Theoretical study on the electronic, structural, properties and reactivity of a series of mono-, di-, tri- and tetrachlorothiophenes as well as corresponding radical cation forms as monomers for conducting polymers

In this paper, electrical and structural properties of mono-, di-, tri- and tetrachlorothiophenes and their radical cations have been studied using the density functional theory and B3LYP method with 6-311++G** basis set. The effects of the number and position of the substituent of chlorine atoms on the properties of the thiophene ring for all chlorothiophenes and their radical cations have been studied. Vibrational frequencies, nuclear chemical shielding constants, spin-density distribution, size and direction of dipole moment vector, ionization potential, electric polarizabilities and NICS values of these compounds have been calculated as well. The analysis of these data showed that double bonds in 3-chlorothiophene are more delocalized and it is the best possible candidate monomer among all chlorothiophenes for the synthesis of corresponding conducting polymers with modified characteristics

Incidence of low birth weight and associated risk factors during March 2002-2003 in Tonekabon, Iran

Background and purpose: Low birth weight (LBW; birthweight 2500 g. or below) is a public health problem, because it is associated with increased risk of morbidity and mortality. This prospective study was conducted during March 2002 - 2003, to determine the incidence of low birth weight infants and associated risk factors in neonates born at Shahid Rajaee Hospital in Tonekabone, Iran.Materials and methods: For every LBW case, maternal age, sex, gestational age, parity, route of delivery and spacing between pregnancies of low birth weight were analyzed. For control, the first baby born before and immediately after the LBW baby who weighed more than 2500 g. at birth were analyzed.Results: The results revealed that the incidence of low birth weight was 4.2 % which is lower than population of other cities and only 0.34% (7 cases) of newborns weighted 1500 g. or less. The higher incidence of low birth weight was found in the primigravid (P=0.042), in cesarean section (P=0.025) and close spacing of pregnancy (P=0.033). Maternal age and sex of baby had no significant effect on the incidence of low birth weight. There were more premature deliveries in cases than controls (P=0.000).Conclusion: According to present findings, LBW incidence of albeit in Tonekabon in comparison with other cities throught the country is at acceptable level, prevention of premature delivery and conduction of health education programs for high risk groups, especially primigravid can lower the rates

Synthesis and structures of monocyclic 1,4-diaza-2,3-diborine species

New monocyclic 1,4-diaza-2,3-diborine derivatives 3ad, 3ae and 3bc and bicyclic 1,4-diaza-2,3-diborine 8a were prepared by reacting 1,4-diaza-2,3-diene dianion (5) with 1,2-dichlorodiborane (6) and 1,2-dichloro-1,2-diborolane (7). The structures of these new derivatives, which are likely ligands for metal complexes, have been characterized by nuclear magnetic resonance (NMR). The crystal structures of lad and 3bc have been determined by single crystal X-ray diffraction technique. In the crystal structure of 3ad, the asymmetric unit contains one-half of the molecule, with the other half generated by (x,y,3/2-z) symmetry operation. Considering the X-ray crystallographic results of these compounds, the B-B bonds are typical for single bonds, with the bond lengths of 1.700 and 1.697 angstrom. Optimized geometric results and Natural Bond Orbital analysis also endorsed that these bond types are single bonds. In 3ad, diazadiborine ring is almost planar, while this ring is in half-chair conformation in 3bc. These compounds, although many aminoboranes are stable in air, were observed not to be stable in air. They have also shown non-aromatic characteristics. (C) 2015 Elsevier B.V. All rights reserved