Theoretical study of the dimerization of rhodanine in various tautomeric forms

Abstract

The density functional theory (DFT) was used to calculate the relative stability of rhodanine dimers and the energy of intermolecular interaction in them. Analysis of the electron density showed hydrogen bonding in the dimers. The energies of individual hydrogen bonds were determined for the symmetrical dimers. The polarizable continuum model was used to calculate the solvation (hydration) energies of the structures studied. The effect of dimerization on the position of infrared absorption bands was demonstrated.Rhodanine (2-thioxothiazolidin-4-one) and its derivatives, which are common reagents in analytical and coordination chemistry, attract special interest in medicine, biochemistry, and photochemistry. Rhodanine derivatives modified at the methylene group (ylidenerhodanines) possess antibacterial [1], antifungal [2-4], antidiabetic [5], and anticancer activity [6]. This accounts for the use of rhodanine in the pharmaceutical industry [5].Free rhodanine is used for the synthesis of indoline, triphenylamine, and phenothiazine sensitizing dyes for solar cells [7]. The rhodanine group in dye compositions acts as an electron density acceptor. Rhodanine also forms strong colored coordination compounds with many heavy metal ions such as Pd 2+ , Pt 2+ [8], Ag + , Au + [9], Cu + [10], Ni 2+ , Co 2+ [11], Cu 2+ , Hg 2+ , Au 3+ , and Ru 3+ [12] what is used for their spectrophotometric determination.Rhodanine may exist in ketone, enol, and thioenol tautomeric forms [13][14][15][16][17] due to the presence of ketone and thioketone functional groups in a molecule and an active hydrogen atom of the NH bond (with dissociation constant K d = 10 -8 in water [13,14]). The enol and thioenol tautomers can each form two rotamers, while a total of eleven tautomers and rotamers exist taking account of the possible dissociation of rhodanine at the methylene group CH bond [17]. Thus, we might expect the existence of a wide variety of dimeric complexes, which may be formed in crystals, solutions, and the gas phase.Loncharich et al. [13] have carried out an X-ray diffraction structural analysis and experimentally identified some of the dimers predicted in our earlier work. This offered the prospect of identifying other dimeric complexes.In the present work, we present the results of quantum-chemical modelling for various rhodanine dimers. These data contribute to a general understanding of the dimerization behavior and may be useful for developing the chemistry of rhodanines and ylidenerhodanines as well as for methods of infrared spectral

2-Thiohydantoin Moiety as a Novel Acceptor/Anchoring Group of Photosensitizers for Dye-Sensitized Solar Cells

“…The explanation of this phenomenon, as well as differences in behavior in different solvents, is the formation of thiohydantoin aggregates. The formation of such associates has already been predicted theoretically and observed for the molecules of similar structures [37][38][39]. The formation of these aggregates must be dependent on the polarity of the medium in which they are dissolved, which might be the reason for the difference between the voltammograms measured in DCM and THF.…”

Insights into Plasmon-Induced Dimerization of Rhodanine–A Surface-Enhanced Raman Scattering Study

“…Its molecular structure contains the active methylene group (CH 2 ), which helps it to undergo a conventional Knoevenagel condensation reaction with aldehydes and ketones, resulting in the formation of unsaturated (CC) ketonic products. , It may exist in various tautomeric forms (keto-thione, keto-thiol, enol-thione, and enol-thiol) predicted by theoretical calculations. − Among all tautomeric forms, the keto-thione tautomer is considered to be the most stable form . In recent times, such types of heterocyclic bio-molecules have been the focus of SERS investigation to probe the adsorption behavior on MNPs in view of their biological importance.…”

“…72,73 It may exist in various tautomeric forms (keto-thione, keto-thiol, enol-thione, and enol-thiol) predicted by theoretical calculations. 74−76 Among all tautomeric forms, the keto-thione tautomer is considered to be the most stable form. 77 In recent times, such types of heterocyclic bio-molecules have been the focus of SERS investigation to probe the adsorption behavior on MNPs in view of their biological importance.…”

Domestic Wastewater Treatment: The Influence of Silver Impregnated Polyrhodanine Nanofibers on Gram-Positive and Gram-Negative Bacteria

“…Rhodanine and rhodanine derivatives have been widely used for a variety of applications, including antiviral, antibacterial, and anticorrosion agents and it has been widely used in the pharmaceutical field; however, new technologies are arising that include it in the engineering and nanotechnology field [38][39][40]. This study describes the fabrication of a polyrhodanine-silver complex in the form of nanofibers and the Domestic Wastewater Treatment: The Influence of Silver Impregnated Polyrhodanine Nanofibers on Gram-Positive and Gram-Negative Bacteria antimicrobial effectiveness against Gram-positive and Gram-negative bacteria, which are frequently found in domestic wastewater sources.…”