The 2-isocyanoazulene-gold(I) fragment as a versatile element for organometallic dyes and liquid crystals

Abstract

This manuscript reports the synthesis and liquid crystal behavior of isocyanoazulene gold(I) complexes [AuX(CN-Az)] (Az = azulene; X = halide, perhalophenyl or alkynyl) and [µ-4,4'-C6F4C6F4{Au(CN-Az)}2]. The comparison of the X-ray structures of homologous compounds, reveals that the introduction of a long substituent in the system produces a loss of molecular planarity that induces a decrease in the melting temperatures. The free 2isocyanoazulene is not a liquid crystal itself, but its gold complexes bearing a C10 hydrocarbon chain display a SmA mesophase, whose formation is driven by nanosegregation between molten chains and aromatic parts. The free isocyanide is strongly colored and displays fluorescence in solution associated with the azulene fragment, which is largely diminished upon coordination to the gold fragment.

Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

“…In addition, single molecules and nanostructures of 2-isocyano-1,3-di- tert -butoxycarbonylazulene adsorbed on Au(111), where the 2-isocyanoazulenic moieties are decoupled from the gold surface by bulky tert -butoxycarbonyl substituents, have been recently shown to be amenable to controlled manipulations by Scanning Tunneling Microscopy (STM) methods [ 23 ]. Redox-active complexes of ruthenium(II) tetraphenylporphyrin, featuring coordinated 2-isocyanoazulene [ 24 ], and liquid crystals based on the 2-isocyanoazulene complexes of gold(I) [ 25 ] have been reported as well.…”

Liquid crystalline self-assembly of azulene–thiophene hybrids and their applications as OFET materials

“…18 They also showed that the herringbone pattern was conserved in the crystallized film and fabricated potent organic field effect transistors (OFETs) with great application potential. [19][20][21][22][23] Although there have been several reports on azulene-based liquid crystals [24][25][26][27][28] and OFETs (Fig. 1(c) and (d)), [29][30][31][32][33][34][35][36][37] the combination of the unique properties of azulene Az and the strong templating effect of the SmE phase remains unknown.…”

“…Although there have been several reports on azulene-based liquid crystals 24–28 and OFETs (Fig. 1(c) and (d)), 29–37 the combination of the unique properties of azulene Az and the strong templating effect of the SmE phase remains unknown.…”

Electronic Properties and Solid-State Packing of Isocyanofulvenes and Their Gold(I) Chloride Complexes

“…In recent years, new ligands with increased steric bulk − and chelating functional groups ,,,, have been developed to generate new molecular architectures and tune optical properties and catalytic activity. Notably, isocyanoarenes are also known to facilitate electronic communication between metal centers, a property that has been expanded recently in the development of redox-active azulene- − and ferrocene-derived isocyano ligands (Chart B) …”

“…Moreover, electronic properties can also change in response to external stimuli such as temperature, mechanical stress, ,− ,,, irradiation, or the presence of solvent vapors . Only recently, liquid crystalline isocyano–gold­(I) complexes have also been reported (Chart B) …”