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Abstract

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Enhanced Fluorescence of Remote Functionalized Diaminodicyanoquinodimethanes in the Solid State and Fluorescence Switching in a Doped Polymer by Solvent Vapors

“…The current model is consistent with the qualitative picture proposed earlier for the matrix dependence of light emission from similar molecules. [12] It is important to note that in the model we develop for the DADQ×s, the role of molecular aggregation is to facilitate further, the inhibition of excited state structure relaxation, rather than to force any kind of ground state geometry changes as implied in the models put forward in the case of the systems reported earlier.…”

“…[12] However, the solid sample as well as 3 doped in polymer films, polyvinyl alcohol (PVA) and poly(sodium 4-styrenesulfonate) (PSS) show bright green light emission when excited near their absorption peaks. The polymer films show clearly visible fluorescence even under ambient lighting.…”

“…Remote functionality refers to groups which are not in p-conjugation with the DADQ chromophore unit and therefore do not disturb the low lying electronic states of the chromophore. The role of viscous solvents and polymer matrices in enhancing the light emission of two related molecules have been investigated by Bloor et al [12] Even though similar effects in solids were briefly noted, no detailed studies were presented or the impact of the molecular assembly in crystals analyzed. Further, these molecules do not possess remote functionalities involved in intermolecular noncovalent interactions, which as we will demonstrate below is a crucial feature in our systems.…”

Orientation and Solvatochromism of Dyes in Liquid Crystals

“…The spectra of the dyes in the LC host showed varying degrees of solvatochromism relative to the isotropic solvents methanol (MeOH) and acetonitrile (MeCN). These are polar solvents with solvent density parameters of 0.308 and 0.305 respectively [14]. The data are listed in table 1.…”

“…Merocyanine compounds 1, 2 and 3 were synthesised according to [13] and MORPIP were synthesised according to [14]. The structures of the compounds are shown in figure 1.…”