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A DFT study on nitrotriazines

In this study, all possible mono-, di- and tri-nitro-substituted triazine compounds have been considered as potential candidates for high-energy density materials (HEDMs) by using quantum chemical treatment. Geometric and electronic structures, thermodynamic properties and detonation performances of these nitro-substituted triazines have been systematically studied using density functional theory (DFT, B3LYP) at the level of 6-31G(d,p), 6-31+G(d,p), 6-311G(d,p), 6-311+G(d,p) and cc-pVDZ basis sets. Moreover, thermal stabilities have been evaluated from the homolytic bond dissociation energies (BDEs). Detailed molecular orbital (MO) investigation has been performed on these potential HEDMs. According to the results of the calculations, mono-, di- and tri-nitro-substituted derivatives of symmetric 1,3,5-triazine have been found to be more stable than their 1,2,3 and 1,2,4 counterparts.

A theoretical study on vomitoxin and its tautomers

In the present work, the structural and electronic properties of vomitoxin (deoxynivalenol, a mycotoxin) and all of its possible tautomers have been investigated by the application of B3LYP/6-31G(d,p) type quantum chemical calculations. According to the results of the calculations, tautomer V(4) has been found to be the most stable one among all the structures both in the gas and aqueous phases. The calculations also indicated that, vomitoxin and V(2) possess the deepest and the highest lying HOMO levels, respectively. Hence, V(2) is to be more susceptible to oxidations than the others. On the other hand, V(5)(S) and vomitoxin have the lowest and the next lowest LUMO energies, respectively. Whereas, V(1) and V(2) possess quite highly lying (within the group) LUMO energy levels which result in comparatively unfavorable reduction potentials. Some important geometrical and physicochemical properties and the calculated IR spectra of the systems have also been reported in the study.

Synthesis and investigation of intra-molecular charge transfer state properties of novel donor–acceptor–donor pyridine derivatives: the effects of temperature and environment on molecular configurations and the origin of delayed fluorescence

A novel series of donor-acceptor-donor (D-A-D) structured pyridine derivatives were synthesised and detailed photo-physical investigations were made using mainly steady-state and time-resolved spectroscopy techniques at varying temperatures. The investigations showed that the molecules have solvent polarity and temperature dependent excited-state configurations, confirmed in two different polarity solvents (295-90 K), i.e. methyl cyclohexane (MCH) and 2-methyltetrahdrofurane (2-MeTHF). In MCH, the investigations revealed dual fluorescence over the temperature range of 295-90 K. At 295 K, the ground-state configuration of the molecules has a partially twisted geometry as determined by DFT calculation, yet the emission originates totally from a locally excited (LE) state, however once the temperature is lowered to 90 K, the twisted molecular configuration is stabilised, and the emission originates from a fully-relaxed intramolecular charge transfer state (ICT), this is contrary to the systems where structural reorganisation stabilises ICT and this is frozen out at low temperatures. The DFT calculations revealed different ground state molecular configurations due to the presence of different electron-donating groups, e.g. the molecule including anthracene groups has a near 90° twisted geometry whereas the triphenylamine including molecule has a pyramidal geometrical folding, therefore, the decrease in temperature restricts the donor degree of rotational freedom. In 2-MeTHF solution, the fluorescence spectrum of both molecules is always of ICT character, but gradually red-shifts through the fluid to glass transition temperature (∼135 K), in this case, the fluorescence occurs after structural and solvent-shell relaxations, however, upon cooling below 135 K, the spectra dramatically shift back to blue giving rise to strong emission from an ICT excited-state (but not the LE state) where the molecules have unrelaxed geometries. This significant change in the nature of the emitting species was explained with specific solvent-solute dynamic interactions in the vicinity of the solvation shell and the effect of thermal excitation of molecular vibrational modes of the C-C bond linking donor and acceptor units. Finally, we confirmed that the molecules have ICT ground-state geometry in the solid-state phase (spin-coated films), and the time-resolved decay dynamics were investigated comparing the spin-coated films (at RT and 25 K) and MCH solutions (at 295 K and 90 K).

A DFT Study on Nitro Derivatives of Pyridine

The heat of formation values of all possible nitro derivatives of pyridine have been calculated by the application of various density functional theory (DFT) methods by a proper isodesmic reaction. The heat of formation data trends in series are found to be independent of the selected DFT method, although some differences have been observed in value. Total energies and nucleus-independent chemical shift (NICS(0)) values have also been calculated in order to jugde the aromatic stabilities for the nitropyridine derivatives. Moreover, a novel topological (Türker-Gümüş, TG) index has been defined for modeling the detonation properties of the explosives.

ELECTROLUMINESCENT PROPERTIES OF CERTAIN POLYAROMATIC COMPOUNDS: PART 2–ORGANIC EMITTERS

This review is based on the electroluminescent and optical properties of certain polyaromatics in OLEDs with special attention to their specific function in the emitting layer, performance and emissive color. DAD and TDAD dopants depending on their concentration in the emitting layer exhibit good efficiencies and color purity for blue emission. When copolyethers with diphenylanthracene emitting segments are used in a single layer diode, visible pure blue light (440 nm maximum) around 15-20V can be achieved. J-Aggregates including anthracene moieties contribute to the efficient IR electroluminescence. Blue, white, yellow and orange electroluminescent devices can be obtained by ADN- or ADN-doped with rubrene at ultra low concentrations. Pyrene derivatives (P1, P2) linked to fluorene exhibit high thermal stability, bright blue emission and improved hole injection ability. Aminobenzanthrone derivatives as host emitters emit orange-to-red light with high brightness (25000 cd.m−2), current efficiency (3.52 cd.A−1) and power efficiency. Due to its bipolar transport property, when doped in Alq3 or NPB, tetraphenylnaphtacene shows excellent yellow electroluminescence. Multiple quantum well (MQW) structures including rubrene are helpful in narrower and tunable spectral emission, as well as higher emission efficiency. Perylene derivatives such as copolymer+PVK blend show sharp red emission peaks, photochemical and thermal stability. Pentacene derivatives, DPP, 1-DNP and 2-DNP can be used to obtain highly pure purple color. An increase in the doping concentration of DPP enhances photoluminescent peak intensity. New blue-green emitting dopants like coronene, decacylene and conjugated ladder systems based on phthalocyanines are centers of attraction for electroluminescence in recent years.

MOLECULAR ORBITAL TREATMENT OF SOME ENDOHEDRALLY DOPED C60 SYSTEMS

The present review article is a collection of the theoretical studies about some endohedrally doped C 60 systems, based on density functional theory and ab initio calculations. The energies of the composite system, as well as molecular orbital energies depend on the type of dopant, symmetry of the system and the spin state. In the case of C@C 60 , the dopant interacts with the cage depending on the symmetry and spin state, whereas in Be@C 60 , Be is found to be unbound. In certain cases (as Ca, Sc and Y) the interaction results in electron transfer from the dopant to the cage.

Substituent effect on the aromaticity of 1,3-azole systems

Abstract The effects of substituent type and position on the aromaticity of certain derivatives of oxazole, imidazole and thiazole have been theoretically investigated by using density functional theory at the levels of B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p) methods. The second heteroatom substitution decreases aromaticity of furan, pyrrole and thiophene. The decreased aromaticity is gained back to some extent by the substitution of strong electron withdrawing groups or atoms (NO2 and F). Nucleus-independent chemical shift (NICS) data have been considered to determine the aromaticity of the systems. The most effective substitution to enhance the aromaticity has been calculated to be at position 4. The variation of the bond lengths of the main skeleton supports the findings through NICS calculations. The frontier molecular orbital energies have also been reported to draw a general correlation between these energies and the aromaticity of the system.

Synthesis, Characterization, and Theoretical Studies on Some Metallophthalocyanines With Octakis Phenoxyacetamide Substituents

The synthesis of substituted metallophthalocyanines bearing phenoxyacetamide moieties was achieved by cyclotetramerization of 1,2-bis(phenoxyacetamide)-4,5-dicyanobenzene in the presence of metal (Zn (4), Mg (5), Ni (6)) salts. These compounds were purified by several techniques such as crystallization, column chromatography, and wash with different solvents. The new compounds were characterized by elemental analysis, IR, 1H-NMR, and UV-Vis spectral data. The ground-state geometries of the complexes were optimized using density functional theory (DFT) methods at B3LYP/6-31G (d, p) level. The results of thermal analysis of novel phthalocyanines 4–6 have also been reported herein.

Computational Study on All Possible Diamino-Dinitropyrimidines and Their Mono- and Dioxide Derivatives

Diamino-dinitropyrimidines and their mono- and dioxidized products were subjected to theoretical analysis at the level of density functional theory with the application of the B3LYP/6-31G(d,p) method of theory. The electronic energies and the nucleous-independent chemical shift (NICS) data were considered in order judge the stabilities of the systems. 4,6-Diamino-2,5-dinitropyrimidine (11), 2,6-diamino-4,5-dinitropyrimidine-1-oxide (8a), and 2,4-diamino-5,6-dinitropyrimidine-1,3-dioxide (8c) were calculated to be the most stable structures among pyrimidines and mono- and dioxide derivatives, respectively. Because these compounds are potential high-energy-density materials, their detonation parameters are also reported herein, together with bond dissociation energies regarding homolytic bond dissociation of the C-NO2 bond.

AB INITIO AND DFT STUDIES ON CERTAIN η6-ANTHRAQUINONE -Cr(CO) 3 COMPLEXES

η6-1,2-, 1,4- and 9, 10-Anthraquinone-Cr (CO)3 complexes are subjected to RHF/6-31 G(d, p), B3LYP/6-31 G(d) and B3LYP/6-31 G(d, p) type quantum chemical treatment. In each case the 9, 10-anthraquinone complex has been found to be more stable than the others. The least stable complexes originate from 1, 2-anthraquinone.