Reductive Aromatization of 5,7,12,14-Pentacenetetrone: Approach Towards Substituted Pentacenes?

Herein we report a convenient access to asymmetrically substituted, well soluble pentacene derivatives synthesized from commercially available 5,7,12,14-pentacenetetrone via reductive one step functionalization. Zinc or potassium are used as reducing agents and the reduced intermediates are trapped with electrophiles such as acetyl, triisopropylsilyl or cationic methyl synthons. The reduction allows for an unsymmetric functionalization whilst one dione moiety is maintained due to partial reduction. The resulting dyes are characterized by UV/Vis and photoluminescence spectroscopy. Their redox potentials are studied by cyclic voltammetry. The experimentally determined molecular frontier orbital energies are rationalized by density functional theory. The spatial molecular packing motive in the solid state is studied as a function of the substituent size by X-ray crystallography. Attempts of reducing the second quinone moiety towards a functionalized pentacene led to an over-reduced 6,13-dihydropentacene derivative, which by means of an XRD structural analysis surprisingly displays a planar molecular conformation and unique optoelectronic properties.

Organic Donor-Acceptor Complexes As Potential Semiconducting Materials

In this review article, the synthesis, characterization and physico-chemical properties of the organic donor-acceptor complexes are highlighted and a special emphasis has been placed on developing them as semiconducting materials. The electron-rich molecules, i. e., donors have been broadly grouped in three categories, namely polycyclic aromatic hydrocarbons, nitrogen heterocycles and sulphur containing aromatic donors. The reactions of these classes of the donors with the acceptors, namely tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), tetracyanobenzene (TCNB), benzoquinone, pyromellitic dianhydride and pyromellitic diimides, fullerenes, phenazine, benzothiadiazole, naphthalimide, DMAD, maleic anhydride, viologens and naphthalene diimide are described. The potential applications of the resulting DA complexes for physico-electronic purposes are also included. The theoretical investigation of many of these products with a view to rationalise their observed physico-chemical properties is also discussed.

First-principle study on the stability of Cd passivates in soil

The stable existence of heavy metals in soil under natural conditions is the core issue in heavy metal pollution solidification and remediation technology. However, the existing research is limited to soil passivation tests of different materials or biochar adsorption tests and cannot reveal the internal mechanism of functional groups of different compounds in soil passivation. This paper takes the common heavy metal ion Cd2+ as an example to analyze the stability of the combination of heavy metal ions and common ion groups in soil. The stability and existing form of Cd are analyzed by using first-principle calculations, and the free energy, band structure, and partial density of states of CdCO3, CdSO4, CdCl2, and CdSiO3 are computed. The stability of Cd binding to common anions in soil is determined. Results show the descending order of structural stability of cadmium compounds is CdSiO3, CdSO4, CdCO3, and CdCl2. SO42- and SiO32- can be used as preferred functional groups for cadmium pollution passivation. Anhydrous sodium sulfate and sodium silicate are promising passivators.

Unravelling Supramolecular Features and Opto-electronic Properties of Binary Charge Transfer Cocrystal of Blue Fluorescent Di-carbazole and TFT

Co-assembled crystalline organic systems demonstrate advanced opto-electronic properties by maintaining high molecular order in the crystal packing through non-covalent interactions. In this contribution, a 1:2 donor acceptor charge transfer cocrystal...