Electrical properties and non-volatile memory effect of the [Fe(HB(pz)3)2] spin crossover complex integrated in a microelectrode device

We report on the deposition of thin films of the [Fe(HB(pz)3)2] (pz = pyrazolyl) molecular spin crossover complex by thermal evaporation. By means of impedance measurements and Raman microspectroscopy, we show that the films maintain the structure and properties of the bulk material. The conductivity of the films decreases by ca. 2 orders of magnitude when the freshly deposited compound goes through a first (irreversible) thermal phase change above ca. 380 K. This property can be exploited as a non-volatile (read-only) memory effect

Correction: Reactivity of a pyridinium-substituted dimethyldihydropyrene switch under aerobic conditions: self-sensitized photo-oxygenation and thermal release of singlet oxygen

Correction for 'Reactivity of a pyridinium-substituted dimethyldihydropyrene switch under aerobic conditions: self-sensitized photo-oxygenation and thermal release of singlet oxygen' by Saioa Cobo et al., Chem. Commun., 2015, 51, 13886–13889

Re-investigation of the spin crossover phenomenon in the ferrous complex [Fe(HB(pz)3)2]

The temperature dependence of the magnetic susceptibility, optical reflectivity and electrical conductivity of [Fe(HB(pz)3)2] (pz = pyrazolyl) revealed irreversible changes in the material during the low-spin to high-spin transition when the ‘‘as-prepared’’ sample was heated above B400 K for the first time. During this first heating sequence, the initially fine powder sample became coarse, and its crystal structure changed from tetragonal to monoclinic. Single-crystals of the monoclinic form suitable for X-ray analysis could be isolated after the first thermal cycle, and their structure was resolved in the P21/n (Z = 4) space group. Successive cooling and heating cycles did not lead to further modification of the crystal structure, and the temperature dependence of the physical properties remained invariable. Remarkably, the electrical conductivity of the sample measured at 293 K dropped from 6.1 108 to 2.1 1011 S m1 following the first thermal cycle—suggesting possible applications of this material in read-only memory devices (ROM)

Optical modulation of cell nucleus penetration and singlet oxygen release of a switchable platinum complex

International audienceThe activation of anticancer molecules with visible light constitutes an elegant strategy to target tumors and to improve the selectivity of treatments. In this context, we report here a visible-light activatable bis-platinum complex (DHP-Pt2) incorporating an organic photo-switchable ligand based on the dimethyldihydropyrene moiety. Illumination of this metal complex with red light (660 nm) under air readily produces the corresponding endoperoxide form (CPDO2-Pt2). These two metal complexes exhibit different DNA binding properties and, more importantly, we show that only the photogenerated CPDO2-Pt2 is able to penetrate into cancer cell nuclei, where it is then capable of releasing cytotoxic singlet oxygen. This study represents the first proof-of-concept showing that dimethyldihydropyrene derivatives can be used to transport and deliver singlet oxygen into cancer cell nuclei upon visible-light activatio

Spin crossover in {Fe(pyrazine)[M(CN)₄]} (M = Ni, Pt) thin films assembled on fused silica substrates

International audienceThin films with thicknesses in the range between ca. 10–50 nm of the spin crossover (SCO) compound {Fe(pyrazine)[μ4-M(CN)4]} (M = Ni, Pt) have been deposited on fused silica substrates using a sequential assembly method and 4-pyridinecarboxylic acid as anchoring layer. Film morphology and crystallinity were assessed by means of atomic force microscopy and grazing incidence X-ray diffraction, respectively. The intensity of the π–π* transition of the pyrazine ligand at 270 nm, being rather insensitive to the spin state of the complex, was used to follow the film growth as a function of different deposition parameters. On the other hand, the spin state changes were inferred from the temperature dependence of absorption bands appearing at 540, 490 and 310 nm in the low spin state. In line with their amorphous nature, each film displays a very gradual thermal spin crossover between ca. 100–300 K, independently of its thickness and deposition conditions. These results are not only interesting to better understand the effects of size reduction and organization on the SCO phenomenon, but the deposition of these SCO compounds on electrically insulating and/or optically transparent oxide surfaces opens also the door for various photonic or electronic applications

A new surface-bound molecular switch based on the photochromic dimethyldihydropyrene with light-driven release of singlet oxygen properties

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A redox- and photo-responsive quadri-state switch based on dimethyldihydropyrene-appended cobalt complexes

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Synthesis of Redox-Active Photochromic Phenanthrene Derivatives

International audienceA phenanthrene unit has been functionalized by several methylthiophene units in order to bring it a photochromic behavior. These compounds were characterized by NMR, absorption and emission spectroscopies, theoretical calculations as well as cyclic voltammetry. The association of a phenanthrene group with a photochromic center could open the door to a new generation of organic field-effect transistors

New Insights into the Redox Properties of Pyridinium Appended 1,2-Dithienylcyclopentenes

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Photochromic Metallopolymer Based on Dithienylethene as a Molecular Calculator

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