Aggregation-enhanced emission

Keywords Aggregation-induced enhanced emission (AIEE) Fluorescent organic nanoparticles Ion-association method Organic dye nanoparticles Reprecipitation method Restriction of intramolecular rotation Size-dependent optical properties... 

Fig. 5 A proposed mechanism for enhanced emission (or AIEE) in solid-state organic dye nanoparticles. The dye considered here is trans-biphenylethylene (CN-MBE) compound. The geometry is optimized by the density functional theory (DFT) calculation at the B3LYP/6-31G level. Molecular distortion such as twisting and/or subsequent planarization causes prevention of radiationless processes along with specific aggregation such as the /-aggregate in the nanoparticles...

Qian Y, Li S, Zhang G, Wang Q, Wang S, Xu H, Li C, Li Y, Yang G (2007) Aggregation-induced emission enhancement of 2-(2 -hydroxyphenyl)benzothiazole-based excited-state intramolecular proton-transfer compounds. J Phys Chem B 111 5861-5868... 

Fig. 5.16 Selected fluorophores 44 with aggregation-induced enhanced emission. soi, fluorescence quantum yield in dioxane < agg, fluorescence quantum yield in dioxane-water (20 80).

However, above the CMC, biexponential lifetime profiles and enhanced emission quantum yields are observed for both complexes. Comparison with the excited lifetime of the parental complexes showed that the longer component can be assigned to the aggregated species. Such findings could be explained in terms of smaller nonradiative rate constant, as consequence of... 

Aggregation-induced enhanced emission polymeric nanoparticles... 

A self-assembled chitosan polymeric nanoparticle conjugated with fluorescent stilbene derivatives that exhibit aggregation-induced enhanced emission (AIEE) in vivo was reported by Lim et al. The AIEE phenomenon occnrs in a special class of dyes that have lower flnorescence in solution, but in a concentrated environment (snch as when encapsnlated in a nanoparticle or vesicle), the dyes show a marked enhancement in emission intensity, in contrast to common organic dyes. Dipolar tricyanostilbene derivatives... 

The other key point is that the recognition event should then produce differences in the fluorescence properties of the sensor molecule in the presence of the two enantiomers of the analyte. Several mechanisms can be used to generate the fluorescence response (Figs. 2 and 11) by changing the electronic properties and the conformation of the sensor. Aggregation induced emission enhancement (AIEE) [49] was recently shown to be able to generate an enantioselective fluorescence response. Special optical techniques such as circularly polarized luminescence (CPL) are now available to detect enantioselective interactions occurring in the excited state or in the second coordination-sphere interactions [49]. 

A similar aggregation-induced enhanced emission is reported by the same group of Park and co-workers (Fig. 17). Trifluoromethyl-based cyanostilbene 32 acts as a gelator for 1,2-dichlormethane. The formed gel is strongly fluor-... 

NTPs), such as ATP, UTP, CTP, TTP, and GTP, over mono- and diphosphates (NMPs and NDPs, respectively), with enhancement of the fluorescence emission. In addition, it was postulated that, in the presence of probe 23b, NTPs induce aggregation, leading to an increase in fluorescence emission called aggregation-induced emission. 

Steiner, M., Debus, C., Failla, A. V., and Meixner, A. J. [2008] Plasmon-enhanced emission in gold nanoparticle aggregates, /. Phys. Chem. C, 112,3103-3108. 

The 2 + 2/3 + 2-cycloaddition reactions of cyclic ketimines formed functionalized sultam-fused azetidines and dihydropyrroles in good yields and high enantio-selectivities. The Cu(I)/Lewis acid-catalysed 3+2/2+2-cycloaddition reaction of 0 sulfonyl azides (1) with terminal alkynes (2) yielded bis-/V-sulfonylcyclobutenes (3) that exhibit aggregation-induced emission enhancement in the solid state (Scheme 1). Density functional theory (DFT) at the B3LYP/6-311++G(d,p) level has been used to investigate the Mo(CO)6-catalysed intramolecular 2+2- or 2 + 2+ 1-cycloaddition reactions of 5-allenyl-l-ynes." ... 

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