Electronic grade semiconductor films have been obtained via the sintering of solution processed PbS and PbSe nanocrystals at room temperature. Prior attempts to achieve similar films required the sintering of nanocrystals at higher temperatures (>350 °C), which inhibits the processing of such films on a flexible polymer substrate, and it is also expensive. We reduced the sintering temperature by employing two important strategies: (i) use of ligand-free nanocrystals and (ii) oriented attachment of nanocrystals. Colloidal ligand-free PbS and PbSe nanocrystals were synthesized at 70 °C with high yield (∼70%). However, these nanocrystals start to agglomerate with time in formamide, and upon the removal of the solvation energy, nanocrystals undergo oriented attachment, forming larger elongated crystals. PbS and PbSe nanocrystal films made on both glass and flexible substrates at room temperature exhibit Ohmic behavior with optimum DC conductivities of 0.03 S m(-1) and 0.08 S m(-1), respectively. Mild annealing of the films at 150 °C increases the conductivity values to 1.1 S m(-1) and 137 S m(-1) for PbS and PbSe nanocrystal films, respectively. AC impedance was measured to distinguish the contributions from grain and grain boundaries to the charge transport mechanism. Charge transport properties remain similar after the repeated bending of the film on a flexible polymer substrate. Reasonably high thermoelectric Seebeck coefficients of 600 μV K(-1) and 335 μV K(-1) for PbS and PbSe nanocrystal pellets, respectively, were obtained at room temperature.

A novel method to synthesize isoquinolones via oxidative annulation of N‐alkoxy benzamides and alkynes using binaphthyl‐stabilized palladium nanoparticles (Pd‐BNP) as catalyst has been developed. This methodology affords various isoquinolone derivatives in good to excellent yields with high regioselectivities in the presence of air as oxidant. N‐Methoxybenzothioamide was also found to undergo oxidative annulation with alkyne successfully and provided a sulfur analogue of isoquinolones in moderate yields. The Pd‐BNP catalyst was easily recovered and reused up to four times without any apparent agglomeration.magnified image

An efficient protocol for the straightforward, single-step synthesis of 3-aryl-1-indanones from 2'iodochalcone via reductive Heck reaction using phosphine free, stable and reusable binaphthyl stabilized palladium nanoparticle (Pd-BNP) as a catalyst has been described. An immense array of substrate scope with electron-rich and deficient 2'-iodochalcones have been synthesized. Further derivatization of product indanones have been achieved successfully. The heterogeneous nature of the Pd-BNP has been validated by centrifugation test and mercury poisoning experiment. Pd-BNP has been successfully recycled up to 5 cycles without any significant loss in reaction yield and particle size of nanoparticles, confirmed by TEM analysis. 3-(4-(Trifluoromethyl)phenyl)-2,3-dihydro-1H-inden-1-one(2 r): 78% yield (53.8 mg); Yellow liquid; R f 0.53 (10% ethyl acetate in hexanes); 1 H NMR (400 MHz, CDCl 3 ): δ 2.66 (dd, cm À 1 ; HRMS (m/z): [M + Na] + calcd for C 16 H 11 OF 3 Na: 299.0660; found: 299.0651. 3-(3-Nitrophenyl)-2,3-dihydro-1H-inden-1-one (2 s): 70% yield (44.3 mg); Greenish solid; mp 125°C; R f 0.42 (20% ethyl acetate in hexanes); 1 H NMR (400 MHz, CDCl 3 ): δ 2.66 (dd,

An efficient, binaphthyl-backbone-stabilized palladium nanoparticles (Pd-BNP) catalyst for the 1,4-addition of aryl halides to enones has been developed. Thes cope of the reactionh as been studied with various substituted and sterically hindered aryl halides and enones to affordt he conjugate addition productsing oodt oe xcellent yields.T he catalyst has been recovered and reused up to five times without anya ppreciable change in particles ize or reactivity.Scheme 3. Substrate scope of chalcones. Reaction conditions: 1a (0.5 mmol), 2a (0.5 mmol except 3bb where 1mmol was used), Pd-BNP (0.005 mmol), DIPEA(2equiv.) and THF (1 mL) at 80 8 8C; isolatedyields. 1 HNMR (400 MHz, CDCl 3 ): d = 3.63-3.78 (m, 2H), 4.81 (t, J = 7.6 Hz, 1H), 6.90-6.99 (m, 2H), 7.14-7.32 (m, 7H), 7.38-7.48 (m, 2H), 7.48-7.60 (m, 1H), 7.89-7.96 (m, 2H); 13 CNMR (100 MHz, CDCl 3 ): d = 44.9, 45.3, 115.4 (d, J =

A single-step, stereoselective protocol for the synthesis of unsymmetrically substituted (E)-3-allylideneoxindole and (E)-3-allylidenebenzofuran from readily accessible starting materials using palladium binaphthyl nanoparticles (Pd-BNPs) has been developed. Pd-BNP showing a wide range of functional group tolerance and an immense array of substrate scope have been explored with the successful synthesis of the drug molecule “tubulin polymerization inhibitor” free from trace metal impurities. The model reaction is extended to a gram-scale synthesis, and one of the products is utilized for derivatization. The Pd-BNP has been recycled up to 5 catalytic cycles without any loss in reaction yields and particle size of nanoparticles.