Electrochemical study of 1,3-indandione derivatives of terthiophenes

Properties and behavior of a group of four newly synthesized derivatives of terthiophene and terthienylenvinylene was studied. All four investigated monomers bear a 1,3-indandione substituent at the central thiophene ring and two of them (ThIV, ThIVM) have additional vinyl bonds introduced between the thiophene rings. In addition, ThIM and ThIVM have 5 positions of the two terminal rings blocked with methyl groups. The measurements were done using cyclic voltamperometry (CV) in solutions of 0.1M Bu4NBF4 in CH2Cl2. It was found that ThI and ThIV polymerise easily. CV of ThI reveals a reduction peak resulting probably from the abstraction of a proton. During polymerisation of ThIV a group of peaks is observed indicating its stepwise oxidation process. The polymerisation potential of ThIV was found to be lower than that of ThI which could mean that formation of radical-cation is easier in the former. Stability measurements indicated that polymer films of ThI are electrochemically stable in CH2Cl2 and films of ThIV are not. Efforts to polymerise ThIM and ThIVM failed. Their CVs revealed only peaks coming from oxidation of the monomers, some of which were semi-reversible

Electrochemical and optical aspects of cobalt meso-carbazole substituted porphyrin complexes

A series of cobalt (II) porphyrin complexes modified with carbazole rings at one or more meso positions of the macrocycle were synthesized and characterized as to their spectroscopic and basic electrochemical properties in non-aqueous media. The effect of the number and position (syn and anti) of carbazole groups on the complexes properties were investigated. The comparison was made to cobalt (II) porphyrin containing mesityl groups at the meso-positions. The relation between the site of redox processes in cobalt meso-carbazole substituted porphyrins were analysed. It was shown that the conjugated π-ring system of the porphyrin macrocycle, the cobalt central metal ion and the carbazole peripheral substituents are redox-active

1,8,14,20-Tetraoxa-11,23-dithiatricyclo[21.3.0.09,13]hexacosa-9,12,21,24-tetraene

Crystals of the title compd. are orthorhombic, space group Pbca; Z = 4. Mols. lie on crystallog. centers of inversion, but have approx. C2h mol. symmetry. The parallel thiophene rings are almost exactly planar; the overall conformation of the mol. is chair-like. The mols. have voids that could, in principle, accommodate small guest mols., although in the crystal structure access to these voids is blocked by neighboring mols

The Role of Electrochemical and Spectroelectrochemical Techniques in the Preparation and Characterization of Conjugated Polymers: From Polyaniline to Modern Organic Semiconductors

This review article presents different electrochemical and spectroelectrochemical techniques used to investigate conjugated polymers. The development of this research area is presented from an over 40-year perspective—the period of research carried out by Professor Mieczyslaw Lapkowski. Initial research involved polymers derived from simple aromatic compounds, such as polyaniline. Since then, scientific advances in the field of conductive polymers have led to the development of so-called organic electronics. Electrochemical and spectroelectrochemical methods have a great influence in the development of organic semiconductors. Their potential for explaining many phenomena is discussed and the most relevant examples are provided

Application of FT-IR microspectroscopy to the study of an injectable composite for bone and dental surgery.

Hydroxypropylmethylcellulose (HPMC) of high-viscosity grade is used as a ligand for a bioactive calcium phosphate ceramic (the filler) in a ready-to-use injectable sterilized biomaterial for bone and dental surgery. Application of physico-chemical methods such as XPS, NMR, or Raman spectroscopy encounters difficulties when used to study such a multiphased material. This paper reports on the application of FT-IR microspectroscopy (FT-IRM) for the investigation of inorganic and organic phases of the rough composite and separated phases obtained by mechanical or chemical extraction methods. A comparison of FT-IRM with the conventional KBr pellet method was made and indicates that the macro and micro FT-IR methods are complementary: the former revealed new chemical groups not visualized with the KBr method whereas the latter detected the major compound of the blend. FT-IR microspectroscopy was revealed to be a powerful method of analysis that is complementary to other existing spectroscopic methods. Moreover, it is expected to be a useful tool in the study of biomaterials in biological samples

Effect of π-conjugation on electrochemical properties of poly(terthiophene)s 3′-substituted with fullerene C60

The series of copolymers based on terthiophene 3′-substituted with C60-pyrrolidine or styryl group, were electrochemically synthesized and characterized. The dense distribution of C60 side group caused the steric effects between them and the perturbation in the extent of π-electron delocalization of the poly(terthiophene) backbone. The ESR spectroscopy showed the presence of close-packed clusters especially in homopolymer: poly(terthiophene-C60). The oxidative electrochemical copolymerization of terthiophene units was performed to avoid this steric interactions and in results to extend the effective π-conjugation length in the polymer. The use of different ratio of the co-monomers contributed to the variable distribution of C60 unit and different effective π-conjugation of the resulting polymers. Those changes affected electrochemical and photocurrent-generating properties of these materials

Electrochemical and spectroelectrochemical studies on the reactivity of perimidine–carbazole–thiophene monomers towards the formation of multidimensional macromolecules versus stable π-dimeric states

During research on cross-linked conducting polymers, double-functionalized monomers were synthesized. Two subunits potentially able to undergo oxidative coupling were used—perimidine and, respectively, carbazole, 3,6-di(hexylthiophene)carbazole or 3,6-di(decyloxythiophene)carbazole; alkyl and alkoxy chains as groups supporting molecular ordering and 14H-benzo[4,5]isoquinone[2,1-a]perimidin-14-one segment promoting CH· · · O interactions and π–π stacking. Electrochemical, spectroelectrochemical, and density functional theory (DFT) studies have shown that potential-controlled oxidation enables polarization of a specific monomer subunit, thus allowing for simultane-ous coupling via perimidine and/or carbazole, but mainly leading to dimer formation. The reason for this was the considerable stability of the dicationic and tetracationic π-dimers over covalent bonding. In the case of perimidine-3,6-di(hexylthiophene)carbazole, the polymer was not obtained due to the steric hindrance of the alkyl substituents preventing the coupling of the monomer radical cations. The only linear π-conjugated polymer was obtained through di(decyloxythiophene)carbazole segment from perimidine-di(decyloxythiophene)-carbazole precursor. Due to the significant difference in potentials between subsequent oxidation states of monomer, it was impossible to polarize the entire molecule, so that both directions of coupling could be equally favored. Subsequent oxidation of this polymer to polarize the side perimidine groups did not allow further crosslinking, because rather the π–π interactions between these perimidine segments dominate in the solid product

The role of furyl substituents of pyrene on monomer and polymer properties

This paper estimates the influence of substituents number on basic electrochemical, optical and electronic properties of monomers compared to their polymers. Results exhibit differences of these effects in monomers and polymers. The crosslinking effect has impact on basic properties of studied polymers. Polymers were created from their monomers by electropolymerization. Optical properties of a series of furyl derivatives of pyrene were investigated by UV-vis spectroscopy. Basic electrochemical properties of the studied compounds were investigated by cyclic voltammetry. ESR-UV-vis spectroelectrochemistry reveals differences in doping processes of obtained conjugated polymers. Good electrochemical stability of novel furyl-pyren pi-conjugated polymers confirm the application potential of this group of materials for the development of organic semiconductors in particularly for possible applications in electrochromic devices, light emitting electrochemical cells and spintronic. (C) 2014 Elsevier B.V. All rights reserved