The structures and properties of [n]sila-acenes (n=2-4) were investigated by density functional theory method. The results of calculations were obtained at B3LYP/6-311G (d,p) level on model species. Energetic criteria suggest that 2-1b (n=2), 3-1b (n=3), and 4-1b (n=4) isomers enjoy stabilization. By frontier orbital analysis, these systems are among the most stable of the family. Also, calcula...

Procedures for the synthesis, separation and determination of structure of the bilirubin-IX isomers are described. 1. The four biliverdin-IX isomers were prepared by oxidative cleavage of haemin and were separated as their dimethyl esters. The individual esters were reduced with NaBH4, and the bilirubin esters obtained were subjected to alkaline hydrolysis yielding the corresponding bilirubin-I...

The organogermanium chemistry covers huge fields, as shown by a survey covering the crystallographic and structural data of over four hundred and fifty examples. Over 10 percent of those compounds exist as distortion isomers (around 97 %) and ligand isomers (around 3 %). These are discussed in term of coordination around the Ge(II), Ge(IV) and Ge2 +3 atoms, and correlations are drawn between do...

Enumeration of chiral isomers of substituted fullerene cages (CZO-C~O) is considered using the generalized character cycle index (GCCI) of the alternating representation of the point group of the parent cage. It is shown that there are no chiral isomers for the monosubstituted CZO, c24, C28, C30, c36, and CW fullerene cages but there are chiral isomers for other monosubstituted cages. All cages...

A combined experimental and Density functional theory (DFT) B3LYP/6-311+G* study on the IR spectra of four stable isomers of 2-N,N-dimethylaminecyclohexyl 1-N’,N’-dimethylcarbamate was performed. Our theoretical calculations reveal that two new isomers of this compound exist and may be more stable than the known isomers. In addition the entropy, heat capacity, and the enthalpy content of the st...

background: the presence of organochlorine pesticides in the environment is a serious threat to human health and requires continuous monitoring. therefore, in the present systematic review, the residual amount of different organochlorine pesticides in human samples has been investigated.   methods: all accessible databases in english and farsi were searched by using organochlorine and related p...

hexachlorocyclohexane, an organochlorine insecticide has been used in agriculture and public health programmes since a very long time. it is very resistant to degradation and thus accumulates in the environment for long time. a microbial consortium was developed in our laboratory which could degrade hexachlorocyclohexane very efficiently in water. a study was carried out to understand the biode...

Polycyclic Hydrocarbons. In their Communication (e202304937), Chunyan Chi et al. report the synthesis and isolation in single-crystal form of two fused indacene dimer isomers. Both isomers display an open-shell singlet ground state.

naphthol isomers were simultaneously and spectrophotometrically determined in wastewater, using a model based on net analyte signal (nas). the calibration method used is a variation of the original hybrid linear analysis method as proposed by goicoechea and olivieri (hla/go). owing to spectral interferences, the simultaneous determination of mixtures of naphthol isomers, using a spectrophotomet...