title: Self-assembled metalla-bowls for selective sensing of multi-carboxylate anions.
abstract: Two new tetranuclear cationic metalla-bowls 4 and 5 were self-assembled from a bis-pyridine amide ligand (H(2)L) (1) and arene-ruthenium acceptors, [(Ru(2)(μ-η(4)-C(2)O(4))(η(6)-p-cymene)(2)](O(3)SCF(3))(2) (2) and [Ru(2)(dhnd)(η(6)-p-cymene)(2)](O(3)SCF(3))(2) (dhnd = 6,11-dihydroxy-5,12-naphthacenedionato) (3), respectively. The metalla-bowls were characterized by multinuclear NMR, ESI-MS, UV-Vis spectroscopy, and single crystal X-ray diffraction study of 4. The crystal structure of 4 reveals unambiguous proof for the molecular shape of the metalla-bowl and the encapsulation of one triflate anion in the cavity through hydrogen bonding. The metalla-bowl 5 has been evaluated for anion binding studies by use of amide ligand as a hydrogen bond donor and arene-Ru acceptor as a signalling unit. UV-Vis titration studies showed that 5 selectively binds with multi-carboxylate anions such as oxalate, tartrate and citrate in a 1 : 1 fashion with high binding constants of 4.0-5.5 × 10(4) M(-1). Furthermore, the addition of multi-carboxylate anions into a solution of 5 gave rise to a large enhancement of fluorescence intensity attributable to the blocking of a photo-induced electron transfer process from the arene-ruthenium moiety to the amidic donor in 5. However, the fluorescence intensity almost remains unchanged upon addition of other anions including F(-), Cl(-), PF(6)(-), MeCOO(-), NO(3)(-) and PhCOO(-), as identically seen in the UV-Vis titration experiments, pointing to the high selectivity of 5 for the sensing of multi-carboxylate anions.
authors: Department of Chemistry, University of Ulsan, Ulsan, 680-749, Republic of Korea.
authors: Anurag
authors: A
authors: Mishra
authors: Vaishali
authors: V
authors: Vajpayee
authors: Hyunuk
authors: H
authors: Kim
authors: Min Hyung
authors: MH
authors: Lee
authors: Hyunji
authors: H
authors: Jung
authors: Ming
authors: M
authors: Wang
authors: Peter J
authors: PJ
authors: Stang
authors: Ki-Whan
authors: KW
authors: Chi
mesh_terms: D000042:Absorption; D000577:Amides / Q000737:chemistry; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry
chemical_list: D000577:Amides; D002264:Carboxylic Acids; D009942:Organometallic Compounds; D011725:Pyridines; D012428:Ruthenium; C023666:pyridine