Solvent Dependence of the Hydrodynamical Volume of Dendrimers with a Rubicene Core

Backer, Steven De; Prinzie, Y.; Verheijen, Wendy; Smet, Mario; Desmedt, Kurt; Dehaen, Wim; Schryver, F. C. De

doi:10.1021/jp9734336

Cited by 71 publications

(82 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…De Backer came to similar conclusions using fluorescence depolarization measurements. 19 Both of these studies are in qualitative agreement with the theoretical study of Lescanec and Muthukumar 4 in which the end groups can be found throughout the dendrimer volume, i.e., backfolding occurs. Using rotational-echo double-resonance (REDOR) NMR, Wooley et al were able to show that backfolding occurs in the solid state.…”

Section: Introductionsupporting

confidence: 86%

Conformational Analysis of Triazine Dendrimers: Using NMR Spectroscopy To Probe the Choreography of a Dendrimer’s Dance

Moreno

Simanek

2008

Macromolecules

View full text Add to dashboard Cite

One-dimensional (1D) and two-dimensional (2D) NMR studies are used to probe the conformation of a melamine dendrimer bearing unique NMR signals from the core to the periphery. Four conceptual anchors for dendrimer conformation emerge from these experiments. First, changes in isomer populations observed by 1 H NMR reveal the onset of globular structure. Second, NOE complexity emerges with globular structure: variable temperature NOESY studies show that the peripheral groups, BOC-protected aliphatic amines, fold back into the globular core of the macromolecule at 75 °C in DMSO-d 6 . Third, variable temperature coefficients measured for NH protons suggest that solvent is largely excluded from the interior of the dendrimer: the carbamate NH groups of the periphery are most sensitive to temperature while the NHs nearest the core show little temperature dependence. Conformation is influenced by solvent choice: backfolding is observed in DMSO-d 6 , but not in either CDCl 3 or CD 3 OD. Finally, relaxation studies show that peripheral groups are more dynamic than groups at the core. These anchors consolidate observations made by many groups on disparate systems within a common architecture.

show abstract

Section: Introductionsupporting

confidence: 86%

Conformational Analysis of Triazine Dendrimers: Using NMR Spectroscopy To Probe the Choreography of a Dendrimer’s Dance

Moreno

Simanek

2008

Macromolecules

View full text Add to dashboard Cite

show abstract

“…The CO affinities of the two dendritic iron porphyrins are 3 ± 6 times higher in H 2 O than in dry toluene. Differences in the hydrodynamic volume [49] [50] of the dendrimers could contribute to these changes in affinity. In H 2 O, favorable interactions between the dendritic oligoether branches and the solvent induce a larger hydrodynamic volume, whereas, in dry toluene, the polar branches presumably pack tightly together in order to avoid contact with the apolar solvent.…”

Section: Fe II -12-dimeimmentioning

confidence: 99%

Dendritic Iron(II) Porphyrins as Models for Hemoglobin and Myoglobin: Specific Stabilization of O2 Complexes in Dendrimers with H-Bond-Donor Centers

Zingg

Felber

Gramlich

et al. 2002

HCA

View full text Add to dashboard Cite

Two types of dendritically functionalized iron(II) porphyrins were prepared (Scheme) and investigated in the presence of 1,2-dimethylimidazole (1,2-DiMeIm) as the axial ligand as model systems for T(tense)-state hemoglobin (Hb) and myoglobin (Mb). Equilibrium O 2 -and CO-binding studies were performed in toluene and aqueous phosphate buffer (pH 7). UV/VIS Titrations (Fig. 4) revealed that the two dendritic receptors 1 ¥ Fe II -1,2-DiMeIm and 2 ¥ Fe II -1,2-DiMeIm ( Fig. 2) with secondary amide moieties in the dendritic branching undergo reversible complexation ( Fig. 5) with O 2 and CO in dry toluene. Whereas the CO affinity is similar to that measured for the natural receptors, the O 2 affinity is greatly enhanced and exceeds that of T-state Hb by a factor of ca. 1500 (Table). The oxygenated complexes possess half-lives of several h (Fig. 6). This remarkable stability originates from both dendritic encapsulation of the iron(II) porphyrin and formation of a H-bond between bound O 2 and a dendritic amide NH moiety (Fig. 11). Whereas reversible CO binding was also observed in aqueous solution (Fig. 10), the oxygenated iron(II) complexes are destabilized by the presence of H 2 O with respect to oxidative decay (Fig. 9), possibly as a result of the weakening of the O 2 ¥¥¥ HÀN H-bond by the competitive solvent. The comparison between the two dendrimers with amide branchings and ester derivative 3 ¥ Fe II -1,2-DiMeIm (Fig. 2), which lacks H-bond donor centers in the periphery of the porphyrin, further supports the role of H-bonding in stabilizing the O 2 complex against irreversible oxidation. All three derivatives bind CO reversibly and with similar affinity (Fig. 8) in dry toluene, but the oxygenated complex of 3 ¥ Fe II -1,2-DiMeIm undergoes much more rapid oxidative decomposition (Fig. 7).

show abstract

“…It has already been shown in the past that fluorescence depolarization [12,13] is a suitable technique to study the rotational dynamics of fluorescent molecules. There are many parameters that influence this rotational behavior: viscosity, temperature, form of the rotor, interactions between solvent and probe.…”

Section: Introductionmentioning

confidence: 99%

The Photo Physical Properties of Dendrimers Containing 1,4‐Dioxo‐3,6‐Diphenylpyrrolo[3,4‐c]pyrrole (DPP) as a Core

Verheijen

Hofkens

Metten

et al. 2004

Macro Chemistry & Physics

View full text Add to dashboard Cite

Summary: The photophysical properties of dendrimers with 1,4‐dioxo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole, also known as DPP, as a core were studied. DPP itself has a high quantum yield of fluorescence, as well as a high molar decadic absorption coefficient, ε (ε = 33 000 L · mol−1 · cm−1). The dendrimers, which differ by their substitution pattern, either at the nitrogen (DPPN) or at the carbon (DPPC), are studied in various solvents with different viscosity and solvent‐probe interaction and this for several generations and thus varying molecular volume. The stationary measurements show no difference in the absorption and emission spectra for the different generations nor a solvent‐effect. Single photon timing is used to determine the fluorescence lifetime, τ. For both dendrimers, the decay curves can be fitted to a mono‐exponential model. By means of fluorescence depolarization and fluorescence correlation spectroscopy, the hydrodynamic volumes (Vh) are determined. The results for both dendrimers as well as for both techniques are compared. The hydrodynamic radii of DPPN are similar when obtained by FCS compared with anisotropy. When the properties of the different dendrimers are compared, it can be shown that the hydrodynamic volumes of the first generation DPPC dendrimer are much larger compared to Vh of the DPPN dendrimers. The volumes for the third generation are comparable for both substitution patterns. magnified image

show abstract

Solvent Dependence of the Hydrodynamical Volume of Dendrimers with a Rubicene Core

Cited by 71 publications

References 36 publications

Conformational Analysis of Triazine Dendrimers: Using NMR Spectroscopy To Probe the Choreography of a Dendrimer’s Dance

Conformational Analysis of Triazine Dendrimers: Using NMR Spectroscopy To Probe the Choreography of a Dendrimer’s Dance

Dendritic Iron(II) Porphyrins as Models for Hemoglobin and Myoglobin: Specific Stabilization of O2 Complexes in Dendrimers with H-Bond-Donor Centers

The Photo Physical Properties of Dendrimers Containing 1,4‐Dioxo‐3,6‐Diphenylpyrrolo[3,4‐c]pyrrole (DPP) as a Core

Contact Info

Product

Resources

About