Solvatochromic mixture property

The solvatochromic fluorescence properties of amino- and imide-iV-alkyl-substituted phthalimides were studied by several groups. The response of 4-aminophthalimide (63) in aqueous solutions of various substituted alkanes was used by Saroja and Samanta66 to monitor their coiling and aggregation. The solvatochromic shifts of 3-amino-lV-methyl-phthalimide (64) were studied in mixtures of decalin and propanol by Gorbatsevich and Smirnova67. 

A great variety of models for a quantitative description of the composition dependence of the physicochemical properties of solutes dissolved in binary solvent mixtures have been developed [257-261, 373-378]. For example, using a rather simple two-step solvent-exchange model [374, 377], the behaviour of seventy binary solvent mixtures towards a solvatochromic betaine dye (structure see Fig. 6-2 in Section 6.2.1) can be quite precisely described, even for so-called synergetic solvent mixtures [377]. 

In solvent mixtures the phenomenon of preferential solvation of the solvatochromic probe by one component of the mixed solvent often takes place. Care must therefore be taken when such combinations of mixed solvents and probes are employed for the characterization of the mixed solvent as regards its solvation properties for any arbitrary solute other than the particular probe studied5. It has been argued that, contrary to the case of neat solvents, where the use of a single probe can be justified18,27, it ought to be more... 

Bosch, Roses and coworkers explored the use of solvatochromic probes in solvent mixtures involving various alcohols with water as well as with other alcohols, hexane and benzene in a series of papers106-110. The aniline derivatives they employed were 5 for the polarity/polarizability and the 8/5 probe pair for the EPD/HBA properties of the mixtures, in conjunction with other suitable non-aniline probes. In order to ensure that what is being... 

Another attempt to relate the results from the use of a solvatochromic probe (Phenol Blue (66)) to the inherent properties of solvent mixtures was made by Phillips and Brennecke122. They obtained the interaction energies (required for the application of the non-random two-liquid (NRTL) approach) of 66 with each of the solvent components from its solubility in the neat solvent. The mixtures studied contained cyclohexane as one component and acetone, triethylamine, ethyl butyrate, cyclohexanone, toluene and acetophenone as the other. Then the local compositions deduced from the solvatochromism of 66 were compared with those calculated by the NRTL equation and reasonable agreement was found. 

Abstract This chapter presents the design and analysis of the microscopic features of binary solvent systems formed by ionic liquids, particularly room temperature ionic liqnids with molecular solvents. Protic ionic liquids, ethylammonium nitrate and l-n-butyl-3-methylmidazohum (bmim)-based ILs, were selected considering the differences in their hydrogen-bond donor acidity. The molecular solvents chosen were aprotic polar (acetonitrile, dimethylsulphoxide and MA(-dimethylformide) and protic (different alcohols). The empirical solvatochromic parameters n, a and P were employed in order to analyse the behaviour of each binary solvent system. The study focuses on the identification of solvent mixtures of relevant solvating properties to propose them as new solvents . Kinetic study of aromatic nucleophilic substitution reactions carried out in this type of solvent systems is also presented. On the other hand, this is considered as a new approach on protic ionic liquids. Ethylammonium nitrate can act as both Bronsted acid and/or nucleophile. Two reactions (aromatic nucleophilic substitution and nncleophilic addition to aromatic aldehydes) were considered as model reactions. 

In order to take into acconnt this ionic liqnid effect on the solvatochromic property (T) of the mixtures, the wave numbers of maximum absorptions of the solvatochromic indicators (A,iV-diethyl-4-nitroaniline, 4-nitroaniline and Reichardt s betaine dye) at different compositions of SI (alcohol) and S2 (IL) were fitted to the equations. 

Ray et al. [87] have studied solvatochromism of POT using mixed solvents of NMP and CH2CI2 and have plotted the solvent effect against the mole fraction of the polar solvent, and it revealed preferential solvation of POT by NMP. The Onsager function (/(e) and/(n ) are additive properties in the case of ideal mixed solvents. Therefore, the polarity function for the mixture can be written as... 

Several photophysical and ultrafast spectroscopic studies were undertaken in these RTILs [20-69]. Aki et al. [20] determined the polarity of the imidazolium-andpyiidinium-based RTILs using UV-Vis absorption and fluorescence spectroscopy. Muldoon et al. [21] determined the polarity of the RTILs using solvato-chromic probes. Carmichael et al. [22] determined the polarity of several neat l-aIkyl-3-methylimidazolium-based RTILs using the solvatochromic dye Nile red. Using Prodan, pyrene, 1-pyrenecarboxaldehyde, Reichardt s betain dye, and Rhodamine 6G as the solvatochromic probes various bulk properties and polarity of various RTILs-cosolvents mixtures were determined [23-26]. Recently, one excellent review article was published by Reichardt to determine the polarity of RTILs by means of solvatochromic betaine dyes [27]. Femtosecond optical Kerr effect... 

The solute descriptors such as Jt, a, and P can be extracted from the hterature [2-5] and are in most cases empirically determined by spectroscopic measurements. Their calculation is based on the shift of absorption bands of the given solutes due to varying solvatochromic effects when the dipolar or hydrogen-bond donor /acceptor properties of the solvent mixture used for spectroscopy are altered. Hence, they are not true thermodynamic data. Abraham and co-workers also determined descriptors from GC retention data and octanol/water partition coefficients [6-9]. With the help of such descriptors, the so-called solvation equation (Eq. 5) can be set out [10,11] ... 

The system of SDS/DTAB has been also investigated by Wan et al. ° The system involves the evolution of vesicles on mixing micelles of SDS and DTAB at a weight ratio of 1.6 1. Included in the reaction mixture was a low concentration of the solvatochromic probe 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridino) phenoxide ( (30)), which has been used previously to probe the interfacial properties of micelles and vesicles. Wan et al.i suggest that a vesicle interfacial environment is established rather rapidly, on the time scale of... 

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