Supramolecular structure of azodyerhodanine compounds and their complexes: a review

The optical absorption properties of 5-(4′-derivatives phenylazo)-2-thioxothiazolidin-4-one (HL_n) (where X = H) thin films have been studied. It was found that the values of the energy band gap, E_g, for derivatives were in the range of 1.77–2.29 eV depending on the nature of the substituent. The optical values of the energy band gap (E_g) for all derivatives near the absorption edge were found to be direct allowed transition. The synthesized ligands (HL_n) (where X = H) were screened as antibacterial and antifungal agents. The proton–ligand dissociation constant of the rhodanineazo derivatives (HL_n) (where X = H and X = P-OCH₃Ph) and metal–ligand stability constants of their complexes with metal ions (Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) have been determined potentiometrically in 0.1 M KCl. The stoichiometries of copper(II) and cadmium(II) complexes of HL_n (where X = Ph) were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes. The molar ratio of ligand (HL_n) (where X = H) and Ru(III) complexes is (1:2)/(1:3)(M:L_n), respectively. The study revealed octahedral geometry around Ru(III) complexes. A series of heterocyclic mixed ligands of oxovanadium(IV) complexes have been synthesized by the reaction of vanadium(IV) sulfate with rhodanineazo (HL_n) (where X = H) in the presence of β-diketone (LH). Palladium(II) complexes of the general formula [Pd(L_n)L] (where LH = diketone = acetylacetone, HL_n = azorhodanine) have been synthesized. In these complexes, the azo ligand acts as a monobasic bidentate ligand and is coordinated to the metal ion through the azo-nitrogen, enolic oxygen atoms forming stable six-membered heterocyclic rings. The D.C. electrical conductivity of HL_n (where X = Ph) and their complexes were measured. The bond lengths and the force constants have been calculated for uranyl complexes (26–30) of HL_n (where X = Ph). The plotting of r₁, r₂ and r₃ (bond distance, r_U–O) versus ν₃ give a straight line with increasing the value of ν₃ and decreasing r_U–O