Substituent effects on the spectral properties of some 3-substituted formazans

Experimental and computational studies on the absorption properties of novel formazan derivatives

“…Similar π -π * transitions were noted in the case of 4a-4g at λ max 1 of 475-540 nm in different polarity solvents, indicating the existence of a chelate form due to the inner-molecular hydrogen transfer over a sixmembered ring (Scheme 2). 28,30,37,38 Contrary to the other compounds, 4h (λ max 1 = 361 − 402 nm) shows the 713 TÜRKOGLU and Ç INAR/Turk J Chem blue shift arisen from the hydrogen bond between oxygen of the ortho −NO 2 group and Ph 1 −NH equilibrium structure, which hinders the formation of chelation of formazan (Scheme 3).…”

“…Hence, the electron attractive quality of the -NO 2 group decreases, resulting in disappearance of the resonance effect. 28,37,38 Based on these results, electron donating groups and halogens acting with resonance electron effects generally lead to bathochromic shifts, whereas the electron withdrawing units result in hypsochromic shifts.…”

Frontiers of Formazans Chemistry: A Review

“…These peaks are due to π-π* electronic transitions in formazan skeleton. [166] The electronic absorption spectra of the unsubstituted 1,3,5-triphenylformazan show one band at 482nm in visible region. [167] It is a characteristic of formazan structure due to π-π* transitions within the N=N group influenced by charge transfer within the whole molecule.…”

“…antifertility activity, [180] antiinflammatory active, [181][182][183][184][185][186][187][188] antiviral activity, [189][190][191][192][193][194] anti-tubercular activity, [195][196][197] anticancer and anti HIV activities, [198][199][200][201][202] anticonvulsant activity, [203][204][205] anthelmintic activity, [206][207] antiparkinsonian activity, [208][209] cardiovascular activity, [210] antiproliferative activity, [211] analgesic activity [212] as markers of cell vitality and antioxidant activity [212][213][214][215][216][217][218][219][220][221][222][223][224][225]…”

One-Pot Four Component Reaction for the Synthesis of Formazans in an Environmentally Benign Procedure Mediated by KHSO<sub>4</sub>

“…Further to obtain the formazans in satisfactory yield strict control of pH of the medium is necessary. Newer methods of synthesis are reported and notable among them are the use of solid-liquid phase transfer catalysts [18]- [21], liquid-liquid systems and crown ethers [22], methods reported by Tezcan et al [23]- [26] and a green method using solid Lewis acid namely nano BF 3 -SiO 2 [27]. The commonly used method of synthesis involves three steps namely preparation of the aldehydehydrazones and the diazonium ions separately before reacting both in a suitable medium to give the formazan.…”