Solvent polarity scales: determination of new E_T(30) values for 84 organic solvents

Abstract

The solvent polarity parameter E T (30) is newly measured from the solvatochromism of the betaine dye 30 for 84 solvents and re-measured for 186 additional ones. The results are organized in a database. It is shown that the validity of linear solvation energy relationships used for the determination of secondary E T (30) values is limited to non-hydrogen-bond donor solvents. Relationships with the chain length n are given for the determination of tertiary E T (30) values of the homologous H(CH 2 ) n Y solvent series. The parameter E T (30) is orthogonal to the function of the refractive index (n 2 À 1) / (2n 2 + 1). For non hydrogen-bond donor solvents, this allows to enter E T (30) as an almost pure electrostatic parameter in a new linear solvation energy relationship.

Mechanochromism, Twisted/Folded Structure Determination, and Derivatization of (N‐Phenylfluorenylidene)acridane

“…[18] As expected, we found that the ratio of the twisted conformer increased in polar solvents such as dichloromethane and acetonitrile through stabilization of the charge-transfer form of FA.I n nonpolar solvents such as n-hexane,t he ratio of the folded conformer increased. Spectra recorded in methanol and 2propanol also showed ah igh ratio of the folded conformer, even though methanol and 2-propanol are polar solvents.The solubility of 4 in methanol is low,a nd this might cause aggregation of the folded forms.I ndeed, ap lot of the absorption maxima around 650 nm against the solvent polarity parameter E T (30) [19] clearly indicated that as olvent of higher polarity stabilized the twisted conformer, except in the case of the alcohols ( Figure S4).…”

Exploring the Solvatochromism of Betaine 30 with Ab Initio Tools: From Accurate Gas‐Phase Calculations to Implicit and Explicit Solvation Models

“…This choice is also consistentw ith recent successful TD-DFT investigations on B30. [5,46] The excitation energies andp roperties of B30 were calculated with three methods:C AM-B3LYP,a sam ethodo fc hoice for TD-DFT,a nd both relaxed and unrelaxed CC2 as the only affordable methodi nt he CC hierarchy.T he results in Ta ble 3 firstly show as maller sensitivity of the CC2 results to the orbital relaxation than in PyPo:inB 30 the rlx/unrlx Dm values differ by approximately 1.5 Do nly.B oth approaches also closely agree for the magnitudeo fDa.W eu nderline that the nature of the excited-state in B30 seems less methodd ependent than in the model PyPo, and the latter molecule is therefore probably harder to describe. For instance, in PyPo, the CC2 transition encompasses as mall contribution from the HOMOÀ1t ot he LUMO orbital transition (not found with CCSD), whereas in B30, the HOMO-LUMO contribution is largely dominantf or all tested levelsoft heory.O ur calculations clearly confirm that the dipole moment is dramatically decreasing upon excitation and that Dm attains approximately À7D,w hich we consider as the most accurate gas-phase value to date.…”

“…[1][2][3][4] For instance, the visible absorption band of B30 shows an extremelyl arge negative solvatochromism:i ts trongly shifts towards highere nergies in more polar solvents,g oing from l = 882 nm in CCl 4 to l = 453 nm in water. [1,5] The position of the absorption maximum (in kcal mol À1 )o fB 30 has been used to define the widely applied E T (30) polaritys cale forn umerous solvents. [5,6] Applications of B30 encompass ionic liquids research, [7,8] study of cyclodextrinsi ns olution, [9] chemo-sensors [10] as well as classroome xperiments.…”

“…[1,5] The position of the absorption maximum (in kcal mol À1 )o fB 30 has been used to define the widely applied E T (30) polaritys cale forn umerous solvents. [5,6] Applications of B30 encompass ionic liquids research, [7,8] study of cyclodextrinsi ns olution, [9] chemo-sensors [10] as well as classroome xperiments. [11,12] The interested readerm ight find exhaustive lists of B30 applicationsi nt he reviewso fReichardt and co-workers.…”

Selective glycerol oxidation over ordered mesoporous copper aluminum oxide catalysts

“…65 The E T (30) value is derived from the solvatochromism of the dye betaine 30 and is a descriptor for the hydrogen bond and electrostatic interactions of solvents. 81 Low E T (30) values correspond to low solvent polarities. As mentioned earlier, the polarity of a solvent strongly influences the degree of solvation of reactants, and, consequently, their interaction with the catalyst's surface.…”