Current Organic Chemistry - Volume 24, Issue 3, 2020

Phosphines are widely used ligands in transition metal-catalyzed reactions. Arylphosphines, such as triphenylphosphine, were among the first phosphines to show broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich trialkylphosphines began to receive attention as supporting ligands. These ligands were found to be particularly effective at promoting oxidative addition in cross-coupling of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine, coupling of aryl bromides could be achieved at room temperature. More importantly, the less reactive, but more broadly available, aryl chlorides became accessible substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application in a wide range of late transition-metal catalyzed coupling reactions. This success has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review will discuss the general properties and features of monodentate trialkylphosphines and their application in cross-coupling reactions of C–X and C–H bonds.

Macrocyclic compounds have attracted tremendous attention for their superior performance in supramolecular recognition, catalysis, and host-guest interaction. With these admirable properties, macrocyclic compounds were used as modifiers for enhancing the sensitivity and selectivity of electrodes and optical sensors. The classic macrocyclic compounds, including crown ethers, cyclodextrins, calixarenes, cucurbiturils, and pillararenes, were employed as receptors for electrochemical and optical sensors to develop new analytical methods with the wilder detection range, lower detection limit, and better tolerance of interference. Macrocyclic molecules functionalized with nanomaterials, the small entities with dimensions in the nanoscale, realized the versatility and diversification of the nano-hybrid materials, which improved the capabilities of recognition and response with the combining characteristics of two components. Herein, this review focused on the development in the research field of hybridization of organic macrocycles with nanoparticles and their applications for chemosensors, aiming at both existing researchers in the field and who would like to enter into the research.

The catalytic activity of silver and its salts in various reactions leads to a vast variety of organic compounds having significant applications in organic synthesis. This review gives a comprehensive study on silver-catalyzed multi-component reactions that attracted the interest of the scientific world through ecofriendly, atom-economic and mild conditions. The silver-catalyzed multi-component synthesis of organic compounds including aliphatic, aromatic and heterocycles are divided into subsections based on the types of bond formed and covers literature up to 2019.

Molecular orbitals are critical in the rationalization of several chemical reactions. Thus, the frontier molecular orbital theory, proposed by Fukui's group, postulated the importance of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) for chemical reactions. It should be kept in mind, however, that there are limitations of this theory and new perspectives about the chemical reactivity have recently been arisen based on composition and location of other frontier molecular orbitals. In this review, we have reported the development and the most recent applications of the Frontier Effective-for-Reaction Molecular Orbital (FERMO) concept, which describes the breaking and formation of new chemical bonds and can in turn, provide important clues that modulate chemical reactivity of atoms and molecules.

A new tetra triazole functionalized calix[4]resorcinarene macrocycle (5) is synthesized and utilized for the detection of copper ions in the aqueous medium. The photophysical potential of compound (5) is examined by a range of cations (Ba2+, Ca2+, Co2+, Hg2+, K+, Mg2+, Mn2+, Na+, NH4 + and Pd2+). The triazole based calix[4]resorcinarene macrocycle (5) has interacted with Cu2+ ion in preference of other cations. A significant quenching has been observed after the addition of 15 μM Cu2+ ion solution, which produced 4.2 folds drift in the absorption intensity of compound (5). Tetra triazole functionalized calix[4]resorcinarene macrocycle showed high selectivity towards copper ion chemosensing without any interference in competitive studies. The pH studies of compound (5) with Cu2+ indicated the maximum chelation between 7- 7.5 pH. The compound (5) is capable to recognize Cu2+ at 1 μM detectable limit. Copper ion was detected in tap water with 15 μM concentration. Job’s plot showed 1:2 binding ratio between macrocycle (5) and Cu2+.