2,5-di-2-thienylthiazolo[4,5-d]thiazole

The mol­ecules of the title compound, C12H6N2S4, lie on centres of symmetry. The thio­phene and thia­zole rings are almost planar and their planes make a dihedral angle of 1.68 (8)°. In the crystal structure, there is a relatively short intermolecular S⋯S contact distance of 3.5786 (9) Å

A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo and electrochemical control

An electroactive nitrospiropyran-substituted polyterthiophene, 2-(3,3′′-dimethylindoline-6′-nitrobenzospiropyranyl)ethyl 4,4′′-didecyloxy-2,2′:5′,2′′-terthiophene-3′-acetate, has been synthesized for the first time. The spiropyran, incorporated into the polymer backbone by covalent attachment to the alkoxyterthiophene monomer units, leads to multiple coloured states as a result of both electrochemical isomerization of the spiropyran moiety to merocyanine forms as well as electrochemical oxidation of the polyterthiophene backbone and the merocyanine substituents. While electrochemical polymerization of the terthiophene monomer could occurs without the apparent oxidation of the spiropyran, the subsequent electrochemistry is complex and clearly involves this substituent. In order to understand this complex behaviour, the first detailed electrochemical study of the oxidation of the precursor spiropyran, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6’-nitrobenzospiropyran, was undertaken, showing that, in solution, an irreversible electrochemical oxidation of the spiropyran occurs leading to reversible redox behaviour of at least two merocyanine isomers. With these insights, an extensive electrochemical and spectroelectrochemical study of the nitrospiropyran-substituted polyterthiophene films reveals an initial irreversible electrochemical oxidative ring opening of the spiropyran to oxidized merocyanine. Subsequent reduction and cyclic voltammetry of the resulting nitromerocyanine-substituted polyterthiophene film gives rise to the formation of both merocyanine π-dimers or oligomers and π-radical cation dimers, between polymer chains. Although merocyanine formation is not electrochemically reversible, the spiropyran can be photochemically regenerated, at least in part, through irradiation with visible light. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerizes to the planar merocyanine moiety affording a smoother polymer film. The conductivity of the freestanding polymer film was found to be 0.4 S cm-1

5-Chloro-1-phenyl-1H-pyrazol-4-amine

In the crystal structure of the title compound, C(9)H(8)ClN(3), amino–pyrazole N—H⋯N hydrogen bonds connect the mol­ecules along the [010] direction; the chains interact with each other only by van der Waals-type inter­actions. The pyrazole and phenyl rings are inclined at a dihedral angle of 45.65 (6)

1-(3-Chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carboxamide

In the crystal structure of the title compound, C11H9ClN4O3,pairs of NH N(imidazole) hydrogen bonds connect themolecules into centrosymmetric dimers, which are furtherconnected by NH O(carbamoyl) hydrogen bonds intoC(4) chains along [010]. Interplay of these two kinds ofhydrogen bonds connect the molecules into layers perpendicularto [101]. The imidazole [maximum deviation0.0069 (9) A ] and phenyl rings are inclined at a dihedral angleof 58.44 (6); the nitro group is almost coplanar [dihedralangle 5.8 (2)] with the imidazole ring while the carbamoylgroup is almost perpendicular [70.15 (13)] to it

Isomorphism in Two (E)-1-(4-Halophenyl)-N-[1-(4-Methylphenyl)-1H-Imidazol-4-yl]Methanimines (Halide = Cl, Br)

The crystal structures of two imidazole-4-imines, (E)-1-(4-chlorophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine (1, C17H14ClN3), and (E)-1-(4-bromophenyl)-N-[1-(4-methylphenyl)-1H-imidazol-4-yl]methanimine, (2, C17H14BrN3), are isomorphous, the isostructurality index is 99.4 %. Both compounds crystallize in the triclinic space group P-1 with unit cell parameters at 100(1) K as follows: for (1), a = 7.9767(5) Å, b = 10.9517(7) Å, c = 16.6753(12) Å, α = 80.522(6)°, β = 87.046(6)°, γ = 89.207(5)°, and for (2), a = 8.0720(7) Å, b = 10.9334(10) Å, c = 16.8433(13) Å, α = 81.161(7)°, β = 86.605(7)°, γ = 89.505(7)°. The structures contain two symmetry—independent but conformationally similar molecules in the asymmetric unit (Z’ = 2). In both compounds the overall twist of the molecule, defined as the dihedral angle between the terminal phenyl ring planes is significant, around 56°. The crystal packing is determined mainly be weak specific intermolecular interactions: the C–H···N hydrogen bonds connect molecules into infinite chains, and the chains are linked via C–H···X hydrogen bonds and by π–π interactions. This study illustrates the significant role of the weak interactions, which—in spite of their weakness—can robustly repeat in the crystal structures of similar compounds

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

Negative phototaxis behaviour of organic droplets in channels

Along the evolutionary path from single cells to multicellular organisms with a central nervous system, there are species of intermediate complexity that possess many autonomous cells programmed to respond to environmental stimuli. One of the more striking responses is phototaxis[1], in which motile organisms adjust their locomotory path according to the incident light in a finely controlled manner, either towards or against the light source (positive or negative phototaxis). Inspired by them we developed an inanimate/chemical system in which an organic droplet is self-propelled in response to a photo-stimulus. The centimetre-scale directional movement of the organic droplet on the aqueous solution is powered by the combination of photo-induced pH change and surface tension effects

Photo-chemopropulsion – light-stimulated movement of microdroplets

The controlled movement of a chemical container by the light-activated expulsion of a chemical fuel, named here photo-chemopropulsion , is an exciting new development in the array of mechanisms employed for controlling the movement of microvehicles, herein represented by lipid-based microdroplets. This chemopropulsion effect can be switched on and off, and is fully 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