200133-18-2Relevant academic research and scientific papers
Spatially resolved derivatization of solid-phase-synthesis beads with fluorescent dendrimers: Creation of localized microdomains
Cardona, Claudia M.,Jannach, Stephan H.,Huang, Hao,Itojima, Yukiko,Leblanc, Roger M.,Gawley, Robert E.,Baker, Gary A.,Brauns, Eric B.
, p. 3532 - 3558 (2002)
Second and third generation Newkome-type trifurcated dendrimers, containing either a coumarin or dansyl fluorescent probe at the dendrimer core, have been synthesized and attached to ArgoGel solid-phase-synthesis beads. Subsequent reaction with rhodamine dye shows that the dye can penetrate throughout the beads to acylate the remaining sites. Thus, it is possible to achieve a spatially resolved microdomain for library formation at the core of the dendrimer, primarily on the bead's periphery, and a second microdomain suitable for derivatization by other reagents such as encoding tags and fluorescent sensors.
High-affinity multivalent DNA binding by using low-molecular-weight dendrons
Kostiainen, Mauri A.,Hardy, John G.,Smith, David K.
, p. 2556 - 2559 (2007/10/03)
(Chemical Equation Presented) Nine spermines are better than one: Compound C2 exhibits high-affinity, salt-independent DNA binding as a consequence of the spermine array on its surface. Comparison with smaller dendrons and model compounds indicates a clea
Macrocyclization on the Fullerene Core: Direct Regio- and Diastereoselective Multi-Functionalization of |60|Fullerene, and Synthesis of Fullerene-dendrimer Derivatives
Nierengarten, Jean-Francois,Habicher, Tilo,Kessinger, Roland,Cardullo, Francesca,Diederich, Francois,Graemlich, Volker,Gisselbrecht, Jean-Paul,Boudon, Corinne,Gross, Maurice
, p. 2238 - 2276 (2007/10/03)
The macrocyclization between buckminsterfullerene, C60, and bis-malonate derivatives in a double Bingel reaction provides a versatile and simple method for the preparation of covalent bis-adducts of C60 with high regioand diastereoselectivity. A combination of spectral analysis, stereochemical considerations, and X-ray crystallography (Fig. 2) revealed that out of the possible in-in, in-out, and out-out stereoisomers. the reaction of bis-malonates linked by o-, m-, or p-xylylene tethers afforded only the ouy-out ones (Scheme 1). In contrast, the use of larger tethers derived from 1,10-phenanthroline also provided a first example, (±)-19 (Scheme 2), of an in-out product. Starting from optically pure bis-malonate derivatives, the new bis-functionalization method permitted the diastereoselective preparation of optically active fullerene derivatives (Schemes 4 and 5) and, ultimately, the enantioselective preparation (enantiomeric excess ee > 97%) of optically active cis-3 bis-adducts whose chirality results exclusively from the addition pattern (Fig. 6). The macrocyclic fixation of a bis-malonate with an optically active, 9,9′-spirobi[9H-fluorene]-derived tether to C60 under generation of 24 and ent-24 with an achiral addition pattern (Scheme 4) was found to induce dramatic changes in the chiroptical properties of the tether chromophore such as strong enhancement and reversal of sign of the Cotton effects in the circular dichroism (CD) spectra (Figs. 4 and 5). By the same method, the functionalized bis-adducts 50 and 51 (Schemes 10 and 11) were prepared as initiator cores for the synthesis of the fullerene dendrimers 62, 63, and 66 (Schemes 12 and 13) by convergent growth. Finally, the new methodology was extended to the regio- and diastereoselective construction of higher cyclopropanated adducts. Starting from mono-adduct 71, a clipping reaction provided exclusively the all-cis-2 tris-adduct ( ±)-72 (Scheme 14), whereas the similar reaction of bis-adduct 76 afforded the all-cis-2 tetrakis-adduct 77 (Scheme 15). Electrochemical investigations by steady-state voltammetry (Table2) in CH2Cl2 (+ 0.1M Bu4NPF6) showed that all macrocyclic bis(mcthano)fullerenes underwent multiple reduction steps, and that regioisomerism was not much influencing the redox potentials. All cis-2 bis-adducts gave an instable dianion which decomposed during the electrochemical reduction. In CH2Cl2, the redox potential of the fullerene core in dendrimers 62, 63, and 66 is not affected by differences in size and density of the surrounding poly(ether-amide) dendrons. The all-cis-2 tris- and tetntkis(methano)fullerenes (±)-72 and 77, respectively, are reduced at more negative potential than previously reported all-e tris- and tetrakis-adducts with methano bridges that are also located along an equatorial belt. This indicates a larger perturbation of the original fullerene π-chromophore and a larger raise in LUMO energy in the former derivatives.
