Synthesis, spectroscopy and photophysical properties of ruthenium triazole complexes and their application as dye-molecules in regenerative solar cells

The complexes [Ru(dcb)2(L)] (L = 3-(2-phenol)-5-(pyridin-2-yl)-1,2,4-triazole (2-ppt), 3-(4-phenol)-5-(pyridin-2-yl)-1,2,4-triazole (4-ppt), 3,5-bis(pyrazin-2-yl)-1,2,4-triazole (bpzt), 3-(2-phenol)-5-(pyrazin-2-yl)-1,2,4-triazole (2-ppzt) and dcb = 4,4’-(CO2H)2-2,2’-bipyridine) have been synthesized, spectroscopically characterized and anchored to nanocrystalline TiO2 electrodes for the conversion of light into electricity in regenerative solar cells. The different efficiencies observed have been rationalized on the basis of an analytical expression relating the incident photon-to-current-conversion efficiency (IPCE) to the kinetic parameters of the relevant electron transfer processes involved in the solar cell

Solvent templated synthesis of metal-organic frameworks: structural characterisation and properties of the 3D network isomers {[Mn(dcbp)]1/2DMF}n and {[Mn(dcbp)].2H2O}n

The identity of the metal–organic framework formed by Mn(II) and 4,4?-dicarboxy-2,2?-bipyridine (H2dcbp) depends upon the predominant solvent employed in the synthesis and yields the robust network isomers {[Mn(dcbp)]·½DMF}n, 1, and {[Mn(dcbp)]·2H2O}n, 2, which possess vastly different physical properties: 1 irretrievably binds DMF, whereas 2 reversibly binds water whilst retaining crystallinity

Coordination and hydrogen bonded networks featuring 4,4?-dicarboxy-2,2?-bipyridine (H2dcbp): structural characterisation of H2dcbp, [Co(dcbp)(H2O)4]·4H2O, and {[Cu(dcbp)(H2O)2]·2H2O}n

complexes it forms with Co(II), [Co(dcbp)(H2O)4]·4H2O, 1, and Cu(II), {[Cu(dcbp)(H2O)2]·2H2O}n, 2. H2dcbp adopts the anti conformation in the solid-state, with a dihedral angle of 148° between each pyridyl ring. Face-to-face ?? interactions reinforce intermolecular hydrogen bonding (O–HN) involving both carboxylate oxygen and pyridyl nitrogen atoms forming a 2D inter-helical network. Alternate 2D layers are of opposite chirality and are linked into 3D through (C–HO) hydrogen bonds. In both 1 and 2 the ligand is deprotonated giving neutral complexes with 1 ? 1 stoichiometry. Although 1 is monomeric, extensive hydrogen bonding between the deprotonated carboxylates, lattice water, and coordinated water molecules results in a 3D network which also contains face-to-face ?? interactions between adjacent dcbp ligands. Within 2, pseudo-octahedral coordination about the Cu(II) centre is furnished by bidentate bipyridyl nitrogens, two monodentate carboxylates (from two adjacent dcbp ligands) and two water molecules. Coordination of dcbp in this instance forms a 2D coordination polymer, which is further linked by extensive hydrogen bonding between carboxylates and water molecules, giving a 3D network

The ligand, the metal and the 'Holey'-host: Synthesis, structural and magnetic characterisation of Co(ii), Ni(ii) and Mn(ii) metal-organic frameworks incorporating 4,4'-dicarboxy-2,2'-bipyridine

We report herein the single crystal structures of four metal–organic framework complexes incorporating the 4,4?-dicarboxy-2,2?-bipyridine ligand, H2dcbp: ?-[Co(dcbp)(H2O)2], 1; ?-[Co(dcbp)(H2O)2], 2, [Ni(dcbp)(H2O)2], 3 and {[Mn(dcbp)]·½DEF}, 4 (DEF = diethylformamide). In each complex the ligand is deprotonated giving neutral species with 1 ? 1 stoichiometry that form three-dimensional coordination polymers. Supramolecular isomerism (polymorphism) in 1 and 2 arises from the different ligand connectivity around the octahedral Co(II) centres. The two coordinated water molecules in 1 occupy cis positions, which are trans to the chelating bipyridine nitrogen atoms, leaving the carboxylate oxygen atoms in axial trans positions. In 2 all like donors occupy cis positions. Different modes of carboxylate coordination in 1 and 2 give dissimilar network topologies. A rare example of two interpenetrating 6482-b (quartz-like) chiral networks in 1 results from both dcbp carboxylate groups coordinating in a monodentate fashion to adjacent Co(II) centres, whereas in 2 only one carboxylate group bridges between adjacent Co(II) centres giving rise to a single chiral (10,3)-a net. In 1 and 2 the coordinated water molecules hydrogen bond to the non-coordinated carboxylate oxygen atoms. These interactions give rise to water–carboxylate double helices in 1, and support the coordination network in 2. Strikingly for a pair of dimorphs the crystal densities of 1 and 2 differ by ca. 0.3 g cm?3 (1.654 vs. 1.940 g cm?3, respectively). Compound 3 is isomorphous with 1 and likewise features two chiral interpenetrating nets of quartz topology. In 4, chelating bipyridine nitrogen atoms and four carboxylate oxygen atoms from a total of five adjacent dcbp ligands provide distorted octahedral geometry around Mn(II). The carboxylate groups bridge adjacent Mn(II) centres to produce bis-carboxylato chains which cross-link and generate a 3D network that is perforated with channels. The channels are occupied with disordered DEF molecules. The network topology in 4 is quite different to 1–3 and has a (4.62)(42.6)(43.66.86) Schläfli notation. Magnetic susceptibility studies performed on 1, 2, {[Mn(dcbp)]·½DMF} 5 (DMF = dimethylformamide) and {[Mn(dcbp)]·2H2O} 6 reveal very weak antiferromagnetic coupling between the metal centres in each case