Theoretical electronic spectra for models having ferredoxin-core

Ferredoxin-core model [Fe4S4] type iron-sulfur cluster having four cysteine moieties in the amide form, has been considered theoretically for electronic excitation spectrum. The neutral as well as the -/+ 2 charged forms of the model have been investigated within the restrictions of ZINDO/S (RHF) approach involving configuration interaction considerations. The charged forms, especially the negative one exhibited some bathochromic shift and hyperchromic effect

Structure-impact sensitivity relation of some substituted 1,3,5-trinitrobenzenes

Structure-impact sensitivity relation of some substituted 1,3,5-trinitrobenzene type explosives is investigated by using a topological approach. It has been found that the sensitivity increases with decreasing of a previously defined upper bound (U) of the deepest lying molecular orbital energy, x(1), or the fourth coefficient (a(4)) of the secular polynomial of the molecular graph of the isoconjugate hydrocarbon system within the Huckel molecular orbital framework

A topological approach to the stabilities of isomeric Huckel and Mobius type cyclacenes

Within the constraints of Huckel molecular orbital theory, Huckel and Mobius type cyclacenes were investigated in terms of their angle of total pi-electron energy, O pi, and cos O pi to find out how structural changes affect the stabilities. It has been theoretically deduced that as the number of benzenoid rings (R) increases the isomeric Huckel and Mobius type cyclacenes should have comparable stabilities, although for low values of R odd-Huckel type and even-Mobius type are predicted to be more stable

Quantum chemical studies on -/+ 1 charged forms of nitroglycerine

Semiempirical quantum chemical calculations at the level of AMI (UHF) method are performed on the neutral as well as 4: 1 charged systems originated from nitroglycerine. The geometry optimized systems standing for 4: 1 charged forms fragmented. All the neutral and charged systems are found to be stable and exothermic with the exception of cationic system which is endothermic in nature. The fragmentation occurs by the cleavage of ester O-N bond of the terminal ester group in the charged forms while in the cationic form also the rapture of C-C bond occurs

A theoretical study on camptothecin-AM1 treatment

Camptothecin (irinotecan), a new cytotoxic agent having antitumor activity and especially used in the treatment of advanced colorectal cancers is considered for AM1-RBF type semiempirical quantum chemical treatment together with some analogs of camptothecin. The structural properties and energetics of these molecules have been compared. The structures arising from monoprotonation of camptothecin at various sites are analyzed from thermodynamic point of view

Endohedrally Be, C, Si and Ge doped C-80 - AM1 treatment

M@C-80 type C-80 structure endohedrally doped with Be, C, Si and Ge atoms were subjected to AMI (RHF) type quantum chemical studies. All the structures are expected to be stable but highly endothermic. However, Ge atom seems to be quite a potent dopant to stabilize C-80 cage. Some calculated properties of the structures are presented as well

Contemplation on resemblance of molecules

A novel index has been defined in general sense to give an idea about resemblance of two molecules. For that purpose, property vectors defined on n-dimensional Euclidean linear space have been used. A necessary condition is derived for two molecules to have high resemblance

A First-Order Linear Model for the Estimation of Detonation Velocity

A linear multivariable model has been derived for the estimation of detonation velocity. Then, its two simplified forms, first-order linear models, have been proposed as estimators of detonation velocities of a large population of explosives having different skeletal structures. Then, the models are analyzed mathematically and regression equations are obtained and discussed. The first model possesses two independent variables E/M and density, whereas the second one is based on E/M only. The total energy (E) is obtained at the level of UB3LYP/6-31G(d) and M is the molecular weight of the explosive considered

Isomerization of 4,6-DinitrobenzofuroxanA DFT Study

The present study concentrates on the isomerization process of 4,6-dinitrobenzofuroxan and the monoionic forms of its bicyclic isomers. The ionic forms shed some light on the stability of those isomers in an ionizing electric field or static charging. To achieve the goals of the study, certain density functional theory (DFT) calculations have been carried out at the restricted and unrestricted levels of B3LYP using 6-31G(d) and 6-311+G(d,p) basis sets. The stabilities and some other quantum chemical properties of the isomers and the ionic forms were obtained. It was found that upon charging, the bicyclic isomers undergo ring opening of the five-membered ring to yield stable structures

AM1 treatment of certain thyroid hormones

Some thyroid hormones, T-4, T-3 and reverse T-3 are considered for Austin model 1 restricted Hartree-Fock type semi-empirical molecular orbital calculations. The zwitterionic form in every case was found to be less stable and less exothermic as compared to the nonionic form of them