Daniel J. Fanna

Constructing coordination nanocages: the metalloligand approach

Abstract The focus on this mini-review is on the use of metalloligands for the construction of discrete self-assembled, polyhedral metallo-cages. This metalloligand approach employs metal bound multifunctional ligand building blocks that display predetermined, well-defined electronic and structural preferences that facilitate the rational design and construction of both homo- and heteronuclear cages. The assembled cages exhibit a variety of defined topologies that, for example, range from trigonal bipyramidal to rhombododecahedral.

A large spin-crossover [Fe 4 L 4 ] 8+ tetrahedral cage

A large discrete face-capped tetranuclear iron(II) cage, [Fe4L4](BF4)8·n(solvent), was synthesised via metal-ion directed self-assembly. The cage is formed from a rigid tritopic ligand that incorporates chelating imidazole-imine functional groups. The cage displays temperature induced spin-crossover and LIESST effects and is amongst the largest iron(II) tetrahedral cages with such properties reported. The synthesis, structure and magnetic properties of this new metallo-cage are presented.

3d transition metal complexes with a julolidine–quinoline based ligand: structures, spectroscopy and optical properties

A Schiff base type ligand with the combination of the julolidine and the quinoline groups has been reported as a potential chemosensor in detecting the cobalt(II) ion among other heavy and transition metal ions in solution. However, no crystal structure of such a ligand with any metal ions has been reported. In this work, its complexation with 3d transition metal ions (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) has been investigated with five new complexes being synthesised, and spectroscopically and structurally characterised. [Mn2L2(CH3OH)2(CH3COO)2]·CH3OH (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} shows a dinuclear structure with two Mn : L : acetate (1 : 1 : 1) units bridged by two methanol molecules. [CoL2(NO3)]·CH3OH·H2O (2) and [NiL2]·H2O (3) exhibit mononuclear structures with a Co : L or Ni : L ratio of 1 : 2. [CuL(CH3COO)]·1/3CH3OH (4) demonstrates a mononuclear structure and the Cu ion has a square planar coordination polyhedron with a L ligand and a highly non-symmetrical acetate anion. [Zn2L2(CH3COO)2]·CH3OH (5) has two types of dinuclear units, both with two ZnL units bridged by two acetate anions but in three different bridging coordination modes. Their vibrational modes, absorption and photoluminescence properties have also been investigated.

Dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI) complexes with a tridentate Schiff base ligand

The complexation of a julolidine–quinoline based tridentate ligand with three oxo-metal ions, dioxo-vanadium(V), oxo-rhenium(V) and dioxo-uranium(VI), has been investigated with four new complexes being synthesised and structurally characterised. (VO2L)·2/3H2O (1) {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} has a VO2L neutral mononuclear structure with a five-fold coordinated vanadium metal centre in a distorted trigonal bipyramidal geometry. (ReOL2)2(ReCl6)·7DMF (2) [DMF = dimethylformamide] exhibits a mixed valent rhenium complex with a (ReOL2)+ cationic unit in a distorted octahedral metal coordination geometry, charge balanced with (ReCl6)2− anions. [(UO2)L(H2O)2]2·2(NO3)·HL·4H2O (3) and [(UO2)L(CH3OH)2](NO3)·CH3OH (4) both have (UO2L)+ cationic mononuclear structures with either coordinated water or methanol molecules in pentagonal bipyramidal coordination geometries for the uranium metal centres. Intra-/intermolecular interactions including hydrogen bonding and π–π interactions are common and have been discussed. In addition, optical absorption and photoluminescence properties have been investigated.

Dinuclear complexes of europium(III) and gadolinium(III) ions with a julolidine–quinoline-based tridentate ligand

Abstract The reaction of europium(III) or gadolinium(III) acetates with a Schiff base ligand {HL (C22H21N3O) = ((E)-9-((quinolin-8-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol)} in methanol affords two dinuclear complexes which have been characterized by powder X-ray diffraction, Raman spectroscopy, scanning electron microscope–electron dispersive spectroscopy, absorption and emission spectroscopies as well as single-crystal X-ray diffraction. [Eu2L2(CH3COO)4(CH3OH)2] (1) and [Gd2L2(CH3COO)4(CH3OH)2] (2) are iso-structures, each consisting of two M : L : CH3COO : CH3OH (1 : 1 : 1 : 1) units bridged by two acetate anions with the metal center in a distorted capped square antiprismatic coordination geometry. Their vibration modes, electronic structures, and photoluminescent properties are reported.

CCDC 1489722: Experimental Crystal Structure Determination

Related Article: Li Li, Alexander R. Craze, Daniel J. Fanna, Aidan J. Brock, Jack K. Clegg, Leonard F. Lindoy, Janice R. Aldrich-Wright, Jason K. Reynolds, Feng Li|2017|Polyhedron|125|44|doi:10.1016/j.poly.2016.08.049