Strongly emitting, centrosymmetric, ladder-type bis-coumarins with crankshaft architecture.

Quadrupolar bis-coumarins bearing dialkylamino groups, prepared by a double Pechmann reaction and subsequent oxidation, strongly emit yellow-orange light. Comparison with non-substituted analogs reveals that, the photophysical properties of the conjugated bis-coumarins are controlled both by the dialkylamino substituents and by the π-system. Analogous but non-conjugated bis-coumarins emit blue light both in solution and in crystalline state. Unusually fast oxidation process in the crystalline state is responsible for the presence of two bands in their solid-state emission. Two-center, charge-transfer transition from an orbital delocalized on the entire molecule to the central benzene ring is responsible for photophysical properties.

A sensitive zinc probe operating via enhancement of excited-state intramolecular charge transfer.

Novel highly sensitive fluorescent probes for zinc cations based on the diketopyrrolopyrrole scaffold were designed and synthesized. Large bathochromic shifts (≈80 nm) of fluorescence are observed when the Zn2+-recognition unit (di-(2-picolyl)amine) is bridged with the fluorophore possessing an additional pyridine unit able to participate in the coordination process. This effect originates from the dipolar architecture and the increasing electron-withdrawing properties of the diketopyrrolopyrrole core upon addition of the cation. The new, greenish-yellow emitting probes, which operate via modulation of intramolecular charge transfer, are very sensitive to the presence of Zn2+. Introduction of a morpholine unit in the diketopyrrolopyrrole structure induces a selective six-fold increase of the emission intensity upon zinc coordination. Importantly, the presence of other divalent biologically relevant metal cations has negligible effects and typically even at a 100-fold higher concentration of Mg2+/Zn2+, the effect is comparable. Computational studies rationalize the strong bathochromic shift upon Zn2+-complexation. Decorating the probes with the triphenylphosphonium cation and morpholine unit enables selective localization in the mitochondria and the lysosome of cardiac H9C2 cells, respectively.

Probing the flux of mitochondrial potassium using an azacrown-diketopyrrolopyrrole based highly sensitive probe.

The diketopyrrolopyrrole bearing an aza-18-crown-6 as a binding unit as well as a PPh3+ group is highly sensitive towards K+ and localizes selectively in mitochondria of cardiac H9C2 cells. Fast efflux/influx of mitochondrial K+ can be observed upon stimulation with nigericin.

Switch-On Diketopyrrolopyrrole-Based Chemosensors for Cations Possessing Lewis Acid Character.

For the first time diketopyrrolopyrroles (DPPs) have been synthesized directly from nitriles possessing (aza)crown ethers leading to macrocycle-dye hybrids. Depending on the nature of the linkage between DPP and macrocyclic ring, various coordination effects are found. The strong interaction of the cations possessing Lewis acid character such as Li+ , Mg2+ and Zn2+ with 2-aminopyridin-4-yl-DPPs, leading to a bathochromic shift of both emission and absorption, as well as to strong enhancement of fluorescence was rationalized in terms of strong binding of these cations to the N=C-NR2 functionality. The same effect has been observed for protonation. Depending on the size and the structure of the macrocyclic ring the complexation of cations by aza-crown ethers plays an important but secondary role. The interaction of Na+ and K+ with 2-aminopyridin-4-yl-DPPs leads to moderate enhancement of fluorescence due to the aza-crown ethers binding. The very weak fluorescence of DPP bearing 2-dialkylamino-pyridine-4-yl substituents is due to the closely lying T2 state and the resulting intersystem crossing.

Level, motivation and barriers to participate in physical activity among late adolescents in Puducherry.

BACKGROUND: One in every ten deaths globally is accounted for by physical inactivity-related risks. Adolescents constitute 18% of the world's total population and are at risk of becoming physically inactive in the future. Thus, this study aims to find the level of physical activity (PA) among late adolescents and factors that motivate and prevent them from being active. METHODOLOGY: Four hundred and fifty adolescents in the age group of 18-19 years were included in the study. Standardized self-administered questionnaires such as the Global Physical Activity Questionnaire and the Behavioral Regulation in Exercise Questionnaire were used to assess the level of PA and level of motivation, respectively. In addition, barriers to participating in PA were also elicited. RESULTS: This study found that about one third of the subjects (32.4%) were physically inactive. The motivation levels were more pooled towards the self-determined motives and girls are more motivated towards PA than boys. However, PA among males is significantly higher than females. Healthy practices in families was also found to have significant association with increased PA. The major barriers found were the excessive use of electronic gadgets and lethargy. CONCLUSION: One third of the adolescents in this study were physically inactive and several barriers that prevent them from taking up PA were elicited. Therefore, efforts should be taken to emphasize the importance of physical activity among individuals, family members and the peers at institutional level and community level so as to lay foundations for healthy lifestyles in the future. Basic prevention in the emergence of risk factors for non-communicable diseases (NCDs) like PA is vital to curb the growing burden of chronic diseases in our country.

Efficient Blue and Yellow Organic Light-Emitting Diodes Enabled by Aggregation-Induced Emission.

A new class of donor-bridge-acceptor (D-π-A) π-conjugated light-emitting molecules comprising carbazole as donor and maleimide (Cbz-MI, Cbz-MI(d)), phthalimide (Cbz-Pth) as acceptor units with phenyl ring as spacer have been synthesized in good yields. These compounds exhibit high quantum yield with three distinct emission colors yellowish-green (Cbz-MI), bright yellow Cbz-MI(d), and sky blue (Cbz-Pth) in the solid state. Single-crystal X-ray and quantum chemical calculations reveals that twisting of the phenyl rings with high torsional angle on maleimide and phthalimide units reduce the effective inter-chromophore electronic coupling, furnish dramatic changes in their photophysical properties in solution and solid states. Intriguingly, Cbz-MI(d) and Cbz-Pth exhibits a unique aggregation-induced blue-shifted emission (AIBSE) due to restricted intramolecular rotation (RIR) process, while Cbz-MI shows red-shifted emission in the solid state. The solvatochromic study reveal that combined RIR and excited state migration augment AIE (aggregation-induced emission) properties. The electrochemical properties reveal that Cbz-MI exhibits high oxidation propensity while Cbz-Pth shows low reduction values. Subsequently, organic light-emitting diodes (OLEDs) were fabricated with a simple three-layer device containing Cbz-Pth and Cbz-MI(d) as emitting layers. Cbz-MI(d) exhibits high performance yellow OLED with an external quantum efficiency exceeding ∼4.1% and a brightness exceeding ∼73915 cd/m2, which is among the best performance reported for bright yellow fluorescence organic light-emitting diodes.

Kinetic modeling of growth and lipid body induction in Chlorella pyrenoidosa under heterotrophic conditions.

The aim of the present work was to develop a mathematical model to describe the biomass and (total) lipid productivity of Chlorella pyrenoidosa NCIM 2738 under heterotrophic conditions. Biomass growth rate was predicted by Droop's cell quota model, while changes observed in cell quota (utilization) under carbon excess conditions were used for the modeling and predicting the lipid accumulation rate. The model was simulated under non-limiting (excess) carbon and limiting nitrate concentration and validated with experimental data for the culture grown in batch (flask) mode under different nitrate concentrations. The present model incorporated two modes (growth and stressed) for the prediction of endogenous lipid synthesis/induction and aimed to predict the effect and response of the microalgae under nutrient starvation (stressed) conditions. MATLAB and Genetic Algorithm were employed for the prediction and validation of the model parameters.