Figure 1 - uploaded by Hasan R. Obayes
Content may be subject to copyright.
The optimized structure for two isomers (4-aminocoumarin and 4-iminocoumarin ) and values of ∆S, ∆H.
Source publication
As there are no thermodynamic studies on the 4-aminocoumarin tautomerization molecule, this study was done for the first time in the world. 4-Aminocoumarin molecule stability was studied in the gaseous state and it has two isomers (imino form and amino form). The theoretical study and based on the results of density functions theory (DFT), imino po...
Context in source publication
Context 1
... the Wittig reaction in N,N-diethylaniline was also conveniently applied for the synthesis of coumarins [15]. The thermodynamical properties of the title compounds in have been calculated using DFT (B3LYP) method. This calculation is valuable for providing insight into molecular parameters, entropy and the enthalpy. The aim of this work is to explore the molecular dynamics and the structural parameters that govern the chemical structure, and to compare predictions made from theoretical observations. 4-iminocoumarin and 4-aminocoumarin are two isomers as showed in Figure 1. The stability of these forms from the calculations of chemical quantum theory using the density functions theory (DFT) method indicated that the 4-iminocoumarin isomer is more stable than 4-aminocoumarin isomer (Table 1). This is evidenced by the value of the total energy calculated from each of them, that the energy of 4-iminocoumarin isomer is more than 4-aminocoumarin isomer by -0.032 a.u. or -19.951 Kcal.mol-1. Thermodynamic results showed that reaction (1) is spontaneous because of the positive value of the entropy change (∆S = +0.063 cal.mol -1 .K -1 ) and therefore 4-iminocoumarin isomer is more stable than 4- aminocoumarin isomer. The negative value of enthalpy change (∆H= -0.577 Kcal.mol -1 ) indicates that the reaction (1) is exothermic, while reaction (2) is not spontaneous and endothermic with values of ∆S and ∆H being -0.063 cal.mol -1 .K -1 and +0.577 Kcal.mol -1 , respectively. The stability of 4-iminocoumarin isomer is as shown in Figure (1). In solid state physics, a band gap, also called an energy gap, is an energy range in a solid where no electron states can exist. The gap energy generally refers to the energy difference (in electron volts) between the Low Unoccupied Molecular Orbital (LUMO) and the HOMO in insulators and semiconductors. This is equivalent to the energy required to free an outer shell electron from its orbit about the nucleus to become a mobile charge carrier, which is able to move freely within the solid material. These molecules were calculated in gas phase media and hence the energy gap is based an approximation. The band gap energy values of these two isomers, namely, 4-iminocoumarin and 4- aminocoumarin are 5.126 eV and 4.567 eV, respectively; this indicates that thin molecule in gas phase is insulators for the electrical conductivity. Figure 2 shows the HOMO and the LUMO electronic distributions for both of the isomers. Other observations account for absorption maximum wavelength (λ max ) of both isomers of 4-iminocoumarin and 4-aminocoumarin to be 451.37 nm and 402.15 nm, respectively. The two isomers have no center of symmetry at all symmetry element hence they are classified as the identity, E. Such molecule belongs to the C 1 point group. The dipole moments of 4-aminocoumarin and 4-iminocoumarin were also calculated and listed in Table 1 . The dipole moment for 4-aminocoumarin and 4-iminocoumarin were oriented ...
Similar publications
Molecular structure, isomerism, conformational stability and intramolecular hydrogen bonding (IHB) of cis-enol forms of 1-(n-pyridyl)butane-1,3-diones (nPBD) (n = 2, 3, or 4) have been investigated by means of density functional theory (DFT) calculations. Energy differences for all possible nPBD cis-enol forms of isomers with respect to the most st...
High level Density Functional Theory (DFT) using B3LYP/6-311++G(2df,2p)//6-311+G(d,p) calculations on therelative stabilities and structures of the neutral, protonated and deprotonated isorhodaninetautomeric forms are reported in the gas phase and solution. Gas phase and solution B3LYP calculations predict that the oxo/thione tautomer is the most s...
Pyridine, C5H5N, and pyridine derivatives of the structure C5(S)nH5-nN (S = -C≡C-X; X = F,
Cl, Br, I) have been studied theoretically using DFT computation employing the B3LYP/LanL2DZ
level of theory. Effects of substituent halogenation on electron density enrichment of the pyridine
nitrogen, and thus its effectiveness as an electron donor have bee...
The selected isomers of C8H13+ are calculated to predict its relative energies and their stability for each species at the levels of density functional theory (DFT) using 6-311G+dp basis set. We also attempted to predict the isomerisation or mechanistic pathways by locating the transition States through the interruption of diagonal matrix as confir...
The structure, isomerization pathways and vibrational spectra of the important heterocyclic 2-(1,2,4-triazolyl)phenol molecule were investigated by DFT calculations and matrix isolation FTIR spectroscopy. Among forty five minima located on PES three isomers with intramolecular hydrogen bond O-H···N, 2-TRP1, 1-TRP1 and 1-TRP2, are the most stable fo...
Citations
... Kcal.mol -1 ) depending on the values of high occupied molecular orbital (HOMO) in the table (1). Comparing the values gap energy for two compounds (Imide1 and Imide2) are: (2.6090 eV, 3.3328 eV) respectively, shows us that the compound (Imide2) is more stable because the greater the value of gap energy leads to increased stability [15,16] . ...
N,N’-(biphenyl)bisphthalimide and N-(4’-amino __ biphenyl)phthalimide were chosen in this study to compare the stabilitytheoretically by density function theory (DFT) using B3LYP/6-31Gmethod, the electronic properties of these imides indicate that compound(N,N’-(biphenyl)bisphthalimide) is more stable than the compound (N-(4’-aminobiphenyl) phthalimide) by (-0.8422 eV or -19.4215 Keal.mo!'')depending on the values of HOMO, synthesis _ reaction of imide isspontaneous and endothermic at temperature 150°C according to the valuesof A,S, A,G and A,H thermodynamically.INTRODUCTION Imides are organic compounds for N-monoacy] derivatives of amidewhich may be open or cyclic chain. Cyclic imide constitute an importantclass of compounds possessing bis-amide linkage with common nitrogen.Imide very important molecules because their activity as antibacterial,antifungal, anti nociceptive, anticonvulsant and antitumor!, They havebeen useful building blocks in the synthesis of natural products’! and otherheterocycles as well!*!, Their ability to cross biological membranes in-vivo,due to their hydrophobicity is well established'“!,The preparation of imideshas received considerable attention during recent year A number ofmethods such as acylation of amides with acyl chlorides, anhydrides andcarboxylic esters or acids), amino carbonylation of aryl bromides'*! havebeen reported for the preparation of acyclic imides.COMPUTATIONAL METHODS Molecular geometries of the all molecules were fully optimized withthe hybrid density functional theory (DFT) B3LYP method!”"'"! using the6-31G basis set!!?!3! by means of the Gaussian 09, revision A.02!"4! usedfor all geometry optimizitions, thermodynamic functions at conditions
... The thermodynamic parameters for coumarin isomers were done using the (DFT). The results showed the stability of the amino and imine structures were different depend on ∆S and ∆H data [17]. ...
The phenomena of the tautomerism forms of the substituted triazoles compounds which are named [1-A] (5-phenyl-1H-1,2,4-triazol-3-amine), [1-B] (3-phenyl-1H-1,2,4-triazol-5-amine), [2-A] (5-(pyridin-2-yl)-1H-1,2,4-triazol-3-amine), [2-B] (3-(pyridin-2-yl)-1H-1,2,4-triazol-5-amine), [3-A] (5-(pyridin-3-yl)-1H-1,2,4-triazol-3-amine), [3-B] (3-(pyridin-3-yl)-1H-1,2,4-triazol-5-amine), [4-A] (5-(pyridin-4-yl)-1H-1,2,4-triazol-3-amine) and [4-B] (3-(pyridin-4-yl)-1H-1,2,4-triazol-5-amine) have been evaluated by Hartree-Fock (HF) method at the basis set (6-31G) in the both gas phase and at different type of solvents. This study of solvents effect was containing polar and non-polar solvent like water, acetone, acetonitrile, benzene and CCl4. The physico-chemical data's were evaluated for eigenvalues at different kinds of energy levels (HOMO, HOMO-1, HOMO-2, HOMO-3, LUMO, LUMO+1, LUMO+2 and LUMO+3). The difference of the energy gap (LUMO-HOMO) values for structures showed that the forms (1A, 2A, 3A and 4A) are more stable compare with (1B, 2B, 3B and 4B). From the results, we can showed that there is a difference between the two forms depends on the parameters. So, the imino form is not stable compare with the other structure.
... All theoretical calculations of the compounds included in the research were done using the Gaussian 09, revision A.02 program [15], and the combination of the Becke's threeparameter hybrid (B3) [16] exchange functional and the Lee-Yang-Parr (LYP) [17] correlation functional (B3LYP) [18]. A version of the density function theory (DFT) method and the basis set 6-311G [19] calculate all geometry optimizations, and the highest occupied molecular orbital energies (E HOMO ), lowest unoccupied molecular orbital energies (E LUMO ), and basis set 6-31G calculate the enthalpy and entropy thermodynamic functions [20]. ...
Both [5]-circulene and [7]-circulene can be selected to design the molecular tweezers theoretically using the DFT method. Leaning on the cyclic polymerization mechanism, we obtain four new tweezer compounds. Theoretical results offer that tweezer compound (I) is additionally stable than other compounds because it has better energies than other compounds. The values were as follows: − 2606.83372937 a.u. for the total energy, − 5.39820 eV for (EHOMO), and 2.87407 eV for gap energy. The thermodynamic theoretical outcome showed that all reactions are exothermic and spontaneous, suggesting that tweezer compound (I) might correlate with several aromatic compounds, such as pyrene, benzo[ghi]perylene, ovalene, and hexabenzocoronene. The correlation energy results showed an increase as the aromatic compound becomes larger, while the correlation distance decreases. All correlation energy kinds are electrostatic. The value of the electrostatic correlation energy of tweezer compound (I)-ovalene is (− 6.4928615 kJ mol−1). The tweezer compound (I) has a spherical cavity equal to 3.73640 nm3, which adds an important application in the ability to capture chemicals, bacteria, or viruses that are close to the size of the cavity with ease.
... Once MeCN and CeCl 3 were established as suitable solvent and promoter, respectively, the optimization of the reaction time and temperature, as well as the amount of the promoter were undertaken (entries [19][20][21][22][23][24][25][26][27]. It was found that refluxing for 3 h in MeCN with 50 mol% CeCl 3 gave the best results (66% yield, entry 21) and that the use of an argon atmosphere provided no significant improvement (65% yield, entry 22). ...
... Probably, this is a result of the slightly better reactivity of their amino groups, considering that 4-aminocoumarins could be involved in iminoenamino type tautomerism. [27] Interestingly, however, no clear trend emerged when a performance comparison was made between the conventional heating and microwave-irradiation conditions. Unexpectedly, however, despite the microwave irradiation alternative delivered the products in much shorter reaction times (15-30 min), most of the compounds (3 c-f) were obtained in up to 30% lower yields (entries 1 and 2 vs entries 3-6). ...
Facile and efficient syntheses of 4‐(1H‐pyrrol‐1‐yl)‐coumarins and 6‐(1H‐pyrrol‐1‐yl)‐coumarins from the corresponding aminocoumarins are reported. The transformations were optimized and their corresponding scope and limitations were assessed. Selected (1H‐pyrrol‐1‐yl)‐coumarins were further subjected to a mild thiocyanation, undergoing selective functionalization on the pyrrole nucleus. A set of 10 differently substituted compounds was submitted to activity testing against various fungal strains. It was found that the introduction of a SCN moiety increased the antifungal activity, turning some compounds into fungicidal agents, to the point that one of the thiocyanato derivatives displayed an antifungal profile comparable to those of fluconazole and nystatin.
... 45 After 60 min and 120 min interval compound (29,32) and 34 quinolin-2(1H)-one derivative showed maximum anticonvulsant activity. Compound (28,30,31,33, and 34) and 35 quinolin-2(1H)-one derivative exhibited better activity, with duration of hind limb extensor. 45 Antitumor activity ...
Umbelliferon, the natural crenelated coumarin distributed in the plants of a piaceae family, has shown various biological activities, especially as a cancer chemo preventive agent. Coumarins have been categorized as a member of family of benzo-pyrone, that consist of pyrone ring united to benzene ring. The benzo-pyrones may be sectioned to alfa type that coumarins belong and the gama type that flavonoids have been major members. Coumarins are chemical entity which has being synthesized in the past few years many forms of its derivatives; the entity provides the principal origin of motivating to numerous chemist to investigate its diverse medical efforts especially with regards to the anticoagulant activity. In present article we review recent 4-Methylumbelliferon, (4-MU) that are synthesized with it pharmacological activities antioxidant, anti-inflammatory, antimicrobial activity, ant hepatitis, hepatoprotective, anticancer, antipyretic and analgesic activity.
... However, it was found that the amino group in compound 1 was a very weak nucleophile. N-substituted derivatives of 1 have been obtained by the reactions of amino compounds with 4-chlorocoumarin [28,29] or 4-hydroxycoumarin 2 [30,31]. solvent-free conditions in good to excellent yields [32][33][34]. ...
Coumarin and their derivatives are important groups of heterocyclic compounds. They have attracted considerable interest because of their great biological importance. This review describes the work on the synthesis and heterocyclization reactions of aminocoumarines. It was found that the cyclocondensation process depended mainly on the chemoselective and regioselectivity states of the enamino skeleton.
Graphical Abstract
Open image in new window
... Kcal.mol-1) depending on the values of high occupied molecular orbital (HOMO) in the table (1). Comparing the values gap energy for two compounds (Imide1 and Imide2) are: (2.8314 eV, 4.0104 eV) respectively, shows us that the compound (Imide2) is more stable because the greater the value of gap energy leads to increased stability [20,21]. ...
Based on DFT (density functional theory) using B3LYP/6‐31G method, theoretical investigations applied to demonstrate the structural, electronic properties and stability of (N,Nˊ‐ (1,4‐phenylene)bis(1,8‐naphthalimide)) is more stable than the compound (N‐(4‐amino phenyl)1,8‐ naphthalimide) by (‐1.2762 eV or ‐29.4299 Kcal.mol‐1) depending on the values of HOMO, synthesis reaction of imide is spontaneous and endothermic at temperature 275˚C according to the values of ∆rS, ∆rG and ∆rH.
... T h e m o l e c u l e 8 -hy d r ox y q u i n o l i n e electrophilic aromatic substitution reaction theoretically has six possibilities due to the presence of six hydrogen on aromatic carbon atoms which is associated with the C-2 to C-7, for the purpose of discussing the possibilities of this reaction there are two explanations: first explanation depends on the reactant molecules or call the name (explanation of the pre-reaction), which now has a lot of research, the second explanation depends on the stability of the product molecules, which we will focus on in this work [29][30][31][32][33] . Figure 1. ...
Theoretical investigations of organic molecules for the objective of their structural stability are the most important techniques in this regards. Recently calculations and simulation reactions utilizing theoretical studies become attractive conventional method for the researchers. Density function theory (DFT) method was used to study the reaction of 8-hydroxyquinoline with 4-ethoxycarbonyl-benzene diazonium chloride as electrophilic aromatic substitution reaction. To study any reaction there are two explanations: first explanation depends on the reactant molecules and second explanation depends on the stability of the product molecules. Determine the stability of the molecule by comparing the energies (total energy, energy level of (HOMO), and energy gap), we have three stable molecules, are: HQ-7-YBAEE (II) for the total energy, HQ-6-YBAEE (II) for the energy level of (HOMO) and HQ-2-YBAEE (II) for the energy gap. The molecule HQ-4-YBAEE (II) is always at least stability in all data.
... To compute the ground-state geometry, Gaussian 03, Revisions C.01 and polarization premise sets (3-21G) [8,9]. A combination of the Becke three-parameters hybrid (B3) [10] exchange utilitarian and the Lee-Yang-Parr (LYP) [11] relationship useful (B3LYP) [12,13], an interpretation of the DFT [14,15] was utilized to focus all enhanced geometries, EHOMO, ELUMO and physical properties for the chlorophenlos in this study. ...
Geometrical optimization and electronic structure of chlorophenols were researched by DFT (B3LYP) utilizing a 3-21G basis set. We have likewise researched the aggregate electronic properties, Highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and energy gap. The calculated HOMO and LUMO energies demonstrate that charge transfer occurs within the molecule.
... To calculate the ground-state geometries, Gaussian 03, Revision C.01 [40] was optimized to a local minimum without symmetry restrictions using the valence and polarization basis set (3-21G) [41,42]. A combination of the Becke three-parameter hybrid (B3) [43,44] exchange functional and the LeeYang-Parr (LYP) [45] correlation functional (B3LYP) [46,47], a version of the (DFT) method [48][49][50][51][52], was used to determine all optimized geometries, HOMO energies (EHOMO), LUMO energies (ELUMO), and physical properties for the molecules in this study. ...
New coumarins, namely (E)-N′-(2-methylbenzylidene)-2-((2-oxo-2H-chromen-4-yl)oxy)acetohydrazide 4, N-(4-oxo-2-(o-tolyl)thiazolidin-3-yl)-2-((2-oxo-2H-chromen-4-yl)oxy)acetamide 5, and N-(4,7-dioxo-2-(o-tolyl)-1,3-oxazepin-3(2H,4H,7H)-yl)-2-((2-oxo-2H-chromen-4-yl)oxy)acetamide 6, were synthesized starting from 4-hydroxycoumarin and methyl bromoacetate. They were characterized by different spectroscopic techniques (FT-IR and NMR) and micro-elemental analysis (CHNS). Density Functional Theory calculations of the synthesized coumarins were performed using molecular structures with optimized geometries. Molecular orbital calculations have provided detail description of the orbitals, including spatial characteristics, nodal patterns, and the contributions of individual atoms.
