The copolymerisation of 3,3′″ Dihexyl-2,2′:5′,2″:5″,2′″-quaterthiophene (DHQT) and (R)-(-)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate (DNBP) was successfully performed electrochemically in acetonitrile (CH3CN) containing tetrabutylammonium tetrafluoroborate ((C4H9)4NBF4) by direct oxidation of monomer mixtures in different feed ratios. Copolymerisation improved the properties of the films of both polymers PDHQT and PDNBP, in respect to the adhesion of PDHQT onto ITO/glass surface and the chromatic contrast of these electrochromic materials. PDHQT, PDNBP and P(DHQT-co-DNBP) films were characterised by FTIR spectroscopy, fluorescence spectroscopy, Scanning Electron Microscopy (SEM) and spectroelectrochemical techniques. Solutions of PDHQT and its copolymers with DNBP (independently of the feed ratio) in N-methylpyrrolidone are fluorescent with emission bands at 555 and 585nm when excited at 375nm. Reversible changes in the hue and saturation occur in all the copolymer films from yellow or orange in the reduced state to green or blue in the oxidised state, but were dependent on the proportion of the comonomers used to prepare the copolymers. These changes are more significant for P(DHQT-co-DNBP) films deposited onto ITO/glass with 1:5 feed ratio, as shown by the track of the CIE 1931 xy chromaticity coordinates and by the electrochromic parameters in which this film (thickness 0.8±0.2μm) presented chromatic contrast (Δ%T) at 660nm of 62%, coloration efficiency (η) of 266cm2C−1 and stability to redox cycling (Δ%T=17% at the 1000th cycle). Therefore, these copolymers are potentially applicable in displays and optoelectronic devices as electrochromic and fluorescent materials.

In this study we have compared energy and electron transfer reactions in termolecular systems using a nanosecond diffuse reflectance laser flash photolysis technique. We have previously investigated these processes on silica gel surfaces for bimolecular systems and electron transfer in termolecular systems. The latter systems involved electron transfer between three arene molecules with azulene acting as a molecular shuttle. In this study we present an alternative electron transfer system using trans β-carotene as an electron donor in order to effectively immobilise all species except the shuttle, providing the first unambiguous evidence for radical ion mobility. In the energy transfer system we use naphthalene, a structural isomer of azulene, as the shuttle, facilitating energy transfer from a selectively excited benzophenone sensitiser to 9-cyanoanthracene. Bimolecular rate constants for all of these processes have been measured and new insights into the factors determining the rates of these reactions on silica gel have been obtained.