Suspensions of Organic Microcrystals Produced in the Presence of Polymers: Diversity of UV/Vis Absorption and Fluorescence Properties According to the Preparation Conditions

Abstract

Free-standing microcrystals of an organic fluorescent dye, specifically, 4-n-octylamino-7-nitrobenz-2-oxa-1,3-diazole, were prepared using a solvent-exchange process at room temperature, in the presence of polymers used as additives. Parameters such as the dye concentration, the nature and concentration of the polymer, and the pH of the solution were varied. Six samples of microcrystals were therefore obtained and characterized by fluorescence microscopy and by electron microscopy (TEM and SEM). They differed by their content in microcrystals, the shape and size of which depends strongly on experimental conditions. Curiously, the UV/vis absorption spectra of the microcrystal suspensions were very different from one sample to another. As a result the emission spectra were also varied. The diversity of the optical response obtained was attributed to the presence of several dye populations in the microcrystal suspensions. A distinction was made between the intrinsic spectral properties of the microcrystals and artifacts due to the presence of the additives.

Reversible fluorescence switching and topochemical conversion in an organic AEE material: polymorphism, defection and nanofabrication mediated fluorescence tuning

“…34,35 50 Temperature controlled polymorph dependent reproducible fluorescence switching have been demonstrated by Toshiki et al 36,37 Interestingly, some of the strongly fluorescent AEE materials responded to external stimuli due to highly twisted or rigid molecular conformation that undergoes conformational or 55 phase change. 24,25,46,47 1D selfassembly of azo-benzene fluorophore leads to strong fluorescence enhancement that was switched off by applying heat or 60 pressure. 24,25,46,47 1D selfassembly of azo-benzene fluorophore leads to strong fluorescence enhancement that was switched off by applying heat or 60 pressure.…”

Nano/Microstructure Fabrication of Functional Organic Material: Polymorphic Structure and Tunable Luminescence

“…[48][49][50] Recently, Lei et al utilized amphiphilic ligands to control the morphology of perylene, giving square and rhombus sheet structures. 51 These effects were attributed to the preferential adsorption or interaction of additives on particular surfaces of the microcrystal such that interference occurs in the crystal growth along that direction.…”

Application of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in analysis: Fluorescent dyes and unexpected reaction with tertiary amines

“…NBD fragments are applied in the synthesis of fluorescent nanoparticles [23][24][25][26] as a tool of nanoparticles investigation and also for design of fluorescent nanoprobes, thermal sensors and optical devices.…”