Local Reactivity Descriptors Research Articles

Dissolution of Alumina in Cryolite Melts: A Conceptual DFT Study

Interactions between alumina and cryolite clusters were investigated using chemical reactivity descriptors based on Conceptual DFT such as global hardness, $\eta$, global softness, $S$, fukui functions, $f$, and local softness, $s$. Hard and Soft Acids and Bases (HSAB) Principle was applied for identifying clusters that are most likely to interact with alumina, Al$_2$O$_3$. Local reactivity descriptors were employed to predict the most probable regions of interaction within the cluster.

Theoretical studies on cycloaddition reactions of N-allyl substituted polycyclic Isoindole-1,3-dione with nitrones and nitrile oxides

Bridged polycyclic molecular skeletons and related systems are key structural motifs in medicinal chemistry. The most efficient and widely accepted method for the syntheses of the bridged molecular polycyclic scaffolds is the 1,3-dipolar cycloaddition reactions. Herein, a systematic study on (3 + 2) cycloaddition reaction (32CA) of norbornene imide A with three-atom components (TACs), nitrile oxides and nitrones are presented at the M06-2X/6–311++G(d,p)-PCM(toluene), M06-2X-D3/6–311++G(d,p)-PCM(toluene) and MPWB1K/6–311++G(d,p)-PCM(toluene) levels of theory. The different reactivities of the strained endocyclic CC bond in the carbocyclic fragment and the less hindered N-allyl imide double bond in the alkene are evaluated. In the reaction of A and the nitrile oxides, four reaction pathways are characterized whereas eight distinctive reactive channels are located for nitrones. Trends in the calculated activation energies show that the 32CA reaction between A and nitrile oxides competitively occur at the endocyclic CC bond in the carbocyclic fragment and the N-allyl imide double bond. The cycloaddition of the nitrones favorably add across the less hindered N-allyl imide double bond. The trends in reactivity are in perfect agreement with local reactivity descriptors. Evaluation of TS geometries and bond distances validate that these 32CA reactions follow a one-step asynchronous molecular mechanism as proposed by Domingo. The activation energies suggest favored exo approach along all the reaction pathways, for that leads to better stabilization. Frontier molecular orbital analysis and global reactivity descriptors demonstrate that all the 32CA reactions proceed via an inverse electron demand character. Results from the local electrophilic (PK+) and nucleophilic (PK-) Parr functions show that the 32CA takes place at the atomic centers with the largest radical atomic spin densities in complete agreement with experimental outcomes.

Molecular structure spectroscopic Elucidation, IEFPCM solvation (UV–Vis, MEP, FMO, NBO, NLO), molecular docking and biological assessment studies of lepidine (4-Methylquinoline)

Quinoline compounds have attracted the curiosity of chemists due to their fascinating biological potential. In the present study, the molecule 4-methylquinoline or lepidine is characterised by DFT/B3LYP with 6–311++G(d,p) basis set to explore the optimised structure. Experimental calculations are compared to the computed FT-IR, FT-Raman and UV–Vis spectra. Theoretical and observed spectra are found to be very comparable. Various polar and non-polar solvents are used to investigate the electronic solvation properties of the title compound using the TD-DFT/IEFPCM model (M062X for UV–Vis and B3LYP for NBO, NLO, HOMO-LUMO, MEP). The occurrence of charge transfer in a molecule is explained by Natural Bond Orbital (NBO) analysis. The local reactivity descriptor describes the reactive regions of the molecule. The title compound's kinetic stability and reactivity are demonstrated using thermodynamic and Frontier Molecular Orbital (FMO) functions. The substance under research has excellent NLO properties. For the head compound, topological analyses such as ELF, LOL and RDG are performed and reported. The biological features (drug-likeness, toxicity and ADME) are calculated, which reveals the pharmaceutical activities of the compound. Molecular docking studies are used to investigate ligand–protein interactions, to show the insulin inhibitor activity of the chemical under research.

Vital theoretical and inter molecular docking study of (E)-3-[(2,6-dimethylphenyl)diazenyl]-7-methyl-1H-indazole

The current literature presents a systematic theoretical and experimental comparison of (E)-3-[(2,6-dimethylphenyl)diazenyl-7-methyl-1H-indazole employing the DFT/B3LYP approach on the 6-311G(d, p)/6–311++G(d, p) basis sets. The predicted optimum values are in comparison with experimental one display good agreement. An excellent correlation has been obtained between recorded IR spectra and computed vibrational frequency of the title compound. Electronic properties have also been figured out at B3LYP/6–311++G (d, p) level of theory. The excited state analysis in the continuum matches its recorded ultraviolet spectra quite well at the same level of theory and basis set. To depict the chemical reactivity of the molecule, key parameters such as global and local reactivity descriptors are used. For authentication of hydrogen bonding within the atom a magnificent AIM's assessment has also been performed. A complete charge transfer depiction of title compound has been done using its full NBO study. The biological activity of title molecule is also discussed. The docking study on the basis of the full fitness score and binding affinity shows that of title molecule bind well with 2B7A protein confirming it as a good anticancer agent.

Comparative theoretical analysis using DFT & MP2 calculations, ADMET profiling and docking studies of the drug telotristat ethyl

The title drug, Ethyl(2S)-2-amino-3-(4{2-amino-6-[(1R)-1-[4-chloro-2-(3-methyl-1H-pyrazol-1-yl) phenyl]-2,2,2-trifluoroethoxy] pyrimidin-4-yl}phenyl)propanoate was reported for carcinoid syndrome diarrhea and approved by FDA in the year 2017. DFT (B3LYP) and Moller-Plesset Second Order (MP2) quantum chemical calculations in the 631G basis set were used to optimize the drug and evaluate the global and local reactivity descriptors. Molecular docking was performed against the tryptophan hydroxylase-1 inhibitor protein to study the binding interactions of the drug with the protein and rationalize the structure-activity relationship. The bond length between drug and protein established the presence of good binding with more interaction or reactivity. Fukui functions were invoked to describe the reactivity and stability of the drug molecule. ADMET profiling of the drug molecule predicts poor solubility and limited absorption in the gastrointestinal tract. BOILED Egg representation displayed low absorption, impermeability to the Blood-Brain barrier, and induced P-gp Substrate. Descriptor parameters were compared between DFT and MP2 optimized structures for each atom, and the most reactive and stable atoms were reported. The current research focuses on the structural and bioactive properties of the title molecule. The study was conducted further to find suitable reactivity centers. This aspect would help to evaluate more reactivity patterns of such types of molecules in future.

Understanding the Chemical Reactivity of Dihydroxyfumaric Acid and its Derivatives through Conceptual DFT

The chemical reactivity descriptors have been calculated through Molecular Electron Density Theory encompassing Conceptual DFT. The validity of �Koopmans� theorem in DFT� (KID) has been assessed by a comparison between the global descriptors (electronegativity, total hardness, and global electrophilicity) calculated through vertical energy values and those arising from the HOMO and LUMO values. These results suggest that the KID procedure is valid and may be used, in conjunction with the B3LYP/3-611G(d, p) level of theory in further studies of related compounds in the aqueous medium. The active sites for nucleophilic and electrophilic attacks have been identified and verified using the local reactivity descriptors: the dual descriptor, the electrophilic and nucleophilic Parr functions, the local reactivity difference index Rk and MEP maps. Obtained results suggest that the antioxidant/antiradical power of investigated compounds may be explained by the highest ambiphilic activation of the oxygen atoms of the hydroxyl groups in the ene-diol moiety.

Kinetics and Thermodynamics of CO Oxidation by (TiO2)6.

Molecular level insights into the mechanism and thermodynamics of CO oxidation by a (TiO) cluster have been obtained through density functional calculations. Thereby, in this study, as an example, two different structural isomers of (TiO) are considered with the purpose of understanding the interplay between local structure and activity for the CO oxidation reaction. Active sites in the two isomeric forms were identified on the basis of global and local reactivity descriptors. For the oxidation of CO to CO, the study considered both sequential and simultaneous adsorption of CO and O on (TiO) cluster through the ER and LH mechanisms, respectively. Three different pathways were obtained for CO oxidation by (TiO) cluster, and the mechanistic route of each pathway were identified by locating the transition-state and intermediate structures. The effect of temperature on the rate of the reaction was investigated within the harmonic approximation. The structure-dependent activity of the cluster was rationalized through reactivity descriptors and analysis of the frontier orbitals.

Effect of the bifunctionalization of aminomethylphosphonic acid on the structural, electronic, vibrational, thermodynamic and antioxidant activity: Microwave-assisted synthesis, Density Functional Theory studies and DPPH radical scavenging activity

We report here a practical and efficient synthesis of α-aminotrismethylphosphonic acid (ATMP) from (Aminomethyl)phosphonic acid (AMPA) under green conditions using microwave irradiation, via Irani-Moedritzer reaction. The ATMP was characterized by FT-IR, 1H NMR, 13C NMR, 31P-NMR and Elemental Analysis. It was found that the synthesis method gave a higher yield within very short reaction times in comparison with conventional method. In order to know the effect of phosphonomethylation moiety on the structures, electronic, vibrational and thermodynamic and optical properties for AMPA and ATMP molecules were carried out by DFT calculations in gas and water phases. Indeed, stable structures of the two molecules were optimized by using the hybrid B3LYP/6–31 G method and their HOMO-LUMO energy, MESP, global and local reactivity descriptors and NLO properties were calculated. Moreover, antioxidant activity of both investigated compounds was evaluated by DPPH. radical scavenging methods where a strong activity has been found.

Two-Dimensional Infrared Correlation Spectroscopy, Conductor-like Screening Model for Real Solvents, and Density Functional Theory Study on the Adsorption Mechanism of Polyvinylpolypyrrolidone for Effective Phenol Removal in an Aqueous Medium.

The discharge of industrial effluents, such as phenol, into aquatic and soil environments is a global problem due to its serious negative impacts on human health and aquatic ecosystems. In this study, the ability of polyvinylpolypyrrolidone (PVPP) to remove phenol from an aqueous medium was investigated. The results showed that a significant proportion of phenol (up to 74.91%) was removed using PVPP at pH 6.5. Isotherm adsorption experiments of phenol on PVPP indicated that the best-fit adsorption was obtained using Langmuir models. The response peaks of the hydroxyl groups of phenol (OH) and the carboxyl groups (i.e., C=O) of PVPP were altered, indicating the formation of a hydrogen bond between the PVPP and phenol during phenol removal, as characterized using 1D and 2D IR spectroscopy. The resulting complexes were successfully characterized based on their thermodynamic properties, Mulliken charge, and electronic transition using the DFT approach. To clarify the types of interactions taking place in the complex systems, quantum theory of atoms in molecules (QTAIM) analysis, reduced density gradient noncovalent interaction (RDG-NCI) approach, and conductor-like screening model for real solvents (COSMO-RS) approach were also successfully calculated. The results showed that the interactions that occurred in the process of removing phenol by PVPP were through hydrogen bonding (based on RDG-NCI and COSMO-RS), which was identified as an intermediate type (∇2ρ(r) > 0 and H < 0, QTAIM). To gain a deeper understanding of how these interactions occurred, further characterization was performed based on adsorption mechanisms using molecular electrostatic potential, global reactivity, and local reactivity descriptors. The results showed that during hydrogen bond formation, PVPP acts as a nucleophile, whereas phenol acts as an electrophile and the O9 atom (i.e., donor electron) reacts with the H22 atom (i.e., acceptor electron).

Synthesis, spectroscopic analyses, DFT calculations and molecular docking studies of Pd(II) complex of hydrazone ligand derived from ethyl carbazate

A new Pd(II) metal complex of the ethyl-3-(3-ethoxy-2-hydroxybenzylidene)-carbazate (ehbcH2) ligand was obtained. The ligand and its complex were characterized using the several spectroscopic techniques. The molecular structure of the complex was established using single-crystal X-ray diffraction. Computational examination of the ligand and its complex was performed using density functional theory (DFT) to obtain an optimized geometry. The HOMO/LUMO energy levels, and the global and local reactivity descriptors were calculated to obtain an insight into the structure and reactivity behavior. The molecular docking studies were used to investigate the interaction of all compounds with the B-DNA dodecamer.

Computational, spectroscopic and molecular docking investigation on a bioactive anti-cancer drug: 2-Methyl-8-nitro quinoline

2-Methyl-8-nitroquinoline (2M8NQ) is optimized using density functional theory with B3LYP/6-311++G(d,p) basis set. The vibrational (FT-IR, FT-Raman) frequencies with potential energy distribution (PED) and the geometrical parameters of headline molecule is obtained and compared with the experimental data. Multiwave-functions like Reduced gradient density (RDG), Electron localisation function (ELF), Localised orbital locator (LOL) is computed. HOMO-LUMO energy gap is analysed for different orbital level. HOMO-LUMO energy gab for the molecule in various solvent has studied and are correlated with theoretical electronic spectra. The reactivity of the examined molecule is analysed with DFT methods such as Molecular electrostatic potential (MEP), Local reactivity descriptors are understood. Natural bond orbital (NBO) and Nonlinear optical behaviour (NLO) are also analysed. Furthermore, biological parameters from Molinspiration-preADME and GUSAR such as drug-likeness, ADME, Toxicity properties are studied. Ramachandran plot are drawn to understood the stability of anticancer proteins. Docking analysis reveals that the molecule is a potent anti-cancer drug.

Structural insights, spectral and H-bond analyses, of nitrofurantoin-phenazine cocrystal and comparison of its chemical reactivity with other nitrofurantoin cocrystals

This work gives the unified insight of vibrational spectroscopy (FT-IR and FT-Raman) and density functional theory (DFT) calculations to get an understanding of the hydrogen bonding pattern and chemical reactivity of a cocrystal of nitrofurantoin (NF, an antibacterial drug) with phenazine (PHEN). FT-Raman (100-3700 cm−1) and infrared (400-4000 cm−1) spectroscopic techniques were used for the characterization of the NF-PHEN cocrystal and NF drug itself in the solid state. The intermolecular H-bonding is affirmed by natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) studies. The reactivity studies of NF-PHEN through global and local reactivity descriptors have also been performed. The global reactivity parameters of NF-PHEN have been compared with that of NF itself and two other cocrystals of NF [nitrofurantoin-melamine monohydrate (NF-MELA-H2O) and nitrofurantoin-urea (NF-urea)] where hetero-atom (nitrogen) rich coformers have been used. It is established that all the three cocrystals show more chemical reactivity than NF itself. And amongst three NF cocrystals, NF-MELA-H2O is most stable while NF-PHEN is chemically most reactive. In other words, NF-PHEN is chemically softer than other two cocrystals. Molecular electrostatic potential (MEP) map has also been studied as it is correlated to the electronic density and is advantageous in considering sites for electrophilic and nucleophilic strikes together with hydrogen bonding interactions. Molar refractivity (MR) value of NF-PHEN falls within the range set by Lipinski's modified rule and suggests that the studied cocrystal may show drug likeness. Accordingly, structural and reactivity studies could be successfully employed to a pharmaceutical cocrystal, NF-PHEN, considered in this study and for various other multicomponent crystals in gaining insights into their hydrogen bond interactions and physicochemical properties.

Crystal structure, Hirshfeld surface and reactivity of novel ligand-LAT1 derived from dehydroacetic acid: intermolecular interactions with SARS-Cov-2/main protease

The crystals of new ligand, namely (3E)-6-methyl-3-{1-[(pyridin-3-ylmethyl) amino] ethylene}-2H-pyran-2, 4(3H)-dione) (LAT1), were synthesized using the evaporation solution technique. Single-crystal X-ray diffraction and physico-chemical characterization (ATR, proton and carbon-13 NMR and UV-Visible) of LAT1 were reported. In addition, Hirshfeld surface analysis (HSA) of the solid compound, structure optimization, Mulliken and NBO charges, global indices of reactivity, local reactivity descriptors and molecular electrostatic potential (MEP) of the ligand were investigated theoretically. XRD analysis showed that LAT1 crystallizes in the triclinic space group P-1 and the structure was stabilized through hydrogen bonds. HAS revealed that H…H (46.5%) and O…H (25.7%) contacts are in control of crystal stacking. The energy gap (4.679 eV) and reactivity descriptors indicate the stability of LAT1. The Mulliken and NBO charges showed that the protons have a positive charge and the heteroatoms exhibit negative charges. The Fukui function and MEP study revealed that the heteroatoms are the most reactive sites for an electophilic attack on the ligand. Molecular docking simulation shows that the significant binding affinity of LAT1 with SARS-CoV-2/Mpro is due to the formation of high number of hydrogen bonds.

Spectroscopic, density functional theoretical study, molecular docking, and in vitro studies based on anticancer activity studies against A549 lung cancer cell line of diphenylhydantoin adsorbed on AuNPs surface.

The optimized geometry, FT-Raman, FT-IR, surface-enhanced Raman scattering, UV-Vis spectra, frontier molecular orbital analysis, molecular electrostatic potential analysis, and local and global reactivity descriptors of diphenylhydantoin (DPH) and diphenylhydantoin@AuNPs (DPHA) molecule have been investigated with the help of density functional theory method (B3LYP/6-31++G [d,p] together with LANL2DZ) and was compared and analyzed with the corresponding experimental data in order to identify their structural and bonding features responsible for their bioactivity. In-silico (molecular docking) biological activity screening of the molecules together with the in-vitro (SERS and MTT assay) analysis confirms the anticancer activity of DPH and DPHA molecules. The results of the structure-activity studies and bioactivity studies signify that the DPHA molecule is more active than the DPH molecule against lung cancer.

DFT, Electronic absorption spectra and Non-linear optical properties of some 4H-benzo[h]chromene Derivatives. Solvent effect and TD-DFT Approach

The electronic structure of some 4H-benzo[h]chromene derivatives are investigated theoretically at the B3LYP/6-311++G (d,p) level of theory. The extent of delocalization and intramolecular charge transfer are estimated and discussed in terms of natural bond orbital analysis (NBO) and second order perturbation interactions between donor and acceptor MOs. The calculated EHOMO and ELUMO energies of the studied compounds can be used to calculate the global properties; chemical hardness (η), softness (S) and electronegativity (χ). The equilibrium geometries of the studied compounds are determined, and it was found that these geometries are non-planar. The calculated nonlinear optical parameters (NLO); polarizability (α), anisotropy of the polarizibility (Δα) and first order hyperpolarizibility (β) of the studied compounds show promising optical properties. The molecular electrostatic potential (MEP) and Local reactivity descriptors (fukui function) have been studied for the title compound and its derivatives at the same level of theory. Electronic spectra of 4H-benzo[h]chromene derivatives in different organic solvents such as 1,4-Dioxane and DiChloroEthane as non-polar solvents and Ethanol, Methanol and Acetonitrile as polar solvents, are investigated experimentally and theoretically using the time dependent density functional theory (TD-DFT) method at the B3LYP/6-311++G(d,p) level of the theory. The origin of the spectrum of the parent compound is found to be an additive one. The solvent effect is investigated experimentally and theoretically and a blue shift is discerned

Molecular structure determination, Bioactivity score, Spectroscopic and Quantum computational studies on (E)-N'-(4-Chlorobenzylidene)-2-(napthalen-2-yloxy) acetohydrazide

Density functional theory (DFT) approach has become the most cost-effective way to study the molecular structure and has found wide applications related to vibrational spectral biological systems. In this work, we present an integrated experimental and theoretical study of the molecular structure and FT-IR, FT-Raman, NMR spectra of the title compound. A good correlation is shown between experimental and calculated bond lengths and bond angles and vibrational frequencies. The optimized geometric parameters are compared with experimental values of the title compound. The stabilization energy E (2) and Hyper conjugative have been calculated using NBO analysis. The local reactivity descriptors such as Fukui functions (fk+, fk−) analyses are performed to determine the reactive sites within molecule. Nonlinear optical effects (NLO) and hyperpolarizability calculations are also calculated. The molecular electrostatic potential (MEP) and the HOMO and LUMO analysis is used to determine the active site of the molecule. In this computational investigation, we also performed bioactivity and drug likeness parameters calculations for the title compound to design a new molecule have a good pharmacological profile, this study will provide the lead information. Molecular docking was carried out with different proteins using the Auto dock method show that the molecule has inhibitory activity against these receptor.

The density polarization reveals directions of electron displacements due to the substituent effect: Analysis performed on a metal-organic Mo-Oxo catalyst.

Some Mo-oxo complexes bearing pyridine rings have the capability for dihydrogen production from water. However, energy barrier and overall energy vary depending on the effect exerted by several substituent groups located at different positions around one or more pyridine rings which are ligands of these compounds. Based on the Karunadasa and coworkers investigation where the para-position was experimentally tested in compounds derivatised from the 2,6-bis[1,1-bis(2-pyridil)ethyl]-pyridine oxo-molybdenum complex synthesized (Karunadasa et al., Nature, 2010, 464, 1329), we tested the combined effect of electron-withdrawing and electron-donating groups simulated as perturbations represented by point-charges. Then, we used the density polarization concept, δρ(r), a local reactivity descriptor corresponding to the partially integrated linear response function, χ(r, r') (a non-local reactivity descriptor), which is able to reveal different displacements of π-electrons on molecular structures. We perturbed the para-positions in the pentadentate ligand 2,6-bis[1,1-bis(2-pyridil)ethyl]-pyridine in the Mo-based complex by means of point-charges. They were located in three different configurations of the organic ligand (trans, geminal, and cis) which could help to explain energy barriers and overall energy of reactions catalyzed by this type of Mo-complexes. Our results indicate that the trans configuration of point-charges induces the most amount of fraction of electron shifted on the complex. A Mo-based complex bearing the same trans configuration for electron-withdrawing and electron-donating substituent groups (cyano and amino, respectively), leads to a kinetically more favorable H2 release than the cis or geminal configuration of the substituent groups aforementioned.

An insight into the structure and vibrations of 4–nitroindole and 7–nitroindole by spectroscopic and DFT methods

The structure of 4−nitroindole (4NI) and 7−nitroindole (7NI) is optimised by B3LYP level using 6 − 31++G** and cc−pVTZ basis sets. The FT−IR and FT−Raman and NMR spectra of 4NI and 7NI are analysed in detail and compared. The observed 1H and 13C NMR chemical shifts are found good correlation with theoretical chemical shifts calculated by GIAO method. The vibrational frequencies of 4NI and 7NI have been precisely assigned and analysed. The electron density and electrostatic potential of 4NI is more than that 7NI molecule. The bond orbital analysis (NBO) is carried out. The dual Fukui descriptors (Δfk), the dual local softness (Δsk) and the multiphilicity descriptors (Δωk) have clearly reveals that the atoms N1, C2, C3, C4, C8 are more favourable for nucleophilic attack in both 4NI. In the case of 7NI molecule N1, C2, C3, C5, C7 are more prone to nucleophilic attack. The local reactivity descriptors favours electrophilic attack at the carbon atom C9 of 4NI and 7NI molecules.

Investigations of Dianhydro-D-glucitol adsorbed on AuNPs surface: In silico and in vitro approach based on anticancer activity studies against A549 lung cancer cell lines.

The adsorption behavior of a lung cancer agent, Dianhydro-D-glucitol (DIS) on gold nanoparticles (AuNPs) was studied using surface-enhanced Raman scattering techniques. The stabilized geometry, inter- and intra-molecular hydrogen bond, and harmonic vibrational wavenumbers of DIS and DIS adsorbed on AuNPs (DISA) surface have been investigated with the help of the density functional theory (DFT) method. The stability of the molecules arising from stereoelectronic interactions, leading to its bioactivity, has been confirmed using natural bond orbital (NBO) analysis, which was further substantiated by the narrow HOMO LUMO energy gap obtained for DISA, from frontier molecular orbital analysis as well as electronic spectral analysis. The molecular electrostatic potential analysis along with local and global reactivity descriptors predicts the reactive site of the molecules. Molecular docking study was performed to obtain information about protein-ligand reactions for DIS and DISA, with different cancer proteins. This study enlightens the potential of SERS agents for targeted drug delivery and photothermal. The in vitro cytotoxic effects of DPH and DPHA molecules on lung cancer cell lines were analyzed using the MTT assay and the SERS method.

Examinations directed to characterization within the framework of spectroscopic and DFT approach on the structural isomer of the pyridine substituted thiazole

In the present paper, we reported the synthesis of two structural isomers of pyridine-substituted thiazole having heterocyclic moieties, characterized by XRD, FT-IR, NMR, UV-Vis and fluorescence techniques. Their molecular geometries and presence of hydrogen bond interactions were determined with single-crystal X-ray diffraction (XRD) analysis. The process steps of analyses performed with the theoretical approach were carried out with density functional theory (DFT), B3LYP functional and 6-311G(d,p) basis set. The parameters of molecular geometry, spectral vibrational modes base on potential energy distribution (PED) and 1H and 13C-NMR chemical shifts for the structures were evaluated comparatively with DFT results. To determine photophysical properties, absorption bands with the time-dependent DFT (TD-DFT) approach and spectral emission bands were examined. Frontier molecular orbitals (FMOs), global and local reactivity descriptors, atomic charge distributions based on Mulliken and Natural Population analysis (MPA and NPA) were utilized to specify the reactivity properties of the structures. Further, nonlinear optical (NLO) properties and some thermodynamic parameters were investigated at the same theoretical level. The results of these analyses show that most of the spectral parameters examined are sensitive to the position of the substituent and the pyridine substitution 4-position to thiazole structure exhibit chemically more reactive a profile than at 2-position.