The relative retardation of intramolecular charge transfer (ICT) and the solvation dynamics of coumarin 152 in pure AOT, water, methanol, acetonitrile, and formamide reverse micelles have been investigated using picosecond time-resolved emission spectroscopy. The rate of ICT has been retarded almost 7 times at w 0 = 4 and 4 times at w 0 = 32 compared to that in pure water. The rate of retardation of ICT is also observed in the methanol and acetonitrile reverse micelles in comparison to that in pure methanol and acetonitrile. In pure AOT, the solvation time is 12.22 ns, but at w 0 = 4 of water reverse micelles the solvation time is 7.27 ns. The slow dynamics in methanol, acetonitrile, and formamide reverse micelles is also observed. The relative retardation of the ICT rate is much smaller compared to the several thousand fold decrease in the solvation dynamics in the pool of the reverse micelles. The w dependency of solvation time is observed for water and methanol reverse micelles, but it is little for acetonitrile and none for formamide reverse micelles. The various w dependencies of solvation dynamics in water, methanol, and acetonitrile reverse micelles are explained on the basis of the presence and the absence of hydrogen-bonding networks in water, methanol, and acetonitrile, respectively.

No abstract

The ordered modular structure of a covalent organic framework (COF) facilitates the selective incorporation of electronically active segments that can be tuned to function cooperatively. This designability inspires developing COFbased single-source white light emitters, required in nextgeneration solid-state lighting. Here, we present a new anthracene-resorcinol-based COF exhibiting white light emission. The keto−enol tautomers present in the COF give rise to dual emission, which can be tuned by the O-donor and Ndonor solvents. Importantly, when suspended in a solid polymer matrix, this dual emission is retained as both tautomers coexist. A mere 0.32 wt % loading of the COF in poly(methyl methacrylate) (PMMA) gives a solvent-free film with intense white light emission (CIE coordinates (0.35, 0.36)). From steady-state and time-resolved studies, the mechanism of the white light emission has been unambiguously assigned to fluorescence, with the blue emission originating from the π-stacked columns of anthracene, and the mixture of red and green from the keto−enol tautomerized resorcinol units. The study introduces the COF as a new class of readily processable, single-source white light emitter.

No abstract

No abstract