A novel carbon−sulfur (C2S) analogue of polyacene has been synthesized and characterized. The polymer is composed of a nondegenerate trans−cisoid polyacetylene backbone in which all hydrogen atoms are replaced with sulfur atoms to form thiophene rings that are fused into a linear cross-conjugated ladder-type structure. The newly developed synthetic route of the ladder-type polymer is based on an intramolecular condensation of a prepolymer consisting of 3-(alkane-1-sulfinyl)thiophen-2,5-diyl units in triflic acid. The geometric and band electronic structure of the ladder-type polymer were calculated and analyzed at the PM5 level of theory. The fused ring structure imposes strong quinonoid-type character to the originally benzenoid polyene backbone, which destabilizes the HOMO and stabilizes the LUMO and thus reduces the band gap. The shift of absorption and emission maxima to longer wavelengths responding to lower π−π* transition energies than those of polythiophene and the smaller gap between electrochemical p- and n-doping potentials are consistent with the reduction of the band gap. The microstructure of the isolated oligomers in their neutral, singly oixidzed, and doubly oxidized states were computed for short and intermediate chain length. Various energetic and structural aspects of the convergence behavior from the properties of small cations or dications to those of an isolated polaronic or bipolaronic defects on a sufficiently long chain were monitored and are discussed. The geometric structures of the p-doped ladder-type polymer in the form of either polaron or bipolaron were calculated by adopting suitable boundary conditions to represent charged unit cells. The geometry relaxation process for the charged ladder-type backbone induces the appearance of a stronger quinonoidic character than that in the case of polythiophene, which suggests that the fused rings more easily adopt quinonoid forms than thiophene rings. Calculated energetic aspects of the doping behavior and the paramagnetic resonance spectra of p-doped polymers revealed that the ladder-type polymer possesses polaron as the prevailing charged species, in contrast to many other π-conjugated polymers where bipolaron is the lowest-energy charge storage configuration.
Poly(3-chiral methylsulfinyl-1,2-phenyleneoxide) was synthesized, and the regioselective intramolecular ring-closing of the pendant sulfoxide on the polymer formed the corresponding helical ladder structure comprising of a fused phenoxathiine ring. The CD of the ladder polymer gave a Cotton effect which was caused by the chirality of the pendant group.
An adequate maternal iodine intake during pregnancy and lactation is essential for growth and mental development in fetuses and newborns. Both de cient and excess iodine may disrupt normal thyroid function. There are limited data on perinatal iodine metabolism in mothers and infants, as well as the effect of povidone-iodine (PVP-I) antiseptics used in Cesarean delivery. The urinary iodine concentration (UIC), serum iodine, thyrotropin (TSH), free thyroxine (FT4) and breast milk iodine concentration (BMIC) were measured consecutively in a total of 327 mothers and 249 term-infants in two prospective studies.The maternal median UIC was 164 µg/L in the third trimester, increased to 256 µg/L on postpartum day 2, then decreased to 116 µg/L one month later. The BMIC on postpartum days 2 and 30 was 17.6 and 13.5 µg/100g, respectively. In neonatal infants born to the mothers unexposed to PVP-I, the median UIC was 131 µg/L in the rst voiding urine and increased to 272 µg/L on day 4, then slightly decreased to 265 µg/L on day 28 suggesting su cient iodine reserve at birth. PVP-I antiseptics containing 1g of iodine for skin preparation at Cesarean delivery transiently increase maternal serum iodine concentration, UIC and BMIC, however, it has little effect on maternal TSH, FT4 and neonatal UIC, TSH, or FT4. The iodine status of pregnant women and their infants was adequate in this population; however, the UIC in lactating mothers at one postnatal month was low enough to suggest iodine de ciency or near iodine de ciency. Further studies are necessary.This study was not registered to any clinical trials registry (CTR).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.