Precise Synthesis of Alternate Fe(II)/Os(II)-Based Bimetallic Metallo-Supramolecular Polymer.

A novel terpyridine-based bimetallic metallo-supramolecular polymer (polyFeOs) containing alternately complexed Fe(II) and Os(II) ions is synthesized. For precise synthesis of the polymer, a new three-step synthetic pathway is developed to obtain a high yield (%) of product in each step. The first step is the synthesis of dibromo terpyridine-Os(II) complex in 87% yield, the second step is the synthesis of bisterpyridine ligand containing Os(II) (OsL1) in 74% yield, and the last step is the synthesis of polyFeOs in 90% yield. The polyFeOs exhibits high thermal stability with two degradation temperatures at around 390 and 690 °C, which indicate thermal evaporation of the counter anions (Cl- and BF4 - ) and degradation of the coordination bonds, respectively. The combination of two different metal ions in polyFeOs results in an enlarged optical window (λ = 315-675 nm) and two highly stable reversible redox states, which can be of huge interest for potential optical, electro-optical, and electrochemical applications.

Synthesis of an Alternated Heterobimetallic Supramolecular Polymer Based on Ru(II) and Fe(II).

A heterobimetallic supramolecular polymer (polyRuFe) with alternately complexed Ru(II) and Fe(II) is prepared following a stepwise synthetic route through harnessing first the strongly binding metal ion Ru(II) and then the weakly binding metal ion Fe(II). A high yield of product is achieved in each step. The heterometal ions are incorporated into the polymer chain in identical coordination environments formed by two 2,2':6',2″-terpyridine moieties. Characterization is accomplished by NMR spectroscopy, MALDI-TOF mass spectrometry, UV-Vis spectroscopy, and cyclic voltammetry. PolyRuFe shows a wide optical window (λ = 311-577 nm) and a broad distinct reversible redox nature of two types, originated from the coupling of the two heterometallic segments into the polymer chain. Such characteristics of polyRuFe suggest its potential for various electrochemical and electro-optical applications.

Glial fibrillary acidic protein (GFAP) is a novel biomarker for the prediction of autoimmune diabetes.

Glial fibrillary acidic protein (GFAP) is expressed in peri-islet Schwann cells, as well as in glia cells, and has been reported to be an autoantigen candidate for type 1 diabetes mellitus (T1DM). We confirmed that the production of the autoantibodies GFAP and glutamic acid decarboxylase 65 (GAD65) was increased and inversely correlated with the concentration of secreted C peptide in female nonobese diabetic mice (T1DM model). Importantly, the development of T1DM in female nonobese diabetic mice at 30 wk of age was predicted by the positive GFAP autoantibody titer at 17 wk. The production of GFAP and GAD65 autoantibodies was also increased in KK-Ay mice [type 2 diabetes mellitus (T2DM) model]. In patients with diabetes mellitus, GFAP autoantibody levels were increased in patients with either T1DM or T2DM, and were significantly associated with GAD65 autoantibodies but not zinc transporter 8 autoantibodies. Furthermore, we identified a B-cell epitope of GFAP corresponding to the GFAP autoantibody in both mice and patients with diabetes. Thus, these results indicate that autoantibodies against GFAP could serve as a predictive marker for the development of overt autoimmune diabetes.-Pang, Z., Kushiyama, A., Sun, J., Kikuchi, T., Yamazaki, H., Iwamoto, Y., Koriyama, H., Yoshida, S., Shimamura, M., Higuchi, M., Kawano, T., Takami, Y., Rakugi, H., Morishita, R., Nakagumi, H. Glial fibrillary acidic protein (GFAP) is a novel biomarker for the prediction of autoimmune diabetes.

Electrochromic Os(II)-Based Metallo-Supramolecular Polymers.

This work presents the preparation of a series of novel Os(II)-based metallo-supramolecular polymers (polyOss: linear polyOsL1100% and hyperbranched polyOsL1x% L2y% ) that show a broad absorption spanning 312 to 677 nm and a low Os(II)/(III) redox potential of 0.94 V. The electrochromic properties of a polyOs film cast on an ITO substrate is investigated. The change in transmittance (ΔT) of polyOsL1100% is 49.9%, and the switching times for coloration (t c ) and bleaching (t b ) are 0.70 and 0.82 s, respectively. The introduction of a 10% branching structure (polyOsL190% L210% ) further enhanced the electrochromic performance with ΔT = 59.4%, t c  = 0.41 s, and t b  = 0.54 s. The coloration efficiency (η) increased from 396.1 to 467.5 cm2  C-1 upon branching. A solid-state electrochromic device with polyOsL1100% is successfully fabricated to use the polymer for potential applications.

Selective DNA Recognition and Cytotoxicity of Water-Soluble Helical Metallosupramolecular Polymers.

Water-soluble helical Fe(II)-based metallosupramolecular polymers ((P)- and (M)-polyFe) were synthesized by 1:1 complexation of Fe(II) ions and bis(terpyridine)s bearing a (R)- and (S)-BINOL spacer, respectively. The binding affinity to calf thymus DNA (ct-DNA) was investigated by titration measurements. (P)-PolyFe with the same helicity as B-DNA showed 40-fold higher binding activity (Kb = 13.08 × 107 M-1) to ct-DNA than (M)-polyFe. The differences in binding affinity were supported by electrochemical impedance spectroscopy analysis. The charge-transfer resistance (Rct) of (P)-polyFe increased from 2.5 to 3.9 kΩ upon DNA binding, while that of (M)-polyFe was nearly unchanged. These results indicate that ionically strong binding of (P)-polyFe to DNA chains decreased the mobility of ions in the conjugate. Unique rod-like images were obtained by atomic force microscopy measurement of the DNA conjugate with (P)-polyFe, likely because of the rigid binding between DNA chains and the polymer. Differences in polymer chirality lead to significantly different cytotoxicity levels in A549 cells. (P)-PolyFe showed higher binding affinity to B-DNA and much higher cytotoxicity than (M)-polyFe. The helicity in metallosupramolecular polymer chains was important not only for chiral recognition of DNA but also for coordination to a biological target in the cellular environment.

Selective edge modification in graphene and graphite by chemical oxidation.

The effect of edge structures in graphene sheets has been well investigated theoretically but most experimental demonstrations of the functionalization have been for the bulk structures because of only a few reports on chemical methods to modify the edges selectively. We herein report a chemical method using the Lemieux-von Rudloff reagent that selectively oxidizes only the edges of graphene sheets. The selective oxidation at the edges of the graphene sheet was confirmed by thermogravimetric analysis (TGA), Raman mapping measurements, and X-ray photoelectron spectroscopy (XPS). The TGA result of the oxidized graphite with different particle sizes showed a slight weight loss at approximately 350 degrees C (2.29% for the middle particles (35 microm)), which indicates thermal decomposition of the oxidized edge part. The Raman mapping measurement in the inner part of graphene sheets didn't detect any defects or translational symmetry breaking after the oxidation. The XPS data clearly showed that the total carbon atom content present as C--O, C==O, and O--C==C increased from 4.65 to 6.18% by the oxidation. Using the obtained edge-oxidized graphene as a starting material, various functionalizations of the edge structure are expected in the future.

Reversible Electrochromic/Electrofluorochromic Dual Switching in Zn(II)-Based Metallo-Supramolecular Polymer Films.

The introduction of novel materials with multifunctional chromogenic properties, such as electrochromic/electrofluorochromic (EC/EFC) properties, has recently attracted prospective interest in the development of various optoelectronic devices and smart windows. In this study, a novel Zn(II)-based metallo-supramolecular polymer (polyZn) has been developed as an ON/OFF switchable EFC application with prominent EC behavior. In this regard, the polymeric chain of polyZn was first synthesized by 1:1 complexation in a zigzag manner with Zn(II) ions at the metal center and 4,4'-[bis(2,2':6',2″-terpyridinyl)benzene]triphenylamine (LTPY-TPA) as the redox-active ditopic ligand. The polyZn exhibits excellent solubility in organic solvents and can form a very good uniform thin film on an indium tin oxide/glass substrate by spin-coating. In a neutral state, transparent polyZn exhibits a bright yellow color to the naked eye (absorption at ∼325 nm). The electroactive triphenylamine (TPA) core of LTPA-TPY, however, undergoes reversible single-electron oxidation when a positive bias of +1.6 V vs Ag/Ag+ is applied, generating radical cations (TPA ↔ TPA•+) with a significant drop in transparency (77%). A noticeable chromic shift in the hue of the film from brilliant yellow to green was observed with the appearance of a near-infrared absorption band at ∼897 nm with a tail of 1300-1600 nm. Interestingly, in addition to this EC phenomenon, the fabricated solid-state polyZn film exhibits intense, high-contrast reddish-orange photoluminescence with λem = 650 nm, which is significantly desired as a molecular probe for bioimaging. Both the TPA core and the redox-inactive Zn(II)-terpyridine core emit orange-red photoluminescence in polyZn, which is significantly quenched upon the oxidation of the film and is re-emitted at 0.0 V vs Ag/Ag+. This ON/OFF EFC transition was sustained for several cycles. This study should motivate to design and create distinctive new unique materials with combined EC/EFC behavior for the fabrication of optoelectronic devices by combining a metal-fluorescent core with a redox-active spacer.

Nanocomposites of Fe(II)-Based Metallo-Supramolecular Polymer and a Layered Inorganic-Organic Hybrid for Improved Electrochromic Materials.

Fe-based metallo-supramolecular polymer (polyFe), composed of Fe(II) ions and bis(terpyridyl)benzene, is known as a good electrochromic (EC) material. For the first time, to improve the EC properties, we prepared nanocomposites comprising polyFe and a layered inorganic-imidazoline covalently bonded hybrid (LIIm) by simply mixing them in methanol and then examined the effect of the nanocomposition on EC properties. The obtained blue/purple-colored composites (polyFe/LIIm composites) were demonstrated by scanning electron microscopy (SEM) to comprise a structure of LIIm nanoparticles coated with amorphous polyFe. Interestingly, X-ray diffraction (XRD) measurements suggested that there was no intercalation of polyFe in the interlayer space of LIIm. Ultraviolet-visible (UV-vis) spectroscopy measurements demonstrated that light absorption close to 600 nm was attributed to metal-to-ligand charge transfer (MLCT) from the Fe(II) ion to the bisterpyridine ligand and was influenced by LIIm in the composites. The composites exhibited a pair of redox waves, assigned to the redox between Fe(II) and Fe(III), in the cyclic voltammograms; moreover, the composites were estimated to be diffusion controlled. Thin composite films demonstrated reversible EC changes, triggered by the redox reaction of the metal. Furthermore, the results show that the nano-scale composition of the metallo-supramolecular polymers with LIIm can effectively improve the memory properties without reducing the contrast in transmittance (ΔT) of 70-76% in EC changes after applying 1.2 V vs. Ag/Ag+. The EC properties varied with varying ratios (3/0.1, 0.5, 1, and 5) of the polyFe/LIIm, and the ratio of 3/1 exhibited the longest memory and largest MLCT absorption peak among composites. The results show that the polyFe/LIIm composites are useful EC materials for dimming glass applications, such as smart windows.

Tuning of nonvolatile bipolar memristive switching in Co(III) polymer with an extended azo aromatic ligand.

We have fabricated a unique memristive device by molecular engineering and demonstrated that the leakage current tuning in the device is 100 times more efficient than that in a standard device. Molecular analogs of the memristive matrices used here are an electrochemically active conjugated Co(III) polymer (CP) and a nonconjugated Co(III) polymer (NCP), which have been synthesized in good yield and characterized by (1)H NMR spectroscopy. Redox switching of an organic-metallic hybrid polymer generates bistable states with a large ON/OFF ratio that supports random flip-flops for several hours. Thus, we provide a synthetic solution to leakage current restriction, one of the fundamental problems faced when fabricating state-of-the-art electronic devices.

Electrochromic properties of polythiophene polyrotaxane film.

The electrochromic properties of a polythiophene polyrotaxane film consisting of a polythiophene backbone wrapped by the tetra-cationic cyclophane, cyclobis(paraquat-p-phenylene), were characterized. A naked reference polythiophene film, i.e., polythiophene without tetra-cationic cyclophane, was also characterized. The surface morphology and thickness of the film (L) were observed by atomic force microscopy. The surface of the naked reference polythiophene film has micrometer-scale polythiophene aggregates, which causes the darker color of the film and smaller color contrast in the electrochromic process. The polythiophene polyrotaxane gives a more homogeneous and brighter colored film owing to the suppression of molecular interactions between the polythiophene chains by the tetra-cationic cyclophanes. Potential-step chronoamperometric measurement provided the area density of the oxidizable sites (Γ) and the apparent diffusion coefficient of the charge transport in the film. From linear relationship between L and Γ, the concentrations of the oxidizable sites in the polythiophene polyrotaxane and naked reference polythiophene films were calculated to be 1.3 and 2.4 mmol cm(-3), respectively. Interestingly, the polythiophene polyrotaxane film afforded a significantly larger apparent diffusion coefficient than the naked reference polythiophene film. This result suggests that the rate-determining step of the charge transport is not the electron hopping between the polythiophene chains but the transport of charge-compensating counterions from the solvent into the polythiophene. We believe that the counteranions of the tetra-cationic cyclophane provide a pathway allowing the charge-compensating counteranions to migrate from the solvent to polythiophene. The polythiophene polyrotaxane film showed faster color change than the naked reference polythiophene film in the electrochromic reaction. These results indicate that our polythiophene polyrotaxane is a better electrochromic material than the naked reference polythiophene.

Gold nanoparticles with cyclic phenylazomethines: one-pot synthesis and metal ion sensing.

New gold nanoparticles covered with cyclic phenylazomethine (CPA) were obtained by a one-pot synthesis. It is confirmed by XPS that imines of CPA in the nanoparticles (Au-CPA) are partially reduced to amines. The amine part of CPA in Au-CPA is attached to the surfaces of gold nanoparticles, and the imine part works as a redox-active site. A glassy carbon electrode modified with Au-CPA was revealed to work as an electrochemical probe for metal ion sensing.

Aromatic macrocycle containing amine and imine groups: intramolecular charge-transfer and multiple redox behavior.

A cyclic compound that has alternating diphenylamine and quinodiimine units was obtained by condensation of anthraquinone with bis(4-aminophenyl)amine (aniline dimer) in 20% yield. The resulting macrocycle has an absorption of 462 nm, which is assigned to charge transfer transitions between electron-rich diphenylamine units and electron-poor anthraquinone diimine units. Cyclic voltammetry in acidic MeCN shows redox of anthraquinone diimine units (E(1/2) = 0.03 V vs Ag/Ag(+)) and of oxidation of amino groups of higher potentials (0.60 and 0.77 V).

Conjugation of organic-metallic hybrid polymers and calf-thymus DNA.

Strong electrostatic interaction between metallo-supramolecular polymers and DNA was confirmed by UV-vis and CD spectral measurements during titration, and cyclic voltammetry. The stable conjugation structure based on groove binding was revealed by using QM/MM computational methodology and supported by AFM.

Stepwise introduction of three different transition metals in metallo-supramolecular polymer for quad-color electrochromism.

Metallo-supramolecular polymers (MSPs) show unique electrochemical and optical properties, that are different to organic polymers, caused by electronic interactions between metals and ligands. For the development of quad-color electrochromic materials, here we report the stepwise introduction of three different transition metal ions into an MSP, utilizing the different complexation abilities of the transition metals. An MSP with Os(II), Ru(II), and Fe(II) (polyOsRuFe) was synthesized via a stepwise synthetic route through the formation of an Os(II) complex first, followed by the introduction of Ru(II) to the Os(II) complex, and finally the attachment of Fe(II) to the Os(II)-Ru(II) complex to produce the polymer. This synthetic procedure was extended to fabricate MSPs that comprised Co(II)/Ru(II)/Os(II) and Zn(II)/Ru(II)/Os(II). The synthesized MSPs showed a broad optical and electrochemical window due to the coupling of three heterometallic segments into the polymer. Introducing acetate anion as the counter anion greatly enhanced the solubility of polyOsRuFe in methanol. A thin film of polyOsRuFe was prepared on ITO/glass by spin-coating the methanol solution, and its reversible quad-color electrochromism was demonstrated.

Ru(II)-Based Metallo-Supramolecular Polymer with Tetrakis(N-methylbenzimidazolyl)bipyridine for a Durable, Nonvolatile, and Electrochromic Device Driven at 0.6 V.

Low-voltage operation, high durability, and long memory time are demanded for electrochromic (EC) display device applications. Metallo-supramolecular polymers (MSPs), composed of a metal ion and ditopic ligand, are one of the recently developed EC materials, and the ligand modification is expected to tune the redox potential of MSP. In order to lower the redox potential of MSP, tetrakis(N-methylbenzimidazolyl)bipyridine (LBip) was designed as an electronically rich ligand. Ru-based MSP (polyRu-LBip) was successfully synthesized by 1:1 complexation of RuCl2(DMSO)4 with LBip. The molecular weight (Mw) was high (8.8 × 106 Da) enough to provide a simple 1H NMR spectrum, of which the proton peaks could be assigned by the comparison with the spectrum of the corresponding mono-Ru complex. The redox potential (E1/2) between Ru(II/III) was 0.51 V versus Ag/Ag+, which was much lower than the redox potential of previously reported Ru-based MSP with bis(terpyridyl)benzene (0.95 V vs Ag/Ag+). The polymer film exhibited reversible, distinct color changes between violet and light green-yellow upon applying very low potentials of 0 and 0.6 V vs Ag/Ag+, respectively. The appearance and disappearance of the metal-to-ligand charge transfer absorption by the electrochemical redox between Ru(II/III) were confirmed using in situ spectro-electrochemical measurement. A solid-state EC device with polyRu-LBip was revealed to have large optical contrast (ΔT 54%), fast response time (1.37 s for bleaching and 0.67 s for coloration), remarkable coloration efficiency (571 cm2/C), and high durability for the repeated color changes more than 20,000 cycles. The device also showed a long optical memory time of up to 19 h to maintain 40% to the initial contrast under the open circuit conditions. It is considered that the stabilization of the Ru(III) state by LBip suppressed the self-coloring to Ru(II) inside the device.

Reversible four-color electrochromism triggered by the electrochemical multi-step redox of Cr-based metallo-supramolecular polymers.

Four color electrochromism (yellow, magenta, blue, and navy) has been achieved in Cr(iii)-based metallo-supramolecular polymers (polyCr), which were synthesized by 1 : 1 complexation of Cr ions and 1,4-di[[2,2':6',2''-terpyridin]-4'-yl]benzene (L). The polymer structure was determined by X-ray absorption fine structure (XAFS) measurement and X-ray photoelectron spectroscopy (XPS). The molecular weight of polyCr was calculated as 3.2 × 107 Da using right angle light scattering (RALS). The EXAFS fitting indicated that the bond distances of Cr-N are 2.020 Å and 2.208 Å. A film of polyCr shows multi-color electrochromism (EC) or absorption: a sharp peak at 380 nm at 0 V vs. Ag/Ag+ (yellow), a sharp peak at 510 nm and a broad peak at 800 nm at -0.6 V vs. Ag/Ag+ (magenta), a broad peak at 610 nm and between 700-900 nm at -1.2 V vs. Ag/Ag+ (blue), a broad peak between 450-900 nm at -1.8 V vs. Ag/Ag+ (navy). The transmittances change (ΔT), the switching times for coloring and bleaching (T c, T b) and the coloration efficiency (η c, η b): [ΔT, (T c, T b), (η c, η b)] were [39.2%, (5.56 s, 1.39 s), (169 cm2 C-1, 230 cm2 C-1)] at 510 nm between -0.6 and 0.2 V vs. Ag/Ag+, [67.0%, (6.93 s, 2.52 s), (138 cm2 C-1, 172 cm2 C-1)] at 610 nm between -1.2 and 0.2 V vs. Ag/Ag+, [86.1%, (6.80 s, 3.03 s), (167 cm2 C-1, 134 cm2 C-1)] at 780 nm between -1.8 and 0.2 V vs. Ag/Ag+, respectively, during the cycles. The durability experiment indicates that polyCr shows an EC property for at least 100 cycles.

Constructing Alternated Heterobimetallic [Fe(II)/Os(II)] Supramolecular Polymers with Diverse Solubility for Facile Fabrication of Voltage-Tunable Multicolor Electrochromic Devices.

Metallo-supramolecular polymer (MSP)-based electrochromic devices (ECDs) have drawn much attention because of their variable colors and attractive electrochromic (EC) properties. However, fabrication of voltage-tunable multicolor ECDs using single MSP is yet hard to realize. We anticipated alternate introduction of two different redox-active metal ions in an MSP combined with the adjustment of counteranions could be a solution to fabricate multicolor ECDs. The heterometals will induce color variability upon voltage alteration, and counteranions will help to tune the solubility of MSP in different solvents. In an attempt to fulfill this target, we have synthesized four heterobimetallic supramolecular polymers (HBPs) having different counteranions (BF4-, Cl-, PF6-, and OAc-), in which Fe(II) and Os(II) are alternately complexed by two terpyridine units. To apply as EC material, the HBPs should be soluble in methanol and insoluble in acetonitrile for the preparation of EC film as well as ECDs. However, among the HBPs, only HBP-OAc is found to meet this requirement. The EC behaviors of the spray-coating film of HBP-OAc on an indium tin oxide (ITO)-coated glass substrate are investigated in terms of maximum transmittance contrast, coloration voltage, response time, coloration efficiency, and operational stability, which exhibits reversible multicolor electrochromism (the initial purple color of the film is changed to violet followed by greenish-yellow) upon alteration of the voltage from 0.0 to 0.7 V [required to oxidize the Os(II) ion] and to 1.0 V [required to oxidize the Fe(II) ion]. The film is also integrated into a laminated ECD by using lithium-based gel electrolyte. Finally, as a proof-of-concept, a prototype voltage-tunable multicolor EC display (6 cm × 2.5 cm) is fabricated by using a designed image containing a flower, leaves, and a flower pot, which exhibits six different types of multicolor image upon application of tunable voltages.

Transparent Supercapacitor Display with Redox-Active Metallo-Supramolecular Polymer Films.

The use of metallo-supramolecular polymer (MSP) as a thin-film-based redox supercapacitor electrode material is reported for the first time. Fe(II)- and Ru(II)-based MSPs (polyFe and polyRu, respectively) were synthesized by complexation of appropriate metal salts with 4',4″-(1,4-phenylene)bis-2,2':6',2″-terpyridine, and thin films of these polymers were prepared by spray coating onto an indium tin oxide glass substrate. A study of the energy storage performances of the polyFe and polyRu films in a nonaqueous electrolyte system revealed volumetric capacitances of ∼62.6 ± 3 F/cm3 for polyFe and 98.5 ± 7 F/cm3 for polyRu at a current density of 2 A/cm3. To improve the energy storage performance over a wider potential range, asymmetric supercapacitor (ASC) displays were fabricated with suitable combinations of the MSPs as cathodic materials and Prussian blue as the anodic counter material in a sandwich configuration with a transparent polymeric ion gel as the electrolyte. The fabricated ASCs showed a maximum volumetric energy density (∼10-18 mW h/cm3) that was higher than that of lithium thin-film batteries and a power density (7 W/cm3) comparable to that of conventional electrolyte capacitors, with superb cyclic stability for 10 000 cycles. To demonstrate the practical use of the MSP, the illumination of a light-emitting diode bulb was powered by a laboratory-made device. This work should inspire the development of high-performance thin-film flexible supercapacitors based on MSPs as active cathodic materials.

Dual-Redox System of Metallo-Supramolecular Polymers for Visible-to-Near-IR Modulable Electrochromism and Durable Device Fabrication.

Dual-redox metallo-supramolecular polymers with a zigzag structure (polyFe-N and polyRu-N) were successfully synthesized by 1:1 complexation of a redox-active Fe(II) or Ru(II) ion and 4,4-bis(2,2:6,2-terpyridinyl)phenyl-triphenylamine (LTPA) as a redox-active ligand. The polymers had high solubility in methanol, and the polymer solutions showed dark brown (polyFe-N) or orange-red (polyRu-N) coloration. UV-vis spectra of the polymers displayed a strong metal-to-ligand charge transfer (MLCT) absorption in the visible region. Cyclic voltammograms of the polymer films exhibited two pairs of reversible redox waves. The first redox at ∼0.5 V versus Ag/Ag+ was assigned to the redox in the triphenylamine (TPA) moiety of LTPA, and the second redox at 0.8 V versus Ag/Ag+ (polyFe-N) or 0.9 V versus Ag/Ag+ (polyRu-N) was given to the redox of Fe(II)/(III) or Ru(II)/(III), respectively. Upon applying a positive potential of more than 0.5 V versus Ag/Ag+ to the polymer films, a new absorption at ∼820 nm in the near-infrared (NIR) region appeared with wide tailing to the longer wavelength. It is considered that the new absorption in the NIR region is caused by the polaron band of the oxidized ligand in the polymers. When the applied potential was increased to 1.0 V versus Ag/Ag+ (polyFe-N) or 1.1 V versus Ag/Ag+ (polyRu-N), the maximum wavelength of the new absorption in the NIR region shifted to 885-900 nm and the absorbance was further enhanced with disappearance of the MLCT absorption. Eventually, the original colors of the polymers were faint to light green. This visible-to-NIR electrochromism was reversible, and maximum optical contrast (ΔT) reached 52% in the visible region and 80% in the NIR region. A prototype solid-state device with the polymer was fabricated for practical utilization, exhibiting excellent cycle stability of >4000 cycles with maintaining high optical contrast from the visible-to-NIR range.