Emanuele Priola

Facile synthesis of novel blue light and large Stoke shift emitting tetradentate polyazines based on imidazo[1,5-a]pyridine – Part 2

A series of new imidazo[1,5-a]pyridines was obtained through a facile multiple condensation procedure, involving the reaction of two methanamine and several largely available and inexpensive diand tricarboxylic acids. Such poliazine products show different and tuneable coordination motifs suitable for mono-, di-, and tritopic coordination sites. Furthermore they display interesting optical properties: tuneable luminescence, significant quantum yields, large Stokes’ shifts and strong halochromic effects, enabling their technological application.

A new heterometallic multiligand 3D coordination polymer: synthesis and structure of [Pb(OH)]n[Ag(SCN)(CN)]n

The synthesis and structural characterization of a new coordination polymer [Pb(OH)]n[Ag(SCN)(CN)]n, formed by an anionic layer [Ag(CN)(μ3-SCN)]nn− linked to the 1D cationic fragment [Pb(OH)]n through a bridging cyanide, is reported. We have obtained a rational combination of the pattern of laurionite-type structures (Pb(OH)X, with X = halogen, SCN) with the 2D hexagonal pattern of the silver thiocyanate. The title compound shows luminescent behaviour, and the analysis of the computed band structure allows us to describe the electronic transitions.

Autoluminescent Metal–Organic Frameworks (MOFs): Self-Photoemission of a Highly Stable Thorium MOF

A novel thorium(IV) metal-organic framework (MOF), Th(2,6-naphtalenedicarboxylate)2, has been synthesized via solvothermal reaction of thorium nitrate and 2,6-naphtalendicarboxilyc acid. This compound shows a new structural arrangement with an interesting topology and an excellent thermal resistance, as the framework is stable in air up to 450 °C. Most notably, this MOF, combining the radioactivity of its metal center and the scintillation property of the ligand, has been proven capable of spontaneous photon emission.

CCDC 1544702: Experimental Crystal Structure Determination

Related Article: Simone Bordignon, Paolo Cerreia Vioglio, Emanuele Priola, Dario Voinovich, Roberto Gobetto, Yusuke Nishiyama, Michele R. Chierotti|2017|Cryst.Growth Des.|||doi:10.1021/acs.cgd.7b00748

Reticular chemistry studies on CuCN derivatives for new luminescent materials

The construction of coordination polymers has been rationalized through the use of database and a topological approach. The reticular chemistry is based on the specific geometry of tectons that, by combination, form a predictable topology. This abstract procedure, in presence of nodes with a specific coordination form and of directional interactions, allows to obtaining a desired topology. This is often connected with the properties of the materials, like porosity, NLO properties and magnetism. Cyanide is a good ligand in reticular chemistry: its linearity in coordination bond makes equivalent both the coordination form and the coordination polyhedron of metal centers, and permits to clarify the derived structures. Although the lot of work done in recent years [1], some systems are very complex and less predictable than others. For example, the Cu(I)CN system is interesting because this salt, that forms linear polymer in the solid state [2], became very complex in presence of ancillary ligands. Cu(I) metal centers can have different coordination numbers and different coordination geometries. On the other hand, the cyanide itself has a multiform behavior in this system: the μ2 bridging mode , the terminal one and the combination of different bridging behaviors have been observed. For this reasons, a clearly predictable nodal geometry and a defined topological derivation is difficult to obtain, and a lot of work has still to be done. We focalized our attention on three different aspects. The first one is the presence of a terminal or briging ligand with different sterical requirements: to obtain some clarifying informations, we synthesized seven new derivatives of substituted and unsubstituted thioureas, and from their characterization and from a statistical analysis of Databases we correlate the nature of the ligand and the topology of the derived compounds. The second aspect is the effect of the partial substitution of Cu(I) with Cu(II) ion on the topology: to pursue a rationalization, we synthesized and structurally characterized six mixed Cu(I)/Cu(II) coordination polymers that will be commented. The third aspect is the presence of bi-chelating ligands of different rigidity and symmetry (2,2’-terpyridine and 2-(2’pyridyl)-1,8-naphthyridine) on the topology of the derived coordination polymers. This family of ligands, differently from the monochelating ones that follow the usual 1D wavy topology typical of terminal ligands, allows to construct interesting 2D-nets with {63} point symbol [3] and the presence of cuphrophilic interaction based on Secondary Building Units. We synthesized and structurally characterized two new compounds and the effects that favour the previous cited topology will be commented. All the previous analysis have been undertaken in the search of optimal luminescence for LED materials, and a full solid state luminescence characterization of all the 16 CuCN derivatives here presented has been done. In this communication, we will comment the principal effects influencing this property.