Ground State Dipole Moments Research Articles

Fluorescence properties of aromatic asymmetric di-ketone compound in polar and non-polar solvents

Using the quantum chemical and solvatochromic shift technique aromatic unsymmetric di-ketone compound1-(4’-dodecyl-[1,1’-biphenyl]-4-yl)-3-(3,4,5-trimethoxyphenyl)propane-1,3-dione (DK1) fluorescence properties were estimated. The excitation and emission band of recently synthesized DK1 have been examined in various dissolvable. The dipole moments evaluated utilizing Gaussian software and Solvatochromic correlations. Evaluated (μg ) value by Gaussian method is comparatively larger than the solvatochromic shift methods. It is seen that the energized state dipole moments (μe ) are more prominent than the ground state dipole moment (μg ) which authorizes π → π* transition. The (Δμ) were also estimated both from solvatochromic shift method and microscopic solvent polarity parameter (ET N ) and results are compared. The kinetic stability and chemical reactivity of the selected molecules have been studied with the help of quantum chemical properties of the molecule and Frontier molecular orbital analysis using DFT.

Novel far UV–Vis absorbing bis(dihydrophenanthro[9,10-e][1,2,4]triazine) derivative dyes: Synthesis, optical, photophysical and solvatochromic properties

In this paper discussed novel fluorescent derivative dye in far UV–Vis range have been synthesized by bis-alkylation of starting compound 4, 12a-dihydrophenanthro [9, 10-e][1, 2,4]triazine-3(4H)-thione, with the appropriate dibromo compounds. and characterized by standard spectroscopic techniques. Their chemical structures were confirmed by 1HNMR, IR, MS and elemental analysis. Various optical characterizations were carried out in solvents of varying polarity. Optical parameters via extinction coefficient, absorption and emission cross-sections, fluorescence quantum yield, fluorescence lifetime, oscillator strength, the dipole moment, radiative decay rate constant, energy yield of fluorescence and the attenuation length has been determined. The effect of the spacer between two phenanthro[9,10-e][1,2,4]triazine units in new dye and solvent polarities upon the spectral properties are discussed. The ground-state (μg) and excited-state (μe) dipole moments were estimated using solvatochromic correlations. The higher value of Δμ may attribute to the singlet higher excited state of dyes which had strong intramolecular charge transfer character (ICT).

Effects of solvent polarity on the absorption and fluorescence spectra of 3-cyano-7-hydroxy-4-methylcoumarin

The Absorption and fluorescence emission spectra of 3-cyano-7-hydroxy-4-methylcoumarin (3C7H4M) were studied in solvents of different dielectric constant ε and refractive index n. Experimental ground and excited state dipole moments were established by means of solvatochromic shift method. Both the ground state and excited state dipole moments were established. Results revealed that the excited state dipole moments of 3C7H4M were higher than those of the ground state. Further it is evident from these results that, the changes in the dipole moments on electronic excitation are small.

Evaluation of Ground and Excited State Dipole Moments of 2(3)-tetra(tert-butylphenoxy)phthalocyaninato Zinc(II) from Solvatochromic Data

This article presents a semi-empirical determination of ground state dipole moment (mg) and excited state dipole moment (me) of 2(3)-tetra(tert-butylphenoxy)phthalocyaninato zinc(II) (ZnTBPc) using the solvatochromic shift method, which is based on the Onsager’s reaction field theory. A combined application of the Bakshiev’s equation and the Kawski-Chamma-Viallet’s equation was used to determine the ratio me/mg while the use of the molecular-microscopic solvent polarity parameter yielded the term Dm (me- mg). The dipole moment of ZnTBPc in its excited singlet state (me=4.46D) is more than twice as much as that in its ground state (mg=2.14D).These values suggest that the higher charge separation is greater in the excited state of ZnTBPc than in its ground state.

Electronic Structure, Optical Properties and Quantum Chemical Investigation on Synthesized Coumarin Derivative in Liquid Media for Optoelectronic Devices.

The newly synthesized 3,3'-((3-bromo-4-methoxyphenyl)methylene)bis(4-hydroxy-2H-chromen-2-one) (3-BMH) derivative have been investigated in a selected number of organic solvents having different polarity and refractive index at room temperature. From the absorption and emission spectra of the synthesized derivative in studied solvents showed bathochromic shift in both the cases (Uv-vis and emission spectra), the ground state dipole moment (μg) and excited state dipole moment (μe) were obtained by implementing [Chamma-Kwaski-Villate, Bakhshiev, Lippert-Mataga, McRay and Suppan] solvatochromic shift techniques depending on solvent polarity parameters. The larger dipole moment value is observed in the excited state as compared to the ground state dipole moment and this discrepancy in the dipole moment value is due to polar nature of the molecule. From the results of both experimental and theoretical energy gap is found to 3.14eV in average, from this, it can be concluded that the 3-BMH molecule showed a good agreement with the semiconducting material bandgap so that the 3-BMH molecule can be used as a potential material for the optoelectronic application. Also, from results of quantum chemical studies, the electrostatic potential maps studies reveal the molecule is how much stable it describes the defining reactivity of the molecule towards positively and negatively charged reactants, size, shape, the location of nucleophilic and electrophilic sites. Further, the optoelectronic properties were investigated the CIE, CRI, color purity and CCT results of the 3-BMH in all studied solvents revels that this compound exhibits blue emission (National television standard committee system (NTSC) for the ideal blue chromacity coordinate 0.14, 0.08) and from the CIE results show the color emission of the molecule in order to design the desired OLED device application.

An Insight into Photophysical Investigation of (E)-2-Fluoro-N'-(1-(4-Nitrophenyl)Ethylidene)Benzohydrazide through Solvatochromism Approaches and Computational Studies.

A fluoro-based Schiff base (E)-2-fluoro-N'-(1-(4-nitrophenyl)ethylidene)benzohydrazide (FNEB) has been synthesized from condensation of 2-fluorobenzohydrazide and 4'-nitroacetophenone catalyzed by glacial acetic acid with ethanol as the solvent. The dipole moment of FNEB in both the electronic states were found using different solvatochromic approaches such as Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, Reichardt and Bilot-Kawski. The experimental ground state dipole moment of FNEB was calculated using Guggenheim-Debye method and theoretical ground state dipole moment using Bilot-Kawski solvatochromic approach. The solvatochromic behavior of the Schiff base in different solvents was studied using absorption and emission spectra. Catalan and Kamlet-Abboud-Taft parameters were used from the multiple linear regression (MLR) analysis in order to study the solute-solvent interaction. The dipole moments were also calculated using Time Dependent-Density Functional Theory (TD-DFT). The chemical stability of FNEB was determined using computational and Cyclic Voltammetry by the use of obtained energy gap between the frontier orbitals. Using the frontier orbitals energy gap, global reactivity parameters were computed. Further, Light Harvesting efficiency was determined to comprehend the photovoltaic property of the Schiff base.

A neural network protocol for electronic excitations of N-methylacetamide

UV absorption is widely used for characterizing proteins structures. The mapping of UV spectra to atomic structure of proteins relies on expensive theoretical simulations, circumventing the heavy computational cost which involves repeated quantum-mechanical simulations of excited-state properties of many fluctuating protein geometries, which has been a long-time challenge. Here we show that a neural network machine-learning technique can predict electronic absorption spectra of N-methylacetamide (NMA), which is a widely used model system for the peptide bond. Using ground-state geometric parameters and charge information as descriptors, we employed a neural network to predict transition energies, ground-state, and transition dipole moments of many molecular-dynamics conformations at different temperatures, in agreement with time-dependent density-functional theory calculations. The neural network simulations are nearly 3,000× faster than comparable quantum calculations. Machine learning should provide a cost-effective tool for simulating optical properties of proteins.

The Dipole Moments and Solvatochromism of ((4-(Benzyloxy)benzylidene)amino)phenol Compounds as Solvatochromic Materials

Three novel ((4-(benzyloxy)benzylidene)amino)phenol compounds are synthesized and characterized. The electronic structures of the molecules have been investigated by using both experimental and theoretical methods. Kamlet–Taft and Catalan models are used to determinate the contribution of each solute–solvent interaction type. Schiff bases can be used as solvatochromic materials. Experimental ground and excited state electric dipole moments have been determined by using the Bilot–Kawski, Lippert–Mataga, Bakshiev and Kawski–Chamma–Viallet theories. The excited state dipole moment of (E)-2-((4-(benzyloxy)benzylidene)amino)phenol is estimated to be 38.809 times higher than the ground state dipole moment. The electronic absorption spectra, frontier molecular orbitals (HOMO and LUMO), molecular electrostatic potential and solvent accessibility surface of these compounds have been calculated by using the DFT (B3LYP)/6-311++G (d,p) theory and method. In addition, theoretical electronic transitions have been calculated by the B3LYP/6-311++G (d,p) and CAM-B3LYP/6-311++G (d,p) levels of theory. The (E)-2-((4-(benzyloxy)benzylidene)amino)phenol molecule is found to have the greatest semiconductor character.

Investigation of interactional behavior and relative photo-physical properties in a group of bioactive compounds

In recent years, numerous researchers have faced the challenge of synthesizing bioactive compounds. Hence, chalcones with bioactive anti–cancer characteristics have attracted interests in many pharmaceutical studies. In this work, we focused on photo–physical behavior of three chalcones, with similar structures, in various solvent media, in order to study and compare their similarities and differences. Theoretical techniques were used to validate the experimental results. The experimental and theoretical results help to expand and better the realization of the photo–physical characteristics of these compounds and reveal essential information about the activity of this group of compounds in biological systems. The results show that photo–physical behavior of the chalcones is related to the solvent–solute interactions. Linear solvation energy relationship (LSER) model of Kamlet–Abboud–Taft and Catalán were used to analyze the interactions of chalcones in various media. The ground and excited state dipole moments of these bioactive compounds were obtained using Lippert’s, Bakshiev’s and Ghamma–Viallet’s solvatochromic shift methods and their molecular resonance forms were presented. Finally, these results were compared and discussed by time–dependent density functional theory and configuration interaction calculations.

Estimation of ground and excited state dipole moments of newly synthesized coumarin molecule by Solvatochromic shift method and Gaussian software

Estimation of ground and excited state dipole moments of newly synthesized coumarin molecule by Solvatochromic shift method and Gaussian software

Solvent dependent spectroscopic properties of fingerprint reagent - 1,8-Diazafluoren-9-one

The photophysical and photochemical properties of fingerprint reagent - 1,8-diazafluoren-9-one (DFO) - were studied using steady-state, time-resolved spectroscopic techniques and semiempirical quantum-chemical calculations. In order to understand how microenvironment influences the excited-state properties of DFO, fluorescence quantum yields, lifetimes and rate constants were determined. Spectroscopic studies and theoretical calculations indicate that the energy-level disposition of close-lying nπ* and ππ* states of DFO is significantly modified by solvent polarity. The multiple linear regression analyses proposed by Kamlet-Taft and Catalán reveal that DFO solvation is mainly determined by dipolar solute-solvent interactions, whereas the specific interactions play a less significant role. Finally, the difference in the ground and excited state dipole moments of investigated dye was obtained using solvatochromic shift methods based on the Onsager's description of general solute-solvent interactions.

Synthesis, photophysical, DFT and solvent effect studies on biologically active benzofuran derivative: (5-methyl-benzofuran-3-yl)-acetic acid hydrazide

Abstract The synthesis, photophysical, DFT and solvent effect studies on novel benzofuran derivative namely, (5-methyl-benzofuran-3-yl)-acetic acid hydrazide [5MLBH] are reported. The probe is characterized by 1H NMR, 13C NMR, IR and mass spectral methods. Absorption and fluorescence maxima of 5MLBH are determined for different solvents of varying polarity and solvatochromic behavior and dipole moments are investigated. Results indicate that, excited state dipole moment (μe) values are higher than ground state dipole moment (μg) values and suggest that, probe molecule 5MLBH is more polar in excited state than ground state. Energy band gap is determined from HOMO-LUMO and absorption threshold wavelengths. Using HOMO-LUMO energies, chemical hardness of probe molecule is estimated. From DFT molecular electrostatic potential (MESP) plots, electrophilic site and nucleophilic site were identified. Using Catalan parameters, solute-solvent interactions were analyzed. Preliminary investigations suggest, probe 5MLBH may be considered as potential candidate for luminescence materials, fluorescent probes and for designing non-linear optical materials in future.

Theoretical Predictions for the Magnetic Dipole Moment of ^{229m}Th.

A recent laser spectroscopy experiment [J. Thielking et al., Nature, (London) 556, 321 (2018)] has determined for the first time the magnetic dipole moment of the 7.8eV isomeric state ^{229m}Th. The measured value differs by a factor of approximately 5 from previous nuclear theory predictions based on the Nilsson model, raising questions about our understanding of the underlying nuclear structure. Here, we present a new theoretical prediction based on a nuclear model with coupled collective quadrupole-octupole and single-particle motions. Our calculations yield an isomer magnetic dipole moment of μ_{IS}=-0.35μ_{N} in surprisingly good agreement with the experimentally determined value of -0.37(6)μ_{N}, while overestimating the ground state dipole moment by a factor 1.4. The model provides further information on the role and strength of the Coriolis mixing and the most probable value of the gyromagnetic ratio g_{R} and its consequences for the transition probability B(M1). The key role of the magnetic moment values as constraints in the determination of the isomer decay rates is discussed.

Defined Merocyanine Dye Stacks from a Dimer up to an Octamer by Spacer-Encoded Self-Assembly Approach.

A series of well-defined chromophore stacks is obtained upon self-assembly of merocyanine and bis(merocyanine) dyes in nonpolar solvents. Careful design of the spacer moieties linking the dipolar chromophores within the bis(merocyanine) dyes allows one to direct the dipole-dipole interaction driven aggregation into stacks of desired size from dimer up to octamer. The spacer-encoded self-assembly process was investigated by UV/vis absorption spectroscopy showing an increase of the hypsochromic shift with increasing stack size. The structure of the largest aggregate comprising eight chromophores was analyzed by 1D and 2D nuclear magnetic resonance spectroscopic studies revealing a perfectly interdigitated centrosymmetric organization of the dipolar dyes and concomitant annihilation of the ground state dipole moment is observed in the UV/vis absorption spectra. This unprecedented series of dye stacks from dimer to octamer enabled a systematic study of the optical absorption properties in dependence of the stack size disclosing that the absorption features can be rationalized by molecular exciton theory. Our results show that the noncovalent synthesis approach based on dipolar aggregation is suitable for the design of well-defined dye aggregates of specific size, allowing in-depth studies to manifest structure-property relationships.

Viscosity sensitive semisquaraines based on 1, 1, 2-trimethyl-1H-benzo[e]indole: Photophysical properties, intramolecular charge transfer, solvatochromism, electrochemical and DFT study

1, 1, 2-Trimethyl-1H-benzo[e]indole based D-π-A type semisquaraines denoted as, SSK 1–3 were synthesized to investigate their primary photophysical properties, intramolecular charge transfer, solvatochromism, electrochemical properties and viscosity dependent enhanced emission. These semisquaraines contain 1, 1, 2-trimethyl-1H-benzo[e]indole and squaryl ring as donor and acceptor respectively. These dyes displayed absorption between 437 and 444 nm and emission in the range of 469–493 nm. Stokes shift of the synthesized compounds were in the range of 32–54 nm. The SSK 1–3 exhibited intense yellow-orange colored solid state fluorescence (Fmax = 520–549 nm). These dyes exhibited intramolecular charge transfer characteristics which were confirmed from their oscillator strengths, transition dipole moments, ground and excited state dipole moments and generalized Mulliken-Hash analysis (GMH). Moreover, the positive emission solvatochromic behaviour (Δλem = 21–24 nm) of these dyes was quantitatively analyzed from different solvent polarity plots. More interestingly, these D-π-A type FMRs displayed viscosity sensitive emission enhancement (23 to 32 fold increase in fluorescence intensity) in 99% methanol:glycerol system at the visible region of electromagnetic spectrum (450–650 nm). The molecular structures of SSK 1–3 were correlated with photophysical properties using density functional theory (DFT) and theoretical absorption spectra in eight different solvents were obtained from time dependent density functional theory (TD-DFT).

Experimental and theoretical insights on the effect of solvent polarity on the photophysical properties of a benzanthrone dye.

Benzanthrone derivatives show interesting solvent dependent photophysical properties. Understanding of their photophysical properties is essential for developing the fluorescence probes based on benzanthrone derivatives. The photophysical properties of 3-(N'-chlorophenyl)piperazino-7H-benzo[de]anthracen-7-one [ClPh-PBA] molecule are reported in different solvents and solvent mixtures. The change in Stokes shift, quantum yield, fluorescence life time and radiative rate constants as a function of solvent polarity shows that the Intermolecular Charge Transfer (ICT) is affected by solvent polarity and hydrogen bonding. The quantum yield and fluorescence life time values decrease and the nonradiative decay rate constant (knr) values are observed to be higher in polar solvents. The weak emission of ClPh-PBA in polar solvents is primarily due to the non-radiative torsional motion of the chlorophenyl group around benzanthrone moiety. The torsional motion of chlorophenyl group at the remote nitrogen around benzanthrone moiety is also evident from TDDFT calculations performed using B3LYP/6-311+ G (d, p) basis set. The ground state and excited state dipole moments, absorption and emission maxima (nm) along with other quantum chemical parameters are obtained using B3LYP/6-311+ G (d, p) basis set. The experimental and theoretical results follow the similar trends.

Synthesis and optical properties of novel thermally stable bis-merocyanine dyes

A new series of thermally stable linked bis-merocyanine dyes were synthesized from thiazolium salt derivatives and bis-rhodanines in good yields. The synthesized compounds were fully characterized by FT-IR, UV/Vis, NMR and mass spectrometry and their thermal properties were determined by TGA and DSC. The shape of the absorption spectra of bis-merocyanine dyes is affected both by the nature of the spacer and the polarity of the solvent. Absorption and fluorescence spectra of compound B1T6 were measured at room temperature (298 K), in various solvents to investigate their solvatochromic behaviour. The ground and excited state dipole moments of B1T6 compound were estimated experimentally by solvatochromic shift method using Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet and Reidchardt's microscopic solvent polarity functions. It was observed that the excited-state dipole moment was found to be higher than the corresponding ground-state dipole moments, due to a substantial redistribution of electron densities and charges in a more polar excited-state. The geometry of this compound was optimized; HOMO-LUMO energy values and the ground state dipole moment μg were also evaluated theoretically by quantum chemical calculations using the DFT method by adopting B3LYP/G-31 G (d, p) of theory (Gaussian 09).

Ab initio calculations of permanent dipole moments and dipole polarizabilities of alkaline-earth monofluorides

The ground-state permanent dipole moments (PDMs) and molecular dipole polarizabilities (DPs) of open-shell alkaline-earth monofluorides, and atomic DPs of alkaline-earth- and fluorine atoms are reported at the Kramers-restricted configuration interaction level of theory limited to single and double excitations (KRCISD), using the finite-field approach. Sufficiently large basis sets such as quadrupole-zeta (QZ) and augmented-QZ basis sets together with the generalized active space technique is employed to carry out the field-dependent energy calculations at the KRCISD level. The PDMs and the components of DPs are extracted from the linear- and quadratic fit of energies against perturbative electric field, respectively. Accuracy of the present calculations for the electronic properties is examined by comparison with the measurements and calculations where ever available.

Synthesis, characterization and photophysical studies on novel benzofuran-3-acetic acid hydrazide derivatives by solvatochromic and computational methods

In the present studies, synthesis of two novel benzofuran-3-acetic acid hydrazide derivatives namely, (6-methyl-benzofuran-3-yl)-acetic acid hydrazide [6MLBH] and (6-methoxy-benzofuran-3-yl)-acetic acid hydrazide [6MOBH] are reported. The probes are characterized by IR, 1H-NMR, 13C-NMR and mass spectral methods. The absorption and fluorescence maxima of novel derivatives 6MLBH and 6MOBH are determined for different solvents of varying polarity and the solvatochromic behavior and dipole moments are investigated. Stoke's shift exhibits a red shift with increase in solvent polarity for both the probe molecules indicating a π→π* transition. The ground state dipole moment (μg) of both the molecules in gaseous phase is estimated from ab initio computations by using Gaussian 09 W software and also from solvatochromic method and the results are compared. Further, the ground state dipole moments of the probe molecules in different solvents were also estimated theoretically by using the integral equation formalism of polarizable continuum model (IEF-PCM). By using solvatochromic correlations like Lippert's, Bakhshiev's, Kawski-Chamma-Viallet's and solvent polarity parameter (ETN), the excited state dipole moments (μe) are determined. Results show that, the excited state dipole moments (μe) are higher than the ground state dipole moments (μg) and suggest that, the probe molecules 6MLBH and 6MOBH are more polar in the excited state. The HOMO-LUMO energy gaps computed from density functional theory (DFT) and from absorption threshold wavelengths are found to be in agreement and also support intramolecular charge transfer (ICT). Using HOMO-LUMO energies, the chemical hardness (η) of the molecules are determined and the chemical stability is discussed. Further, using DFT molecular electrostatic potential (MESP) plots, the electrophilic site and nucleophilic site which are useful in photochemical reactions were identified. The various types of interactions present between the solute-solvent were analyzed by multiple linear regression analysis using Catalan parameters. The preliminary observations and results suggest that, the probe molecules 6MLBH and 6MOBH can be considered as potential candidates for luminescence materials, fluorescent probes and for designing non-linear optical materials in future.

Synthesis, characterization of binary and ternary copper(II)-semicarbazone complexes: Solvatochromic shift, dipole moments and TD-DFT calculations

A novel semicarbazone O2N donor ligand, HL, was synthesized by condensation of 2-aminochromone-3-carboxaldehyde with semicarbazide hydrochloride. The HL ligand is allowed to react with several copper(II) salts namely: AcO–, NO3–, SO42– and Cl–, in absence and presence of secondary ligand (SCN-, 8-HQ and 1,10-phen), forming binary and ternary copper complexes. Characterization of the compounds has been done using various techniques like elemental analyses, magnetic moments, conductance measurement, thermogravimetry and FT-IR, UV-Vis, 1H and 13C NMR, EPR and mass spectroscopy. The HL ligand acts as monoanionic O2N tridentate in most complexes, forming Cu(II) complexes with an octahedral and square planar geometrical arrangements. The compounds exhibit luminescence property; promising interesting potential applications as photoactive materials. The ground state (µg) and excited state (µe) dipole moments are estimated from solvatochromic shifts of absorption and fluorescence spectra as a function of the dielectric constant (Ɛ) and refractive index (n) by using Bilot–Kawski, Lippert–Mataga, Bakhshiev, Kawski–Chamma–Viallet and Reichardt correlation methods. Excited state dipole moment is observed as larger than the ground state dipole moment. The molecular structural parameters of the ligand and its Cu(II)- complexes have been calculated on the basis of DFT level implemented in the Gaussian 09 program at the B3LYP/6-31G(d,p) level and the theoretical data are correlated with the experimental data. The antibacterial properties of the ligand and its complexes have been screened against selected kinds of bacteria and fungi.