallocycle for 1 and 2, 34-membered macrometallocycle for 3 and 4) was formed by two biscarbene ligands (L1-L4 for 1-4) and two silver(I) ions. In the crystal packings of 1-4, 2D supramolecular layers are formed via intermolecular weak interactions including hydrogen bonds and π-π interactions. Additionally, the selective recognition of o-phenylenediamine (OPD) using 4 as a host compound was investigated by fluorescence and UV/vis titrations. The results indicate that 4 can distinguish effectively o-phenylenediamine with other aromatic amines.