Isocyano-Triphenylene Complexes of Gold, Copper, Silver, and Platinum. Coordination Features and Mesomorphic Behavior

Abstract

Stable organometallic complexes [AuX­(CN-TriPh)] [X = Cl, C6F5, C6F4O-C10H21, C6F4O-(R)-2-octyl], [(μ-4,4′-C6F4C6F4)­{Au­(CN-TriPh)}2], [CuCl­(CN-TriPh)], trans-[PtI2(CN-TriPh)2], and [Ag­(CN-TriPh)2]­BF4, bearing the previously unreported triphenylene-isocyanide ligand 1-isocyano-2,3,6,7,10,11-hexadodecyloxytriphenylene (CN-TriPh), have been synthesized. The coordination features of the metal ion determine their thermal behavior. The free isocyanide ligand and all of the monomeric gold derivatives display enantiotropic mesomorphic behavior over a wide range of temperature (from 5 to 220 °C), while the copper complex, with the same stoichiometry but not isostructural with the gold complexes, melts directly to an isotropic liquid. The bis-isocyanide platinum and silver complexes also melt directly to an isotropic liquid at low temperatures. In this case, the two trans coordinated isocyanide ligands, connected by a too short linker, cannot become coplanar, which prevents the formation of a mesogenic structure. On the contrary, in the dinuclear gold complex the two isocyanide trans ligands are, due to the long Au–C6F4–C6F4–Au bridge, sufficiently separated to become coplanar, and this complex gives rise to a mesophase. The structures of the mesophases were determined by small-angle X-ray scattering. All materials prepared show a fluorescent emission centered on the triphenylene core.

Triphenylene-Imidazolium Salts and Their NHC Metal Complexes, Materials with Segregated Multicolumnar Mesophases

“…We have already reported mesomorphic organometallic complexes containing triphenylene moieties where π-stacking of the triphenylene discs in columns and aggregation of the metallic moieties into segregated columnar zones coexist in a well-ordered manner in the mesophase . With metallic fragments able to produce Pt···Pt interactions, highly stabilized phosphorescent mesophases based on these interactions were obtained. ,− …”

“…19,20 The strong stacking tendency of triphenylene provides an efficient structure for one-dimensional charge mobility. 21 The functionalization of the triphenylene core with long chains containing different functional groups, 22 including organometallics or coordination metal complexes, [23][24][25][26][27][28][29] offers many opportunities to modulate the properties of the system while conserving the tendency to columnar organization. We have already reported mesomorphic organometallic complexes containing triphenylene moieties where π-stacking of the triphenylene discs in columns and aggregation of the metallic moieties into segregated columnar zones coexist in a wellordered manner in the mesophase.…”

“…30 With metallic fragments able to produce Pt•••Pt interactions, highly stabilized phosphorescent mesophases based on these interactions were obtained. 29,31,32,33 The successful design of metal-containing mesomorphic triphenylene complexes reported in our initial studies prompted us to extend this investigation further to imidazolium triphenylene halides, their gold(I) and platinum(II) salts, and some N-heterocyclic carbene (NHC) complexes of Cu I , Ag I , Au I and Pt II . Imidazolium salts are precursors of Nheterocyclic carbene metal complexes extensively studied not only in organometallic chemistry and catalysis, but also in biological applications.…”

Striking Increase in Hole Mobility upon Metal Coordination to Triphenylene Schiff Base Semiconducting Multicolumnar Mesophases

“…There have been many reports where electron-withdrawing or -donating side groups are covalently bonded directly to the triphenylene core: nitro and amino groups, − cyano group, halides, , alkyl/alkoxy fragments, , and organometallic moieties. − In all of them the π–π interactions, critical for the columnar stacking, are sensitive to the substituents. There have also been reports where the triphenylene is functionalized at the end of one of the alkoxy substituents, so that the triphenylene core and the functional group are far apart and are electronically disconnected.…”

Platinum-based metallomesogens bearing a Pt(4,6-dfppy)(acac) skeleton: synthesis, photophysical properties and polarised phosphorescence application

“…Phosphorescent metallomesogens, that is the metal-containing liquid crystals, are of interest to both chemists and physicists because of their unique mesomorphic properties based on the inclusion of the metal atom and the theoretical 100% internal quantum efficiency. [9][10][11][12] To date, a considerable number of phosphorescent metallomesogens have been designed and prepared [13][14][15][16][17] and the most effective strategy for the design of such materials has been the modification of known chromophores in such a way as to introduce the anisotropy necessary for liquid crystal phase formation. For example, phosphorescent metallomesogens based on lanthanides, [18][19][20][21] platinum, [22][23][24][25][26][27][28][29][30][31][32][33][34] iridium, [35][36][37][38][39] and palladium 40 have been reported.…”