Spectral Study of Two Carbanion Mono-substituted 4�-phenyl-1,2,4-triazol-1-ium Phenacylids in Binary Protic Solvents

Abstract

The visible electronic absorption band of two 4�-phenyl-1,2,4-triazol-1-ium phenacylids was studied in two binary solvents: water (1) + ethanol (2) and water (1) + methanol (2) with variable content in water. The nature and the contribution of the intermolecular interactions to the spectral shifts in ternary solutions of the studied ylids were estimated based on the Kamlet Taft parameters (�*, a and a) previously measured by Buhvestov and all. The influence of the universal and specific interactions on the visible electronic band of the studied ylids depends on the water concentration in binary solvent. At small water concentrations in binary solvent, the hydrogen complexes of the type ylid-alcohol are predominant, while at high water concentrations, the complexes made by hydrogen bonds between water and ylid molecules prevail. The difference between the energies corresponding to molecular pairs of the types: ylid-water and ylid-alcohol was estimated based on the statistic cell model of the ternary solutions.

Solvatochromic Study of Two Carbanion Monosubstituted 4-Tolyl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures

“…An increase in the wavenumber of the visible band of the studied ylids (TTPY and TTNPY) is emphasized in Table 1 and Table 2 when the water content increases in the binary solvent mixture water (1) + alcohol (2), both for the solvent achieved with ethanol and methanol. The same tendency has been observed in the binary solvent mixture solutions of the carbanion monosubstituted p -phenyl-triazol-1-ium ylids [ 23 ]. This tendency could be explained by the increase of the electric permittivity of the binary solvent mixture when its content in water increases, determining the increase of the universal interactions of the orientation–induction type in solutions.…”

“…As relation (1) suggests, the sign plus of the correlation coefficients reflects a spectral shift to high wavenumbers (blue shift) in the electronic spectra. All coefficients are positive, showing a hypsochromic effect both of universal interactions (described by the π *, the polarity/polarizability parameter of the solvent) and of the specific interactions (described by the solvent parameters α and β ) [ 21 , 22 , 23 ]. This tendency has been observed in other binary hydroxylic solvent mixture solutions of some cycloimmonium ylids [ 22 , 38 ].…”

“…Some correlations [ 21 , 22 , 23 ] between the wavenumber in the maximum of the electronic absorption band and the solvent parameters, such as the hydrogen bond donor (HBD, noted by α ), hydrogen bond acceptor (HBA, noted by β ), and polarity/dipolarity number ( ), known as KAT parameters, were established: …”

Some Aryl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures. Computational and Spectral Study

“…Knowledge about the interactions between triazolium ylids and solvent molecules are very useful because the majority of the ylids reactions take place in situ. Some information about the intermolecular interactions from liquid solutions of triazolium ylids have previously been published [11][12][13][14] based on spectral studies in the visible range. Both the universal and specific interactions were emphasized in binary and ternary solutions of 1,2,4-triazol-1-ium ylids.…”

“…Spectral studies were achieved in a reduced number of solvents, both in protic and aprotic solvents [13][14][15], due to the reduced solubility of 1,2,4-triazol-1-ium ylids in the majority of liquids. This is the reason why an extensive solvatochromic study of these ylids has not yet been published.…”