-
2
-
-
0030767579
-
-
For a recent discussion of the chirality of dendrimer systems, see: (a) Peerlings, H. W. I.; Meijer, E. W. Chem. Eur. J. 1997, 3, 1563. (b) Thomas, C. W.; Tor, Y. Chirality 1998, 10, 53. (c) Seebach, D.; Rheiner, P. B.; Greiveldinger, G.; Butz, T.; Sellner, H. Top. Curr. Chem. 1998, 197, 125.
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Peerlings, H.W.I.1
Meijer, E.W.2
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3
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0031931653
-
-
For a recent discussion of the chirality of dendrimer systems, see: (a) Peerlings, H. W. I.; Meijer, E. W. Chem. Eur. J. 1997, 3, 1563. (b) Thomas, C. W.; Tor, Y. Chirality 1998, 10, 53. (c) Seebach, D.; Rheiner, P. B.; Greiveldinger, G.; Butz, T.; Sellner, H. Top. Curr. Chem. 1998, 197, 125.
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Chirality
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-
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Thomas, C.W.1
Tor, Y.2
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4
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0000491602
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-
For a recent discussion of the chirality of dendrimer systems, see: (a) Peerlings, H. W. I.; Meijer, E. W. Chem. Eur. J. 1997, 3, 1563. (b) Thomas, C. W.; Tor, Y. Chirality 1998, 10, 53. (c) Seebach, D.; Rheiner, P. B.; Greiveldinger, G.; Butz, T.; Sellner, H. Top. Curr. Chem. 1998, 197, 125.
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Seebach, D.1
Rheiner, P.B.2
Greiveldinger, G.3
Butz, T.4
Sellner, H.5
-
5
-
-
20644451148
-
-
note
-
We define "conformational order" as the presence of stable secondary structure within the branch segments of the polymer.
-
-
-
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6
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0028321472
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(a) Chow, H.-F.; Fok, L. F.; Mak, C. C. Tetrahedron Lett. 1994, 35, 3547.
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(a) Newkome, G. R.; Lin, X.; Weis, C. D. Tetrahedron: Asymmetry 1991, 10, 957.
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(b) Lartigue, M.-L.; Caminade, A.-M.; Majoral, J.-P. Tetrahedron: Asymmetry 1997, 8, 2697.
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Lartigue, M.-L.1
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12
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33748224868
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-
The examples in ref 5 exhibit rotations that increase with increasing numbers of chiral termini. However, in the following system, due to dense packing on the surface occurring due to hydrogen bonding, optical activity decreased as the number of amino acid termini present on poly(propylene imine) dendrimers was increased: Jansen, J. F. G. A.; Peerlings, J. H. W. I.; de Brabander-Van den Berg, E. M. M.; Meijer, E. W. Angew. Chem., Int. Ed. Engl. 1995, 34, 1206. Dyes encapsulated in the poly(propylene imine) system with an optical rotation of zero exhibited a small induced circular dichroism which could be the result of the achiral pockets adopting chiral, nonracemic conformations: Jansen, J. F. G. A.; de Brabander-van den Berg, E. M. M.; Meijer. E. W. Recl. Trav. Chim. 1995, 114, 225.
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Jansen, J.F.G.A.1
Peerlings, J.H.W.I.2
De Brabander-Van Den Berg, E.M.M.3
Meijer, E.W.4
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13
-
-
20644460734
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-
The examples in ref 5 exhibit rotations that increase with increasing numbers of chiral termini. However, in the following system, due to dense packing on the surface occurring due to hydrogen bonding, optical activity decreased as the number of amino acid termini present on poly(propylene imine) dendrimers was increased: Jansen, J. F. G. A.; Peerlings, J. H. W. I.; de Brabander-Van den Berg, E. M. M.; Meijer, E. W. Angew. Chem., Int. Ed. Engl. 1995, 34, 1206. Dyes encapsulated in the poly(propylene imine) system with an optical rotation of zero exhibited a small induced circular dichroism which could be the result of the achiral pockets adopting chiral, nonracemic conformations: Jansen, J. F. G. A.; de Brabander-van den Berg, E. M. M.; Meijer. E. W. Recl. Trav. Chim. 1995, 114, 225.
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14
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(a) Seebach, D.; Lapierre, J.-M.; Greiveldinger, G.; Skobridis, K. Helv. Chim. Acta 1994, 77, 1673.
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Seebach, D.1
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15
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33748219359
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(b) Seebach, D.; Lapierre, J.-M.; Skobridis, K.; Greiveldinger, G. Angew. Chem., Int. Ed. Engl. 1994, 33, 440.
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16
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(d) Murer, P. K.; Lapierre, J.-M.; Greiveldinger, G.; Seebach, D. Helv. Chim. Acta 1997, 80, 1648.
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18
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0031931652
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(a) Peerlings, H. W. I.; Struijk, M. P.; Meijer, E. W. Chirality 1998, 10, 46.
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Peerlings, H.W.I.1
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(c) Peerlings, H. W. I.; Trimbach, D. C.; Meijer, E. W. J. Chem. Soc., Chem. Commun. 1998, 497
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(b) Fréchet, J. M. J.; Hawker, C. J.; Wooley, K. L J. Macromol. Sci., Pure Appl. Chem. 1994, A31, 1627.
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-
25
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20644435279
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-
note
-
Hydrogenolysis of the secondary benzyloxy group competes with deprotection of the benzyl groups and is minimized by using Raney-Ni.
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-
-
-
26
-
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1542341274
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The dendron monobromides were prepared using a slightly modified procedure developed by Fréchet: Hawker, C. J.; Wooley, K. L.; Fréchet, J. M. J. J. Chem. Soc., Perkin Trans. 1 1993, 1287.
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27
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20644470254
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-
note
-
In the absence of DMF, the alkylation efficiency decreases significantly.
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-
-
-
28
-
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20644444268
-
-
note
-
All dendrimers gave satisfactory combustion analysis and monodisperse GPC traces.
-
-
-
-
30
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20644444049
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-
note
-
Fragmentation at this benzylic position was also observed in the mass spectrum of central core 2.
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-
-
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31
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0026909675
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1 relaxation time measurements of PAMAM dendrimers have revealed that internal segment density increases with increasing generation: Meltzer, A. D.; Tirrell, D. A.; Jones, A. A.; Inglefield, P. T. Macromolecules 1992, 25, 4549. Further studies:
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20644434080
-
-
note
-
1-6 exhibit their most intense UV absorptions bands at 250-260 nm; however, 4-6 also exhibit a less intense absorption band at 308, 308, and 282 nm, respectively. Dendrimers 7-9 exhibit the most intense bands at 246 nm with a weaker absorption at 260-270 nm. These electronic differences are not solely responsible for the difference in optical rotatory power that is observed because the additional bands at longer wavelength in 4-6 should lead to a slight increase in rotation which is not observed.
-
-
-
-
43
-
-
20644441281
-
-
note
-
Since the terminal esters are electronically different than the tribenzoyl core, an interaction of these chromophores would be expected to generate a more complex Cotton effect than is observed.
-
-
-
-
45
-
-
20644457050
-
-
note
-
3 implemented in Macromodel 5.0.
-
-
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46
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0030823475
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-
47
-
-
20644466978
-
-
note
-
Such variation of rotation values with solvent is not unusual. For an example of a solvent-induced reorientation of dipoles that reverses the sign of an ORD curve, see ref 18c.
-
-
-
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49
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0001765649
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