Investigation of the photoconductive properties of thiophene substituted metallo-phthalocyanines

The synthesis of 4-(thiophen-3-ylethynyl)phthalonitrile was achieved via the Sonogashira cross-coupling reaction. Herein, we report the synthesis of symmetrical metallo-phthalocyanines with cobalt, zinc, and manganese as the metal ions, and tetrakis(ethynylthiophene) groups substituted at the peripheral positions. The new compounds have been characterized by using mass, ¹H NMR, ¹³C NMR, FT-IR and UV-vis spectroscopy. Dark and photoconductivity measurements were carried out on spin coated thiophene substituted metallo-phthalocyanines at various temperatures fixed between 300 and 440 K. Photocurrent generation and charge transport mechanisms are discussed as well. The evaluation of the photoconductive properties of these compounds indicated that the photocurrent generation efficiency and charge transport mechanism exhibited a strong temperature dependence. On the other hand, conductivity measurements revealed that the temperature dependence of the conductivity can be described by the Arrhenius type exponential equation under dark conditions. Furthermore, it was found that the photoconductive behavior of the film can be described successfully by the variable range hopping model for the whole investigated temperature range.

Electron-Rich π-Extended Diindolotriazatruxene-Based Chemosensors with Highly Selective and Rapid Responses to Nitroaromatic Explosives

A series of electron-rich π-extended diindolotriazatruxene-based compounds DIT, 4Py-DIT (bearing pyrene units) and 4PyF-DIT (bearing fluorene units) have been explored and investigated as fluorescence chemosensors. Quantitative analysis through fluorescence titrations showed that the resulting DIT molecules exhibited highly selective response to electron-deficient nitroaromatic explosives. The calculated Stern-Volmer quenching constants (>4.0×10³  M^-1 ) revealed that these sensors were much more sensitive in solution compared to most of the existing small-molecule fluorescence chemosensors based on pyrene, triphenylene, triphenylamine, and triazatruxene skeletons. Fluorescence quenching showed that the sensors adsorbed on paper were sensitive to explosives in the solid, solution, and vapor phases, with fast response times of about 10 s. Moreover, these chemosensors are reusable for the detection of nitroaromatic compounds as they recover their fluorescence intensity after quenching.

Diruthenium(ii)-capped oligothienylethynyl bridged highly soluble organometallic wires exhibiting long-range electronic coupling

Organometallic molecular wires with π-conjugation along their molecular backbones are of considerable interest for application in molecular-scale electronics. In this regard, thienylethynyl-based π-conjugated oligomers of three, five and seven thienylethynyl units with -C[triple bond, length as m-dash]C-H termini have been successfully synthesized through stepwise Pd(0)/Cu(i)-catalyzed Sonogashira coupling. The corresponding highly soluble diruthenium(ii) diacetylide complexes (O1-Ru2, O3-Ru2, O5-Ru2 and O7-Ru2, respectively) have been prepared by the reaction of cis-Ru(dppe)2Cl2 and NaPF6 in DCM with the corresponding rigid rod-like thienylethynyl oligomers with one, three, five and seven thienylethynyl π-conjugated segments containing alkynyl termini (O1, O3, O5 and O7). These Ru(ii)-Cl capped diacetylide complexes have been further functionalized by incorporating a phenylacetynyl moiety to afford [Ru(ii)-C[triple bond, length as m-dash]C-Ph]-capped diacetylide organometallic wires (O1-Ru2-Ph, O3-Ru2-Ph, O5-Ru2-Ph and O7-Ru2-Ph). The photophysical properties of the highly soluble thienylethynyl-based oligomers and Ru(ii)-organometallic wires have been explored to understand their electronic properties. Electrochemical studies of the binuclear ruthenium(ii)-alkynyl complexes showed highly interesting results, revealing long-range electrochemical communication between the two remote Ru(ii) termini connected even with five and seven thienylethynyl units. DFT computational studies further support the long range electrochemical communication between the redox active metal termini through heavy participation of the thienylethynyl bridge in the corresponding mono-oxidized mixed valence species of the organometallic wire-like complexes.

Preparation and electrochemical properties of cobalt-phthalocyanine-decorated Fe3O4 nanoparticles

Phthalocyanines (Pcs) have been known for excellent electron transfer properties owing to their extended [Formula: see text]-conjugated structures. In addition, functionalized iron oxide nanoparticles (Fe[Formula: see text]O[Formula: see text] NPs) have attracted considerable interest owing to their unique spectral and electronic properties. Hence, it can be reasonably expected that Fe[Formula: see text]O[Formula: see text] NPs decorated with Pc molecules could provide a useful electrocatalytic system. Herein, we present the preparation and electrochemical properties of cobalt-phthalocyanine (CoPc)-decorated Fe[Formula: see text]O[Formula: see text] NPs (CoPc@Fe[Formula: see text]O[Formula: see text]. The Fe[Formula: see text]O[Formula: see text] NPs were first coated with a silica layer to produce SiO[Formula: see text]@Fe[Formula: see text]O[Formula: see text]. Subsequently, CoPc with a siloxane end group (CoPc-TEOS) was anchored to the outer surface of the SiO[Formula: see text]@Fe[Formula: see text]O[Formula: see text]. The CoPc@Fe[Formula: see text]O[Formula: see text] thus prepared was fully analyzed using various characterization methods. Distinctive electrochemical responses of CoPc and CoPc@Fe[Formula: see text]O[Formula: see text] in the presence of picric acid were observed, demonstrating the potential application of the current approach to electrochemical catalysis.

Density functional theory approach to CO2 adsorption on a spinel mineral: determination of binding coordination

Adsorption mechanisms of CO₂ on MgAl₂O₄ (100) surface.

Imidazole-appended 9,10-anthracenedicarboxamide probe for sensing nitrophenols and selective determination of 2,4,6-trinitrophenol in an EtOH–water medium

A novel imidazole-appended anthracenedicarboxamide probe (AIM-D) discriminated TNP among nitrophenols based on ratiometric response in 1 : 1 EtOH–H₂O with a very low detection limit of 1 nM.

π-Electron rich small molecule sensors for the recognition of nitroaromatics

In this review article we provide an overview of the recent developments made in small molecule-based turn-off fluorescent sensors for nitroaromatic explosives with special focus on organic and H-bonded supramolecular sensors.