The Ullmann-type cross coupling of a variety of aromatic, aliphatic amines with aryl halides is reported using a CuI-based catalytic system in combination with an easily accessible prolinamide ligand in aqueous media. The method is mild and tolerant to air, moisture, and a wide range of functional groups, providing a novel way to access a variety of aminated products. Secondary amines like heteroaromatic amines and nucleobases have also been used, affording the corresponding coupling products in good to excellent yields. Moreover, this method has been employed for chemoselective C-N arylation of aminophenols and further utilized for the synthesis of carbazole natural products, avoiding the protection and deprotection steps.

The previously unexplored Grignard addition to oxindoles provides a regiospecific approach to 2- and 2,3-disubstituted indole derivatives in high yields via a one-pot aromatization driven dehydration pathway. This method allows a convenient preparation of diallyl indoles that are used as ring-closing metathesis (RCM) precursors for the orthogonal synthesis of pyrido[1,2- a]indoles and carbazoles. The synthetic utility of this method is illustrated by the synthesis of a microtubulin inhibitor and naturally occurring carbazole alkaloids.

A first principles based density functional theory (DFT) has been employed to identify the signature of Stone-Wales (SW) defects in semiconducting graphene quantum dot (GQD). Results show that the G mode in the Raman spectra of GQD has been red shifted to 1544.21 cm −1 in the presence of 2.08% SW defect concentration. In addition, the intensity ratio between a robust low intense contraction-elongation mode and G mode is found to be reduced for the defected structure. We have also observed a Raman mode at 1674.04 cm −1 due to the solo contribution of the defected bond. The increase in defect concentration, however, reduces the stability of the structures. As a consequence, the systems undergo structural buckling due to the presence of SW defect generated additional stresses. We have further explored that the 1615.45 cm −1 Raman mode and 1619.29 cm −1 infra-red mode are due to the collective stretching of two distinct SW defects separated at a distance 7.98 Å. Therefore, this is the smallest separation between the SW defects for their distinct existence. The pristine structure possesses maximum electrical conductivity and the same reduces to 0.37 times for 2.08% SW defect. On the other hand, the work function is reduced in the presence of defects except for the structure with SW defects separated at 7.98 Å. All these results will serve as an important reference to facilitate the potential applications of GQD based nano-devices with inherent topological SW defects.

We herein report a highly regioselective reaction for the palladium‐catalyzed oxidative acylation of carbazole derivatives with various aromatic and aliphatic aldehydes as the acyl source. The carbazole derivatives are N‐protected with an easily removable pyridine moiety, which directs the Pd‐catalyzed ortho acylation to occur at the C‐1 and C‐8 positions. The reactions of dibromo‐ and diiodo‐substituted N‐pyridylcarbazole derivatives, however, provide only the 1‐acylated products. This method can be applied to a broad scope of substrates. A reaction mechanism has also been proposed.

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