An inherently non-peroxide forming ether solvent, 2,2,5,5-tetramethyltetrahydrofuran (2,2,5,5-tetramethyloxolane), has been synthesized from readily available and potentially renewable feedstocks, and its solvation properties have been tested.
The photophysical and hydrodynamic properties of dendrimers (GnPZn and GnTPPH2) with
zinc porphyrin (PZn) and tetraphenylporphyrin (TPP) cores are studied in tetrahydrofuran (THF) and
dimethylformamide (DMF). UV−vis absorption spectra of GnPZn exhibit a small red shift of the Soret
band upon increasing the generation as a result of interactions between the dendrons and the core. All
fluorescence decays obtained from global analysis show a monoexponential profile. The intrinsic viscosity
obtained for GnPZn from the hydrodynamic volume (V
h) passes through a maximum as a function of
generation (G) in agreement with earlier experimental findings and calculations suggesting that the
internal density profile of dendrimers decrease monotonically outward from the center of the molecule.
Within the investigated range (G = 1−3), GnTPPH2 exhibits an approximately constant intrinsic viscosity
due to the linear dependence between the hydrodynamic volume and the molecular weight. The differences
observed between GnPZn and GnTPPH2 are correlated to structural differences in their cores. The
additional phenyl group of the TPP in GnTPPH2 increases the distance between the branches and the
porphyrin moiety compared to GnPZn, resulting in a more flexible structure. The enhanced flexibility
allows the terminal groups to sample more conformational space and therefore decreases the volume of
the dendrimer as compared to the theoretical fully extended structure where V
h ∝ G
3. A comparison of
the results obtained from analysis of fluorescence anisotropy decays with previously reported viscometry
measurements shows a dependence of the structural collapse on the core size.
The size of poly(benzyl ether) dendrimers with different molecular architectures was measured by small angle neutron scattering (SANS). Both polar and non‐polar solvents were used to measure the effect of solvent type. The radius of gyration (Rg) of all of the dendrimers follows a scaling law of Rg ∝ M1/3 consistent with literature values of other chemically different dendrimers. The effect of solvent type on dendrimer size was minimal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.