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The spectroscopic data for a range of cyclopenta-[d][1,2,3]-triazine derivative dyes have been evaluated using various standard computational approaches. Absorption data of these dyes were obtained using the ZINDO/S semi-empirical model for vertical excitation energies of structures optimised with the AM1, PM3, and PM6 methods. These studies were conducted under vacuum and solution states using the polarisation continuum model (PCM) for implicit solvation in the linear response model. The accuracy, along with the modest computational costs of using the ZINDO/S prediction, combined with the PM3 optimisation method for absorption data was reliable. While a higher computational cost is required for the time-dependent density functional theory (TDDFT), this method offers a reliable method for calculating both the absorption and emission data for the dyes studied (using vertical and adiabatic excitation energies, respectively) via state-specific solvation. This research demonstrates the potential of computational approaches utilising solvation in evaluating the spectroscopic properties of dyes in the rational design of fluorescent probes.

The structural parameters and average molecular structures of the asphaltenes obtained from the Aguacate oilfield, located in the Golden Lane of Mexico, have been investigated combining experimenta...

In the present work, a theoretical study was carried out to study the molecular structure, harmonic vibrational frequencies, normal force field calculations, and Raman scattering activities for fluorene π-conjugation spacer containing azo-based dye named trans- and cis-bis(9H-fluoren-2-yl)diazene (AzoFL) at density functional theory using B3LYP (Becke-3-Lee-Yang-Parr) functional and 6-31+G(d,p) basis set. The theoretical calculations have also been performed with fluorene and the trans- and cis-isomers of diazene, difluorodiazene by the same method DFT-B3LYP/6-31+G(d,p) and basis set. The present DFT calculation shows that the trans-AzoFL is more stable than the cis-AzoFL by 16.33 kcal/mol. We also report the results of new assignments of vibrational frequencies obtained on the basis of the present calculations. Time-dependent DFT (TD-DFT) and ZIndo calculations have been performed to study the UV-vis absorption behavior and frontier molecular orbitals for the above-mentioned compounds. The UV-vis spectrum from TD-DFT calculation shows the π-π* transition bands at λmax 423.53 nm (emax 6.0 × 104 M-1 cm-1) and at λmax 359.45 nm (emax 1.7 × 104 M-1 cm-1), respectively, for trans- and cis-AzoFL. Compared to parent trans-diazene (λmax 178.97 nm), a significant variation to longer wavelength (∼245 nm) is observed due to the incorporation of the fluorene (FL) ring into the -N=N- backbone. The co-planarity of the two FL rings with the longer N=N bond length compared to the unsubstituted parent diazene indicates the effective red shift due to the extended π-conjugation in trans-AzoFL. The nonplanarity of cis-AzoFL (48.1° tilted about the C-N bond relative to the planar N=N-C bond) reflects its ∼64 nm blue shift compared to that of trans-counterpart.

The third order static and dynamic nonlinear optical (NLO) responses of Ih symmetry fullerenes (C60, C240, and C540) and fullerene onions (C60@C240 and C60@C240@C540) are predicted using the ZINDO method and the sum-over-states model. The static second hyperpolarizability of Ih symmetry fullerenes increases exponentially with fullerene size [from 10.00 × 10−34 esu in C60 to 3266.74 × 10−34 esu ≈ γ0(C60) × 92.63 in C540]. The external fields of strong third order NLO responses of Ih symmetry fullerenes change from ultra-violet (C60) to the visible region (C540) as the fullerene size increases. The outer layer fullerene in the fullerene onions has dominant contributions to the third order NLO properties of the fullerene onions, and the inter-shell charge-transfer excitations have conspicuous contributions to the third order NLO properties. The two-dimensional two-photon absorption spectra of C60 and C240 show that those fullerenes have strong two-photon absorptions in the visible region with short wavelength and in the ultra-violet region.

Efficient prediction of the aggregation-induced callback of organic chromophores for utilization in molecular sensorics is a desirable development goal in modern computational chemistry. Dye aggregates are complicated to study when utilizing conventional quantum chemistry approaches, since they are usually composed of too many atoms to be effectively analyzed, even with high-throughput parallel systems. Here, we present a successful attempt to develop a protocol to assess the spectroscopic changes happening in BODIPY dyes upon aggregation from the first principles utilizing extended tight-binding (XTB) and Zerner’s intermediate neglect of differential overlap (ZINDO) Hamiltonians. The developed sampling technique for aggregate configurational space scanning was found to be sufficient to both reproduce peculiarities and justify experimental data on the spectroscopic behavior of chromophore aggregates. The sTDA, sTD-DFT (GFN2-XTB) and CIS (ZINDO) approaches were assessed, and then sources of errors and benefits were outlined. Importantly, our goal was to keep any of the mentioned calculations within a computational cost feasible for a single workstation, whereas scaling was possible at any point in time. Finally, several aggregate structures were investigated in the external field to try to achieve distributions similar to the ones observed in the electrostatic potential of the air–water interface to assess the borderlines of practical applicability of the suggested scheme.

The purpose of this review is to demonstrate advances, challenges and perspectives of quantum chemical approaches in molecular spectroscopy of the condensed phase. Molecular spectroscopy, particularly vibrational spectroscopy and electronic spectroscopy, has been used extensively for a wide range of areas of chemical sciences and materials science as well as nano- and biosciences because it provides valuable information about structure, functions, and reactions of molecules. In the meantime, quantum chemical approaches play crucial roles in the spectral analysis. They also yield important knowledge about molecular and electronic structures as well as electronic transitions. The combination of spectroscopic approaches and quantum chemical calculations is a powerful tool for science, in general. Thus, our article, which treats various spectroscopy and quantum chemical approaches, should have strong implications in the wider scientific community. This review covers a wide area of molecular spectroscopy from far-ultraviolet (FUV, 120–200 nm) to far-infrared (FIR, 400–10 cm−1)/terahertz and Raman spectroscopy. As quantum chemical approaches, we introduce several anharmonic approaches such as vibrational self-consistent field (VSCF) and the combination of periodic harmonic calculations with anharmonic corrections based on finite models, grid-based techniques like the Numerov approach, the Cartesian coordinate tensor transfer (CCT) method, Symmetry-Adapted Cluster Configuration-Interaction (SAC-CI), and the ZINDO (Semi-empirical calculations at Zerner's Intermediate Neglect of Differential Overlap). One can use anharmonic approaches and grid-based approaches for both infrared (IR) and near-infrared (NIR) spectroscopy, while CCT methods are employed for Raman, Raman optical activity (ROA), FIR/terahertz and low-frequency Raman spectroscopy. Therefore, this review overviews cross relations between molecular spectroscopy and quantum chemical approaches, and provides various kinds of close-reality advanced spectral simulation for condensed phases.

Three transition metal complexes [Co (II), Ni (II) and Fe (III)] of the ligand 5-[(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl]-6-hydroxy-1,4-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile(L) which was found from the diazo-coupling reaction below 5 °C. The freshly synthesized metal chelates were characterized by both experimental and theoretical studies. Based on physico-chemical evidence, the azo dye acts as a tridentate ligand with nitrogen and oxygen atoms of the azo, carbonyl and phenyl groups are the coordinating sites. Non-electrolytic nature was observed for all the metal chelates because of their low molar conductivity. The electronic and magnetic susceptibility measurements suggested octahedral geometrical environment around all the metal ions. Quantum study of the synthesized moleculesby Zindo method to explaining about the electronic structure of the molecules.

In this work, a series of novel D-π-A structure coumarin-benzoxazole derivatives have been synthesized. The third-order NLO properties of the coumarin derivatives in DMSO are investigated by Z-scan measurement, and the photophysical properties of the compounds are studied through experimental and theoretical calculation methods. The results showed that the introducing specific functional groups at multiple active sites of coumarin reduced the π-π intermolecular stacking, while the formation of push-pull structure decreased E-gap of entire molecule. The excellent third-order NLO responses based on chromophore 4c with maximum nonlinear absorptive coefficients is 50.64 × 10−13 esu and the largest second-order NLO hyperpolarizability is 7.12 × 10−30 esu. Experimental results have also been confirmed through DFT, TDDFT and ZINDO calculations. Our results indicate that the coumarin fluorescent dyes are promising candidate materials for NLO applications.

Introduction. Gas exchange for living organisms is a very important biochemical process. Hemoglobin blood – imioglobin plays a leading role in him, located in the muscle fibers. In the study of various indicators of the cardiovascular and respiratory systems, the question arose about the competition of different gases for binding to Fe 2+ h a em h a emoglobin. Purpose. Until this time, nobody considered the possibility of binding of СО 2 to iron of haemoglobin. For the first time, we have taken an attempt to consider this connection. Methods. Calculations were made using ZINDO / 1 and PM3 methods in the HyperChem program. Results . The issue of gas exchange with participation of haemoglobin is discussed. The potential curves of haem iron binding with CO, СО 2 and О 2 gases are calculated. The possibility of forming a complex for the haem model with carbon (IV) oxide is shown for the first time. The role of the upper occupied MO of iron-phosphorus and ligand in the formation of coordination bonds and charge transfer in the complex of haem with СО 2 is determined. The role of charge polarization in the haem model is considered comparing СО 2 with other gases. Conclusion . Our quantum-chemical calculations show that СО 2 can be coordinated with the iron ion in haemoglobin, although its binding energy is significantly less than that for the CO complex with haemoglobin and is about 34.5 kcal / mol.

An insight into the electronic structure of the metal-free, unsubstituted, and nonperipherally substituted with electron-donating groups tetraazaporphyrin (H2TAP), phthalocyanine (H2Pc), naphthalocyanine (H2Nc), anthracocyanine (H2Ac) platforms has been gained and discussed on the basis of experimental UV-vis and MCD spectra as well as density functional theory (DFT), time-dependent DFT (TDDFT), and semiempirical ZINDO/S calculations. Experimental data are suggestive of potential crossover behavior between the 1 1B2u and 1 1B3u excited states (in traditional D2h notation) around 800 nm. A large array of exchange-correlation functionals were tested to predict the vertical excitation energies in H2TAPs, H2Pcs, H2Ncs, and H2Acs both in gas phase and solution. In general, TDDFT-predicted energies of the Q x and Q y bands and the splitting between them correlate well with the amount of Hartree-Fock exchange present in a specific exchange-correlation functional with the long-range corrected LC-BP86 and LC-wPBE functionals providing the best agreement between theory and experiment. The pure GGA (BP86) exchange-correlation functional significantly underestimated, while long-range corrected LC-BP86 and LC-wPBE exchange-correlation functionals and semiempirical ZINDO/S method strongly overestimated the intramolecular charge-transfer (ICT) transitions experimentally observed for -OR, -SR, and -NR2 substituted at nonperipheral position phthalocyanines and their analogues in the 450-650 nm region. The hybrid CAM-B3LYP, PBE1PBE, and B3LYP exchange-correlation functionals were found to be much better in predicting energies of such ICT transitions. Overall, we did not find a single exchange-correlation functional that can accurately (MAD < 0.05 eV) and simultaneously predict the energies and the splittings of the Q x and Q y bands as well as energies of the ICT transitions in a large array of substituted and unsubstituted metal-free phthalocyanines and their benzoannulated analogues.

We make an overview of chemical/physical computational simulation models for materials and biomolecular systems emphasizing basic philosophies, theoretical foundations and underlying limitations from Schrodinger´s equation to actual state of the art modeling as well as future trends and perspectives. We start with the ab initio models, including HF, CI, CC, MPT, MCSCF, CASSCF, MRC, offering good accuracy, whereas the need to address larger complex systems and computational limitations led to semiempirical models (ZDO, CNDO, INDO, ZINDO, NDDO, MNDO, AM1, PM3, PM6, PM7, DFTB) with inherent simplification/parametrization of integrals. Limitations of the ab initio approach and lack of accuracy for semiempirical models, when not specifically parameterized, led to density functional methods with excellent cost/performance/advantages and wide applications in both materials and biomolecular systems which resulted, however, in decades-long search for the best density functionals organized by Jacob’s ladder (LSDA, GGA, mGGA, GH, LH, RSH, DH, MCKS, PT2/RPA). Methods such as TDFT, MC, MD, MM and AIMD are summarized. Localized/all-electron/PW basis functions, OPW, APW, LMTO, LAPW, pseudopotential (PAW, NCPP, USPP) approach within the framework of DFT, Al, SE, AIMD, introduced methodologies for electronic structure/properties calculations for the solid material state which, with support of efficient, versatile computer codes, made feasible simulations of a wide range of properties in materials/biomolecular systems. We introduce recent cognitive overload addressed by sharing/feedback/free access of data/software/technical experience and discuss as well methodologies, research areas, databases of the so-called second computer revolution/fourth scientific paradigm (material learning models applied to material science). We also address Docking, Pharmacophore, Homology modeling for Biomolecular Systems as well as Coarse-Grained methodology including Force Matching, Inverse Boltzmann, Inverse Monte Carlo, Bayesian Dissipative Particle Dynamics with applications in Soft Matter, Macromolecules, Polymers, Interfacial Systems (polymer/material), Biomolecules, Water, Proteins, Carbohydrates.

Graphene quantum dots (GQDs) represent single layers up to dozens of graphene layers smaller than 30 nm. GQDs are newish molecules that have aroused great interest in research because of their exceptional and manageable optical, electrical, chemical, and structural properties. In this work, we report electrostatic potential energy maps, or molecular electrostatic potential surfaces, illustrate the charge distributions of GQDs three-dimensionally. Knowledge of the charge distributions can be used to determine how GQDs interact with one another. To analyze the distribution of molecular charges accurately, a large number of electrostatic potential energy values must be calculated. The best way to transmit these data is to visualize them as in the electrostatic potential map. A ZINDO semi-empirical quantum chemistry method then imposes the calculated data onto an electron density model of the GQDs derived from the Schr\"odinger equation. To make the electrostatic potential energy data of GQDs easy to interpret, a color spectrum, with red as the lowest electrostatic potential energy value and blue as the highest, is employed to convey the varying intensities of the electrostatic potential energy values. The results of the four GQD models suggest that the energy of the ionization potential lies in a range of -7.20 eV to -5.31 eV and the electron affinity is -2.65 to -0.24 eV., Comment: 2nd International Conference and Exhibition on Powder Technology (ICePTi) 2019

2-(3,4-Dihydroxyphenyl)-5,7-dihydroxy-3-[(2S,3R,4S,5R,6R)-3,4,5-trihydroxy-6-(hydroxymethyl) oxan-2-yl]oxychromen-4-one is known as quercetin 3-D-galactoside (Q3G) (C21H20O12). Under theoretical study of Q3G and the potential energy surfaces of the molecule, about 12 bonds were obtained through 360o full scanning by 6o increments. All conformers were optimized by using (DFT/B3LYP and DFT/LSDA) methods with the 6-31G (d,p) basis set in gas and ethanol phases. Twenty-one and 25 conformers of Q3G in gas phase were obtained. The most stable conformers (Q3G-G1 in gas phase and Q3G-E1 in ethanol phase) were re-optimized by two different basis sets. HOMO–LUMO energy gaps of Q3G molecule were calculated to be 4.96 for Q3G-G1 and 3.98 eV for Q3G-E1. UV spectra of Q3G were calculated using TD-DFT and ZINDO methods. Two strong transitions were obtained at 365.2 and 359.1 nm in gas and ethanol phases, respectively. The formations of hydrogen bonds were examined by natural bond orbital analysis, and three important intramolecular H-bonds were found. Normal coordinate analysis of Q3G-G1 was made, and all the bands of the vibrational spectra were interpreted by emphasizing intramolecular interactions.

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No. of bitstreams: 3 Disserta????o-Thainnar.pdf: 7515283 bytes, checksum: 1ad3386db3ca73296bce10dea38c79f8 (MD5) ataaprova??ao.pdf: 300087 bytes, checksum: 24797850ec88a9f6cddc07f1d05fb5ac (MD5) CartaEncaminhamentoAutodep??sito.pdf: 39108 bytes, checksum: 96c3d514edbe69939a99f257586189aa (MD5) Previous issue date: 2020-03-30 Funda????o de Amparo a Pesquisa do Estado do Amazonas - FAPEAM CAPES - Coordena????o de Aperfei??oamento de Pessoal de N??vel Superior Thymol belongs to the terpene family. The aromatic monoterpenoid molecule is the main constituent of several essential oils extracted from aromatic plants. Thymol is reported to have strong anti-inflammatory, anti-oxidant, antibacterial, antifungal, anticarcinogenic activities. Due to its broad spectrum os action, currently, it is among the most studied essential oil constituents. Thymol is the most potent of the phenols, abundantly found in the essential oil of Lippia menosides Cham. (Verbanaceae), the rosemary-pepper ", a typical specimen of the Brazilian Northeast. In this work, performed a detailed characterization of the thymol molecule by analyzing its structural, electronic and spectroscopic properties, both in gas and in solution, with methanol as solvent, using quantum calculations based on Density Functional Theory (DFT). Two quantum chemical models were used to perform the calculations: B3LYP / 6-31 ++ G (d, p) and B3LYP / augcc-pVDZ. The presence of the solvent was treated with the autoconsistent reaction field method (SCRF) using, in particular, the Continuous Polarizable Model (PCM). For the study of UV-Vis spectra we used two theoretical methods: Time Dependent Density Theory (TD-DFT) and the semi-empirical method ZINDO. To complement our study, we collaborated with Nanostructured Polymers Laboratory (NANOPOL) of UFAM for experimental measurements of the UV-Vis spectrum of thymol in methanol. Between the two methods, the ZINDO result is comparatively better than TDDFT. A mol??cula C10H14O pertencente ?? fam??lia dos terpenos. O monoterpeno arom??tico timol ?? o principal constituinte de v??rios ??leos essenciais extra??dos de plantas arom??ticas. Atualmente, encontra-se entre os constituintes de ??leos essenciais mais estudados, sobretudo devido ao amplo espectro de a????o, como anti-inamat??rio, antioxidante, antibacteriano, antif??ngico, anticarcinog??nico ?? o mais potente dos fen??is, sendo encontrado abundantemente no ??leo essencial de Lippia sidoides Cham. (Verbanaceae), o \alecrim-pimenta", um exemplar t??pico do Nordeste brasileiro. Neste trabalho, fizemos uma carateriza????o detalhada da mol??cula timol analisando as propriedades estruturais, eletr??nicas e espectrosc??picas, tanto em fase gasosa quanto em solu????o, tendo metanol como solvente, utilizando c??lculos qu??nticos baseado em Teoria do Funcional da Densidade (DFT). Foram usados dois modelos qu??mico qu??nticos para realizar os c??lculos: B3LYP/6-31++G(d,p) e B3LYP/augcc-pVDZ. A presen??a do solvente foi tratado com o m??todo campo de rea????o autoconsistente (SCRF) usando, em particular, o Modelo Cont??nuo Polariz??vel (PCM). Para o estudo dos espectros UV-Vis utilizamos dois m??todos te??ricos: Teoria do Funcional da Densidade Dependente do Tempo (TD-DFT) e o m??todo semiemp??rico ZINDO. Para complementar nosso estudo, realizamos em parceria com o Laborat??rio de Pol??meros Nanoestruturados (NANOPOL) da UFAM para medidas experimentais do espectro UV-Vis do timol em metanol. Entre os dois m??todos, o resultado do ZINDO ?? comparativamente melhor do que TDDFT.

In the present work density functional theory (DFT) and time-dependent semiempirical ZNIDO/S (TD-ZNIDO/S) methods have been used to investigate the ground state geometries, electronic structures and excited state properties of triad systems. The influences of the type of metal in the porphyrin ring, change in bridge position and porphyrine-ZnP duplicate on the energies of frontier molecular orbital and UV-Vis spectra has been studied. Geometry optimization, the energy levels and electron density of the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO), chemical hardness (η), electrophilicity index (ω), electron accepting power (ω+) were calculated using ZINDO/S method to predict which molecule is the most efficient with a great capability to be used as a triad molecule in solar industry. Moreover the light harvesting efficiency (LHE) was calculated by means of the oscillator strengths which are obtained by TD-ZINDO/S calculation. Theoretical studies of the electronic spectra by ZINDO/S method were helpful in interpreting the observed electronic transitions. This aspect was systematically explored in a series of C60-Porphyrine-Metalloporphyrine (C60-P-Mp) triad system with M being Fe, Co, Ni, Ti, and Zn. Generally, transition metal coordination compounds are used as effective sensitizers, due to their intense charge-transfer absorption over the whole visible range and highly efficient metal-to-ligand charge transfer. We aim to optimize the performance of the title solar cells by altering the frontier orbital energy gaps. The results reveal that cell efficiency can be enhanced by metal functionalization of the free base porphyrin. Ti-porphyrin was found to be the most efficient dye sensitizer for dye sensitized solar cells (DSSCs) based on C60-P-Mptriad system due to C60-Por-TiP complex has lower chemical hardness, gap energy and chemical potential as well as higher electron accepting power among other complexes. In addition, the performance of solar cells favors better with doubly and increasing the π conjugated of the bridge.

Pyrogallol was identified for the first time from the natural extract of Abrus precatorius Linn seeds using GC–MS technique. The vibrational analysis of pyrogallol was investigated in solid phase by FT-IR and FT-Raman spectroscopic techniques in the region 4000–400 cm−1 and 4000–40 cm−1, respectively. The optimized molecular geometry, wave number and intensity of the vibrational bands of pyrogallol and its isomers were obtained by DFT method with different basis sets. The electronic transition energy and intensities, HOMO-LUMO energy gap have been computed with the ZINDO, CIS, TDDFT theory for isomers and the differences were compared with UV–vis absorption spectra. The observed wave numbers in FT-IR, FT-Raman and UV–vis spectra were analyzed and assigned to various fundamental modes of vibration in the molecules. Experimentally observed vibrational frequencies and electronic transitions were assigned with the help of theoretical vibrational and electronic spectra, respectively. The differences between observed and calculated wave number values of most of the fundamental modes are very small. The calculated parameters were found to be in best agreement with experimental findings, thereby confirming the monomer and dimer structure of the identified molecule as well as its isomers.

Biomolecular aggregation is omnipresent in nature and important for metabolic processes or in medical treatment; however, the phenomenon is rather difficult to predict or understand on the basis of computational models. Recently, we found that electronic circular dichroism (ECD) spectroscopy and closely related resonance Raman optical activity (RROA) are extremely sensitive to the aggregation mechanism and structure of the astaxanthin dye. In the present study, molecular dynamics (MD) and quantum chemical (QC) computations (ZIndo/S, TDDFT) are used to link the aggregate structure with ECD spectral shapes. Realistic absorption and ECD intensities were obtained and the simulations reproduced many trends observed experimentally, such as the prevalent sign pattern and dependence of the aggregate structure on the solvent type. The computationally cheaper ZIndo/S method provided results very similar to those obtained by TDDFT. In the future, the accuracy of the combined MD/QC methodology of spectra interpretation should be improved to provide more detailed information on astaxanthin aggregates and similar macromolecular systems.

p-Terphenyl is used as a component in a variety of optical devices. In this investigation, the electronic transitions of p-terphenyl are investigated by synchrotron radiation linear dichroism (SRLD) spectroscopy in the range 30000 – 58000 cm–1 (330 – 170 nm) on molecular samples aligned in stretched polyethylene, thereby extending the region investigated by polarization spectroscopy into the vacuum UV. The resulting partial absorbance curves reveal that the vacuum UV band system with a maximum at 55000 cm–1 (180 nm) is predominantly short axis-polarized. This result is of interest in the optical applications of p-terphenyl, for example as a wavelength shifter. The observed polarization spectra are compared with the results of quantum chemical model calculations. Convoluted versions of the transitions predicted with the semiempirical ZINDO method and with the long range-corrected time-dependent density functional theory (TD–DFT) procedures TD–CAM-B3LYP, TD–LC-PBE, and TD–B97XD are in similar qualitative ...

A study of electron mobility in a PCBM system is performed by means of analytical considerations and Kinetic Monte Carlo simulations. Orbital energies are calculated at the ZINDO level of theory and successively corrected considering contributions from permanent charges and polarization interactions. The relative importance of these environmental effects is analyzed in details, furthermore the predicted mobilities are compared with experimental results and similar simulations performed in C60.

Four liquid crystalline molecules in the homologus series of 5,5′-Bis-(alkylpyridinyl)-2,2′-bithiophenes (nPBTP with n = 7, 8, 10, 12) have been investigated for UV sensing mechanism. Optimization of these compounds has been carried out through hybrid functional B3LYP along with 6-31 + G (d) basis set based on the crystallographic parameters as input. The UV absorption spectra of the molecules have been calculated and the configuration interaction singles (CIS) approach has been employed to study the electronic transitions features along with excited states calculation with the help of semiempirical Hamiltonian ZINDO. The INDO/S + CI method has been implemented for the same for comparison of the results. Various spectral parameters associated have been reported. The HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies estimations, and the transition energies, the electron excitation nature concerning on the structural variations in the molecules are clarified. The results obtained suggest model UV sensing mechanism for full colour display applications. A comparison has been made between nematic and smectic systems.

In the present work, the solvatochromism of two large nonpolar laser dyes Exalite 384 (E384) and Exalite 416 (E416) has been studied both experimentally and computationally. The steady state absorption and fluorescence spectra have been measured in a series of polar protic, polar aprotic and non-polar/weakly polar solvents to investigate their solvatochromism and determine dipole moments. Various solvent correlation techniques, like Lippert–Mataga, Bilot–Kawski, Kawski–Chamma–Viallet, Bakhshiev and Reichardt methods were used to evaluate the singlet excited and ground state dipole moments. Kamlet–Taft and Catalan solvent parameters were used by means of multiple linear regression (MLR) method to analyze specific and non-specific solute-solvent interactions. Computational studies were carried out to optimize ground and excited state geometries using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), respectively, in vacuum. This study also extends to evaluate the electronic transition energies from ground to first electronic excited state of solvated laser dyes employing semiempirical wave function model. In particular, the semiempirical method ZINDO has been combined with integral equation formalism of polarizable continuum model (IEF-PCM) to calculate solute-solvent interaction potential which is comparatively studied with E T (30) polarity scale along with experimental. The intramolecular charge transfer and hybridization is demonstrated by natural bond orbital analysis (NBO). The ground (μ g ) and excited state dipole moments (μ e ) of these dyes computed and those determined experimentally are compared and the results are discussed.