Determination of the Absolute Enantiomeric Excess of the Carbon Nanotube Ensemble by Symmetry Breaking Using the Optical Titration Method.

Symmetry breaking of single-walled carbon nanotubes (SWNTs) has profound effects on their optoelectronic properties that are essential for fundamental study and applications. Here, we show that isomeric SWNTs that exhibit identical photoluminescence (PL) undergo symmetry breaking by flavin mononucleotide (FMN) and exhibit dual PLs and different binding affinities (K). Increasing the FMN concentration leads to systematic PL shifts of SWNTs according to structural modality and handedness due to symmetry breaking.

The effects of dendrimer size and central metal ions on photosensitizing properties of dendrimer porphyrins.

A series of dendrimer porphyrins (G(n)DP(M); n = generation of dendrimer, n = 1-3; M = coordination metal, M = freebase, Zn, Pt) were prepared and their photosensitizing properties were compared. All G(n)DP(M) exhibited sharp absorption in organic solvents. However, the Soret absorptions of G(n)DP(M)(CO(2)H) in 10 mM phosphate buffer solution (pH = 7.

Effect of tight flavin mononucleotide wrapping and its binding affinity on carbon nanotube covalent reactivities.

The controlled functionalization of single-walled carbon nanotubes (SWNTs) is a key to using them in high-end applications. We show that nanotube reactivity after covalent diazonium modification is governed by a chirality-specific surfactant binding affinity to SWNTs. Both metallic and semiconducting SWNTs tightly organized by a helical flavin mononucleotide (FMN) assembly exhibit two hundred times slower reactivity toward 4-methoxy benzenediazonium (4-MBD) than those wrapped by sodium dodecyl sulfate and this reactivity enables chirality- and metallicity-specific behaviours to be probed, as confirmed by absorption, Raman, and photoluminescence (PL) spectroscopy.

Binding affinities and thermodynamics of noncovalent functionalization of carbon nanotubes with surfactants.

Binding affinity and thermodynamic understanding between a surfactant and carbon nanotube is essential to develop various carbon nanotube applications. Flavin mononucleotide-wrapped carbon nanotubes showing a large redshift in optical signature were utilized to determine the binding affinity and related thermodynamic parameters of 12 different nanotube chiralities upon exchange with other surfactants. Determined from the midpoint of sigmoidal transition, the equilibrium constant (K), which is inversely proportional to the binding affinity of the initial surfactant-carbon nanotube, provided quantitative binding strengths of surfactants as SDBS > SC ≈ FMN > SDS, irrespective of electronic types of SWNTs.