Syntheses, optical and electrochemical properties of 4,4′-bis-[2-(3,4-dibutyl-2-thienylethynyl)]biphenyl and its oligomers

Electronic transport through single-molecule oligophenyl-diethynyl junctions with direct gold-carbon bonds formed at low temperature

We report on the first systematic transport study of alkynyl-ended oligophenyl-diethynyl (OPA) single-molecule junctions with direct Au-C anchoring scheme at low temperature using the mechanically controlled break junction technique. Through quantitative statistical analysis of opening traces, conductance histograms and density functional theory studies, we identified different types of junctions, classified by their conductance and stretching behavior, for OPA molecules between Au electrodes with two to four phenyl rings. We performed inelastic electron tunneling spectroscopy and observed the excitation of Au-C vibrational modes confirming the existence of Au-C bonds at low temperature and compared the stability of molecule junctions upon mechanical stretching. Our findings reveal the huge potential for future functional molecule transport studies at low temperature using alkynyl endgroups.

Crystal structure of 4,4'-diethynylbiphen-yl

The title compound, C16H10, crystallizes with four unique mol-ecules, designated 1-4, in the asymmetric unit of the monoclinic unit cell. None of the mol-ecules is planar, with the benzene rings of mol-ecules 1-4 inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4)°, respectively. In the crystal, weak C-H⋯π(ring) interactions, augmented by even weaker C C-H⋯π(alkyne) contacts, generate a three-dimensional network structure with inter-linked columns of mol-ecules formed along the c-axis direction.

Formation of photoresponsive gold nanoparticle networks via click chemistry

To tailor highly-functionalized gold nanoparticle (GNP) networks, we investigated the GNP network formation with functionalized spacer group via click chemistry. This is based on its high reactivity and mild reaction conditions. The feature of this protocol is the easy approach to versatile GNP functionalization on the basis of the excellent accessibility and good stability of functional dialkyne derivatives. We achieved the successful formation of GNP networks by reacting azide-appended GNPs and various dialkyne derivatives, supported by infrared absorption spectroscopy and transmission electron microscopy analyses. These GNP networks readily showed the unique physical properties similar to those of classical GNP networks prepared by ligand exchange reaction of bidentate functional spacers. Typically, the GNP network with the azobenzene unit as a functional spacer (GNP3) showed reversible photoinduced formation of three-dimensional aggregates followed by its isomerization in the network.

Rigid rod and tetrahedral hybrid compounds featuring nucleobase and nucleoside end-capped structures

Being aimed at a new type of porous solids, a moduled design strategy of molecular tectons, making use of the conjugation between a shape defined artificial backbone and the bioinspired molecular fragments of nucleobases or nucleobase derivatives as functional end-caps, has been developed. This led to the formation of the new hybrid compounds 1-13 of linear and tetrahedral geometry, containing uracil, adenine, adenosine, guanosine and its acylated analogs as the sticky end-cap sites. The compounds were synthesized from a halogen or ethynyl substituted nucleobase component and the corresponding ethynylated spacer unit following a metal assisted coupling process as the key reaction step. X-Ray crystal structure analysis demonstrates that the parent compound 1 is a solvent complex with DMSO (1:2), showing the DMSO molecules incorporated in a hydrogen bonded layer structure. Specific dependencies of the fluorescence properties of the new compounds in solution on the structure of the molecules are reported. A selection of solid compounds has been studied in respect of their ability to adsorb organic vapours. They revealed significant differences both in the sorption capacity and the selectivity towards particular solvent vapours.

4,4'-Bis[2-(3,4-dibutyl-2-thienylethyn-yl)]biphen-yl

The mol­ecule of the title compound, C₄₀H₄₆S₂, reveals C_i symmetry. An inversion centre is located at the mid-point of the C—C bond of the biphenyl unit; the asymmetric unit comprises one-half of the mol­ecule. The conjugated backbone is nearly planar, with a mean deviation of 0.041 Å.