The heterobinuclear complex OsCl2(PPh3)2[CHC(PPh3)CFcO] (Fc = (C5H4)Fe(C5H5)) (1) in which the two metal centers were connected by the skeleton of the osmafuran and cyclopentadienyl was synthesized via a one-pot reaction of OsCl2(PPh3)3 and FcCOCCH in high yield. Three derivatives (Os(η2-OCOO)(PPh3)2[CHC(PPh3)CFcO] (2), Os(NCS)2(PPh3)2[CHC(PPh3)CFcO] (3), and OsCl2(dppb)[CHC(PPh3)CFcO] (dppb = Ph2P(CH2)4PPh2) (4)) were obtained by the ligand substitution reactions of complex 1 with different reagents (Cs2CO3 (2), NaSCN (3) and dppb (4)), respectively. All of these complexes were characterized by NMR spectroscopy and elemental analysis and the structures of complexes 1, 3 and 4 were further confirmed by single crystal X-ray diffraction. Their electrochemical properties were studied by cyclic voltammetry and square wave voltammetry. The first redox wave was ascribed to the couple Os(II)/Os(III). All of these complexes exhibit two redox processes with a large peak separation. However, UV-Vis-NIR combined with theoretical calculation clearly indicated that (1) the Os center plays a major role in the one-electron oxidation process of heterobinuclear complexes 1–4 and the osmafuran could be better described as a carbene ligand; (2) the electronic communication between the Os and Fe center is absent, and the osmafuran with the electron-withdrawing phosphonium substituent actually functioned as an insulating bridge.

An homologous series of divinylchalcogenophene-bridged binuclear ruthenium complexes [{(PMe3)3Cl(CO)Ru}2(µ-CH=CH-C4H2E-CH=CH)] (4a–4d, E = O, S, Se, Te) have been synthesised and fully characterised by X-ray crystallography and various spectroscopic techniques. The single-crystal X-ray diffraction results reveal a distinct short/long bond-length alternation along the polyene-like hydrocarbon backbone, with geometric constraints imposed by the chalcogenophene leading to an increasing distance between the two metal centres (dRu–Ru) in complexes 4a–4d as the heteroatom in the five-membered ring is changed from oxygen (9.980 Å in 4a) to tellurium (11.063 Å in 4d). The complexes undergo two sequential one-electron oxidation processes, the half-wave potential and separation of which appear to be sensitive to a range of factors, including aromatic stabilisation and re-organisation energies. Analysis of [4a–4d]n+ (n = 0, 1, 2) by UV/Vis/NIR and IR spectroelectrochemical methods, supported by DFT calculations (n = 0, 1), revealed that the redox character of the complexes is dominated by the polyene-like backbone with the chalcogenide playing a subtle but influential, structural rather than electronic, role. In the radical cations [4a–4d]+, the charge is rather effectively delocalised over the 10-atom Ru–[4-s-cis-all-trans-(CH=CH)4]–Ru chain, giving rise to a species with spectroscopic properties not dissimilar to oxidised polyaceylene.

p-Aminothiophenol (PATP) is an important probe molecule in surface-enhanced Raman spectroscopy. The unique and strong SERS signals of PATP distinguished from its normal Raman spectrum were considered as a signal of an existing charge transfer mechanism. Recent theoretical and experimental studies demonstrate that PATP undergoes surface catalytic coupling reaction to produce an aromatic azo species p,p′-dimercaptoazobenzene (DMAB), which should be responsible for the abnormal signals in the observed SERS spectra of PATP. In this work, three aminothiophenol derivatives with different substitute position and conjugation degree between the amino group (−NH2) and mercapto group (−SH) were chosen to study the effects of substituent including adsorption orientation effect and conjugation effect on the reactivity of photoinduced surface catalytic coupling reactions. A combined SERS and DFT study indicated that no surface reactions occurred for compound C1 and compound C2, while compound C3 was converted to the corresponding azo species during their SERS measurements. The differences in reactivity of the selected probe molecules were investigated on the basis of proposed photoexcitation and photoreaction mechanisms.

We have determined the conductance of alkane-linked ferrocene molecules with carboxylic acid anchoring groups using the STM break junction technique, and three sets of conductance values were found, i.e. high conductance (HC), medium conductance (MC) and low conductance (LC) values. The enhancing effect of the incorporated ferrocene on the electron transport in saturated alkane molecular wires is demonstrated by the increased conductance of the ferrocene molecules, attributed to the reduction of the tunneling barrier and the HOMO–LUMO gap induced by the insertion of ferrocene. Furthermore, the electron-withdrawing carbonyl group on the unconjugated backbone has little or no influence on single-molecule conductance. The current work provides a feasible approach for the design of high-performance molecular wires.

The facilitated transfer of alkali metal ions (Li+ and Na+) across the water/1,2-dichloroethane (W/1,2-DCE) interface was studied by using a series of crown ethers as ionophores: 4′-ethynylbenzo-15-crown-5-ether (L1), 3′,6′-diethynylbenzo-15-crown-5-ether (L2) and 4′,5′-diethynylbenzo-15-crown-5-ether (L3). Cyclic voltammetry was employed to study the electrochemical behaviour of the facilitated ion transfer across the W/1,2-DCE interface supported at the tip of a micropipette. The diffusion coefficients of the ionophores in the 1,2-DCE phase were determined, while the metal–ligand complexes formed by these ions with all the ionophores were obtained to be in a 1:1 stoichiometric ratio. The association constants, log β°, for complexes LiL1+, LiL2+, LiL3+, NaL1+, NaL2+ and NaL3+ were calculated to be 3.3, 4.2, 4.0, 2.1, 3.5 and 2.2, respectively. The theoretical calculations have shown that the conjugated constituent groups on the benzene ring have an essential effect on the spatial structures of the crown ether rings, which determine the supramolecular interaction between the ions and ionophores.

We have prepared four isomeric binuclear ruthenium complexes, in which two ruthenium units have been attached to the 1,4- (4a), 1,5- (4b), 1,8- (4c), or 2,6-positions (4d) of a central anthraquinone (Aq) moiety, leading to packed (4c) or extended (4a,b,d) topologies. All of these bimetallic complexes were fully characterized by elemental analysis, 1H, 13C{1H}, and 31P NMR{1H} spectrometry, and UV/vis spectrophotometry. Moreover, the structures of 4a,b were established by X-ray crystallography. The electrochemical properties of the stable binuclear ruthenium complexes 4a−d were investigated, revealing that the two metal centers in 4a−c could interact with each other through an anthraquinone bridge, suggesting that the electron-withdrawing carbonyl chain actually functions as an effective bridge.

We have determined the conductance of alkane-linked ferrocene molecules with carboxylic acid anchoring groups using the STM break junction technique, and three sets of conductance values were found, i.e. high conductance (HC), medium conductance (MC) and low conductance (LC) values. The enhancing effect of the incorporated ferrocene on the electron transport in saturated alkane molecular wires is demonstrated by the increased conductance of the ferrocene molecules, attributed to the reduction of the tunneling barrier and the HOMO–LUMO gap induced by the insertion of ferrocene. Furthermore, the electron-withdrawing carbonyl group on the unconjugated backbone has little or no influence on single-molecule conductance. The current work provides a feasible approach for the design of high-performance molecular wires.

The facilitated transfer of alkali metal ions (Li+ and Na+) across the water/1,2-dichloroethane (W/1,2-DCE) interface was studied by using a series of crown ethers as ionophores: 4′-ethynylbenzo-15-crown-5-ether (L1), 3′,6′-diethynylbenzo-15-crown-5-ether (L2) and 4′,5′-diethynylbenzo-15-crown-5-ether (L3). Cyclic voltammetry was employed to study the electrochemical behaviour of the facilitated ion transfer across the W/1,2-DCE interface supported at the tip of a micropipette. The diffusion coefficients of the ionophores in the 1,2-DCE phase were determined, while the metal–ligand complexes formed by these ions with all the ionophores were obtained to be in a 1:1 stoichiometric ratio. The association constants, log β°, for complexes LiL1+, LiL2+, LiL3+, NaL1+, NaL2+ and NaL3+ were calculated to be 3.3, 4.2, 4.0, 2.1, 3.5 and 2.2, respectively. The theoretical calculations have shown that the conjugated constituent groups on the benzene ring have an essential effect on the spatial structures of the crown ether rings, which determine the supramolecular interaction between the ions and ionophores.