Cyclic Voltammetric Study of 3,5-Diaryl-1-phenyl-2-pyrazolines

The development of a novel bio-based corrosion inhibitor: using biomass-derived 5-hydroxymethylfurfural (5-HMF) as a starting material

An environmentally friendly corrosion inhibitor was prepared from the bio-based platform 5-hydroxymethylfurfural. This corrosion inhibitor was confirmed to be an efficient mixed-type corrosion inhibitor through a weight loss experiment and electrochemical experiment. Both thermodynamic and kinetic parameters were calculated and discussed, indicating that the adsorption of this bio-based inhibitor on a steel surface is a chemisorption process. Moreover, quantum chemical calculations were performed and further confirmed the formation of an effective productive film of this bio-based inhibitor on the metal surface. It is worth noting that the synthesis route of this bio-based corrosion inhibitor is green and environmentally friendly, and does not involve toxic chemical reagents.

Electronic and steric substituent effects on the fluorescence emission of 2-pyrazoline derivatives

A series of substituted 2-pyrazolines were synthesized, and the steric and electronic effects of substituents on the C3 - and C5 -positions of the heterocyclic ring on their fluorescent ability were investigated. Two different conjugative intramolecular charge transfer (ICT) and intramolecular charge transfer through space (spiro-conjugation) affect the fluorescence intensity of these compounds. The extent of the ICT process and spiro-conjugation depends on the electronic nature of the additional substitution and its position on the attached aryl rings. In addition, the effects of the concentration and the solvent polarity on the fluorescence emission were studied. Density functional theory (DFT) calculations were carried out to gain insight into the geometric, electronic, and spectroscopic properties of the pyrazoline derivatives. The results of both experimental and computational studies explain the effects of the geometrical orientation of the C3 - and C5 -aryl rings toward the heterocyclic ring and also the electronic nature of their additional substitutions on the fluorescence intensity.

Spectroscopic Behaviour of Copper(II) Complexes Containing 2-Hydroxyphenones

Theoretical investigations by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods shed light on how the type of ligand or attached groups influence the electronic structure, absorption spectrum, electron excitation, and intramolecular and interfacial electron transfer of the Cu(II) complexes under study. The findings provide new insight into the designing and screening of high-performance dyes for dye-sensitized solar cells (DSSCs).

Investigating ESIPT and donor-acceptor substituent effects on the photophysical and electrochemical properties of fluorescent 3,5-diaryl-substituted 1-phenyl-2-pyrazolines

This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV-Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C₆H₄ (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C₆H₄ (c), 4-F-C₆H₄ (d), 4-OCH₃-C₆H₄(e), 4-NO₂-C₆H₄ (f), 4-(N(CH₃)₂)-C₆H₄(g). The UV-Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents.

A highly selective A-π-A “turn-on” fluorescent probe for hypochlorite in tap water

A highly selective fluorescence probe (BON) for hypochlorite (ClO-) was designed and synthesized. The probe was based on boron-dipyrromethene (BODIPY) dye as the fluorophore and diaminomaleonitrile (DAMN) as the recognition...

Photooxidation of 2,3-dihydroquinazolin-4(1H)-ones: retention or elimination of 2-substitution

A series of mono and disubstituted 2,3-dihydroquinazolin-4(1H)-ones (DHQZs) were synthesized and the electronic and steric effects of the C₂- and N₃-substitutions on the retention or elimination of the C₂-substitution by exposing them to the ultraviolet light were investigated. Electron transfer from photo-excited dihydroquinazolinones to chloroform solvent is proposed, in which both lone pairs on the N₁- and N₃-atoms can be involved in this process. The extent of the N₁- and N₃-atoms contributions in this electron-transfer process and also the retention or elimination of the C₂-substitutions are dependent on the nature and steric hindrance of both C₂- and N₃-substitutions. The experimental results are supported by the computational studies. Photoinduced electron-transfer reaction of a series of mono and disubstituted 2,3- dihydroquinazolin-4(1H)-ones was investigated.