Electrochemical and optical studies of furan and thieno[3,2‐b]thiophene end capped benzotriazole derivatives

Two new 2‐dodecyl benzotriazole (BTz) based donor‐acceptor‐donor (DAD) type polymers were synthesized and characterized in terms of their electrochemical and spectral properties. These DAD type polymers were synthesized electrochemically from furan or thieno[3,2‐b]thiophene (TT) end‐capped BTz monomers. Furan based and thieno[3,2‐b]thiophene based monomers showed monomer oxidations at 1.15 and 1.25 V, respectively, which eased the formation of conducting polymer films without overoxidation. Cyclic voltammetry and spectroelectrochemistry studies showed that both materials are multicolored electrochromic polymers. Results and comparison with properties of other BTz based DAD type polymers are highlighted in detail. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis,photoluminescence, and electrochromism of polyamides containing (3,6‐di‐tert‐butylcarbazol‐9‐yl)triphenylamine units

A new carbazole‐derived, triphenylamine (TPA)‐containing aromatic dicarboxylic acid monomer, 4,4′‐dicarboxy‐4″‐(3,6‐di‐tert‐butylcarbazol‐9‐yl)TPA, was synthesized, and it led to a series of electroactive aromatic polyamides with main‐chain TPA and pendent 3,6‐bis(tert‐butyl)carbazole units by reacting it with various aromatic diamines via the phosphorylation polyamidation technique. The polyamides were amorphous with good solubility in many organic solvents and could be solution‐cast into flexible and strong films. They showed high glass‐transition temperatures (282–335 °C) and high thermal stability (10% weight loss temperatures >480 °C). The electroactive polymer films had well‐defined and reversible redox couples with good cycle stability in acetonitrile solutions. The polymer films also exhibited fluorescent and multielectrochromic behaviors. The anodically electrochromic polyamide films had moderate coloration efficiency (～100 cm²/C) and high optical contrast ratio of transmittance change (Δ%T) up to 47% at 813 nm and 48% at 414 nm for the green coloring. After hundreds of cyclic switches, the polymer films still retained good redox and electrochromic activity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

电致变色氧化钨薄膜锂离子阈值注入量的研究

探讨了ＷＯ３薄膜与１ＭＬｉＣｌＯ４－ＰＣ溶液之间的界面电位差的变化规律及测量方法，制备了三种具有不同电致变色性能的ＷＯ３薄膜，并对它们进行了界面电位差随Ｌｉ＾＋注入量大小变化的测量，通过实验发现，界面电位差的变化趋势能够反映出氧化钨薄膜的Ｌｉ＾＋离子阈值注入量的大小。进而找到了用电阻热蒸发方法制备了电致变色氧化钨薄膜的最佳工艺条件。     

Optical Properties of Sol-Gel Derived Vanadium Oxide Films

Vanadium oxide gels can be made from vanadate aqueous solutions or from vanadium alkoxides. The condensation of vanadic acid gives long ribbon-like oxide particles which macroscopically orient in the same direction in aqueous sols when their concentration is larger than 0.12 mol·l⁻¹. These anisotropic sols and gels should be considered as lyotropic nematic liquid crystals. Thick films in which ribbons align along the same direction can be deposited. These oriented coatings exhibit improved electrochemical properties as reversible cathodes for lithium batteries. Amorphous oxo-polymers are formed via the controlled hydrolysis of vanadium alkoxides. They allow the deposition of optically transparent thin films that exhibit interesting electrochromic properties and turn reversibly from yellow to green upon electrochemical reduction. Moreover these alkoxide derived films can be easily reduced into vanadium dioxide. These VO₂ thin films exhibit thermochromic properties and could be used as optical switches in the infrared. The transition temperature of these VO₂ films can be modified by doping the vanadium oxide with other cations.     

Unconventional Aluminum Ion Intercalation/Deintercalation for Fast Switching and Highly Stable Electrochromism

Electrochromic devices have many important commercial applications ranging from electronic paper like displays, antiglare rear‐view mirrors in cars, to energy‐saving smart windows in buildings. Monovalent ions such as H⁺, Li⁺, and Na⁺ are widely used as insertion ions in electrochromic devices but have serious limitations such as instability, high‐cost, and hard handling. The utilization of trivalent ions as insertion ions has been largely overlooked probably because of the strong electrostatic interactions between ions and intercalation framework and the resulted difficulties of intercalation. It is demonstrated that the trivalent ion, Al³⁺, can be used as efficient insertion ion by using metal oxide hosts in nanostructured form, which brings the desired fast‐switch, high‐contrast, and high‐stability as well to electrochromic devices. Differing from the usual structure degradation by repeated guest intercalation/deintercalation, the Al³⁺ insertion introduces strong electrostatic forces, which on some degree stabilize the crystal structure and consequently yield much enhanced performances.     

Optical and electronic properties of fluorene‐based copolymers and their sensory applications

A series of novel, fluorene‐based conjugated copolymers, poly[(9,9‐bis{propenyl}‐9H‐fluorene)‐co‐(9,9‐dihexyl‐9H‐fluorene)] ( P1 ), poly[(9,9‐bis{carboxymethylsulfonyl‐propyl}fluorenyl‐2,7‐diyl)‐co‐(9,9‐dihexyl‐9H‐fluorene)] ( P2 ) and poly[(9,9‐dihexylfluorene)‐co‐alt‐(9,9‐bis‐(6‐azidohexyl)fluorene)] ( P3 ), are synthesized by Suzuki coupling reactions and their electrochemical properties, in the form of films, are investigated using cyclic voltammetry. The results reveal that the polymer films exhibit electrochromic properties with a pseudo‐reversible redox behavior; transparent in the neutral state and dark violet in the oxidized state. Among the three polymers, P2 possesses the shortest response time and the highest coloration efficiency value. These polymers emit blue light with a band gap value of around 2.9 eV and have high fluorescent quantum yields. Their metal ion sensory abilities are also investigated by titrating them with a number of different transition metal ions; all of these polymers exhibit a higher selectivity toward Fe³⁺ ions than the other ions tested with Stern–Volmer constants of 4.41 × 10⁶M^?1, 3.28 × 10⁷M^?1, 1.25 × 10⁶M^?1, and 6.56 × 10⁶M^?1 for P1 , P2 , water soluble version of P2 ( P2S ) and P3 , respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

A platform to synthesize a soluble poly(3,4‐ethylenedioxythiophene) analogue

Alkyl‐substituted polyhedral oligomeric silsesquioxane (POSS) cage is combined with 3,4‐ethylenedioxythiophene under the same roof. The corresponding monomer called EDOT‐POSS is used to get soluble poly(3,4‐ethylenedioxythiophene) (PEDOT‐POSS) analogue. Both chemically and electrochemically obtained polymers are soluble in common organic solvents like dichloromethane, chloroform, tetrahydrofuran, and so forth. The PEDOT‐POSS has somewhat higher band gap (1.71 eV at 618 nm) than its parent PEDOT (1.60 eV at 627 nm) and as expected the PEDOT‐POSS exhibits higher optical contrast (74% at 618 nm) and coloration efficiency (582 cm²/C for 100% switching), lower switching time (0.9 s), higher electrochemical stability (93% of its electroactivity retains after 5000 cycles under ambient conditions) when compared to the PEDOT. A number of advantages of the PEDOT‐POSS over the PEDOT can make it a promising material in the areas of electro‐optical applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3935–3941     

Innocent or guilty? Redox activity in and magnetic and optical behaviour of dinuclear molydenum complexes

The phenomenon of ‘non-innocence’, first articulated by J?rgensen in 1966, is briefly reviewed. Spectroelectrochemical studies of a range of dinuclear complexes of the type [Mo(NO)Tp*Cl₂(bridge)] (bridge = dipyridyls) and [Mo(O)Tp*Cl₂(bridge)] (bridge = diphenolates) which are redox active, show that oxidised or reduced forms of these species exhibit ‘non-innocence’. The spectral behaviour is associated with metal-to-ligand or ligand-to-metal charge transfer phenomena, probably the first time that monodentate bridging ligands have been implicated in ‘non-innocent’ behaviour. These bridging ligands also determine the nature and extent of magnetic interaction between the unpaired spins in [Mo(NO)Tp*Cl₂(bridge)] and [Mo(O)Tp*Cl₂(bridge)], the dominant mechanism of spin-exchange relying on the extent of {ie291-01}-delocalisation within the bridging ligands. The unusual optical behaviour of these dinuclear complexes when oxidised (oxomolybdenum diphenolates) or reduced (nitrosyl molybdenum dipyridyls) has led to the exploration of electrochromism as a means to develop variable optical attenuators operating in the near-infrared region.     

多金属氧酸盐电致变色材料

多金属氧酸盐具有多样的结构和良好的电化学可逆性,在电致变色器件(例如军事伪装、后视镜、智能窗以及高对比度信息显示器)上有着广阔的应用前景。本文综述了多金属氧酸盐在电致变色领域的研究进展情况。概述了多金属氧酸盐的电致变色机理以及制备多金属氧酸盐电致变色薄膜的方法,主要包括:溶胶-凝胶方法、电沉积法、Langmuir-Blodgett方法、层接层自组装方法。按照多金属氧酸盐的结构类型分类,结合最新文献报道,介绍了同多酸(盐)型和杂多酸(盐)型电致变色材料性能的研究现状。最后,对其未来的发展方向进行了展望。