Reduction of diphenylacetylene using Al powder in the presence of noble metal catalysts in water

Diphenylacetylenes can be reduced to the corresponding diphenylethanes (2) in water in excellent yield using Al powder and Pd/C at 60 °C for 3 h in a sealed tube. In addition, the complete reduction of both aromatic rings required 80 °C for 15 h with Al powder in the presence of Pt/C. However, the nature of hydrogenated product formed was found to be strongly influenced by the reaction temperature, time, volume of water and the amount of catalyst being employed

Reduction of phenylacetylenes using Raney Ni-Al alloy, Al powder in the presence of noble metal catalysts in water

Dedicated to Prof. Kenneth Laali on the occasion of his 66th birthday Received mm-dd-yyyy Accepted mm-dd-yyyy Published on line mm-dd-yyyy Dates to be inserted by editorial office Abstract The chemoselective reduction is based on the reaction of Raney Ni–Al alloy with Al powder in water which produces in situ hydrogen to utilize the hydrogenation of the targeted functional groups. Raney Ni–Al alloy with Al powder can reduce phenylacetylenes to the corresponding ethylbenzene (3) in water in excellent yield at 120 °C for 6 h in a sealed tube. In addition, the complete reduction of aromatic ring to ethylcyclohexane (4) required 60 °C for 12 h with Raney Ni–Al alloy, Al powder in the presence of Pt/C. The appropriate selection of the reaction conditions allowed the selective preparation of ethylbenzene as well as ethylcyclohexane from phenylacetylene. 1a : R = H ,1b : R = CH 3 , 1c : R = OCH 3 ,1d : R = C(CH 3)

Solvent effect and fluorescence response of the 7-tert-butylpyrene-dipicolylamine linkage for the selective and sensitive response toward Zn(II) and Cd(II) ions

The different binding behaviour of 7-tert-butylpyrene based chemosensors bearing dipicolylamine (Dpa) linkages at the 1,3-positions was investigated in various solvents for the sensing of Zn(II) and Cd(II).The potential mono-chelating ligand L1 follows the same binding pattern in both THF and methanol–water solvent systems, exhibiting higher selectivity and sensitivity for Cd(II) over Zn(II) mainly in THF solvent system. The potential bis-chelate ligand L2 can selectively bind both Zn(II) and Cd(II) in a 1:1 ratio in THF, whereas in methanol–water (7:3) at pH = 7.0; a 1:2 binding ratio was observed. In THF, two sites of ligand L2 can only selectively and sensitively bind one Zn(II) or Cd(II). The different complexation behaviour of L1 and L2 in different solvents were studied by means of fluorescence spectra and ¹H-NMR titration experiments in the presence of Zn(II) and Cd(II)

A review on the recent advances in the reductions of carbon–carbon/oxygen multiple bonds including aromatic rings using Raney Ni–Al Alloy or Al powder in the presence of noble metal catalysts in water

Over the past few years, heterogeneous catalysts have attracted much attention with a view to lowering reaction temperatures and improving the selectivity of many organic syntheses. When it comes to designing or optimizing a catalyst, a lot of attention is needed to be devoted to the nature of the active sites and how they interact with the reactants, intermediates and products of the catalytic process. To this end, Raney Ni–Al alloy and noble metal catalysts such as Ru/C, Rh/C, Pd/C and Pt/C turn out to be very effective in both selective and complete reductions of various functional groups as well as aromatic rings in water. Moreover, Al powder coupled with a noble metal catalyst has been found to be capable of reducing carbonyl group, an alkyne moiety and also the aromatic rings of biphenyl, fluorene, 9,10-dihydroanthracene, polyarenes and N-heterocycles in water under mild reaction conditions. So this review offers an overview on the most recent developments especially in this particular methodology

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrenes

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrene

Synthesis and fluorescence emission properties of 1,3,6,8-tetraarylpyrenes

This paper was accepted for publication in the Journal of Molecular Structure and the definitive version can be found at: http://dx.doi.org/10.1016/j.molstruc.2013.04.07

A brief review on novel pyrene based fluorometric and colorimetric chemosensors for the detection of Cu2+

© 2021 the Partner Organisations. The development of colorimetric and fluorometric chemosensors that capable of detecting Cu2+ ions by a change in colour and fluorescence intensity has been described. Herein, chemosensors having pyrene functional groups as a signaling moiety are discussed in detail as pyrene derivatives show significant photophysical properties being superior to those of other commonly used scaffolds. This review article provides a detailed overview of pyrene containing chemosensors based on fluorescence mechanisms, such as excimer/exciplex formation, photoinduced electron transfer (PET), photoinduced charge transfer (PCT), aggregation induced emission (AIE), ligand to metal charge transfer process (LMCT), chelation enhanced quenching mechanism (CHEQ), Cu2+-selective reactions for the selective and sensitive detection of Cu2+. Potential future applications are also discussed because of the fact Cu2+ ion recognition has a great significance in the biological, environmental and medical sectors