Solvatochromic Correlations Research Articles

Synthesis, crystal structure and photophysical properties of (E)-4-(4-(2-hydroxybenzylideneamino)benzyl)oxazolidin-2-one

A new Schiff base, (4-(benzylideneamino)benzyl)oxazolidin-2-one has been synthesised from 4-(4-aminobenzyl)oxazolidin-2-one and salicylaldehyde by a simple condensation reaction. Single-crystal X-ray analysis of (E)-4-(4-(2-hydroxybenzylideneamino) benzyl)oxazolidin-2-one (HBOA) revealed that there is a 1-D, slipped, face-to-face motif with off-set, head-to-tail stacked columns. Detailed studies on photophysical properties of the synthesised compound in solutions indicate their potential applications in the field of organic light emitting devices and nonlinear optical materials. Absorption and fluorescence study of HBOA has been conducted in a series of solvents with increasing polarity at room temperature. Ground and excited state dipole moments have been determined experimentally by using Lippert–Mataga polarity function, Bakhshiev solvent polarity parameter, Kawskii–Chamma–Viallet solvent polarity parameter and Richardt׳s microscopic solvent polarity parameter. Due to the considerable π-electron density redistribution, the excited state dipole moment was found to be larger than that of the ground state. The ground state dipole moment value was determined by quantum chemical method which was used to estimate excited state dipole moment through solvatochromic correlations. Kamlet–Taft and Catalan methods were used to get the information of both non-specific solute–solvent interactions and hydrogen bonding interactions. TD-DFT (B3LYP/6-311G(d,p)) has been used for the determination of HOMO–LUMO energies. Mulliken charges and Molecular electrostatic potential were also evaluated from DFT calculations.

Effect of solvents, solvent mixture and silver nanoparticles on photophysical properties of a ketocyanine dye.

The effect of solvents of varying polarity and hydrogen bonding ability, solvent mixture and silver nanoparticles on the photophysical properties of a ketocyanine dye, 2,5-di[(E)-1-(4-diethylaminophenyl) methylidine]-1-cyclopentanone (2,5-DEAPMC), is investigated at room temperature. Solvent effect is analyzed using Lippert-Mataga bulk polarity function, Reichardt's microscopic solvent polarity parameter, and Kamlet's and Catalan's multiple linear regression approaches. The spectral properties better follow Reichardt's microscopic solvent polarity parameter than the Lippert-Mataga bulk polarity function. This indicates that both general and specific solute-solvent interactions are operative. Kamlet's and Catalan's multiple linear regression approaches indicate that polarizability/dipolarity solvent influences are greater than hydrogen bond donor and hydrogen bond acceptor solvent influences. The solvatochromic correlations are used to estimate excited state dipole moment using the experimentally determined ground state dipole moment. The excited state dipole moment of the dye is found to be larger than its corresponding ground state dipole moment and ground and excited state dipole moments are not parallel, but subtend an angle of 77°. The absorption and emission spectra are modulated in the presence silver nanoparticles. The fluorescence of 2,5-DEAPMC is quenched by silver nanoparticles. The possible fluorescence quenching mechanisms are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Response to "comment on 'structural determinants of drug partitioning in surrogates of phosphatidylcholine bilayer strata'".

We used the solvatochromic correlation to explain the influence of characteristics of studied compounds on the partition coefficients (P) measured using n-hexadecane (C16) and the novel headgroup surrogate (diacetyl phosphatidylcholine, DAcPC), and compared them with those in other systems, including the C16/water (W) system. The comment analyzes why our correlation for the C16/W system has the standard deviation (SD) higher than that published previously. The main reason is that in our, much smaller, data set the measured P values are complemented by the P values predicted by a reliable, unrelated method. We believe that this approach is acceptable for the aforementioned comparison. We did not use just experimental values, as suggested in the comment, because the solvatochromic correlation, although exhibiting 35% reduction in the SD, was accompanied by a sign change of one of the regression coefficients. The recommended use of special solvatochromic solute characteristics for a few compounds and replacement of a predicted PC16/W value by the experimental value resulted in improved correlations. The observed differences between our correlation and those published in the comment and in a previous article do not affect our main conclusions regarding the solvation of solutes in the surrogates (DAcPC and C16) of intrabilayer strata.

Fluorescence characteristics of aryl boronic acid derivate (PBA)

The absorption and fluorescence spectra of newly synthesized aryl boronic acid derivative namely Phenyl boronic acid (PBA) have been recorded in various solvents of different polarities. The ground state dipole moment of PBA was obtained from quantum chemical calculations. Solvatochromic correlations were used to estimate the ground state (μg) and excited state (μe) dipole moments. The excited state dipole moments are observed to be greater than the ground state dipole moments. Further, the ground and excited state dipole moments are not parallel but subtend by an angle of 70°. The changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and microscopic solvent polarity parameter (ETN), and the values are compared. Solvent effects on the absorption and fluorescence spectra were quantified using Reichardt’s and bulk solvent polarity parameters were complemented by the results of the Kamlet–Taft treatment.

Photophysical characteristics of biologically active 4-aryloxymethyl coumarins 4PTMBC and 1IPMBC

The absorption and fluorescence characteristics of biologically active coumarin derivatives 4-p-tolyloxymethyl-benzo[h]coumarin (4PTMBC) and 1-(4-iodo phenoxymethyl)-benzo[f]coumarin (1IPMBC) are studied at room temperature in a series of organic solvents and 1,4-dioxane – acetonitrile solvent mixture. The effect of pure solvents on the spectral properties are analyzed using Lippert–Mataga polarity function, Reichardt’s microscopic solvent polarity parameter, Kamlet’s and Catalan’s multiple linear regression approaches. Both general solute – solvent interactions and hydrogen bonding interactions are operative in these systems. However, the contribution of hydrogen bonding interactions is less compared to general solute–solvent interactions. The solvatochromic correlations are used to estimate excited state dipole moment using experimentally determined ground state dipole moment. The bathochromic shift of the emission spectra and the increase in excited state dipole moment indicate the intramolecular charge transfer (ICT) character in the emitting singlet state. The solvation studies in 1,4-dioxane – acetonitrile solvent mixture suggest that these dyes are preferentially solvated by 1,4-dioxane.

"Estimation of ground and excited state dipole moments of aryl boronic acid derivative by solvatochromic shift method".

In the present work, the absorption and fluorescence spectra of newly synthesized aryl boronic acid derivative namely 2-Methylphenyl boronic acid (2MPBA) have been recorded in various solvents of different polarities. The ground state dipole moment of 2MPBA was obtained from quantum chemical calculations. Solvatochromic correlations were used to estimate the ground state (μ g ) and excited state (μ e ) dipole moments. The excited state dipole moments are observed to be greater than the ground state dipole moment and ground and excited state dipole moments are not parallel but subtend by an angle of 88(0). Further, the changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and microscopic solvent polarity parameter (E T (N) ), and the value are compared. The spectral variations were analyzed by Kamlet-Taft parameters.

Solvents effect on the absorption and fluorescence spectra of 7-diethylamino-3-thenoylcoumarin: Evaluation and correlation between solvatochromism and solvent polarity parameters

Effect of solvents of varying polarities on absorption and fluorescence spectra and dipole moment of laser dye: 7-diethylamino-3-thenoylcoumarin (DETC) has been investigated. A small band shift is obtained in the absorption spectra compared to emission spectra. The spectral shifts were correlated with Catalan’s parameters using linear solvation energy relationship. It reveals that non-specific interaction measured by solvent polarity has more influence on absorption and solvent dipolarity contribution is significant in case of fluorescence. A bathochromic shift observed in absorption and emission spectra with increasing solvent polarity, which implied that the transition involved is π→π∗. The solvatochromic correlations were used to estimate the excited state dipole moment using experimentally determined ground state dipole moment. The observed single-state excited state dipole moment is found to be greater than the ground state.

Synthesis and optical properties of coumarins and iminocoumarins: Estimation of ground- and excited-state dipole moments from a solvatochromic shift and theoretical methods

The optical properties of coumarin and iminocoumarin were investigated in different solvents by UV/vis absorption and fluorescence spectroscopy at room temperature (298K). These compounds were characterized by UV–vis, FT-IR, mass spectroscopy and NMR. A bathochromic shift is observed in absorption and fluorescence spectra of our molecules with increasing solvent polarity. Solvatochromic correlations were used to obtain the ground-state and excited-state dipole moments. The excited-state dipole moments for all the molecules were found to be larger than the corresponding ground-state dipole moments.

Determination of ground and excited state dipole moments of dipolar laser dyes by solvatochromic shift method

The absorption and fluorescence spectra of three medium sized dipolar laser dyes: coumarin 478 (C478), coumarin 519 (C519) and coumarin 523 (C523) have been recorded and studied comprehensively in various solvents at room temperature. The absorption and fluorescence spectra of C478, C519 and C523 show a bathochromic and hypsochromic shifts with increasing solvent polarity indicate that the transitions involved are π→π∗ and n→π∗. Onsager radii determined from ab initio calculations were used in the determination of dipole moments. The ground and excited state dipole moments were evaluated by using solvatochromic correlations. It is observed that the dipole moment values of excited states (μe) are higher than corresponding ground state values (μg) for the solvents studied. The ground and excited state dipole moments of these probes computed from ab initio calculations and those determined experimentally are compared and the results are discussed.

Structural determinants of drug partitioning in surrogates of phosphatidylcholine bilayer strata.

The knowledge of drug concentrations in bilayer headgroups, core, and at the interface between them is a prerequisite for quantitative modeling of drug interactions with many membrane-bound transporters, metabolizing enzymes and receptors, which have the binding sites located in the bilayer. This knowledge also helps understand the rates of trans-bilayer transport because balanced interactions of drugs with the bilayer strata lead to high rates, while excessive affinities for any stratum cause a slowdown. Experimental determination of bilayer location is so tedious and costly that the data are only available for some fifty compounds. To extrapolate these valuable results to more compounds at a higher throughput, surrogate phases have been used to obtain correlates of the drug affinities for individual strata. We introduced a novel system, consisting of a diacetyl phosphatidylcholine (DAcPC) solution with the water content of the fluid bilayer as the headgroup surrogate and n-hexadecane (C16) representing the core. The C16/DAcPC partition coefficients were measured for 113 selected compounds, containing structural fragments that are frequently occurring in approved drugs. The data were deconvoluted into the ClogP-based fragment solvation characteristics and processed using a solvatochromic correlation. Increased H-bond donor ability and excess molar refractivity of compounds promote solvation in the DAcPC phase as compared to bulk water, contrary to H-bond acceptor ability, dipolarity/polarizability, and volume. The results show that aromates have more balanced distribution in bilayer strata, and thus faster trans-bilayer transport, than similar alkanes. This observation is in accordance with the frequent occurrence of aromatic rings in approved drugs and with the role of rigidity of drug molecules in promoting intestinal absorption. Bilayer locations, predicted using the C16/DAcPC system, are in excellent agreement with available experimental data, in contrast to other surrogate systems.

Estimation of ground- and excited-state dipole moments of 3-acetoacetyl-coumarin derivatives from a solvatochromic shift method based on the solvent polarity parameter

The optical properties of 1 (3-acetoacetylcoumarin), 2 (3-acetoacetylbenzo[f]coumarin) and 3 (3-acetoacetylbenzo[h]coumarin) were investigated by UV/vis absorption and fluorescence spectroscopy in solvents of different polarities at room temperature (298K). Solvatochromic correlations were used to estimate the ground-state (μg) and excited-state (μe) dipole moments. The excited-state dipole moments for the three molecules were found to be larger than the corresponding ground-state dipole moments.

Solvatochromic shift studies in LD-425 and LD-423: Estimation of ground and excited state dipole moments

The absorption and fluorescence characteristics of 4-methyl-7-(4-morpholinyl)-2H Pyrano [2,3-b] Pyridin-2-one (LD-425) and 1,2,3,8-tetrahydro-1,2,3,3,5-pentamethyl-7H-pyrrolo[3,2-g]quinolin-7-one (LD423) are studied at room temperature in a series of organic solvents and 1,4-dioxane–acetonitrile solvent mixtures. The effects of pure solvents upon the spectral properties are analyzed using Lippert–Mataga polarity function, Richardts microscopic solvent polarity parameter and Kamlet's multiple linear regression approach. Both general solute–solvent interactions and hydrogen bonding interactions are operative in these systems. The solvatochromic correlations are used to estimate excited state dipole moment using experimentally determined ground state dipole moment. The bathochromic shift of the emission spectra and the increase in excited state dipole moment indicates the intramolecular charge transfer (ICT) character in the emitting singlet state. The solvation studies in 1,4-dioxane–acetonitrile solvent mixtures indicates that these dyes are preferentially solvated by 1,4-dioxane.

Effect of solvents on the spectroscopic properties of LD-489 & LD-473: Estimation of ground and excited state dipole moments by solvatochromic shift method

The absorption and fluorescence spectra of 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoro methyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) have been recorded at room temperature in different solvents and 1,4-dioxane–acetonitrile solvent mixtures. The UV–Visible absorption spectra are less sensitive to solvent polarity than the corresponding fluorescence spectra in both the dyes which show pronounced solvatochromic effect. The effects of solvents upon the spectral properties are analyzed using Lippert–Mataga polarity function, Richardts microscopic solvent polarity parameter and Catalán’s multiple linear regression approach. Both general solute–solvent interactions and specific interactions are operative in these systems. The solvatochromic correlations are used to estimate excited state dipole moments using experimentally determined ground state dipole moments. The excited state dipole moment for both the dyes are found to be larger than their corresponding ground state dipole moment and is interpreted based on their resonance structures.

Solvent effect on the spectral properties of dipolar laser dyes: Evaluation of ground and excited state dipole moments

The effect of solvents on absorption and fluorescence spectra and dipole moments of two medium sized dipolar laser dyes 2-(2,7-dichloro-6-hydroxy-3-oxo-3 H -xanthen-9-yl) benzoic acid (Fluorescein 27) (F27) and N -[6-diethylamino)-9-(2,4-disulfophenyl)-3 H -xanthen-3-ylidene]- N -ethylhydroxid (Sulfarhodamine B) (SRB) have been studied comprehensively in polar protic and polar aprotic solvents at room temperature (298 K). The bathochromic shift observed in absorption and fluorescence spectra of F27 and SRB with increasing solvent polarity signifies that the transition involved are π→π*. Solvatochromic correlations were used to obtain the ground and excited state dipole moments. The observed excited state dipole moments are found to be larger than their ground state counterparts in all the solvents studied. The ground and excited state dipole moments of these probes have also been computed from ab initio calculations and compared with those determined experimentally. Further, the experimentally obtained changes in dipole moment (Δ μ ) were compared with those using normalized polarity terms from Reichardt equation.

Fluorescence Properties and Dipole Moments of Novel Fused Thienobenzofurans. Solvent and Structural Effects

The electronic absorption, fluorescence excitation and emission spectra, and fluorescence quantum yields of novel fused thienobenzofurans, including thieno[3,2-b][1]benzofuran (1), [1]benzothieno[3,2-b]furan (2), and [1]benzothieno[3,2-b][1]benzofuran (3), were recorded in fourteen solvents of different polarities at room temperature. Compound 2 was not fluorescent. Experimental ground-state dipole moments of compounds 1-3 were measured in benzene at 298 K and compared with the corresponding theoretical dipole moment values. The solvent effects on the electronic absorption and fluorescence spectra of these thienobenzofurans were quantitatively investigated by means of solvatochromic correlations based on the Kawski-Chamma-Viallet and McRae equations. A weak negative solvatochromic behavior was found for these compounds, showing that their dipole moments are slightly lower in the excited singlet-state than in the ground-state. Kamlet-Abboud-Taft multiparameter relationships were also established for electronic absorption and fluorescence wavenumbers, and fluorescence quantum yields in most solvents, demonstrating the occurrence of specific solute-solvent interactions.

Estimation of ground- and excited-state dipole moments of oxazine 1 in liquid and liquid crystalline media

The absorption and fluorescence spectra of a laser dye, oxazine-1 (OX1), in liquid and liquid crystalline media were studied at room temperature. The solvatochromic method was used to determine the ground- and excited-state dipole moments by means of Lippert–Mataga, Bakshiev, Kawski–Chamma–Viallet polarity functions. The solvent polarity has no large and regular effect on the spectral behavior of OX1, and thus it might be considered as a poor solvatochromic indicator dye. In addition, applicability of solvatochromic method for this dye in anisotropic media was investigated. On the other hand, nature and degree of the solute–solvent interactions were characterized using correlation of multi-parameter solvent polarity scales. Due to the theoretical restrictions and the dye molecular structure, deviations from the solvatochromic correlation were observed.

Estimation of dipole moments of some biologically active coumarins by solvatochromic shift method based on solvent polarity parameter, [formula omitted

The electronic absorption and fluorescence spectra of three newly synthesized coumarin derivatives viz., 4-(5-methyl-3-furan-2-yl-benzofuran-2-yl)-7-methyl-chromen-2-one (MFBMC), 4-(5-chloro-3-furan-2-yl-benzofuran-2-yl)-6-methyl-chromen-2-one (ClFBMC) and 4-(5-methyl-3-phenyl-benzofuran-2-yl)-6-chloro-chromen-2-one (MPBClC) have been recorded at room temperature (296 K) in solvents of different polarities. The effects of the solvents upon the spectral properties are discussed. Solvatochromic correlations were used to estimate the ground-state ( μ g) and excited-state ( μ e) dipole moments. The excited-state dipole moments for all the three molecules are found to be larger than their corresponding ground-state dipole moments. Further, the changes in dipole moment (Δ μ) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter ( E T N ) , and the values are compared.

Amino‐acid‐functionalized solvatochromic probes

AbstractN‐(4‐nitrophenyl)‐L‐proline (2) has been obtained by a nucleophilic aromatic substitution reaction of 4‐fluoronitrobenzene with L‐proline. The corresponding amide derivatives 3–5 have been synthesized by peptide coupling of 2 with different amino acid derivatives and chiral amines. Solvatochromism of the long‐wavelength UV/Vis band in the electronic absorption spectra of the compounds 2–5 has been studied and analyzed using the empirical Kamlet–Taft solvent polarity parameters π* (dipolarity/polarizability), α (hydrogen bond donating ability), and β (hydrogen bond accepting ability). Reasonable Kamlet–Taft solvatochromic correlations (r > 0.95) were established for the three amide derivatives 3–5 in a range of common solvents and three room temperature ionic liquids (RTILs). The UV/Vis absorption of the 4‐nitroaniline derivative 2 showed a hypsochromic shift with increasing concentration due to intermolecular hydrogen bonded aggregate formation in protic solvents, which is not observed for compounds 3–5. Copyright © 2008 John Wiley & Sons, Ltd.

Linear Solvation Energy Correlation of the Solvatochromic Response of Amino Acid Functionalized Chromophores

Solvatochromism of the long wavelength band in the electronic absorption spectra of N-(4-nitrophenyl)-L-proline, NLP, N-(4-nitrophenyl)-D-proline, NDP, and N-(4-nitro-phenyl)-trans-4-hydroxy-L-proline, NHP, was studied and quantitatively described with Kamlet-Taft solvent polarity parameters. To evaluate the environmental effects for NLP, NDP, and NHP, the UV-vis spectroscopic behavior of these compounds was also investigated as pure crystals, as a guest in 2,6-O-dimethyl-beta-cyclodextrin, and also when adsorbed on Aerosil 300 silica particles from nonhydrogen-bond accepting solvents. Excellent Kamlet-Taft solvatochromic correlations were established for the three compounds in most solvents. Multiparameter correlations show the existence of specific solute-solvent interactions. A strong positive solvatochromic behavior was found for these compounds, indicating that their dipole moments were higher in the excited singlet state than in the ground state.

Solvent effect on absorption and fluorescence spectra of coumarin laser dyes: Evaluation of ground and excited state dipole moments

The effect of solvents on absorption and fluorescence spectra and dipole moments of coumarin 307 (C307) and coumarin 522B (C522B) have been studied extensively in various solvents, viz., general solvents, alcohols and binary mixtures (acetonitrile–benzene) at 298 K. The bathchromic shift observed in absorption and fluorescence spectra of C307 and C522B with increasing solvent polarity indicates that transition involved are π → π * . Solvatochromic correlations were used to obtain the ground and excited state dipole moments. The excited state dipole moments are observed to be greater than their ground state counterparts in all the solvents studied. Further, the experimentally obtained Δ μ were compared with those using normalized polarity terms E T N from Reichardt equation.