Empirical Solvent Polarity Parameter Research Articles

Determination of L-Glutamine Solubility in 12 Pure Solvent Systems from 283.15 to 323.15 K

The mole fraction solubility of L-glutamine in 12 pure solvents (methanol, n-propanol, sec-butanol, 2-butanone, ethanol, acetonitrile, n-butanol, ethyl acetate, n-pentanol, water, n-hexane, and isobutanol) was determined by the static gravimetric method at a temperature range of 283.15–323.15 K under a pressure of 98.8 kPa. The equilibrium solid phase of L-glutamine in the solvent systems was characterized by powder X-ray diffraction analysis. The solubility in the 12 monosolvents was found to increase with absolute temperature. The maximum and minimum values were in water and ethyl acetate, respectively. The empirical solvent polarity parameters (ET(30)), cohesive energy density, and hydrogen bond donor/acceptor (HBD/HBA) tendencies were employed to analyze the solubility behavior and solvent effects. The solubility data were fitted using the modified Apelblat model and the Yaws model, at the same time, the model parameters and data deviation values were calculated. These two solubility models were evaluated using the Akaike Information Criteria and Akaike weights. The results showed that the modified Apelblat model had better correlation results. The solubility data could be used in the preparation and optimization of L-glutamine crystallization processes.

Solvent polarity influence on chemiexcitation efficiency of inter and intramolecular electron-transfer catalyzed chemiluminescence

The parameters which determine the efficiency of chemiluminescence, and bioluminescence transformations are a continuous matter of experimental and theoretical studies. In this sense, we report here a study of the solvent polarity influence on four Chemically Initiated Electron Exchange Luminescence (CIEEL) systems. Two of them comprise intermolecular CIEEL systems with low efficiency – catalyzed decomposition of diphenoyl peroxide and spiroadamantyl-1,2-dioxetanone; the other two are highly efficient in producing excited states – the peroxyoxalate reaction through an intermolecular CIEEL, and the induced decomposition of a phenoxy-substituted 1,2-dioxetane derivative via intramolecular CIEEL. These four CIEEL systems are studied in binary solvent mixtures with similar viscosity but different polarity, as measured by the empirical solvent polarity parameter ET(30). Reaction rate constants for all the systems increase with increasing polarity, indicating the occurrence of electron or charge transfer in the rate-limiting step of these transformations. For the intermolecular systems, singlet quantum yields generally rise with medium polarity to a maximum value and decrease for higher polarities. This agrees with stabilization of the radical ion pair intermediate by solvation at an optimal medium polarity. In contrast, higher polarity promotes the separation of these charged species, thereby avoiding electron back-transfer between radical ion pairs, essential for chemiexcitation. The singlet quantum yields in the intramolecular CIEEL system show a steady increase with the medium polarity, reaching values close to the maximum possible quantum yield of 1.0 E mol−1, indicating the importance of biradical ion stabilization and the occurrence of the whole reaction sequence in an intramolecular manner.

Solubility and Solvent Effect Analysis of N-Benzyloxycarbonyl-l-tryptophan in 12 Monosolvent Systems at Multiple Temperatures

The solid–liquid equilibrium solubility and solvent effects of N-benzyloxycarbonyl-l-tryptophan in monosolvent systems (water, isopropanol, ethanol, n-propanol, isobutanol, n-butanol, acetonitrile, n-pentanol, 2-butanone, acetone, methyl acetate, and ethyl acetate) were reported in this work. All the solubility data were measured at 283.15–323.15 K (5 K interval) by the static gravimetric method. It was confirmed by powder X-ray diffraction that the crystal form of N-benzyloxycarbonyl-l-tryptophan did not change in the process of solubility determination. Among the 12 pure solvents, the solubility increased with the increase of absolute temperature. The solubility is the largest in acetone and the smallest in water. The solubility behavior and solvent effects in different monosolvents were first analyzed by taking the empirical solvent polarity parameter (ET(30)) as the main factor. Then the natural logarithm of solubility (lnx1) was linearly fitted to ET(30) for dipolar protic and aprotic solvents, respectively. Lastly, the special solubility behavior in isopropanol and water/acetonitrile was explained by the hydrogen bond acceptor tendencies and the cohesive energy density, respectively. The solvent effect analysis results illustrated that the solubility sequence of N-benzyloxycarbonyl-l-tryptophan in the test solvents resulted from the comprehensive effect of multiple factors. The Yaws model and the modified Apelblat model were employed to correlate the experimental solubility, and the fitting results of the two models were well. In addition, Akaike Information Criterion values and Akaike weights of the two models were calculated to evaluate the fitting level.

Inclusion complexation of 4′,6-diamidino-2-phenylindole (DAPI) with cucurbit[7]uril and cyclodextrins (native β-, 2,6-di-O-methylated β-, and γ-cyclodextrin): characteristic inclusion behaviour and fluorescence enhancement

Herein, we investigated the inclusion complexation of a fluorescent probe [4′,6-diamidino-2-phenylindole (DAPI)] using various cyclodextrins (CDs) and cucurbit[7]uril (CB7). Using the continuous variation method, DAPI was found to form a 1:1 inclusion complex with CDs and CB7. 1H-NMR and 2D ROESY (1H-1H rotating frame nuclear Overhauser effect) spectroscopy indicated that the inclusion of DAPI by the CDs and CB7 occurs via the encapsulation of the phenyl group and indole moiety of DAPI. The stability of the CB7 inclusion complex was higher than that of the CDs: the stability was attributed to the extra interaction formed between the dicationic dye (DAPI) and polar carbonyl groups at the portals of CB7. Furthermore, we determined the fluorescence quantum yield (Φ) of the inclusion complexes. The Φ values of DAPI were significantly enhanced upon its inclusion by CB7 and increased as the empirical solvent polarity parameter (ET(30)) decreased. Based on these results, we concluded that the polarity of the microenvironment and protonation ability of the excited state of DAPI play important roles in emission efficiency.

Norharmane prototropism in choline chloride-based deep eutectic solvents

Deep eutectic solvents (DESs) are gaining widespread attention as novel and alternate solvents in chemical and biological sciences. Prototropic equilibria are known to be governed by the solubilizing milieu, and thus, it is imperative to study them within DESs. Prototropic behavior of β-carboline commonly named as norharmane (9H-pyrido[3,4-b]indole) is investigated in eight different DESs constituted of the salt choline chloride with eight different H-bond donors (HBDs) to ascertain their role in controlling prototropism within DESs. UV–vis molecular absorbance is used to obtain information on ground-state prototropism whereas steady-state and time-resolved fluorescence are used to investigate prototropic forms in the excited-state. In the ground-state, DESs with HBDs glycerol and ethylene glycol support both neutral and cationic forms of norharmane, however, within DESs constituted of HBDs urea, 1,4-butane-diol, and acetamide, respectively, only the neutral form exists. Within the remaining three DESs with HBDs tetraethylene glycol, 3-phenylpropionic acid, and malonic acid, respectively, only cationic form is supported. As the cationic form is preferred more over the neutral form of norharmane in the excited-state, DESs with HBDs tetraethylene glycol, 3-phenylpropionic acid, and malonic acid, respectively, support only cationic form in the excited-state. DES with glycerol also supports only the cationic form in the excited-state, DES with ethylene glycol, acetamide, and 1,4-butane-diol support both cationic and neutral forms. The DES with urea as the HBD is the only DES that supports only the neutral form in the exited-state. Excited-state intensity decay data confirms the presence of different prototropic forms of norharmane within investigated DESs with distinct decay times for the neutral and cationic forms. Correlation between the common empirical solvent polarity parameter, ETN, along with Kamlet-Taft parameters, H-bond donating acidity (α) and H-bond accepting basicity (β), of the DESs and the relative presence of the norharmane prototropic forms is established.

Understanding Solvation: Comparison of Reichardt’s Solvatochromic Probe and Related Molecular “Core” Structures

The compound 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate, p-RB, shows distinct colors in different solvents (solvatochromism). The compound 4-(pyridinium-1-yl)phenolate, p-CB, represents the part of p-RB which is responsible for this phenomenon. We compared the solvatochromism of both compounds and also the structurally related 2-(pyridinium-1-yl)phenolate, o-CB, and (2,4-dimethyl-6-(2,4,6-triphenyl-N-pyridinium-1-yl)phenolate, o-RB. In pure solvents, plots of the empirical solvent polarity parameter [ET(probe), kcal/mol] of the different probes correlate linearly with slopes close to unity. That is, these probes are similarly sensitive to specific and nonspecific interactions with the solvents. The solvatochromism of p-CB and o-CB was studied, for the first time, in binary mixtures of water with dimethyl sulfoxide (DMSO) and 1-propanol (1-PrOH). The dependence of ET(probe) on mixture composition was nonideal due to preferential solvation of the probe by one component of the binary solvent mixture. We treated our solvatochromic data using a solvent-exchange model that considers formation of the complex solvents [HOH···O═S(CH3)2] and [HOH···O(H)-C3H7]. The model applies satisfactorily to our data and shows the importance to solvation of hydrogen-bonding and hydrophobic interactions. The preferential solvation of (more hydrophobic) p-RB is more pronounced than that of p-CB or o-CB. The solvent complex [OH2···O(H)-C3H7] is more efficient than [OH2···O═S(CH3)2] because of more possibilities of hydrogen bonding.

Theoretical design, synthesis and studies on the solvatochromic behaviour of low band gap phenylenevinylene based copolymers

A new series of low band gap phenylenevinylene based copolymers was designed by employing density functional theory in the periodic boundary condition using HSE06 exchange correlation functional using 6-31G basis set and synthesized via the Gilch polymerization. The theoretical band gap of the copolymers MD-CA-PPV, MD-FL-PPV, MD-PT-PPV and MD-AN-PPV were found to be 1.98, 2.07, 2.31 and 1.99 eV respectively using the DFT/HSE06/6-31G calculation and the optical band gap of 1.96, 2.03, 2.01 and 1.98 eV respectively, according to the onset edge of lower energy peak of the polymers in solution. The experimental results supported the theoretical prediction. Solvatochromic behaviour of the synthesized copolymers was studied thoroughly in toluene/acetonitrile mixtures of varying polarity at room temperature. The absorption spectrum of the PPV polymers was sensitive to solvent effects which showed bathochromic and hypsochromic shifts with increasing solvent polarity indicating that the transitions involved were π-π* and n-π*. The ground and excited state dipole moments were calculated using solvatochromic correlations. Onsager radius determined from ab initio calculation was used in the determination of dipole moments. The change in the dipole moment (Δμ) was calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter (ETN) and values are compared. It was observed that the excited state dipole moment (µe) was larger than its ground state (µg) counterpart. This indicated that a substantial redistribution of the π-electron densities occurred in the more polar excited state for the selected phenylenevinylene polymers. The third-order nonlinear optical (NLO) properties of the copolymers, evaluated by Z-scan method with nanosecond laser beam at 532 nm, are reported. The nonlinear absorption coefficient of the copolymers were calculated to be 0.17 × 10−10, 2.06 × 10−10, 0.63 × 10−10 and 2.83 × 10−10 esu, respectively for MD-CA-PPV, MD-FL-PPV, MD-PT-PPV and MD-AN-PPV which certified that the polymers showed semiconductor properties.

New linear solvation energy relationships for empirical solvent scales using the Kamlet-Abboud-Taft parameter sets in nematic liquid crystals.

The practical application of liquid crystals (LCs) as anisotropic and ubiquitous solvents is undoubtedly lucrative. Therefore, defining solvent polarity parameters as demonstrating the effects of anisotropic LC media on the photo-physical behavior of solute molecules is increasingly sought to determine their suitability for specific areas. For this fundamental reason, a spectroscopic method was used via Kamlet–Abboud–Taft (KAT) polarity functions to determine the solvatochromic polarity (SP) parameters for different LCs regarding high and low dielectric anisotropy (Δε) at different temperatures and LC phases, both isotropic and anisotropic. According to empirical solvent polarity parameters, our LCs were categorized as a dipolar hydrogen bonding donor solvent. Moreover, typical and overall matrix anisotropy polarity parameters as variations of the SP parameter values between the isotropic and anisotropic phases were sorted according to Δε magnitude. Finally, we introduced the linear solvation energy relationships of empirical solvent scales with the KAT parameters sets for the first time in nematic LCs with the well-established correlations.

A combined spectroscopic and TDDFT investigation of the solute-solvent interactions of two coumarin derivatives.

The UV/Vis absorption and fluorescence characteristics of 3-cyano-7-hydroxycoumarin [CHC] and 7-amino-4-methyl-3-coumarinylacetic acid [AMCA-H] were studied at room temperature in several neat solvents and binary solvent mixtures of 1,4-dioxane/acetonitrile. The effects of solvent on the spectral properties are analyzed using single and multi-parameter solvent polarity scales. Both general solute/solvent interactions and hydrogen bond interactions are operative in these systems. The solvation of CHC and AMCA-H dyes in 1,4-dioxane/acetonitrile solvent mixtures has been studied. The solutes CHC and AMCA-H are preferentially solvated by acetonitrile and a synergistic effect is observed for both molecules in dioxane/acetonitrile solvent mixtures. In addition, using the solvatochromic method the ground- and the excited-state dipole moments of both the dyes were calculated. The ground- and excited-state dipole moments, absorption and emission maxima and HOMO-LUMO gap were also estimated theoretically using B3LYP/6-311+ G (d,p) level of theory in the gaseous phase, dioxane and acetonitrile solvents. Furthermore, changes in dipole moment values were also calculated using the variation of Stokes shift with the molecular-microscopic empirical solvent polarity parameter ( ETN). The observed excited-state dipole moments are larger than their ground-state counterparts, indicating a substantial redistribution of the electron densities in a more dipolar excited state for both coumarins investigated.

Photochromic properties of spiropyran in epoxy resin as anti-counterfeiting coating on flexible materials

A kind of spiropyran derivatives, 1-chloro-3-(3′,3′-dimethyl-6-nitrospiro[chromene-2,2′-indolin]-1′-yl)propan-2-ol (CSP), was synthesized and characterized by FT-IR, 1H NMR, EI-MS, which contained the spiropyran moiety. The photochromism and solvatochromism in the diverse solvents were investigated in details. The polarity of the solvent played a crucial effect on the absorbance of the ring open form (MC) for CSP, characterized by using the relative polarity and Reichardt's empirical solvent polarity parameter (ET(30)). The fatigue resistance was evaluated by the number of cycles required to reduce the initial absorbance at λmax by 50% (Z50). Entrapment of the radical-scavengers such as butylated hydroxyl toluene (BHT) and 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) practically enhanced the duration of CSP and protected most of the molecules from further oxidation in acetone. The parameter Z50 in ethyl acetate was 534 and was much higher than the others. However, it reached to more than 1200 when CSP was doping in the epoxy resin on OPP film. It indicated that the CSP could be applied in the flexible substrate for foods and medicine package.

Spectroscopic Investigation, Effect of Solvent Polarity and Fluorescence Quenching of a New D-π-A Type Chalcone Derivative

A new chalcone derivative 3-(1-methyl-1H-pyrrol-2-yl)-1-naphthalen-2-yl propenone (MPNP) with electron donor-acceptor group has been synthesized and characterized by IR, (1)HNMR, (13)C NMR and X- ray crystallography. Electronic absorption and emission spectra of MPNP have been studied in solvents of different polarity. A remarkable red shift was observed in the emission spectrum of MPNP compared to the absorption spectrum upon increasing the solvent polarity, indicating a higher dipole moment in the excited state than in the ground state and the transition involved are π-π* with charge transfer character. Lippert-Mataga and Reichardts correlations were used to estimate the change in dipole moments (Δμ); suggest that the emissive state of MPNP is of strong ICT character. Fluorescence quantum yield (ϕf) of MPNP was correlated with empirical solvent polarity parameter ET(30), and it is observed that ϕf increases with increase in solvent polarity of polar aprotic solvents and decrease in alcoholic solvents. The interaction of MPNP with colloidal silver nanoparticles (AgNPs) was also studied in ethanol and ethylene glycol using steady state emission measurements. The fluorescence quenching data reveal that dynamic quenching and energy transfer play a major role in the fluorescence quenching of MPNP by Ag NPs.

Dipolarity versus Polarizability and Acidity versus Basicity of Ionic Liquids as a Function of Their Molecular Structures

The four empirical solvent polarity parameters according to the Catalán scale--solvent acidity (SA), solvent basicity (SB), solvent polarizability (SP), and solvent dipolarity (SdP)--of 64 ionic liquids (ILs) were determined by the solvatochromic method. The SA parameter was determined solely by using [Fe(II)(1,10-phenanthroline)2(CN)2] (Fe), the SB parameter by using the pair of structurally comparable dyes 3-(4-amino-3-methylphenyl)-7-phenylbenzo[1,2-b:4,5-b']difuran-2,6-dione (ABF) and 3-(4-N,N-dimethylaminophenyl)-7-phenylbenzo[1,2-b:4,5-b']-difuran-2,6-dione (DMe-ABF), and the SP and SdP parameters by using the homomorphic pair of 4-tert-butyl-2-(dicyanomethylene)-5-[4-(diethylamino)benzylidene]-Δ(3)-thiazoline (Th) and 2-[4-(N,N-dimethylamino)benzylidene]malononitrile (BMN). The separation of SP and SdP for a set of 64 various ILs was performed for the first time. Correlation analyses of SP with physicochemical data related to ionization potentials of anions of ILs as well as with theoretical data show the correctness of the applied method. The found correlations of the Catalán parameters with each other and with the alkyl-chain length of 1-alkyl-3-methylimidazolium-type ILs gives new information about interactions within ILs. An analytical comparison of the determined Catalán parameters with the established Kamlet-Taft parameters and the Gutmann acceptor and donor numbers is also presented.

Solvent effect on the dipole moments and photo physical behaviour of 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene dye

The absorption and emission spectra of fluorescent thiophene dye, namely, 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene, have been recorded at room temperature in solvents of different polarities. The excited state dipole moments (μe) were estimated from Lippert’s, Bakhshiev’s, and Kawski–Chamma–Viallet’s equations using the variation of Stoke’s shift with the solvent dielectric constant and refractive index. The optimized geometry of the molecule and μgwere calculated theoretically by Gaussian 03 software using B3LYP/6-31g* level of theory. The μgand μewere calculated by means of solvatochromic shift method and μewas determined in combination with μg. It was observed that μewere higher than those of the μg, indicating a substantial redistribution of the π-electron densities in a more polar excited state for the selected thiophene dye. Further, the change in the dipole moment (Δμ) was calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter [Formula: see text] and values are compared.

Estimation of ground and excited-state dipole moments of 1, 2-diazines by solvatochromic method and quantum-chemical calculation

Using the theory of solvatochromism, the difference in the excited-state (μe) and ground-state (μg) dipole moments was determined from Lippert–Mataga, Bakhshiev, Kawski–Chamma–Viallet, and McRae equations for three 1,2-diazines (pyrrolo-pyridazine derivatives). All of these equations are based on the variation of Stokes shift with solvent's relative permittivity and refractive index. Further, the change in dipole moment value (Δμ) was also calculated using the variation of Stokes shift with the molecular-microscopic empirical solvent polarity parameter. Theoretical μg values were evaluated by quantum chemical calculations using the DFT method by adopting B3LYP/6-31G* level of theory (Gaussian 03) and using the AM1 method (Chem3D Ultra 8.0). It was observed that, dipole moments of diazines in the excited-state (μe) were greater than the corresponding ground-state values (μg), indicating a substantial redistribution of the π-electron densities in a more polar excited-state. Also, with the increase in the polarity of the solvent, the fluorescence emission peak undergoes a red-shift, confirming a π→π* transition.

Solvent Effect on the Fluorescence Properties of Two Biologically Active Thiophene Carboxamido Molecules

The absorption and fluorescence spectra of two thiophene carboxamido molecules namely 2–( - trimethoxy phenyl) imino–3–N–ethylcarboxamido–4, 5, tetramethylene thiophene (X) and 2-( -N, N-dimethylaminophenyl) imino-3-(N- methylphenyl carboxamido)-4, 5, tetramethylene thiophene (Y) have been recorded at room temperature. The ground (mg) and excited (me) state dipole moments are estimated from Lippert, Bakhshiev, Kawski-Chamma-Viallet equations by using the variation of Stokes shift with microscopic solvent dielectric constant (e) and refractive index (n). The excited dipole moments were also estimated by using the variation of Stokes shift with microscopic empirical solvent polarity parameter and the values are compared. It was estimated that dipole moments of the excited state were higher than those of the ground state of both the molecules. Further, the change in dipole moment (Dm) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter .

Determination of the empirical solvent polarity parameter ET(30) by multivariate image analysis

The solvent polarity ET(30) scale has found wide-spread applications in studying chemical processes in solvents. This parameter is usually measured by vis spectrophotometric measurements of the long-wavelength intramolecular charge-transfer (CT) absorption band of Reichardt's pyridinium-N-phenolate betaine dye, e.g. the ET(30) dye, dissolved in the solvent or solvent mixture of interest. Recent advances in colorimetric measurements based on digital photo-capturing devices suggest these methods as a simple, cheap and fast alternative to spectrophotometric measurements in some analytical applications. In this work, we studied the feasibility of colorimetric measurements coupled with multivariate data analysis to determine the empirical solvent polarity parameter ET(30). The picture of the ET(30) dye dissolved in different solvents was captured by a digital camera and then color values in the RGB space were analyzed by the principal component analysis (PCA) method. PCA scores of the unfolded image were then used as input of multiple linear regression and an artificial neural network model to predict the ET(30) parameter. The ANN models were optimized to gain a model of lower prediction ability utilizing a cross-validation test. Then, this was used to predict ET(30) values for an external solvent test set. The generated model could explain and predict 99% of the variances in the polarity data and can predict ET(30) values with a root mean square error of 2.25 kcal mol−1 (in the ET(30) scale). The results suggest colorimetric measurements as a useful and practical alternative to the vis spectrophotometric measurements for determination of solvent polarity parameters derived from solvatochromic betaine dyes.

Negative solvatochromism of a series of pyridinium phenolate betaine dyes with increasing steric hindrance

The negative solvatochromism of a series of pyridinium phenolates betaine dyes is investigated using three approaches: (a) empirical, based on the empirical solvent polarity parameter ET(30); (b) semi-empirical, based on the π∗, α, β set of parameters used in Kamlet–Taft’s Solvatochromic Comparison Method (SCM); and (c) physical, by means of the Onsager reaction-field model of solvents. Comparison of the obtained correlations underscored the roles of both the two tert-butyl groups ortho to the oxygen atom and the interplanar angle between the phenyl rings on the very blue shifts observed as the polarity increases.

First kinetic evidence for the CH/π and π/π solute–solvent interaction of C60 in the Diels–Alder reaction with cyclohexadiene

The first CH/π solute-solvent interaction of C(60) was evidenced by the kinetic solvent effects in the Diels-Alder reaction with 1,3-cyclohexadiene based on the evaluation of linear free energy relationship of log k(2) with empirical solvent polarity and basicity parameters, E(T)(30) and D(π), respectively.

Optimized synthesis and detailed NMR spectroscopic characterization of the 1,8a-dihydroazulene-1,1-dicarbonitrile photoswitch

An economical and effective protocol for large scale synthesis of the 2-phenyl-1,8adihydroazulene-1,1-dicarbonitrile (DHA) photoswitch has been developed. This compound is ring-opened by light to a vinylheptafulvene (VHF), which is thermally closed back to DHA. This compound serves as an important starting material for dihydroazulene photoswitches incorporating a substituent in the seven-membered ring and as a reference compound for comparison of properties. A detailed NMR spectroscopic characterization has allowed the assignment of all proton and carbon signals. In addition, the compound was characterized by Xray crystallography. A correlation between the rate constant for thermal ring-closure of VHF to DHA and empirical parameters of solvent polarity (ET30) was established.

Solvent Effect on Absorption and Fluorescence Spectra of Three Biologically Active Carboxamides (C1, C2 and C3). Estimation of Ground and Excited State Dipole Moment from Solvatochromic Method Using Solvent Polarity Parameters

The absorption and fluorescence spectra of three Carboxamides namely (E)-2-(4-Chlorobenzylideneamino)-N-(2-chlorophenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(1)), (E)-N-(3-Chlorophenyl)-2-(3, 4-dimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(2)) and (E)-N-(3-Chlorophenyl)-2-(3,4,5-trimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(3)) have been recorded at room temperature in solvents of different polarities using dielectric constant (ε) and refractive index (n). Experimental ground (μ(g)) and excited (μ(e)) state dipole moments are estimated by means of solvatochromic shift method and also the excited dipole moments are estimated in combination with ground state dipole moments. It was estimated that dipole moments of the excited state were higher than those of the ground state of all three molecules. Further, the changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter (E(N)(T)) and the values are compared.