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Sb-Doped nanocrystalline SnO2 (SnO2:Sb) thin films functionalized with cyclometalated ruthenium complexes 1 or 2 on FTO conductive glasses have been prepared and characterized. These complexes contain a redox-active amine unit separated from the ruthenium ion by a phenyl or biphenyl linker, respectively, to modify the absorption wavelengths at different redox states. Near-infrared electrochromism of both films has been examined by oxidative spectroelectrochemical measurements and double-potential-step chronoamperometry. A contrast ratio (ΔT%) of 33% at 1070 nm and 63% at 696 nm has been achieved for the SnO2:Sb/1 film in two stepwise oxidation processes, respectively. The other film with complex 2 shows two-step electrochromism at 1310 and 806 nm with ΔT% of 36% and 76%, respectively. The response time of electrochromic switching is around a few seconds. Taking advantage of the good contrast ratio, the rapid response, and the long retention time of each oxidation state, these films have been successfully used to demonstrate surface-confined flip-flop memory functions with a high ON/OFF ratio. [ABSTRACT FROM AUTHOR]

A polypyridyl monoruthenium complex with a dangling coordination site shows dual fluorescence/phosphorescence emissions at room temperature. The emission properties can be modulated by multiple stimuli including solvents, O2, and metal ions. [ABSTRACT FROM AUTHOR]

The ITO/active material/Au sandwiched devices of a cobalt(ii) bis-terpyridine complex decorated with two triphenylamine motifs display appealing flash-type resistive switching with a large ON/OFF ratio (＞103) and low operating voltages (＜±3 V). In contrast, devices with the triphenylamine-appended terpyridine ligand show WORM-type memory behaviour. [ABSTRACT FROM AUTHOR]

In response to the application of low electrochemical potentials, ruthenium-tris(bipyridine) complexes decorated with multiple electron-rich and redox-active amine substituents show reversible absorption and emission spectral changes in the deep-red to NIR region. The number of amine substituents strongly affects the electrochemical and spectroscopic properties and the spin density distributions of the complex in the one-electron-oxidized state. [ABSTRACT FROM AUTHOR]

A series of C^N ligands with donor–acceptor (D–A) frameworks, i.e. TPA-BTPy, TPA-BTPy-Fl and Fl(TPA-BTPy)2, as well as their mono- and di-nuclear platinum(ii) complexes of (TPA-BTPy)Pt(pic), (TPA-BTPy-Fl)Pt(pic) and [Fl(TPA-BTPy)2]Pt2(pic)2 are respectively designed and synthesized, in which triphenylamine (TPA) and fluorene (Fl) are used as the D units, 4-(pyrid-2-yl)benzothiadiazole (BTPy) as the A unit, and the picolinate anion (pic) as the auxiliary ligand. Their thermal, photophysical and electrochemical characteristics were investigated. Compared to mono-nuclear platinum complexes and their free ligands, this dinuclear one of [Fl(TPA-BTPy)2]Pt2(pic)2 shows an obvious interaction from the platinum atom to ligand and dual emission peaks at 828 and 601 nm in thin films. Upon oxidation with antimony pentachloride in dichloromethane, charge transfer transitions between the platinum and ligand are observed for the three complexes. The single-emissive-layer polymer light-emitting devices doped with [Fl(TPA-BTPy)2]Pt2(pic)2 display a strong electroluminescence with dual emission peaks at 780 and 600 nm at a dopant concentration over 4 wt%. A maximum external quantum efficiency of 0.02% with a radiance of 59 μW cm−2 is obtained in the device at 30 wt% dopant concentration. This work indicates that the use of an extended D–A-type ligand is an effective strategy to achieve NIR emission for platinum complexes in PLEDs. [ABSTRACT FROM AUTHOR]

Hybrid films of functional molecules and metal nanoparticles have been considered to be novel photo-functional devices. Here we have successfully constructed hybrid films of silver nanoparticles and ruthenium polypyridine derivatives on substrates. In order to hybridise them on a surface, a self-assembled monolayer method via chemical bond formation and electro-reductive polymerisation (thick layers) via physical attachment have been employed. These methods have the advantage of convenient and reproducible fabrication of complicated hybrid films. Furthermore, it has been clarified that these hybrid films show unique photo-functional behaviours, such as enhanced photocurrent generation. [ABSTRACT FROM AUTHOR]

Recent investigations on polypyridine transi-tion-metal complexes as potential molecular wires have provided new impetus for these long-studied and well-established systems. Using bridging ligands 2,3-di(2-pyridyl)-5,6-diphenylpyrazine (dpdpz) and 2,3,5,6-tetrakis(2-pyridyl)-pyrazine (tppz), a tetrametallic cyclometalated ruthenium complex has been prepared and characterized, with each metal having one Ru--C bond. The electronic properties of this complex and two known monoruthenium and diruthenium complexes with dpdpz (DPDPZ series) were probed by electrochemical and spectroscopic techniques and compared to the previously reported tppz-based noncyclometalated ruthenium complexes (TPPZ series). The frontier orbital energy levels and electronic structures of the two series have been characterized by density functional theory (DFT) calculations. In accordance with the experimental results, these studies suggest that the DPDPZ series oligomers generally have a narrower energy gap relative to the TPPZ series. In addition, the large energy density of states in longer oligomers suggests the possibility of band-type conduction. The DPDPZ series exhibits red-shifted light absorption with enhanced intensity relative to the TPPZ series congeners. Time-dependent DFT computations have been performed to rationalize the electronic absorption of the DPDPZ series. Oxidative spectroelectrochemical measurements of the DPDPZ tetrametallic complex indicate the presence of intervalence charge-transfer transitions among ruthenium sites. [ABSTRACT FROM AUTHOR]

The linear bis-cyclometalated Ru(II) complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+was prepared from the oxidative coupling of the monometalliccomplex [(ttpy)Ru(dtab)]+in good yield, where ttpy is4′-tolyl-2,2′:6′,2″-terpyridine, ttabpis 3,3′,5,5′-tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)biphenyl,and dtab is 1,3-bis(1-butyl-1H-1,2,3-triazol-4-yl)benzene.The electronic properties of these two complexes were studied andcompared by electrochemical and spectroscopic methods and DFT/TDDFTcalculations. The complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+showedtwo consecutive RuII/IIIredox waves at +0.34 and +0.51V vs Ag/AgCl with a comproportionation constant Kcof 760. One-electron oxidation of [(ttpy)Ru(ttabp)Ru(ttpy)]2+by electrochemical methods produced the mixed-valent complex[(ttpy)Ru(ttabp)Ru(ttpy)]3+, which exhibited a symmetricintervalence charge transfer band at 1800 nm (νmax= 5550 cm–1, εmax= 5100 M–1cm–1, Δν1/2= 3580 cm–1). The energy and shape of this bandare very similar in the different solvents studied (CH3CN, DMF, CH2Cl2). [(ttpy)Ru(ttabp)Ru(ttpy)]3+was determined to be a class II/III borderline system withthe electronic coupling parameter Hab=530 cm–1. It displayed a metal-centered rhombicEPR signal at 77 K with an isotropic gfactor of2.109 and total ganisotropy of 0.256, which pointsto an appreciable spin distribution on the bridging ligand in additionto the metal centers. [ABSTRACT FROM AUTHOR]

• A bipolar cobalt coordination polymer bearing triphenylamine-pyridine ligand (poly(CoL) n) is reported. • In-cell electropolymerization effectively decreases solubility of poly(CoL) n in organic solution. • Dual-ion storage capability of poly(CoL) n originates from multiple redox sites of monomer. • The poly(CoL) n cathode delivered a high discharge specific capacity of 192.13 mAh/g at 0.05 A/g. • The poly(CoL) n cathode delivered a stable long-term cycling ability over 2000 cycles with 89% capacity retention at 5 A/g. Metal coordination complexes with remarkable redox activity and high working voltage are plagued by their limited specific capacity and sever dissolution problem. A bipolar cobalt-based coordination polymer (CoL) bearing both p-type and n-type active centers was synthesized via the in-situ electropolymerization method with collective merits of multiple redox sites, dual-ion storage capability, and excellent chemical stability. As-prepared electrodes delivered remarkable performances including a high discharge specific capacity of 192.13 mAh/g (at 0.05 A/g), stable cycling over 2000 cycles with 89% capacity retention (at 5A/g), and excellent rate capability. Moreover, the dual-ion storage processes were unveiled by ex-situ Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. It provides insight to design and synthesis of electropolymerized bipolar electrode for high performance dual-ion batteries. [ABSTRACT FROM AUTHOR]

• Basic switching mechanisms of resistive memory devices are introduced. • Much progress has been made in resistive memory switching using metal complexes. • The control of resistive switching properties by ligand design is discussed. Transition-metal complexes (TMCs) have recently attracted considerable scientific interest for resistive memory switching. The interplay between metal ions and ligand endows TMCs with rich and tunable electrochemical and photophysical properties, making them beneficial for the formation of electrical bi- or multistates in resistive memory devices. This review summarizes the applications of TMCs in resistive memory switching. Following the simple introduction of the basic concept and switching mechanism of resistive memory devices, the recent progress on the applications of ferrocene derivatives, polyazine metal complexes and metallopolymers, alkynyl metal complexes, and porphyrin or phthalocyanine metal complexes are discussed, with an emphasis on the modulation or control of switching properties by ligand design. [ABSTRACT FROM AUTHOR]

New dinuclear ruthenium or osmiumcomplexes with cyclometalatedbonds in either tridentate bridging (BL) or ancillary ligands (L),[(L)M(BL)M(L)] (where M = Ru, Os; L = bis(N-methylbenzimidazolyl)pyridine,-benzene; BL= tetrapyridylpyrazine (tppz), -benzene (tpb)), were synthesized,and their mixed-valence-state characteristics were investigated. Allof the complexes showed successive one-electron redox processes, eachof which correspond to M(II/III) (M = Ru, Os) or ligand reductionwaves. In addition, an M(III/IV) couple was observed in cyclometalated[M2(bis(benzimidazolyl)benzene)2(BL)] complexes(M = Ru, Os). Effects of the cyclometalated bonds on the redox behaviorsand the accessibility to the mixed-valence M(II)–M(III) dinuclearcomplexes are discussed. Introduction of a cyclometalated bond induceda large negative potential shift in the redox potentials of dinuclearruthenium and osmium complexes, depending on either bridging or ancillarysites of the cyclometalated bonds: the change falls within the rangeof −1.0 to −1.2 V for the bridging sites and −0.65to −0.7 V for the ancillary ones. This large negative potentialshift arises from the strong electron-donating property of the phenylanion in a metal–C bond. Replacing the ruthenium by osmiumin the dinuclear complexes with the same bridging ligand results inan increase of the potential separation (ΔE(1)) and the comproportionation constant (Kcom) of the mixed-valence complexes having the tppz bridgingligand (ΔE(1) and Kcomvalues: Os > Ru); however, complexes having the tpb bridgingligandshowed the opposite trend (ΔE(1) and Kcom: Os < Ru). In addition to the resultsof EPR and DFT calculation, it was found that the orbital energy levelsof the central metal ion (namely, either Ru or Os) in the mixed-valencecomplex determines the degree of orbital mixing between metal dπorbitals and bridging-ligand π or π*orbitals,which leads to either hole- or electron-transfer exchange mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: The reductive co-electropolymerization of vinyl-substituted ruthenium complexes 2(PF6) and 3(PF6)2 at ITO glass electrodes have afforded adherent metallopolymeric films, where complex 2(PF6) contains a dipicolylamine (DPA) unit as the ion recognition site and 3(PF6)2 is a ruthenium monomer without DPA. The resulting thin films can selectively detect Cu2+ at the solid-liquid interface on the basis of color, absorption, and electrochemical changes. By using EDTA to remove the incorporated Cu2+, the polymeric film can repeatedly detect Cu2+ with good reversibility and film stability, as supported by XPS and TEM analyses. [Copyright &y& Elsevier]

Three tris-bidentatecyclometalated ruthenium complexes with adi(p-anisyl)amino [5(PF6)],di(p-tolyl)amino [6(PF6)],or di(p-chlorophenyl)amino [7(PF6)] substituent on the cyclometalating phenyl ring have beenprepared, where the amine nitrogen is in the meta position to thecyclometalated site (bridged through the phen-1,3-diyl unit). Thestructure of 6(PF6) has been confirmed bysingle-crystal X-ray diffraction analysis. Two consecutive redox wavesare evident at .48 and .87 V versus Ag/AgCl for 5(PF6), .51 and .02 V for 6(PF6), and .53 and .18 V for 7(PF6), respectively.The first wave is assigned to the Ru(II/III) process, and the secondwave is attributed to the N(0/) process. After one-electron oxidationusing SbCl5, these complexes display distinct absorptionsin the near-infrared region, which are assigned to the nitrogen-to-rutheniumintervalence charge-transfer (ICVT) transitions. The energies of theIVCT transitions vary linearly versus the potential splitting of theRu(II/III) and N(0/) process. The charge-transfer direction in thesecomplexes is reversed with respect to a previously reported ruthenium–aminesystem where the amine nitrogen is in the para position to the cyclometalatedsite (bridged through the phen-1,4-diyl unit). [ABSTRACT FROM AUTHOR]