PMID- 11300912
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20010607
LR  - 20190710
IS  - 0022-3263 (Print)
IS  - 0022-3263 (Linking)
VI  - 66
IP  - 6
DP  - 2001 Mar 23
TI  - Synthesis and properties of new thiourea-functionalized poly(propylene imine) 
      dendrimers and their role as hosts for urea functionalized guests.
PG  - 2136-45
AB  - Five generations of poly(propylene imine) dendrimers have been modified by 
      palmityl and adamantyl endgroups via a thiourea linkage. The synthesis of the 
      thiourea dendrimers DAB-dendr-(NHCSNHAd)(n) and DAB-dendr-(NHCSNHC(16)H(33))(n) 
      (n = 4, 8, 16, 32, 64) proceeds smoothly via the amino-terminated DAB dendrimer 
      and the adamantyl and palmityl isothiocyanates, respectively. The properties of 
      the thiourea dendrimers have been studied by IR and (1)H NMR, including 
      relaxation (T1, T2) measurements. The thiourea dendrimers are used as multivalent 
      hosts for a number of guest molecules containing a terminal urea-glycine unit in 
      organic solvents. The host-guest interactions have been investigated using 1D- 
      and NOESY-NMR. These investigations show that the guest molecules bind to the 
      dendritic host via thiourea (host)-urea (guest) hydrogen bonding, and ionic 
      bonding between the terminal guest carboxylate moiety and the outer shell 
      tertiary amines of the dendrimer. The ability to bind guest molecules of the 
      adamantyl- and palmitylthiourea dendrimers has been compared with their 
      respective urea containing dendrimer analogues, by NMR-titration, and competition 
      experiments. Upon complexation, the thiourea dendrimer hosts show a larger 
      downfield NH shift than the corresponding urea dendrimer hosts, indicative of 
      stronger hydrogen bonding in the complexed state. Furthermore, microcalorimetry 
      has been used to determine binding constants for formation of the host-guest 
      complexes; the binding constants are typically in the order of 10(4) M(-1). Both 
      NMR and microcalorimetric studies show that the thiourea dendrimers bind the urea 
      containing guests with somewhat higher affinity than the corresponding urea 
      dendrimers.
FAU - Boas, U
AU  - Boas U
AD  - Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of 
      Technology, P.O. Box 513, NL-5600 MB Eindhoven, The Netherlands.
FAU - Karlsson, A J
AU  - Karlsson AJ
FAU - de Waal, B F
AU  - de Waal BF
FAU - Meijer, E W
AU  - Meijer EW
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Org Chem
JT  - The Journal of organic chemistry
JID - 2985193R
EDAT- 2001/04/13 10:00
MHDA- 2001/04/13 10:01
CRDT- 2001/04/13 10:00
PHST- 2001/04/13 10:00 [pubmed]
PHST- 2001/04/13 10:01 [medline]
PHST- 2001/04/13 10:00 [entrez]
AID - jo001573x [pii]
AID - 10.1021/jo001573x [doi]
PST - ppublish
SO  - J Org Chem. 2001 Mar 23;66(6):2136-45. doi: 10.1021/jo001573x.