Effect of bromine substitution on blue phosphorescent trans-(N-heterocyclic carbene)Pt(II) acetylide complexes.

N-heterocyclic carbene complexes of the type trans-(NHC)2PtII(CC-Ar)2 (where Ar = phenyl or substituted phenyl) are of interest as violet and blue phosphors. These complexes emit efficient phosphorescence in solution and in the solid state, and they have been applied as phosphors in organic light emitting diodes. This study explores the effect of bromine substitution on the trans-(NHC)2PtII(CC-Ar)2 chromophore through photophysical studies of a pair of complexes in which the phenyl groups feature either 3,5-dibromo- or 4-monobromo-substituents (IPt-DB and IPt-MB, respectively). The Br atoms were introduced as heavy atom(s) with the aim to enhance spin-orbit coupling and increase the radiative and non-radiative decay rates of the phosphorescent triplet state. Both IPt-MB and IPt-DB exhibit sky-blue phosphorescence in solution and in PMMA matrix. Interestingly, the emission quantum yield and lifetime of IPt-MB are substantially lower compared to IPt-DB in solution. This effect is attributed to a substantially larger non-radiative decay rate in the mono-bromo complex. Analysis of the photophysical data, combined with DFT and TD-DFT calculations, suggest that the difference in photophysical properties of the two complexes is related to the position of the Br-substituents on the phenyl acetylide rings. In short, in IPt-MB, the Br-substituents are located para-to the Pt-CC-unit, and this gives rise to stronger electron-vibrational coupling in the excited state, enhancing the rate of non-radiative decay.

Health awareness, lifestyle and dietary behavior of university students in the northeast part of Bangladesh.

INTRODUCTION: University students generally face a variety of challenges. During this period of life, they practice some unhealthy eating patterns and lifestyles. Therefore, we aimed to assess the health awareness status of university students from the northeast part of Bangladesh and to evaluate its associated factors. METHODS: We conducted a cross-sectional study using a stratified random sampling among public and private university students from the northeast region of Bangladesh and interviewed 1143 students. We used a self-reported questionnaire, including questions related to awareness status, lifestyle practice, dietary habit and socio-demographic factors. To assess students' health awareness status and its association with their lifestyle practices and socio-demographic factors, we used logistic regression models. RESULTS: The majority (61%) of the students were not aware of better health status and their dietary habits were not adequate. Smokers [odds ratio (OR): 0.66; 95% confidence interval (CI): 0.44, 0.99] were less likely to be aware of better health status. The participants who thought that they were leading a healthy lifestyle were less likely (OR: 0.71; CI: 0.56, 0.92) to be aware. Moreover, frequency of participating in sports and the psychological factors related to eating behaviors were significantly (p < 0.05) associated with health awareness status. CONCLUSION: Our study findings may help to create a foundation for possible interventional programs on health awareness and nutritional education to improve the health awareness status and dietary behavior of university students. To prevent students from poor eating habits while feeling happy, effective programs (e.g. seminars, projects and media campaigns) should be held, which may include enhancing healthy and recommended amounts of food consumption.