On the triplet state of poly(N-vinylcarbazole)

Triplet state properties including transient triplet absorption spectrum, intersystem crossing yields in solution at room temperature and phosphorescence spectra, quantum yields and lifetimes at low temperature as well as singlet oxygen yields were obtained for poly(N-vinylcarbazole) (PVK) in 2-methyl-tetrahydrofuran (2-MeTHF), cyclohexane or benzene. The results allow the determination of the energy value for the lowest lying triplet state and also show that triplet formation and deactivation is a minor route for relaxation of the lowest excited singlet state of PVK. In addition, they show the triplet state is at higher energy than reported heavy metal dopants used for electrophosphorescent devices, such that if this is used as a host it will not quench their luminescence.http://www.sciencedirect.com/science/article/B6TFN-4DTTJJC-7/1/b605edb9859b607f1a9b1c1348af029

Quinoidization of regioregular oligo(THIENO[3,4-b]THIOPHENE)s

Caracterización de oligotiofenosUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

The Triumph of the blue in nature and in Anthropocene

This research was also supported by AgriFood XXI I&D&I project ( NORTE-01-0145-FEDER-000041 ) cofinanced by European Regional Development Fund (ERDF) , through the NORTE 2020 (Programa Operacional Regional do Norte 2014/2020); We thank Miriam Colaço for raising the question of the blue LASERS. Publisher Copyright: © 2022 The Author(s)Blue was the last color to be spread in Nature by the anthocyanins present in angiosperms, and the last color to be managed by Humans in Anthropocene. Blue also appears in a small number of algae, fungi, and bacteria, but these living beings have very little to do with the profusion of a natural blue hue. Humanity took many long years to figure out how to reproduce and use blue - the classic example of which is indigo dye, extracted from plants like the Indigofera tinctoria. However, even simple anthocyanins are not capable of achieving blue. Plants had to develop strategies to fix this color, mainly by intramolecular copigmentation in acylated anthocyanins and complexation with metals, as in metalloanthocyanins. Blue was absent in the first paleolithic cave paintings. Those depictions were made using reds, yellows, and blacks of all hues, but no blue. In addition, blue LEDs and LASERs came later after red and green. It was only at the end of the 20th century that genetic engineering was able to create blue flowers adapted to the markets to meet consumer demands. Food and beverage producers continue to look for a natural blue as an alternative to synthetic colorants. Blue remained a second-rate color in the West for a long time. Despite that fact, in many countries blue is now the preferred color. In this review we track the appearance of blue in Nature and in the Anthropocene.publishersversionpublishe

The effect of substitution and isomeric imperfection on the photophysical behaviour of p-phenylenevinylene trimers

Spectroscopic and photophysical properties of two p-phenylenevinylene (PV) trimers, 2,5-substituted diheptyl-(p-phenylenevinylene) and di-[(2-ethylhexyl)oxy]-(p-phenylenevinylene), were studied using absorption spectroscopy, fluorescence and laser flash photolysis. The change from alkyl to alkyloxy groups red-shifts the absorption and fluorescence bands. The rate of internal conversion is independent of the substitution, whereas alkyloxy substitution increases the S1 [rightwards wave arrow] T1 intersystem crossing rate by an order of magnitude. The relevance for the behaviour of conjugated PPV polymers is discussed. For diheptyl-PV, a sample having ca. 3% of the cis-configuration was also studied. Comparison between the all-trans and the cis-contaminated samples revealed no significant differences in their photophysical properties.http://www.sciencedirect.com/science/article/B6TFN-4C0TKVG-4/1/bb1be7e4a272bb7910483cae927d04a

Influence of Cellulose Ether Mixtures on Ibuprofen Release: MC25, HPC and HPMC K100M

The influence of cellulose ether derivatives on ibuprofen release from matrix tablets was investigated. Raman spectroscopy and differential scanning calorimetry (DSC) experiments were used, in order to examine the compatibility between the matrix components: both excipients and ibuprofen. While both the DSC and Raman results did not detect any incompatibilities, DSC revealed the existence of some drug:excipient interactions, reflected by variations in the hydration/dehydration processes. Formulations containing mixtures of polymers with both low and high viscosity grades—methylcellulose (MC25) or hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC K100M), respectively—were prepared by a direct compression method (using 20, 25, and 30% of either MC25 or HPC). The tablets were evaluated for their drug content, weight uniformity, hardness, thickness, tensile strength, friability, porosity, surface area, and volume. Parameters such as the mean dissolution time (MDT) and the dissolution efficiency (DE) were calculated in all cases. The solid formulations presently studied demonstrated a predominantly Fickian diffusion release mechanism.http://www.informaworld.com/10.1080/1083745060056134