The synthesis and spectral properties determination of 1,3-substituted phenyl-5-phenylformazans

Abstract

In this study, novel 1,3-substituted phenyl-5-phenylformazans were synthesized with eNO 2 , eCl, eBr, eCH 3 , eOCH 3 groups in the o-, m-, and p-position of the 1-phenyl ring and eNO 2 , eOCH 3 groups in the m-and p-position of the 3-phenyl ring. Their structures were elucidated by elemental analysis and GCemass and their spectral behaviors were investigated with 1 H NMR, 13 C NMR, IR, UVevis spectra. The absorption characteristics of the compounds were examined by UVevis spectra. There was a shift in l max whose amount was dependent upon the type and position of the substituent on the ring. A linear correlation was obtained between this substituent effect and Hammett substituent coefficients.

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.…”

“…The chemical shift values ( ∆λ max ) were determined according to the difference between the λ max 1 value of unsubstituted parent compound 4a and λ max 1 values of substituted formazans (4b-4h). 28,37,38 The UV-vis spectra of 4a-4h are given in Figure 2 in ethanol solution. Table 2, the absorption value (λ max 1 ) of compound 4b possessing an electron donating -OCH 3 subunit at the para-position is recorded ∆λ max = 5 nm longer wavelength than the parent molecule 4a in ethanol.…”

Frontiers of Formazans Chemistry: A Review

“…The weak bands are observed at 3016-3024 cm -1 corresponding to N-H symmetric stretching mode. Some N-H stretching modes observed for different substituted formazans are (3000-3600cm -1 ) [158] and (2850-3120 cm -1 ) . [159] However, band shifts are observed with regard to the different substituent-formazan L or LI structure.…”

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.…”