Pentacene thin film transistors using La2O3 as gate insulator

A study of Pentacene OTFTs using La₂O₃ as gate insulator is presented. The device characteristics were studied and analyzed. The OTFTs exhibit p-type conductivity with field effect mobility 6.5 × 10⁻⁸ m²/V.s, ON/OFF ratio 1.4 × 10², sub-threshold swing 2 mV/decade and hole concentration 4.5 × 10¹⁷ cm⁻³. The SEM and XRD analysis on the semiconductor film are also reported.     

Deterministic inhomogeneous inertia ratchets

We study the deterministic dynamics of a periodically driven particle in the underdamped case in a spatially symmetric periodic potential. The system is subjected to a space-dependent friction coefficient, which is similarly periodic as the potential but with a phase difference. We observe that frictional inhomogeneity in a symmetric periodic potential mimics most of the qualitative features of deterministic dynamics in a homogeneous system with an asymmetric periodic potential. We point out the need of averaging over the initial phase of the external drive at small frictional inhomogeneity parameter values or analogously low potential asymmetry regimes in obtaining ratchet current. We also show that at low amplitudes of the drive, where ratchet current is not possible in the deterministic case, noise plays a significant role in realizing ratchet current.     

Methanol aided synthesis of PdNPs decorated on montmorillonite K 10 and its implication in Suzuki Miyaura type cross coupling reaction under base free condition

An efficient catalyst PdNPs decorated on Montmorillonite K 10 is prepared by simply stirring Pd(OAc)₂ in methanol at room temperature without using any external reducing agent. The catalyst shows excellent activity for Suzuki Miyaura type cross coupling reaction between aryl diazonium salt and arylboronic acid under ligand and base free reaction conditions within short reaction time. The main advantage of this methodology is the easy synthesis of heterogeneous PdNPs @ Mont K 10 catalyst in a mild condition without using any reducing agent or additive and the catalyst is very efficient for biaryl synthesis. The catalyst is well characterized by SEM, EDX, TEM, BET, Powder XRD, TGA, DSC etc. The reaction pathway is greener with aqueous reaction medium, base free reaction condition, room temperature and reusable heterogeneous catalyst.     

Ferrocene conjugated copper(II) complexes of terpyridine and traditional Chinese medicine (TCM) anticancer ligands showing selective toxicity towards cancer cells

Six novel mixed‐ligand copper(II) complexes, namely, [Cu(R‐tpy)(L)]NO₃ ( 1–6 ), where R‐tpy is 4′‐phenyl‐2,2′:6′,2′′‐terpyridine (Ph‐tpy; 1–3 ) and 4′‐ferrocenyl‐2,2′:6′,2′′‐terpyridine (Fc‐tpy; 4–6 ), L is the bidentate O,O donor monoanion of plumbagin (5‐hydroxy‐2‐methyl‐1,4‐naphthoquinone; plum in 1 , 4 ), chrysin (5,7‐dihydroxyflavone; chry in 2 , 5 ) and curcumin (bis(4‐hydroxy‐3‐methoxyphenyl)‐1,6‐diene‐3,5‐dione; curc in 3 , 6 ) have been synthesized and characterized and their in vitro cytotoxicity against cancer cells is evaluated. The energy optimized structures and the frontier orbitals of the complexes have been obtained from the DFT calculations. Complexes 4–6 with a conjugated ferrocenyl moiety and TCM anticancer ligands, namely, plum (in 4 ), chry (in 5 ) and curc (in 6 ) showed potent cytotoxicity giving respective IC₅₀ values of 1.2 μM, 0.62 μM and 0.21 μM in HeLa and 2.0 μM and 1.0 μM and 0.34 μM in MCF‐7 cancer cells while being much less toxic to MCF‐10A normal cells (IC₅₀: 8.3‐17.1 μM). In contrast, complexes 1–3 with a conjugated phenyl moiety were appreciably less toxic to HeLa cells with respective IC₅₀ values of 10.4 μM, 8.1 μM and 5.5 μM when compared with their ferrocenyl analogues 4–6 . Mechanistic studies using Hoechst staining and Annexin‐V‐FITC assays on cancer cells revealed an apoptotic pathway of cell death induced by the complexes. Fluorescence imaging study showed that complex 6 having curcumin as ligand localized primarily in the mitochondria of HeLa cells. Thus, we demonstrate in this study that ferrocene conjugation to copper(II) complexes of TCM anticancer ligands significantly increases the selectivity and cytotoxicity of the resulting complexes towards cancer cells over normal cells.     

Studies on –SO3H functionalized Brønsted acidic imidazolium ionic liquids (ILs) for one-pot,two-step synthesis of 2-styrylquinolines

Four task-specific –SO₃H functionalized imidazolium ionic liquids (ILs) were investigated for Brønsted acidities by Hammett functions. After knowing their thermal stabilities, the catalytic activity was observed for the preparation of 2-styrylquinolines by following consecutive Friedländer and Knoevenagel reactions in solvent-free thermal energy. The acidity order ([Dsim][OOCCF₃] > [Dsim][OTs] > [Dsim][OOCCl₃] > [Msim][OOCCF₃]) of three ILs was consistent with their activity order observed in the acid-catalyzed synthesis of 2-styrylquinolines under solvent-free conditions at 90° C, with the exception of [Dsim][OTs]. The best catalytic activity was shown by 25 mol% of [Dsim][OOCCF₃] IL. The less acidic IL required 50 mol% to give good yield of 2-styrylquinolines under the optimized condition.     

KI‐VO(acac)2‐H2O2‐AcOH,A New Iodinating System for Selective Iodination at C‐5 Position of Activated Pyrimidinediones: A Combined Experimental and Density Functional Study

KI‐VO(acac)₂‐H₂O₂ in aqueous ethanolic medium with acetic acid as additive has been found to iodinate pyrimidinediones and aromatic amines. The methodology is mild, efficient, and environmentally benign. Density functional theory‐based reactivity parameters support the experimentally observed reactivity of pyrimidinedione derivatives.     

Design of Supported Organocatalysts from Carboxylic Acids for the Mannich-Type Synthesis of β-Amino Carbonyl Compounds

New supported acidic organocatalysts were prepared by the impregnation of three carboxylic acids (CF₃COOH, CCl₃COOH, and CH₃COOH) on silica support at room temperature in diethyl ether. The catalysts were characterized by scanning electron microscopy, energy dispersion X-ray analysis (EDX), Brunauer-Emmett-Teller-surface-area-analysis (BET), thermogravitational analysis, Fourier transform infrared, and powder X-ray diffractometry analysis. These solid acids were observed as highly efficient reusable catalysts at room temperature for the selective synthesis of β-amino carbonyl compounds via Mannich-type reactions of acetophenone, arylamine and arylaldehydes using two different conditions in CH₂Cl₂ solution and solvent-free grinding within a short time. The more acidic two catalysts could be recycled for up to five cycles with a small loss in catalytic activity.